Week 6

This was a busy week! I have started a new research project with Dr. Tranbaugh that I am really excited about. The study will be comparing the PCI to CABG ratios over 20 years across all New York City hospitals. I will be continuing work from an original paper published by Dr. Ko and Dr. Tranbaugh, among others, in 2012 (Ko et al., 2012). This paper looked at publicly available New York State reports from 1994-2008 on PCI and CABG procedures within each borough in NYC and across boroughs. The 2012 publication reported that there was an overall decline in CABG procedures, as well as an increase in PCI procedures during the same time period. It also discussed major discrepancies in the ratio of PCI to CABG procedures across hospitals in Manhattan. For example, in 2008, Mount Sinai hospital had just over 16 PCI procedures per CABG procedure, whereas Bellevue had just under 4 PCI procedures per CABG procedure. It was assumed that there were similar patient groups eligible for either procedure at every hospital within Manhattan, so it was surprising that the standard of care was so drastically different among the hospitals. I did not realize that there could be so much variation in procedures performed for the same demographic between hospitals, so this was eye-opening for me. The paper argued that a “heart-team approach” to patient care planning could help unify the treatment for these patients across all hospitals.

I will be updating this study with seven more years of publicly available data and am interested to see how the ratios have changed since 2008. I have already calculated the PCI/CABG ratio across Manhattan from the 2015 NYS reports, and it looks like the ratio has actually fallen from 8.04 to 6.828 since 2008. However, it is important to note that I have not yet included any new hospitals that may have begun performing PCI in Manhattan after 2008. It also looks like the hospital with the highest PCI/CABG ratio in 2015 is still Mount Sinai, but their ratio has fallen from 16.2 in 2008 to 9.07 in 2015. I am interested to see what has happened in the years between- more to come soon!

I was able to observe an exciting new surgery this week with Dr. Worku at Weill Cornell- the installation of the HeartMate 3 ventricular assistive device (VAD). This is the most recent HeartMate edition, and even Dr. Worku had not yet seen the VAD surgical procedure with this new device. A little background: a ventricular assistive device is a pump that takes some of the load off of the left ventricle by pumping blood directly from the ventricle to the aorta (Figure 1). The patient wears a controller outside their body that is directly connected to the pump (“HeartMate 3”, 2016). 

Figure 1. HeartMate 3 device (“HeartMate 3”, 2016).

          During the surgery, a metal docking station was first sewn onto the apex of the heart, where the HeartMate pump attaches. The docking station has a circular opening in the middle, and through this opening the apex was cut. I was not able to see the pump installed into the docking station, but I did see the surgeon measure out what looked like a Dacron vascular graft to attach from the pump to the aorta. A device I can only describe as a tissue hole-punch was used to create an opening in the aorta in order to attach the graft. I think it is amazing and inspiring that technology exists to act as an artificial heart and keep a patient alive that may not survive otherwise, especially for patients who are waiting for heart transplants.

I was also able to observe another TAVR and surgical aortic valve replacement this week. As I have already described these procedures in previous weeks, this week I have included some more diagrams of what I saw (Figure 2, Figure 3). Notably, the surgical aortic valve replacement this week was on a female, rather than a male patient, and I could tell that there was a big difference in the size of the aortic valve. I can see why it may be more risky to perform procedures such as these on female patients- there is much less space and tissue to work with. The surgeon pointed out the thymus to me during the valve replacement, and explained that often the thymus is damaged in opening and sealing the chest cavity, but that it does not matter because the thymus has little function in adult patients.

Figure 2. This figure shows the principles of a TAVR. The artificial valve is housed in a stent-like cage structure (top left) that is collapsed and inserted into the heart using a catheter, and then blown up into place (bottom left). The catheter is inserted through the leg up through the aorta and the new valve is placed inside the aortic valve. As the balloon inflates and expands the artificial valve, the native valve leaflets are pressed out of the way into the wall of the aorta (right). The entire procedure is performed using X-Ray imaging.

Figure 3. This figure shows on the left what the bovine pericardium artificial valve looks like, as well as installation of the valve in the open heart on the right. Notably, many stitches are placed all at once to suture the graft into the correct position in the aorta- as many as 20 at once. The diagram to the right also crudely shows the device that is used to crank open the chest to keep it open during surgery.

This weekend, I went with a group of my classmates to the Metropolitan Museum. I have to say, this is my favorite thing that we have done so far in the city. The sheer size of the museum was unbelievable, and every piece of artwork inside looked priceless. I used to paint and draw quite a bit, and it was amazing to see all of the different styles and techniques employed by artists around the world to create such beautiful artwork. My favorite part was the Van-Goh and Monet section, but honestly the entire museum was incredible. I may return next week, because we were not able to get through the entire museum in one day. I am also looking forward to seeing Phantom of the Opera next week, visiting the Guggenheim, and going on a night cruise around the city!

Citations:

HeartMate 3™ Left Ventricular Assist System. (2016, August 22). Retrieved July 20, 2018, from https://www.sjmglobal.com/en-int/patients/heart-failure/our-solutions/left-ventricle-assist-device/heartmate-3/how-it-works#tab

Ko, W., Tranbaugh, R., Marmur, J. D., Supino, P. G., & Borer, J. S. (2012). Myocardial Revascularization in New York State: Variations in the PCI-to-CABG Ratio and Their Implications. Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease, 1(2), e001446. http://doi.org/10.1161/JAHA.112.001446