Left ventricular cavity obliteration: Mechanism of the intracavitary gradient and differentiation from hypertrophic obstructive cardiomyopathy

Abstract

Background Controversy surrounds the cause of the pressure gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM). Left ventricular cavity obliteration (LVCO) was first described as the cause of the gradient but subsequently systolic anterior motion (SAM) of the mitral valve has been established as the cause. Nevertheless, the two gradients, though different in origin and significance, share similar characteristics. They both have a similar “dagger” profile, are obtained from the cardiac apex, are associated with a hyperdynamic left ventricle, and the gradients are worsened by Valsalva. The distinction has clinical relevance, because treating the intracavitary gradient (ICG) of LVCO as if it were a SAM‐associated gradient associated with HOCM would be inappropriate and possibly harmful. Materials and Methods To clarify the cause and characteristics of the ICG in patients with LVCO in patients without HOCM, we assessed the extent and duration of cavity obliteration, and for differentiation, we compared the spectral profiles with patients with HOCM and severe aortic stenosis (AS). Results Higher ICG is associated with a greater extent and more prolonged apposition of LV walls, and smaller left ventricular cavity size. The spectral profile of patients with AS, HOCM, and LVCO is differentiated by the peak/mean gradient ratios of 2 or less, 2–3, and 3 or greater, respectively, in >90% of patients. Most patients with LVCO without HOCM or severe LVH have an ICG < 36 mm Hg. Conclusion The magnitude of ICG is quantitatively associated with the extent and duration of LVCO. Spectral profiles of severe AS, HOCM, and LVCO can be differentiated by the peak/mean gradient ratio.

Diagnosis and Treatment of Obstructive Hypertrophic Cardiomyopathy

“…LVOT acceleration is initially slow, followed by a second phase of acceleration, whereas in MCO, the second phase of acceleration appears to be steeper and faster. Indeed, the second phase of acceleration of the intraventricular gradient's spectral profile appears to be almost exponential and can be compared, rather than to a "dagger", to one side of an inverted half-pipe skateboard ramp [19].…”

Overcoming the Obstacle of Suicide Left Ventricle After Transcatheter Aortic Valve Replacement Phenomenon

“…Except for the anticipated AS gradient (mean gradient: 44 mm Hg; Vmax: 4.2 m/s), a second Doppler peak characteristic of left ventricular outflow tract (LVOT) obstruction with peak gradient of 81 mm Hg was revealed ( Figure 1 ). 1 However, aortic valve area calculation was not possible owing to the distorted LVOT tracing, so we relied on the computed tomography aortic valve (AV) calcium score (2,700 Agaston units) to verify the severity. Computed tomography was used to plan the procedure.…”

Aortic Stenosis Associated with Hypertrophic Cardiomyopathy: A Double Trouble

“…In contrast to valvular AS where CW spectral Doppler displays a symmetric envelope, in both HCM and in LVCO, the Doppler envelope takes a dagger shape configuration, reflecting end-systolic velocities. A recent report found a peak/mean gradient ratio of 2-3 in HCM and ≥3 in LVCO helpful in differentiating between these two conditions [1]. The second diagnostic challenge is the calculation of functional aortic valve area where in the presence of subaortic stenosis, the high trans-LVOT velocities and the significant viscous friction invalidate modeling assumptions made in derivation of the modified Bernoulli equation [2].…”