The section on the free jejunal flap is the result of work with Akiko Yano, MD, Kochi Medical School.

A clinical investigation of ICG imaging was performed under approval by the Ethics Committee of Kochi Medical School with informed consent from every patient. A total of 25 patients were included, who underwent reconstructive surgery using free jejunal graft following resection of cancer of the pharynx or cervical esophagus between 2011 and 2016. Regarding the US, the video records obtained in clinical practice between 2000 and 2018 have been reviewed. Ethical approval was waived on this, according to the institutional ethical review committee.
1. Transesophageal echocardiography (TEE)
NOTE: TEE, which necessitates the insertion of an esophageal probe, is suitable for making a diagnosis or monitoring in the OR or ICU where CT assessment is not available. TEE provides morphologic and kinetic information as well as the perfusion status of the intestine27,28. Although it requires expertise in visualizing the SMA, it is not so hard for experienced heart and thoracic aorta examiners. The SMA can be visualized with the TEE probe (see Table of Materials) advanced into the stomach and the transducer directed posteriorly (Figure 1A).
<ol>
	<li>Visualize the descending aorta on the short axis (scanning plane 0&#176;), then advance the probe into the stomach with the image of the aorta kept in view by rotating the probe counterclockwise with a slight anteflexion of the probe tip to keep the transducer in contact with the esophageal wall.</li>
	<li>If the image of the aorta moves downward, bend the probe tip further (Figure 1B).</li>
	<li>Use color Doppler mode to facilitate the identification of visceral branches by flow signal, and ensure that the orifice of the celiac artery appears at the 12 o&#39;clock position of the abdominal aorta (Figure 1C). It divides into two or three arteries within a few centimeters of the orifice.</li>
	<li>Advance the probe one inch further so that the SMA appears at the 12-2 o&#39;clock position. 
	NOTE: A leftward bending of the probe tip is helpful to rotate the image and depict the SMA at 12 o&#39;clock position.</li>
	<li>Ensure that the distal portion of the SMA is located between the pancreas (splenic vein) and abdominal aorta, where the left renal vein crosses behind the SMA.</li>
	<li>Rotate the scanning plane to 90&#176; to visualize the long-axis view of the aorta and visceral branches. The distal portion of the SMA can be assessed more easily (Figure 1D). 
	NOTE: Figure 1C,D show the TEE findings in a cardiovascular surgical case without mesenteric ischemia.</li>
</ol>
2. Abdominal US
NOTE: This modality is suitable for suspecting or excluding mesenteric ischemia among several patients with abdominal pain, together with physical examination. It is used for assessing the morphology and kinetics of the intestine and the blood flow in the SMA. Figure 2A shows the place of the probe (see Table of Materials) for each purpose.
<ol>
	<li>Use a convex or sector probe with a frequency range of 2 to 5 MHz to facilitate visualization and above assessment of the intestine via the abdominal wall with adequate resolution and sensitivity. 
	NOTE: Use a transducer with a frequency range between 2.5 and 5 MHz for visualizing the bowels in the abdomen with the gain setting maximal without generating background noise.</li>
	<li>Place the probe on the abdominal wall around the navel to visualize the intestine (Figure 2B). Find any acoustic window (yellow arrow) between the intestinal gas (blue dotted line).</li>
	<li>Check the size and peristaltic movement of the intestine, mucosal edema, or the presence of ascites around it. The latter indicates that intestinal necrosis takes place.</li>
	<li>For assessing the SMA flow, the probe was placed vertically above the navel level. Find the SMA, which arises from the abdominal aorta and directs caudally within a few centimeters (Figure 2C). 
	&#8203;NOTE: The US findings in Figure 2B,C was recorded in healthy individuals.</li>
</ol>
3. ICG imaging
NOTE: This modality is suitable for assessing the perfusion of the tissues in the surgical field.
<ol>
	<li>Prepare the ICG imaging system following the manufacturer&#39;s instructions (see Table of Materials).</li>
	<li>Inject a total of 2.5 mg ICG (see Table of Materials) dissolved in 10 mL of distilled water (0.25 mg/mL) into the central venous line, followed by flushing with 10 mL of saline (Figure 3A).</li>
	<li>Visualize the perfused ICG into the mesenteric artery and then the intestinal tissue on display (Figure 3B). It usually appears approximately 10 to 20 s after injection. 
	&#8203;NOTE: The ICG imaging findings in Figure 3B were recorded in a reconstruction case with a free jejunal graft enrolled in the above study.</li>
</ol>
4. Near-infrared spectroscopy (NIRS)
NOTE: To solve the problem in plastic and reconstructive surgery (as mentioned in the Introduction section), this study proposed the use of the NIRS system, which has been used in cardiovascular surgery29; however, validation to confirm that rSO2 reflects the ischemic status of the jejunum was needed. When the jejunal flap was harvested, an NIRS sensor was placed on the jejunum, and changes in rSO2 were monitored when the artery and vein were clamped, and perfusion was resumed after reconstruction. In addition, rSO2 changes were observed for 3 days postoperatively with the NIRS sensor placed on the skin of the neck. The recommended procedures for assessing the rSO2 of the intestine directly in the surgical field are described here.
<ol>
	<li>Prepare the NIRS system following the manufacturer&#39;s instructions (see Table of Materials) (Figure 4A).</li>
	<li>Use an appropriate sensor for measuring the rSO2 of the tissue according to the depth of the target region to be assessed (Figure 4B). Place the sensor directly on it with light contact so as not to press excessively. 
	NOTE: This study used a sensor with a distance between the emitter and receiver of 2 cm.</li>
	<li>Check the rSO2 value indicated on display, updated every 5 s (Figure 4B).</li>
</ol>

The author has no conflicts of interest regarding this work.

Mesenteric ischemia remains an unsolved problem beyond the clinical field. To solve such a common problem, similar pathology in other organs may be helpful to take a hint. The concept of &#34;ischemic cascade&#34; was proposed for acute myocardial infarction32, and regional wall motion abnormalities (hypokinesis, akinesis, and dyskinesis) located at the early stage of the cascade have been used as an indicator of myocardial infarction instead of coronary blood flow, which cannot be assessed noninvasively in real-time. This concept was applied to the intestine, which is also a muscular organ, to explore the diagnostic measures for mesenteric ischemia (Figure 10A).
Two axes of malperfusion were placed around the cascade, i.e., &#34;severity&#34; and &#34;duration&#34;. For assessing mesenteric perfusion, four modalities using ultrasound and near-infrared light are available in different ways (Figure 10B). They are related to each event that occurs in the ischemic cascade (Figure 10C). The cascade starts from loss of perfusion, followed by reduced distribution of arterial blood, which contains abundant oxygenated hemoglobin, which leads to oxygen deficiency in the tissue. It causes dysfunction of organs, that is, hypokinesis of the intestine. Although it is reversible initially, irreversible damage progresses if perfusion is not restored. The above four modalities can assess each of these steps. Color Doppler mode visualizes blood flow in real-time and can be used for decision making of intervention and for evaluating the efficacy of measures taken. Two modalities, TEE and abdominal US, are used according to the patient&#39;s situation. ICG imaging visualizes how blood is distributed into the tissue. This helps determine the extent of resecting necrotic intestinal segments32,33,34,35. The application of ICG imaging is now spreading among various specialties including cardiovascular surgery36,37, thoracic surgery38, plastic and reconstructive surgery39. Although the use of ICG imaging is available only during laparotomy, it may improve the accuracy of probe laparotomy in which visual inspection and digital palpation of the mesenteric artery have been used.
The severity of damage can be assessed first by kinetic changes, then by morphological changes employing the B mode of US40. Based on the author&#39;s experience, the intestine was already necrotic when the latter five findings in this cascade were obvious. Because hypokinesis appears instantaneously in the intestine and becomes ischemic, abdominal US seems to be the most suitable tool for physicians in various specialties, including general physicians, for distinguishing patients with mesenteric ischemia among patients with abdominal pain. Palm-sized US devices equipped with B and color Doppler modes are already available, and dilatation and/or reduced peristalsis as well as even SMA flow can be examined wherever the patient is situated (Figure 2C). In this sense, US may be included in the physical examination as a &#34;visual stethoscope&#34;, as it is noninvasive and can provide useful information at the bedside. US is currently used for diagnosing bowel diseases41 as well as focusing on events in the ER setting (point-of-care US [POCUS]) such as acute aortic dissection42. As it can visualize blood flow in the SMA43 it is used for the initial diagnosis and/or follow-up of localized SMA dissection44. However, the visualization of the SMA is often challenging in obese patients or those with abundant intestinal gas. As the gas collects at the upper side, the intestine may be depicted from the side of the body. Other findings of mesenteric ischemia include intestinal pneumatosis or hepatic portal venous gas45,46, but these findings result from necrotized intestinal tissue. It is crucial to transfer the patient to the surgical team at this stage as soon as possible. Emergency setting as acute aortic dissection is different because bedside assessment without CT is needed in the OR. To overcome these issues, this study introduced TEE to visualize the visceral arteries in the OR47 and assess mesenteric ischemia41. Other reports recently cited such TEE applications48 and may be used for more patients.
NIRS is the next promising candidate for early diagnosis. The rSO2 has been shown to accurately reflect the perfusion status in the frontal lobe via the skull31 or in the free jejunal flap via the neck skin30 (Figure 10B). Figure 11 schematically illustrates that reduced rSO2 and increased HbI are good indicators of arterial supply and venous congestion, respectively. As the artery is clamped, the supply of oxi-Hb is reduced, leading to a decreased rSO2. As the vein is congested, the rSO2 slightly decreases while the HbI is markedly increased. A NIRS system that provides an absolute rSO2 value of the tissues would enable the detection of reduced intestinal rSO2 from the abdominal surface without laparotomy. Unlike the sensor on the cervical surface, however, the intestines in the abdomen are farther from the sensor and may be beyond the region of detecting rSO2, thus, the provided rSO2 is that of the abdominal wall (Figure 12). To solve this problem, ultrasonography may help determine the distance to the intestines. If the distance is farther than one-half to two-thirds of the distance between the emitter and receiver of the NIRS sensor, the sensor may be compressed toward the abdomen so that the intestines are located within the region for assessing rSO228.
These assessments possess certain limitations. The extent to which data are obtained is limited. The abdominal US readily detects akinetic and dilated intestines, but the blood flow in the SMA is not always easy. Visualization of visceral arterial flow by TEE is limited to the vicinity of its orifice, but the peristalsis of the intestine and mesenteric perfusion around the stomach can be visualized. As TEE necessitates the insertion of a probe, it is suitable for use in anesthetized patients. The use of ICG imaging assessment is limited to laparotomy cases, and penetration of fluorescent light is only a few millimeters. The NIRS assessment appears to provide the information beneath the skin but only collects the data along the path of infrared light, and thus, feasibility on the intestine in the abdomen needs further investigation.
In summary, four modalities are available in addition to CT, potentially helpful for salvaging the intestine and rescuing the patient. In brief, potential ischemia is detected by hypokinesis of the intestine by US, and then the rSO2 of the intestine is measured via the abdominal wall by NIRS. Because the time for salvaging the intestine is limited, it is of primary importance to take the patient to an institute where appropriate intervention can be provided. For this purpose, it is important to have multifaceted solutions against such a multiphasic problem. With the recent development of a palm-sized device, US assessment would be the only modality available everywhere and helpful for distinguishing patients who need a prompt referral to the facilitated hospitals. It may help monitor the perfusion status of patients at risk in any hospital ward. NIRS assessment may be an additional tool as pulse oximetry has become widely used during the COVID-19 pandemic. TEE is useful for perioperative assessment/monitoring, especially in cases with aortic dissection and potential NOMI. ICG imaging is to be used for visually confirming organ/graft perfusion and determining the extent of necrotic dissection.

Acute mesenteric ischemia can be life-threatening unless diagnosed and treated without delay1,2; however, early diagnosis followed by restoration of perfusion before progressing to bowel necrosis, preferably within 4 h, remains challenging for several reasons: (1) mesenteric ischemia is caused via multiple mechanisms and associated with several diseases managed by different specialties; (2) there are no symptoms, signs, or laboratory data specific for mesenteric ischemia; and (3) computed tomography (CT), the gold standard for diagnostic imaging, is misleading because ischemia can be present despite an opacified superior mesenteric artery (SMA)2,3,4,5.
Causes of mesenteric ischemia include embolism, thrombosis, dissection, or non-occlusive mesenteric ischemia (NOMI)3,6. Embolism is caused by a cardiogenic thrombus in patients with atrial fibrillation, dilated left ventricle, or atheroma in the aorta, which is asymptomatic until embolization. Occasionally, a thrombus is generated in the SMA or superior mesenteric vein. It has recently been shown that COVID-19 can lead to thrombus formation7. In aortic dissection, the intimal flap in the aorta occludes the orifice of the SMA, or dissection extends into the SMA, and an expanded false lumen compresses the true lumen. Because this obstruction is &#34;dynamic,&#34; mesenteric ischemia occurs even when the SMA is shown to be opacified on contrast CT. It is not uncommon for mesenteric ischemia to appear together with other critical conditions, such as stroke, myocardial infarction, or aortic rupture, thus necessitating a prompt and accurate diagnosis to prioritize treatment. In patients who undergo blood dialysis for years, the SMA is often narrowed due to calcifications, and the blood flow can be critically reduced following cardiac surgery using extracorporeal circulation or various types of stress8,9,10. NOMI can be caused by inadequate oxygen supply to the SMA due to heart failure, cardiac arrest, or hypoxemia despite a patent SMA11,12,13. Considering various etiologies and patterns of occurrence, not only blood flow in the SMA but also ischemic status in the intestinal wall must be assessed.
Another reason for delayed diagnosis is a lack of key symptoms or physical findings. Defense becomes obvious after the intestine is necrotized. Although several laboratory tests, such as C-reactive protein, lactate, citrulline, or intestinal fatty acid-binding protein, have been investigated as potential indicators of mesenteric ischemia4,14, no laboratory test has been shown to detect an early stage of mesenteric ischemia to date15. Although CT is the standard diagnostic imaging modality of mesenteric ischemia16,17,18, there can be errors in diagnosis or pitfalls in the filming technique5,19, and thus expertise is needed for an accurate diagnosis, which may necessitate the transfer of the patient to another facility. In addition, CT is not available for patients in the operating room (OR), emergency department (ER), or intensive care unit (ICU) who cannot be transferred to the Radiology Department. Allergies to contrast media, renal toxicity, or radiation exposure also limit CT as the initial diagnostic examination for every patient with abdominal pain.
Bowel ischemia is also problematic for plastic and reconstructive surgeons. During radical surgery for pharyngeal cancer, a free jejunal flap is used to reconstruct the resected pharynx. A portion of the jejunum is harvested with an artery and vein pedicle, which is anastomosed to the vessels in the cervical region, followed by anastomosis of the jejunal flap to the pharynx and esophagus. To confirm the competency of the vascular anastomosis, indocyanine (ICG) imaging was performed intraoperatively (sections 3). However, there are occasions when the flap develops necrosis within several days after surgery. Although rare, flap necrosis can be fatal unless detected and treated without delay. Thus, various attempts for detecting jejunal ischemia have been developed, such as frequent ultrasonography (US) to confirm blood flow, repeated endoscopy to verify mucosal color, or designating a sentinel portion of the jejunum to monitor perfusion, which is buried afterward by an additional surgical procedure20,21,22; however, such maneuvers are difficult for both patients and physicians. Other modalities applied to the clinical use for diagnosing bowel ischemia include optical coherence tomography23, laser speckle contrast imaging24, sidestream dark field imaging25, and incident dark field imaging26. These promising modalities are expected to become widely available through further development.
Considering the nature of mesenteric ischemia, which affects several fields in various situations, it is important to have multiple measures for detecting it. This article proposes two potential candidates for this purpose, US and near-infrared light and presents the representative findings.

<table><tbody><tr><td>HyperEye Medical System</td><td>Mizuho Ikakogyo Co., Ltd.</td><td></td><td>ICG imaging system used in Figure 3</td></tr><tr><td>Indocyanine green&amp;nbsp;</td><td>Daiichi Sankyo Co., Ltd.</td><td></td><td>ICG used for ICG imaging in Figure 3</td></tr><tr><td>TEE system</td><td>Philips Electronics</td><td>iE33</td><td>TEE system used in Figure 5</td></tr><tr><td>TOS-96, TOS-OR</td><td>TOSTEC Co.</td><td></td><td>NIRS system used in Figure 4</td></tr><tr><td>Ultrasonographic system</td><td>Hitachi, Co.</td><td>EUB-555, EUP-ES322</td><td>echo system used in Figure 1</td></tr><tr><td>Ultrasonographic system</td><td>Aloka Co.</td><td>SSD 5500</td><td>echo system used in Figure 2</td></tr><tr><td>Vscan</td><td>GE Healthcare Co.</td><td></td><td>Palm-sized echo used in Figure 2</td></tr></tbody></table>

multimodality diagnosis of mesenteric ischemia

Early diagnosis of mesenteric ischemia remains challenging because mesenteric ischemia presents with no key symptoms or physical findings, and no laboratory data specifically indicates intestinal tissue ischemic status before necrosis develops. While computed tomography is the standard for diagnostic imaging, there are several limitations: (1) repeated assessments are associated with increased radiation exposure and risk of renal damage; (2) the computed tomography findings can be misleading because necrosis occasionally occurs despite opacified mesenteric arteries; and (3) computed tomography is not necessarily available within the golden time of salvaging the intestines for those patients in the operating room or at a place far from the hospital. This article describes a challenge to overcome such limitations using ultrasonography and near-infrared light, including clinical studies. The former is capable of providing not only morphologic and kinetic information of the intestines but also perfusion of the mesenteric vessels in real-time without transferring the patient or exposing them to radiation. Transesophageal echocardiography enables precise assessment of mesenteric perfusion in the OR, ER, or ICU. Representative findings of mesenteric ischemia in seven aortic dissection cases are presented. Near-infrared imaging with indocyanine green helps visualize the perfusion of vessels and intestinal tissues although this application requires laparotomy. Findings in two cases (aortic aneurysm) are shown. Near-infrared spectroscopy demonstrates oxygen debt in the intestinal tissue as digital data and can be a candidate for early detection of mesenteric ischemia without laparotomy. The accuracy of these assessments has been confirmed by intraoperative inspections and postoperative course (prognosis).

TEE 
There were two types of findings: (1) &#34;branch type&#34; with a true compressed lumen in the SMA by an expanded false lumen without blood flow, and (2) &#34;aortic type&#34; with the intimal flap at the orifice of the SMA and lack of blood flow in the SMA (Figure 5A). The representative TEE findings of three cases with bowel necrosis caused by acute aortic dissection are shown. In one case of the former type, the true lumen in the SMA were severely compressed (Figure 5B). Bowel necrosis was confirmed upon laparotomy, and bowel resection was performed. The findings of the aortic-type mesenteric ischemia vary among cases. Here two cases are shown. TEE revealed that the true lumen in the aorta was compressed (Figure 5C). The celiac artery was well perfused in one case, whereas blood flow could not be detected in the SMA. In another case, both were not perfused. In both cases, bowel necrosis was confirmed on laparotomy.
Abdominal US 
The US could visualize reduced or absent peristalsis or dilatation of the intestines (Figure 6A). While the normal intestine was usually smaller than 2 cm in diameter (Figure 2B), the dilated intestine was larger than 3 cm with debris swaying in the dilated lumen, and the thickened Kerckring folds28 were obvious. Ascites around the intestines were often seen. In these two cases with aortic dissection, the intestines were already necrotic and necessitated resection.
Figure 6B shows the US findings of thrombosis in the portal vein. Blood flow signals were absent in the left branch of the portal vein to the umbilical portion. The extrahepatic portal vein was dilated with a flow signal defect. Behind the pancreatic body, the superior mesenteric vein was narrowed by a thrombus with accelerated flow into the portal vein visualized on a longitudinal scan. In this particular case, thrombolytic therapy was carried out.
A case involving an acute aortic dissection associated with mesenteric ischemia is presented in which the intestines could be salvaged. The patient presented with mild abdominal pain but significant metabolic acidosis. Despite opacified SMA on CT assessment (Figure 7B), abdominal US revealed a hypokinetic intestine. The blood flow signal was poor in the SMA, whereas it was apparent in the abdominal aorta (Figure 7A). Accelerated blood flow at the SMA orifice and reverse flow into the distal SMA from the jejunal branch were noted, indicating a significant mesenteric ischemia. At emergent laparotomy (Figure 7C), the intestines appeared pale and peristalsis was slightly reduced. After revascularization, the color and peristalsis of the intestines improved (Figure 7D). The intestine was salvaged in this case. Although it was fortunate that the SMA flow could be visualized in this case, there are cases in which the visualization of the intestines or blood flow is difficult.
ICG imaging 
Figure 8&#160;shows the images of two cases with bowel necrosis before and after ICG administration. In the former case, segmental necrosis was apparent only by inspection (Figure 8A). The mesenteric arteries were visualized first, and then the tissue brightened. In the latter case, however, the difference in perfusion was unclear by inspection (Figure 8B). ICG imaging showed a patchy brightening on the left side. The lower portion was totally necrotic. A region on the right brightened with obvious peristalsis. In these two cases, necrotic portions of the intestine were resected. Such information may be available with CT assessment but is not necessarily helpful during laparotomy because the location of the intestine changes.
NIRS 
Figure 9A shows the rSO2 changes in the jejunum, which was harvested for use as a free jejunum flap to reconstruct the resected pharynx30. As the artery was clamped, the rSO2 &#62;60% in every case dropped to a level &#60;60% in many cases. When the flap was reperfused, rSO2 recovered to &#62;60% in every case. After surgery, rSO2 remained &#62;60% without any case of developing necrosis of the jejunal flap. In contrast, as the vein was clamped, rSO2 was slightly reduced, and the hemoglobin index (HbI), which is the relative change in hemoglobin density, was markedly elevated. Application of NIRS to this field was proposed based on the author&#39;s experience with cerebral perfusion monitoring with NIRS in aortic cases25 (Figure 9B) and a case of transient bowel ischemia due to aortic dissection associated with reversible changes of rSO2, which were measured from the surface of the abdominal wall using the conventional NIRS sensor with the distance between emitter and receiver of 4 cm31.
Sensitivity and specificity 
While the results of the NIRS assessment were compatible with the uneventful postoperative course in every enrolled case, the data in the other three applications was not enough to perform statistical analysis, but the assessment was rather &#34;precision medicine&#34;-like one in each individual case. The accuracy of the assessment was individually confirmed by the intraoperative inspection of the laparotomy.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65095/65095fig01.jpg" /> 
Figure 1: Visualization of visceral branches using transesophageal echocardiography (TEE). (A) Scanning planes for visualizing the celiac artery (CEA) and superior mesenteric artery (SMA). (B) Tips for manipulating the probe to visualize a better image at the 12 o&#39;clock position. (C)TEE images of CEA, SMA, and surrounding structures. (D) Long-axis view of CEA and SMA. In (C) and (D), blood flow is shown in red or blue according to the flow direction. Abbreviations: AB-AO: abdominal aorta, L-RA: left renal artery, L-RV: left renal vein. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/65095/65095fig02.jpg" /> 
Figure 2: Visualization of the intestine and superior mesenteric artery (SMA). (A) Places and directions of the probe for each assessment. (B) An acoustic window between the intestinal gas (blue dotted lines) toward the intestine and an image of the normal intestine. (C) An acoustic window for SMA and images of SMA visualized using a palm-sized ultrasonography device. Abbreviations: AB-AO: abdominal aorta, CEA: celiac artery. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/65095/65095fig03.jpg" /> 
Figure 3: Indocyanine green (ICG) imaging.&#160;(A) Mechanism of imaging. As near-infrared light is irradiated to the injected ICG in the tissue, it emits fluorescent light, which is recorded by the camera along with the images of the surgical field. (B) Sequential images of ICG imaging showing perfusion in the free jejunal flap. The fluorescence image is superimposed on the image of the surgical field. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/65095/65095fig04.jpg" /> 
Figure 4: Near-infrared spectroscopy (NIRS) system and application to the jejunal flap. (A) NIRS system. (B) A sensor made for assessing regional oxygen saturation in the surgical field, with a distance between the emitter and receiver of 2 cm. It was covered by a sterile sheath and placed on the jejunum. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/65095/65095fig05.jpg" /> 
Figure 5: Transesophageal echocardiographic findings of mesenteric ischemia caused by the aortic dissection. (A) Two types of mechanisms for malperfusion. (B) Branch type with the compressed true lumen (TL) in the superior mesenteric artery (SMA). (C) Aortic type. In the abdominal aorta (AB-AO), the flap was compressed to the wall. In one case, no flow was detected in the SMA, whereas a good flow signal was in the celiac artery (CEA). In another case, both arteries were malperfused. The absence of color coding indicates that there is no blood flow in the corresponding site. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/65095/65095fig06.jpg" /> 
Figure 6: Abdominal ultrasonographic images of mesenteric ischemia. (A) Images of the ischemic intestine, which was akinetic and dilated, associated with obvious Kerckring folds and ascites. (B) Images of portal vein (PV) thrombosis. There was a flow signal defect by the thrombus (TH) in the PV, which was dilated and larger than the inferior vena cava (IVC). The portion in the vessel where color coding is absent indicates the loss of blood flow because of thrombus formation. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/65095/65095fig07.jpg" /> 
Figure 7: Findings in a case of salvaged intestine associated with acute aortic dissection. (A) The blood flow was poor in the superior mesenteric artery (SMA), but an accelerated flow was noted with the reverse flow into the distal portion from the branch artery. (B) The SMA was opacified. (C) Upon laparotomy, the intestine appeared slightly pale with reduced peristalsis. (D) After revascularization, color and movement improved. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig07large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/65095/65095fig08.jpg" /> 
Figure 8: Indocyanine green imaging of the ischemic intestine. (A) Segmental ischemia. (B) Diffuse ischemia with some portions less ischemic. Peristalsis was noted in the latter portion. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig08large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/65095/65095fig09.jpg" /> 
Figure 9: Changes in regional oxygen saturation (rSO2). (A) The rSO2 changes of the jejunal flap. (B) Changes in rSO2 in the bilateral frontal lobes during arch surgery. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig09large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 10" class="xfigimg" src="/files/ftp_upload/65095/65095fig10.jpg" /> 
Figure 10: Ischemic cascade and multimodality approach to mesenteric ischemia. (A) Ischemic cascade for mesenteric ischemia. The cascade is assessed by ultrasonography (US) and is affected by the severity and duration of malperfusion. The former can be assessed by employing color Doppler mode, indocyanine green (ICG) imaging, and near-infrared spectroscopy (NIRS). (B) Multimodality approach by locations. The abdominal US and transesophageal echocardiography (TEE) emit ultrasound and assess the intestine as well as the abdominal aorta (AB-AO) and superior mesenteric artery (SMA). ICG imaging and NIRS emit near-infrared light. (C) The target of assessment is different in these modalities. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig10large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 11" class="xfigimg" src="/files/ftp_upload/65095/65095fig11.jpg" /> 
Figure 11: Mechanism of changes in regional oxygen saturation (rSO2). As arterial blood flow is interrupted, oxygenated hemoglobin decreases and rSO2 is reduced. As venous congestion occurs, the venous component with rich deoxygenated hemoglobin increases, reducing rSO2 and increasing the hemoglobin index (HbI), which indicates the relative changes in the cumulative amount of hemoglobin in the tissue. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig11large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 12" class="xfigimg" src="/files/ftp_upload/65095/65095fig12.jpg" /> 
Figure 12: Optimization of measurement of regional oxygen saturation (rSO2) of the intestine from the body surface. (A,B) As&#160;the rSO2 is sampled mainly at a depth of one- to two-thirds of the distance between the emitter and receiver of the sensor, that of the abdominal wall muscle is measured. (C) As the sensor is pressed toward the abdomen according to the ultrasonographic information, it reaches the depth of the intestine. The red marking indicates the path of infrared light. The yellow arrow shows how the sensor is pressed. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/65095/65095fig12large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Multimodality Diagnosis of Mesenteric Ischemia at JoVE.com

Multimodality Diagnosis of Mesenteric Ischemia

This article presents a multimodal approach that aims to overcome the limitations of traditional methods in detecting mesenteric ischemia and preventing bowel necrosis. The presented technique offers a promising solution by combining state-of-the-art ultrasonography with cutting-edge near-infrared light technologies.

Early diagnosis of mesenteric ischemia remains challenging because mesenteric ischemia presents with no key symptoms or physical findings, and no ...

multimodality-diagnosis-of-mesenteric-ischemia

Nanyang Technological University

Research

JoVE Journal

Medicine

500 Views.  Kochi Medical School. This article presents a multimodal approach that aims to overcome the limitations of traditional methods in detecting mesenteric ischemia and preventing bowel necrosis. The presented technique offers a promising solution by combining state-of-the-art ultrasonography with cutting-edge near-infrared light technologies.

Video: Multimodality Diagnosis of Mesenteric Ischemia

Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography

Proximal resistance vessels, such as the mesenteric arteries, contribute substantially to the peripheral resistance. These small vessels of between 100-400 &mu;m in diameter function primarily in directing blood flow to various organs according to the overall requirements of the body. The rat mesenteric artery has a diameter greater than 100 &mu;m. The myography technique, first described by Mulvay and Halpern1, was based on the method proposed by Bevan and Osher2. The technique provides information about small vessels under isometric conditions, where substantial shortening of the muscle preparation is prevented. Since force production and sensitivity of vessels to different agonists is dependent on the extent of stretch, according to active tension-length relation, it is essential to conduct contraction studies under isometric conditions to prevent compliance of the mounting wires. Stainless steel wires are preferred to tungsten wires because of oxidation of the latter, which affects recorded responses3.The technique allows for the comparison of agonist-induced contractions of mounted vessels to obtain evidence for normal function of vascular smooth muscle cell receptors.
We have shown in several studies that isolated mesenteric arteries that are contracted with phenylyephrine relax upon addition of cumulative concentrations of extracellular calcium (Ca2+e). The findings led us to conclude that perivascular sensory nerves, which express the G protein-coupled Ca2+-sensing receptor (CaR), mediate this vasorelaxation response. Using an automated wire myography method, we show here that mesenteric arteries from Wistar, Dahl salt-sensitive(DS) and Dahl salt-resistant (DR) rats respond differently to Ca2+e. Tissues from Wistar rats showed higher Ca2+-sensitivity compared to those from DR and DS. Reduced CaR expression in mesenteric arteries from DS rats correlates with reduced Ca2+e-induced relaxation of isolated, pre-contracted arteries. The data suggest that the CaR is required for relaxation of mesenteric arteries under increased adrenergic tone, as occurs in hypertension, and indicate an inherent defect in the CaR signaling pathway in Dahl animals, which is much more severe in DS.
The method is useful in determining vascular reactivity ex vivo in mesenteric resistance arteries and similar small blood vessels and comparisons between different agonists and/or antagonists can be easily and consistently assessed side-by-side6,7,8.

An automated myography method for force measurements in isolated mesenteric arteries is described. It employs a Mulvany-Halpern Auto Dual Wire Myograph 510A to determine responses to phenylephrine and extracellular calcium. The method allows consistent determination of isometric responses to agonists in small vessels of diameters of 60 - 300 &mu;m, independently.

Proximal resistance vessels, such as the mesenteric arteries, contribute substantially to the peripheral resistance. These small vessels of between ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

Assessing Myogenic Response and Vasoactivity In Resistance Mesenteric Arteries Using Pressure Myography

Small resistance arteries constrict and dilate respectively in response to increased or decreased intraluminal pressure; this phenomenon known as myogenic response is a key regulator of local blood flow. In isobaric conditions small resistance arteries develop sustained constriction known as myogenic tone (MT), which is a major determinant of systemic vascular resistance (SVR). Hence, ex vivo&#160;pressurized preparations of small resistance arteries are major tools to study microvascular function in near-physiological states. To achieve this, a freshly isolated intact segment of a small resistance artery (diameter ~260 &#956;m) is mounted onto two small glass cannulas and pressurized. These arterial preparations retain most in vivo characteristics and permit assessment of vascular tone in real-time. Here we provide a detailed protocol for assessing vasoactivity in pressurized small resistance mesenteric arteries from rats; these arteries develop sustained vasoconstriction - approximately 25% of maximal diameter - when pressurized at 70 mmHg. These arterial preparations may be used to study the effect of investigational compounds on relationship between intra-arterial pressure and vasoactivity and determine changes in microvascular function in animal models of various diseases.

Pressure myography is used to assess vasoactivity of small arteries that develop sustained constriction when pressurized. This manuscript provides a detailed protocol to assess in isolated segments of small mesenteric arteries from rats, vasoactivity and the effect of intraluminal pressure on vascular diameter.

Small resistance arteries constrict and dilate respectively in response to increased or decreased intraluminal pressure; this phenomenon known as myogenic ...

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-&#7429;-glucose ([18F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, inter-animal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [18F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes.

The method presented here uses simultaneous positron emission tomography and magnetic resonance imaging. In the cerebral hypoxia-ischemia model, dynamic changes in diffusion and glucose metabolism occur during and after injury. The evolving and irreproducible damage in this model necessitates simultaneous acquisition if meaningful multi-modal imaging data are to be acquired.

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...

Murine Model of Intestinal Ischemia-reperfusion Injury

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, hypotension, necrotizing enterocolitis, bowel transplantation, trauma and chronic inflammation. Intestinal ischemia-reperfusion (IR) injury is a consequence of acute mesenteric ischemia, caused by inadequate blood flow through the mesenteric vessels, resulting in intestinal damage. Reperfusion following ischemia can further exacerbate damage of the intestine. The mechanisms of IR injury are complex and poorly understood. Therefore, experimental small animal models are critical for understanding the pathophysiology of IR injury and the development of novel therapies.
Here we describe a mouse model of acute intestinal IR injury that provides reproducible injury of the small intestine without mortality. This is achieved by inducing ischemia in the region of the distal ileum by temporally occluding the peripheral and terminal collateral branches of the superior mesenteric artery for 60 min using microvascular clips. Reperfusion for 1 hr, or 2 hr after injury results in reproducible injury of the intestine examined by histological analysis. Proper position of the microvascular clips is critical for the procedure. Therefore the video clip provides a detailed visual step-by-step description of this technique. This model of intestinal IR injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Here we describe the detailed procedure of intestinal ischemia-reperfusion in mice which results in reproducible injury without mortality to encourage the standardization of this technique across the field. This model of intestinal ischemia-reperfusion injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, ...

Rat Mesentery Angiogenesis Assay

The adult rat mesentery window angiogenesis assay is biologically appropriate and is exceptionally well suited to the 
study of sprouting angiogenesis in vivo [see review papers], which is the dominating form of angiogenesis in human tumors and non-tumor 
tissues, as discussed in invited review papers1,2. Angiogenesis induced in the membranous mesenteric parts by intraperitoneal (i.p.) injection of a pro-angiogenic factor can be modulated
by subcutaneous (s.c.), intravenous (i.v.) or oral (p.o.) treatment with modifying agents of choice. Each membranous part of the mesentery is 
translucent and framed by fatty tissue, giving it a window-like appearance.
The assay has the following advantageous features: (i) the test tissue is natively vascularized, albeit 
sparsely, and since it is extremely thin, the microvessel network is virtually two-dimensional, which allows the entire network 
to be assessed microscopically in situ; (ii) in adult rats the test tissue lacks significant physiologic angiogenesis, which characterizes
 most normal adult mammalian tissues; the degree of native vascularization is, however, correlated with age, as discussed in1; 
(iii) the negligible level of trauma-induced angiogenesis ensures high sensitivity; (iv) the 
assay replicates the clinical situation, as the angiogenesis-modulating test drugs are administered systemically and the responses 
observed reflect the net effect of all the metabolic, cellular, and molecular alterations induced by the treatment; (v) the assay 
allows assessments of objective, quantitative, unbiased variables of microvascular spatial extension, density, and network pattern 
formation, as well as of capillary sprouting, thereby enabling robust statistical analyses of the dose-effect and molecular 
structure-activity relationships; and (vi) the assay reveals with high sensitivity the toxic or harmful effects of treatments in 
terms of decreased rate of physiologic body-weight gain, as adult rats grow robustly.
Mast-cell-mediated angiogenesis was first demonstrated using this assay3,4. The model demonstrates a high level of 
discrimination regarding dosage-effect relationships and the measured effects of systemically administered chemically or functionally closely related drugs and proteins, 
including: (i) low-dosage, metronomically administered standard chemotherapeutics that yield diverse, drug-specific effects (i.e., 
angiogenesis-suppressive, neutral or angiogenesis-stimulating activities5); (ii) natural iron-unsaturated human lactoferrin, which stimulates 
VEGF-A-mediated angiogenesis6, and natural iron-unsaturated bovine lactoferrin, which inhibits VEGF-A-mediated angiogenesis7; and (iii) 
low-molecular-weight heparin fractions produced by various means8,9. Moreover, the assay is highly suited to studies of the combined 
effects on angiogenesis of agents that are administered systemically in a concurrent or sequential fashion.
The idea of making this video originated from the late Dr. Judah Folkman when he visited our laboratory and witnessed the methodology being demonstrated.
Review papers (invited) discussing and appraising the assay
Norrby, K. In vivo models of angiogenesis. J. Cell. Mol. Med. 10, 588-612 (2006).
Norrby, K. Drug testing with angiogenesis models. Expert Opin. Drug. Discov. 3, 533-549 (2008).

Normal adult vascularized mammalian tissue that lacks physiologic angiogenesis and that has not been exposed to surgical intervention is used to study: (i) the initiation and development of angiogenesis following intraperitoneal administration of test agents; and (ii) modification of angiogenesis following systemic administration of selected test agents.

The adult rat mesentery window angiogenesis assay is biologically appropriate and is exceptionally well suited to the 
study of sprouting angiogenesis in ...

Biology

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Rodent Model of Intestinal Ischemia-Reperfusion Injury via Occlusion of the Superior Mesenteric Artery

Intestinal ischemia-reperfusion injury (IRI) is associated with a myriad of conditions in both veterinary and human medicine. Intestinal IRI conditions, such as gastric dilatation volvulus (GDV), mesenteric torsion, and colic, are observed in animals such as dogs and horses. An initial interruption of blood flow causes tissues to become ischemic. Although necessary to salvage viable tissue, subsequent reperfusion can induce further injury. The main mechanism responsible for IRI is free radical formation upon reperfusion and reintroduction of oxygen into damaged tissue, but there are many other components involved. The resulting local and systemic effects often impart a poor prognosis. 
Intestinal IRI has been the subject of extensive research over the past 50 years. An in vivo rodent model in which the base of the superior mesenteric artery (SMA) is temporarily ligated is currently the most common method used to study intestinal IRI. Here, we describe a model of intestinal IRI utilizing isoflurane anesthesia in 21% O2 medical air that yields reproducible injury, as demonstrated by consistent histopathology of the small intestines. Tissue injury was also assessed in the colon, liver, and kidneys.

We describe how to generate a widely used surgical model of intestinal ischemia-reperfusion injury (IRI) in rodents. The procedure involves occlusion of the superior mesenteric artery followed by the restoration of blood flow. This model is useful for studies investigating occlusive causes of intestinal IRI in both veterinary and human medicine.

Intestinal ischemia-reperfusion injury (IRI) is associated with a myriad of conditions in both veterinary and human medicine. Intestinal IRI conditions, ...

Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues

Altered vascular tone responsiveness to pathophysiological stimuli contributes to the development of a wide range of cardiovascular and metabolic diseases. Endothelial dysfunction represents a major culprit for the reduced vasodilatation and enhanced vasoconstriction of arteries. Adipose (fat) tissues surrounding the arteries play important roles in the regulation of endothelium-dependent relaxation and/or contraction of the vascular smooth muscle cells. The cross-talks between the endothelium and perivascular adipose tissues can be assessed ex vivo using mounted blood vessels by a wire myography system. However, optimal settings should be established for arteries derived from animals of different species, ages, genetic backgrounds and/or pathophysiological conditions.

The protocol describes the use of wire myography to evaluate the transmural isometric tension of mesenteric arteries isolated from mice, with special consideration of the modulation by factors released from endothelial cells and perivascular adipose tissues.

Altered vascular tone responsiveness to pathophysiological stimuli contributes to the development of a wide range of cardiovascular and metabolic ...

Rat Model for Visceral Organ Malperfusion Studies

Controlled Reversible Visceral Arterial Ischemia, Venous Congestion and Combined Malperfusion via Midline Laparotomy in Rats

Besides sepsis and malignancy, malperfusion is the third leading cause of tissue degradation and a major pathomechanism for various medical and surgical conditions. Despite significant developments such as bypass surgery, endovascular procedures, extracorporeal membrane oxygenation, and artificial blood substitutes, tissue malperfusion, especially of visceral organs, remains a pressing issue in patient care. The demand for further research on biomedical processes and possible interventions is high. Valid biological models are of utmost importance in enabling this kind of research. Due to the multifactorial aspects of tissue perfusion research, which include not only cell biology but also vascular microanatomy and rheology, an appropriate model requires a degree of biological complexity that only an animal model can provide, rendering rodents the obvious model of choice. Tissue malperfusion can be differentiated into three distinct conditions: (1) isolated arterial ischemia, (2) isolated venous congestion, and (3) combined malperfusion. This article presents a detailed step-by-step protocol for the controlled and reversible induction of these three types of visceral malperfusion via midline laparotomy and clamping of the abdominal aorta and caval vein in rats, underscoring the significance of precise surgical methodology to guarantee uniform and dependable results. Prime examples of possible applications of this model include the development and validation of innovative intraoperative imaging modalities, such as Hyperspectral Imaging (HSI), to objectively visualize and differentiate malperfusion of gastrointestinal, gynecological, and urological organs.

Author Spotlight: Advancing Spectral Characterization of Physiological and Malperfused Tissues

This article introduces a standardized procedure for controlled, reversible malperfusion of visceral organs in rat models. The aim is to induce these malperfusion states with a high degree of methodological certainty and control while maintaining technical simplicity and error resilience.

Besides sepsis and malignancy, malperfusion is the third leading cause of tissue degradation and a major pathomechanism for various medical and surgical ...