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

Left ventricular cavity obliteration (LVCO) was first described as the cause of the intracavity pressure gradient (ICG) in hypertrophic obstructive cardiomyopathy (HOCM) and has been proposed as the cause of apical aneurysm seen with HOCM. MDs and sonographers sometimes confuse the spectral profiles of the ICG with the LV outflow tract (LVOT) gradient associated with HOCM.

To clarify the cause and characteristics of the ICG in patients with LVCO in paients without HOCM or significant LVH, we assessed 87 patients of the most recent 100 patients mined from our echo database with the phrase "cavity obliteration" entered on the report - 13 patients with HOCM or severe LVH were excluded. ICG was correlated with extent and duration of LV obliteration. For comparison, the spectral profiles of the LVOT gradient in 25 patients with HOCM and severe systolic anterior motion of the mitral valve (SAM), and 25 patients with severe aortic stenosis (AS) were assessed and compared with the spectral profile associated with the ICG seen with LVCO in a subset of 25 patients with ICG of 36 mmHg or greater.

The majority (55%) of patients with LVCO have an ICG less than 36 mmHg, with a range from 2 to 61 mmHg (mean 24 mmHg). Higher ICG is associated with greater extent of LV apposition and more prolonged apposition of LV walls. The spectral profile of patients with AS, HOCM and LVCO can be 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 intra cavitary gradients < 36 mmHg. The magnitude of ICG is quantitatively associated with extent and duration of LVCO. Spectral profiles of severe AS, HOCM, and LVCO can be differentiated by the peak/mean gradient ratio.