Not All Systolic Velocities Indicate Obstruction in Hypertrophic Cardiomyopathy: A Simultaneous Doppler Catheterization Study

Abstract

A 43-year-old man with the diagnosis of hypertrophic cardiomyopathy presented with symptoms of dyspnea on exertion. Magnetic resonance imaging and echocardiography showed severe hypertrophy but no evidence of outflow tract obstruction at rest, by either visualization of systolic anterior motion (SAM) of the mitral valve or turbulent high-velocity jets (Figure 1 and Movie 1). On physical examination, he had no murmur at rest or with provocative maneuvers. Because the clinical symptoms were out of proportion to the noninvasive findings, a cardiac catheterization study with simultaneous transthoracic Doppler echocardiography was undertaken to determine whether a dynamic outflow tract obstruction was present. A high-fidelity micromanometer catheter advanced through a transseptal approach was used to measure the left ventricular (LV) pressure at the base and the apex with a simultaneous central aortic pressure recording. There was no catheter pressure gradient between the aorta and LV apex either at rest or after provocation with isoproterenol (Figure 2). There was no SAM of the mitral valve. Despite the absence of pressure gradient and SAM, there was a systolic late-peaking velocity of 4 m/s on continuous wave Doppler interrogation from the apical window during the isoproterenol infusion (Figure 3). The LV pressure catheter was confirmed to be in the LV apex by 2-dimensional echocardiography during these recordings (Figure 4 and Movie 2).