A 38-year-old woman is being evaluated for shortness of breath. The patient has had poor exercise tolerance for the last several months that she initially attributed to deconditioning. Over the last several weeks, her symptoms have gotten progressively worse and she currently feels short of breath even during mild exertion. The patient has no family history of heart disease. As part of her evaluation, she undergoes right and left heart catheterization. The following data are obtained:
Left ventricular end-diastolic pressure 10 mm Hg (normal: 3-12 mm Hg) Left ventricular peak systolic pressure 110 mm Hg (normal: 100-140 mm Hg) Pulmonary capillary wedge pressure 36 mm Hg (normal: <12 mm Hg)
Which of the following is the most likely cause of this patient's symptoms?
Show Explanatory Sources
A balloon-tipped pulmonary artery (Swan-Ganz) catheter is often used to obtain hemodynamic measurements in patients with shock and certain cardiopulmonary conditions. During pulmonary artery (right heart) catheterization, the catheter is advanced to a small branch of the pulmonary artery and the balloon is inflated to obstruct blood flow in that vessel and its distal branches (which eventually form the pulmonary veins). Because blood flow toward the left atrium (LA) is obstructed beyond this point of occlusion, the pressure at the tip of the "wedged" catheter becomes nearly equal to the LA pressure and left ventricular end-diastolic pressure (LVEDP). This is referred to as the pulmonary capillary wedge pressure (PCWP).
During normal diastole, the LA pressure is nearly equal to the LVEDP as the open mitral valve offers minimal resistance to flow between the 2 chambers. In patients with mitral stenosis, there is resistance to blood flow from the LA to LV that leads to an increase in the LA pressure. This increase in LA pressure is transmitted back to the pulmonary veins and is recorded as elevated PCWP during pulmonary artery catheterization. If the LA pressure is sufficiently high to overcome the resistance between the LA and LV, LV filling may not be significantly affected, resulting in normal LVEDP.
(Choice A) Aortic stenosis causes a pressure gradient between LV and aortic peak systolic pressures. LVEDP and PCWP can be elevated in patients with aortic stenosis; however, both these values would remain in approximately the same range.
(Choice B) Cardiac tamponade leads to equalization of average intracardiac diastolic pressures (left ventricular, right ventricular, and pulmonary artery diastolic pressures). LVEDP and PCWP are both elevated to a similar degree.
(Choices C and E) Both dilated and restrictive cardiomyopathy are associated with pulmonary and systemic venous congestion, resulting in a similar increase in both LVEDP and PCWP. In dilated cardiomyopathy, this occurs due to systolic dysfunction (impaired ventricular contractility), whereas in restrictive cardiomyopathy this occurs due to diastolic dysfunction (impaired ventricular relaxation/filling).
Educational objective:
Under normal circumstances, pulmonary capillary wedge pressure (PCWP) closely reflects left atrial (LA) and left ventricular end-diastolic pressure (LVEDP). Mitral stenosis leads to an increase in the LA pressure that is reflected as elevated PCWP during pulmonary artery catheterization. Left ventricular filling may be normal, resulting in an increased pressure gradient between the LA and LV during diastole.