Week 4

This was a relatively slow week because Dr. Tranbaugh was on vacation. On Monday, I went in to finish some of my code extracting qualified CABG patients from 2015-2017 for our study. We are excluding patients who have had a previous heart procedure or other procedure, stents, acute myocardial infarction, shock, left main only bypass, and bilateral internal mammary artery grafts. We also are only including patients who had multi-vessel disease, meaning that they had two or more blocked arteries, and patients that had at least two bypasses with at least one artery. I have been writing code in excel to extract all the patients that meet these criteria and finished on Monday. Dr. Worku and I were going to use the national death index to look up the patient outcomes, but we discovered that the application takes over 2 months to process, which will be well after I am gone. Thus, we have decided to look up patient outcomes on the hospital database. I applied for access this week, so hopefully I will be able to start on it next week. We are also waiting to obtain data from stenting, which we will use to compare to our CABG single and multi-arterial bypass groups.

Since it is a slow week, I decided to make some diagrams of what I have seen and discuss more in-depth the graft harvesting procedure in CABG. I am not as familiar with the technical details of the graft harvesting, but from what I have seen the procedure is very elegant and seems to leave minimal scarring. It is my understanding that a small incision is made in the wrist of the patient, and then a sheath-like device with an attacked camera (Figure 1, below) is inserted. It looks like a hollow cylinder cut in half length-wise, and is inserted into the arm with the hollow-side down. With this device and camera, the surgeons are able to follow the radial artery down the arm and free it from the connective tissue holding it in place. They use a cauterizer that looks somewhat like a banana clip to mechanically and thermally separate the tissue.  This part of the procedure is fun to watch because the camera that the surgeons use is projected on a large TV, making it easy to see what is going on.

Once the artery has been freed from the surrounding tissue and removed from the patient, all the branching vessels from the artery must be clipped. This is because the branching vessels allow blood to escape the graft and leak into the pericardial space if left open. To seal the branches, small metal clips that look like mini-staples are applied, as described in my week 1 blog post. Once sealed, saline or blood is run through the vessels to ensure that they are sealed without leaks. Dr. Tranbaugh will usually check the seal of the vessel again directly before he attaches the vessels during bypass. The metal clips on the vessel grafts do not biodegrade, and can be seen in CT scans of patients decades after the procedure was performed.

The week before last, I asked Dr. Tranbaugh if family members of CABG patients ever donate their arteries for bypass. I think this would be particularly helpful for CABG patients who have bad arteries or for a repeat procedure with few available autografts. Dr. Tranbaugh said that it is not really done, and that usually an allograft or xenograft would be used in these instances. I wonder why this is- maybe family members rarely donate because they could need the vessels for themselves if they had a heart attack? Family members donate organs all the time though, and vessel donation seems less risky than organ donation to me.

It is hard to believe that immersion is already half over! In the city, was able to see the Macy’s fireworks right on the waterfront this Wednesday with Hania. We are also going together to see Book of Mormon on Broadway this Sunday- I cannot wait! I hope that we find many excuses to visit the city again once we go back to Ithaca because I have been having such a blast!

Figure 1. Rough illustration of radial artery harvesting. Top shows the device inserted through a single incision of the arm, and the bottom shows the camera view of the device on-screen. The device is in the shape of a semi-circular hollow cylindrical tube, and can fit a cauterizer through its opening for vessel extraction.