The overall goal of this procedure is to generate 3D models of the human cardiac venous system for the development of an anatomical database that can be used for the design of cardiac devices employed within these vessels. This is accomplished by first preparing the human heart specimen by fixing it in its end diastolic state and cannulating the coronary sinus with a venogram balloon catheter. In the second step, contrast, CT images of the cardiac venous system are obtained during the final step.
3D models are generated from the CT scans from which various anatomical measurements can be obtained. One of the main advantages of our technique over other methods, such as the in vivo assessment of cardiac venous anatomy, is that there are no exposure to a patient to contrast agents or radiation. We first had the idea for this method when we were originally mapping the cardiac venous system of these profusion fixed hearts using a micro scribe on the epicardial surface.
However, this method had some limitations. It was limited by the amount of adipose tissue as well as it generated 2D models. The use of contrast cts for model generation overcomes these limitations As soon as they're obtained.
Perfusion fix the freshly isolated human hearts in their end diastolic state in 10%buffered formin. Then on the day before scanning, rinse the hearts in water in order to remove the majority of the formin before heading to the scanner. Use a venogram balloon catheter to cannulate the coronary sinus vein within each heart through the inferior vena cava.
Under direct visualization. Once in place inflate the balloon of the venogram catheter to anchor the catheter in the coronary sinus. Now, place each heart within a sealable polymer container on top of a sponge designed to support the heart in its attitudinally correct anatomical position.
Begin by positioning the heart on the CT scanner bed as if a patient was lying supine and headfirst on the scanner. Then connect the proximal end of the venogram catheter to an injector that contains two injection syringes. One for contrast and one for saline.
Now automatically inject 40 milliliters of contrast into the cardiac venous system at five milliliters per second. Eight seconds after the contrast injection is initiated CT scan the heart setting, scan to 512 by 512 pixel resolution with 0.6 millimeter slice thickness. Then flush out the contrast by automatically injecting 40 more milliliters of saline into the cardiac venous system.
At five milliliters per second, export the CT DICOM images onto an external hard drive. Now upload the CT DICOM images into mimic software and generate a mask for the CT images that only contains pixels with high hounds field units. To highlight only the contrast present in the heart, remove any contrast that has leaked into the chambers or diffused into the tissue so that the mask only contains the contrast within the major cardiac veins.
Then manually fill in the air pockets within a given vein frame by frame, and generate a 3D object from the resultant mask. Next smooth and wrap the mask to eliminate any rough geometries, and then generate center lines for each created 3D model. In order to minimize user variability in the generation of the 3D models, it's important that the user carefully follows the detailed protocol as well as has an observer check the model before generating the center lines.
Finally, use the center lines to measure the arc length branching angle, tortuosity and diameters for each major vessel in each heart. In this table, the median anatomical parameters for the major cardiac veins for 42 human heart specimens are presented. All the heart specimens contained one middle cardiac vein and one anterior interventricular vein.
Some specimens contained more than one inferior vein, inferior lateral vein, lateral vein, and or anterolateral vein. While other hearts may not have had one or two of these specific veins present in this movie, a representative 3D model can be observed rotating in space. Follow this procedure, one of the advantages is that you can use visualization with video scopes within the cardiac veins to assess the anatomy, validate the CT models, and also determine where various structures such as cardiac veins exist, which you can't see on CT After its development.
This technique allows researchers in the field of biomedical engineering to explore the cardiac venous system and the development of cardiac devices that utilize these vessels. Ultimately, modeling and mapping of the human cardiac venous system will provide novel insights into the relevant anatomy to perform various clinical procedures.
