Question

1. A patient with deep vein thrombosis in his leg comes into the emergency room because the clot in his leg has broken free. To the dismay of the doctor, the clot, which began in the great saphenous vein of the leg, has now lodged in his kidneys. At first, the doctor is baffled as to how that could happen. However, looking at the patient’s medical records, she discovers that the patient has a history of heart problems. Specifically, the patient has suffered from valvular stenosis of the atrioventricular valves, as well as a foramen ovale that did not close completely at birth.
   1. Why was the doctor initially surprised to find the clot in the kidneys? What organ did she expect it to be in? (1 point)

2. Only one of the two heart conditions listed could explain how the clot got to the kidneys. Which one? (1 point)

3. Trace the path of the clot from the great saphenous vein to the interlobar artery of the kidney in detail, naming all the blood vessels/heart chambers along the way. You may find the last section of Chapter 20 helpful here. (7 points)

Answer 1

a) The pathway of normal blood flow is :

Veins ------------> Right side of heart ------------> Pulmonary vasculature ------------> Left side of heart ------------> Arteries ------------> back to veins.

So, a clot dislodged from the saphenous vein ( a vein in the lower limb) will pass through the right side of heart to the pulmonary vasculature. The clot cannot pass from the pulmonary ateries to pulmonary veins through the capillary network between them. So, it cannot pass to the left side of heart and from there in to the arteries.

This is the reason why the doctor was initially surprised to find the clot in the kidneys. He expected it to get lodged in the pulmonary vasculature - causing pulmonary embolism.

---------------------------------------------------------------------------------------------------

b) Answer : Patent foramen ovale

Patent foramen ovale is a communication between the right atrium and the left atrium. If the patient had patent foramen ovale, then the clot might have reached the left atrium from the right atrium directly, bypassing the pulmonary vasculature.

So, if the patient had patent foramen ovale, then it is possible that the clot enters the arterial system and thereby to the renal arteries.

---------------------------------------------------------------------------------------------------

c) The path of the clot from the great saphenous vein to the interlobar artery of the kidney is as follows :

..