MOKSH USMLE

Q.158 Symptoms or signs of atherosclerotic occlusive disease of the bifurcation of the,

The answer is C. The major threat to patients with arterial occlusive disease is limb loss. Ischemic ulceration, neuropathy, rest pain, and gangrene represent advanced stages of arterial insufficiency and warrant reconstructive surgery whenever clinically feasible. Claudication, in most cases, reflects mild ischemia; the majority of affected patients are successfully managed without surgery (only 2.5% develop gangrene). Most will stabilize or improve with development of increased collateral blood flow following institution of a program of daily exercise, cessation of smoking, and weight loss. Vasodilator drugs have been shown to have little benefit in the conservative management of intermittent claudication.

Q.157 Conservative management rather than reconstructive arterial surgery is generally recommended for patients with,

The answer is D. In a recent prospective, randomized, multicenter trial involving 1662 patients in a study known as the Asymptomatic Carotid Atherosclerosis Study, patients with asymptomatic carotid artery stenosis of 60% or greater reduction in diameter and whose general health made them good candidates for elective surgery were found to have a significant reduction in the 5-year risk for ipsilateral stroke with surgery compared with medically treated cohorts (5.1 vs. 11.0%). Medically treated patients were treated with aspirin on a daily basis. Warfarin has not been shown to be effective in the management of patients with carotid disease. Angioplasty of carotid stenoses is being performed in some institutions on a purely investigational basis and to date has not replaced surgery as the treatment for high-grade carotid stenoses.

Q.156

Q.156 An arteriogram on the above patient is shown below.

The answer is C. Most abdominal aortic aneurysms are asymptomatic and are discovered on palpation by a physician. A radiograph of the abdomen is useful in demonstrating the aneurysm if there is calcification in the walls. Ultrasound is generally the first diagnostic procedure in confirming the presence of an aneurysm, with arteriography being performed if the aneurysm is considered large enough to require resection (greater than 5 cm in diameter). Recently CT scan has been found to be useful as a preoperative study in patients suspected of having aneurysms. Surgery should be performed despite the absence of symptoms and can be carried out with a mortality of less than 5%. With leaking or ruptured aneurysms, the operative mortality associated with this emergency situation is upward of 75%. The patient’s age is not a contraindication to surgery, because several studies have demonstrated a low mortality (less than 5%) and satisfactory long-term survival and quality of life in elderly, even octogenarian, patients.

Q.155

Q.155 An 80-year-old man is found to have an asymptomatic abdominal mass. An arteriogram is obtained, which is pictured below.

The answer is D. The CT scan reveals a fractured ring of calcification in the abdominal aorta with significant density in the paraaortic area. The inferior mesenteric artery (IMA) is always at risk in patients with the changes in the vessel wall characteristic of abdominal aneurysms, but particularly so in the presence of rupture and retroperitoneal dissection of blood under systemic arterial pressures. The incidence of ischemic colitis following abdominal aortic resection is about 2%. Blood flow to the left colon normally derives from the IMA with collateral flow from the middle and inferior hemorrhoidal vessels. The superior mesenteric artery (SMA) may also contribute via the marginal artery of Drummond. If the SMA is stenotic or occluded, flow to the left colon will be primarily dependent on an intact IMA. The IMA is usually ligated at the time of aneurysmorrhaphy. Those patients at highest risk for 278 Surgery diminished flow through collateral vessels are those with a history of visceral angina, those found to have a patent IMA at the time of operation, patients who have suffered an episode of hypotension following rupture of an aneurysm, those in whom preoperative angiograms reveal occlusion of the SMA, and those in whom Doppler flow signals along the mesenteric border cease following occlusion of the IMA. Recognition of bowel ischemia at the time of operation should be treated by reimplantation of the IMA into the graft to restore flow.

Q.154

Q.154 A 76-year-old woman is admitted with back pain and hypotension. A CT scan (shown below) is obtained, and the patient is taken to the operating room. Three days after resection of a ruptured abdominal aortic aneurysm, she complains of severe, dull left flank pain and passes bloody mucus per rectum.

The answer is E. Low-dose heparin and pneumatic compression stockings have been shown to be effective prophylaxis against deep vein thrombosis; however, they are not effective against established thrombosis, the treatment for which is therapeutic heparinization. Salicylate has not been convincingly shown to have either a prophylactic or therapeutic role in the treatment of deep vein thrombosis. Even following prompt, aggressive treatment of deep vein thrombosis of the calf, as many as half of affected patients will develop symptoms of chronic venous hypertension, and a larger number will have abnormal venous hemodynamic findings. Untreated vein thrombosis of the calf may propagate into the larger popliteal veins and cause life-threatening pulmonary embolism.

The answer is C. “Coin lesions” have been defined as densities within the lung field of up to 4 cm, usually round, and free of signs of infections such as cavitation or surrounding infiltrates. Malignant solitary lesions may contain flecks of calcification, but heavy calcification or concentric rings of calcium generally suggest a benign etiology. The differential diagnosis for coin lesions includes primary pulmonary carcinomas, metastatic carcinomas to the lung, benign lung neoplasms such as chondromas and other benign lung processes such as granulomas, or vascular abnormalities such as arteriovenous malformations. The likelihood that a coin lesion is a primary lung malignancy increases linearly with age: 15% at age 40, 40% at age 55, 70% at age 75. With the diminishing frequency of granulomatous disease and the continued rise in lung cancers, such lesions should be removed because there is an excellent chance of cure if the lesion is a primary lung malignancy. If the patient has had a previous malignancy of tissue other than lung, the likelihood that the lesion represents a metastatic lesion depends on the tissue of origin of the previous malignancy. If all patients with a history of prior cancer are considered together, a lung nodule will be a new lung primary in 60%, a metastatic lesion in 25%, and a benign process in 15% of cases. However, 80% of solitary lesions in patients with melanoma represent metastatic disease, while only 40% of lesions in patients with breast cancer represent metastasis, and solitary lesions in patients with colon carcinoma are equally likely to be metastatic or primary lung cancers.