A 64-year-old man comes to the physician with a 2-week history of lightheadedness. He describes episodes of feeling woozy and a sense of heaviness in his head with squatting as he worked in his garden. He also describes occasional headaches that have recently become worse. He has no palpitations and has not lost consciousness. He has known nonischemic cardiomyopathy with a biventricular automatic implantable cardioverter defibrillator placed 2 years ago and a lead revision 1 month ago. Three weeks ago, an echocardiogram showed a left ventricular ejection fraction of 30%.
His supine blood pressure is 122/75 mm Hg, standing blood pressure is 125/78 mm Hg, and pulse is 60/min. Examination shows a plethoric face. The neck and upper chest veins are distended. No enlarged lymph nodes are palpated. A 2/6 holosystolic murmur radiating to the axilla is heard at the apex. Lungs are clear to auscultation. The liver span is 10 cm. There is trace bilateral edema of the lower extremities. Symmetrical pulses are palpated on the upper and lower extremities bilaterally.
Electrocardiogram shows atrioventricular sequential pacing.
Which of the following is the most likely diagnosis?

Question

A 64-year-old man comes to the physician with a 2-week history of lightheadedness.  He describes episodes of feeling woozy and a sense of heaviness in his head with squatting as he worked in his garden.  He also describes occasional headaches that have recently become worse.  He has no palpitations and has not lost consciousness.  He has known nonischemic cardiomyopathy with a biventricular automatic implantable cardioverter defibrillator placed 2 years ago and a lead revision 1 month ago.  Three weeks ago, an echocardiogram showed a left ventricular ejection fraction of 30%.
His supine blood pressure is 122/75 mm Hg, standing blood pressure is 125/78 mm Hg, and pulse is 60/min.  Examination shows a plethoric face.  The neck and upper chest veins are distended.  No enlarged lymph nodes are palpated.  A 2/6 holosystolic murmur radiating to the axilla is heard at the apex.  Lungs are clear to auscultation.  The liver span is 10 cm.  There is trace bilateral edema of the lower extremities.  Symmetrical pulses are palpated on the upper and lower extremities bilaterally.
Electrocardiogram shows atrioventricular sequential pacing.
Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient's clinical presentation (presyncope during squatting and worsening headaches) after recent automatic implantable cardioverter defibrillator (AICD) lead revision suggests superior vena cava (SVC) syndrome. SVC syndrome is most commonly due to tumor compression. However, transvenous AICD implantation can induce thrombosis and occlusion around the leads, resulting in SVC syndrome. Although the body tries to offset the high venous pressure by creating venous collaterals, central venous pressure usually remains high and causes symptoms. Risk factors for SVC include the number of ICD leads, endothelial damage during insertion, thrombophilic state, and infections. Symptoms may develop any time after AICD implantation but usually occur 1-15 months after the procedure. Typical manifestations include dyspnea, head fullness, facial/arm swelling, or chest wall edema that may worsen with bending or lying down. Patients may also develop episodic syncope or presyncope. Bilateral upper-extremity venography is the gold standard for diagnosing SVC syndrome. However, contrast-enhanced chest computed tomography is usually done first to show the extent of the venous blockage, visualize collaterals, and possibly identify the causative factor. Therapy usually involves long-term anticoagulation. Patients with more extensive clot or severe symptoms may require thrombolysis, stent implantation, bypass surgery, or extraction of the leads and re-implantation. (Choice A) Constrictive pericarditis usually presents with worsening peripheral edema or anasarca and extreme fatigability, especially in response to exertion. Physical examination shows an elevated jugular venous pressure, pulsus paradoxus, Kussmaul's sign, and pericardial knock. (Choice B) Pancoast tumor usually invades the brachial plexus, parietal pleura, surrounding fascia, ribs, and vertebral bodies. Patients typically present with shoulder pain, Horner's syndrome, and hand muscle weakness/atrophy. (Choice C) Subclavian steal syndrome is usually due to atherosclerotic narrowing of the proximal subclavian artery, which results in flow reversal in the ipsilateral vertebral artery. This occurs most often on the left side, and many patients are asymptomatic. A significant percentage has symptoms of arterial insufficiency in the affected upper extremity (eg, exercise-induced fatigue, pain, numbness, coolness, fatigue). Some patients have symptoms relative to vertebral-basilar artery insufficiency (eg, dizziness, vertigo, disequilibrium, drop attacks). (Choice E) Ventricular arrhythmias would not explain this patient's dilated neck and upper chest veins. Educational objective: Superior vena cava (SVC) syndrome is most commonly due to tumor compression. However, implantation of a transvenous automatic implantable cardioverter defibrillator can induce thrombosis and occlusion around the leads, resulting in SVC syndrome. Bilateral upper-extremity venography is the gold standard for diagnosing SVC syndrome. However, contrast-enhanced chest computed tomography is usually the initial test of choice. __________ References: Superior vena cava syndrome after implantation of a transvenous cardioverter defibrillator. (http://www.ncbi.nlm.nih.gov/pubmed/7588909) Superior vena cava syndrome and syncope in an implantable cardioverter defibrillator recipient. (http://www.ncbi.nlm.nih.gov/pubmed/15121071)

A 64-Year-Old Man Comes to the Physician with a 2-Week