Day 2 of Cardiology - Sean

In the morning, I was scheduled to be in the "BVG room" with Dr. Chiang, one of the cardiology attendings. When I first got there, Dr. Chou was there to greet me and made sure everything was going well so far. He soon left me to observe Dr. Chiang, and later Dr. Wu (another attending), use Venous Ultrasound imaging to screen the lower extremeties of their patients for any instances of deep vein thrombi (DVT).

As he saw his patients, he took time to describe the basics of reading the images that appeared on the machine's screen. In simple terms, the ultrasound probe is best kept at around a 60 degree angle to the blood vessels for the best detection of blood velocity. The flow direction is also detected by the flow using Doppler effects. If the color showed RED, the flow direction was toward the probe; if it was BLUE, the flow was away from the probe. Using the velocity and direction, Dr. Chiang seemed to find his way around the lower vasculature towards the hidden clots that existed. I noticed while he moved the probe that there were areas where both colors were prominent in the lumen of the vessels. He told me that it was indicative of plaque buildup, which causes turbulence of the blood. Using these cues, he was able to make a rough guess of where a possible clot may reside. I was having trouble in the beginning just trying to orient myself between the vessels and its surroundings, so I was amazed at how he knew where exactly he was in the vasculature.

One technique of identifying the presence of DVT that I thought was interesting involved manually applying pressure to the distal portions of the veins to alter the blood flow. If there was a DVT, the flow would not be affected by the external occlusion. This technique, termed "augmentation", was used on all of the patients that came in that morning. The types of cases that came in included patients with varicose veins, intermittent claudication, pitting edema, and confirmed DVT in the femoral artery. In the patient with a confirmed DVT, it turned out that the major arterial vessels below one of her knees were not functional, but the venous vasculature was fine. The patient, fortunately, showed no signs of gangrene because of collateral vasculature and recanulization that was perfusing a sufficient supply of blood to the area. By lunch time I had seen enough patients to finally get the hang of what I was seeing on the imaging screen.

The afternoon schedule was again in the "BVG room" except this time the attending physician I followed was Dr. Hsu. The patients he examined next all had artificial blood vessels grafted into one of their upper extremities. Dr. Hsu performed follow-up exams on the condition of their grafts and also tried to figure out what was wrong if they experienced problems with the grafts. One of the patients, unfortunately, was experiencing more than 50% stenosis at the graft-venous junction. The placement of a graft involved creating a fistula between an artery and vein. In this case, the graft connected the basilica vein to the brachial artery. The stenosis was affecting the blood flow more than Dr. Hsu would have like, so he decided the patient should go in for an immediate angioplasty.

The angioplasty took place in the Catheterization Lab, where they used flouroscopy to guide the procedure. It was amazing watching them insert a guide wire through the radial artery, through the graft, all the way to the site of the stenosis. Then a catheter with a balloon at the end was inserted over the wire and inflated to expand the collapsed junction. After a few minutes of having the balloon in place, the catheter and wire were removed. I noticed a significant enlargement of the vessel after that. Just a side note, the patient was conscious the entire time! That was probably the most surprising thing because I had no idea that a procedure like that did not require patient sedation. The Cath Lab turned out to be an exciting part of Cardiology, and I am looking forward to spending more time there the rest of the week.