A 65-year-old man with a history of coronary artery disease comes to the physician complaining of progressive exertional shortness of breath, fatigue, and lower extremity swelling. His medical history is significant for a myocardial infarction 5 years ago and an electronic pacemaker implanted 2 years ago. His chest x-ray is shown below. A segment of one of the leads is highlighted (arrow). The highlighted segment most likely lies within which of the following structures?

Question

A 65-year-old man with a history of coronary artery disease comes to the physician complaining of progressive exertional shortness of breath, fatigue, and lower extremity swelling.  His medical history is significant for a myocardial infarction 5 years ago and an electronic pacemaker implanted 2 years ago.  His chest x-ray is shown below.  A segment of one of the leads is highlighted (arrow).  The highlighted segment most likely lies within which of the following structures?

Quizplus · Accepted Answer

11ec160b_355b_2697_9249_37ba12afb196_MD0001_00 This patient has a biventricular pacemaker, a device that requires 2 or 3 leads. If 3 leads are used, the first 2 are placed in the right atrium and right ventricle. The third lead is used to pace the left ventricle. Right atrial and ventricular leads are easy to place as they only need to traverse the left subclavian vein and superior vena cava to reach these cardiac chambers. In contrast, the lead that paces the left ventricle is more difficult to position. The preferred transvenous approach involves passing the left ventricular pacing lead from the right atrium into the coronary sinus, which resides in the atrioventricular groove on the posterior aspect of the heart. It is then advanced into one of the lateral venous tributaries in order to optimize left ventricular pacing. (Choice A) The anterior interventricular sulcus courses toward the apex of the heart on its anterior surface. The anterior descending vessels lie in this sulcus. (Choice C) The pulmonary artery lies just to the left of center on the anterior surface of the heart. It courses from the right ventricle toward the aortic arch. Swan-Ganz catheters traverse the pulmonary artery. (Choices D & E) The right atrium and ventricle are visible on the rightmost section of the cardiac silhouette. Educational objective: Left ventricular leads in biventricular pacemakers course through the coronary sinus, which resides in the atrioventricular groove on the posterior aspect of the heart.

A 65-Year-Old Man with a History of Coronary Artery Disease