Study objectives: Of the hypertrophic obstructive cardiomyopathies, midventricular obstruction (MVO) often has been overlooked. In this study, hemodynamic parameters in patients with MVO were compared with patients with idiopathic hypertrophic subaortic stenosis (IHSS), following which the specific markers for diagnosis of MVO were examined.
Patients and design: Twenty healthy control subjects (mean [± SD] age, 54 ± 8 years), 20 patients with MVO (mean age, 54 ± 13 years), and 12 patients with IHSS (mean age, 58 ± 12 years) participated in this study. Hemodynamic parameters associated with carotid pulse tracing (CPT) and echocardiography were examined.
Measurement and results: Left ventricular ejection time (LVET) and left ventricular pressure gradient (LVPG) were greater in patients with IHSS than in patients with MVO (p < 0.0001 for both). However, left ventricular dimensions and interventricular septal thickness did not vary between patients with MVO and those with IHSS. As specific markers for the diagnosis of patients with MVO, two specific CPT patterns, the “spike-and-dip pattern” and the “spike-and-half-dome pattern,” were identified, but no specific markers were observed echocardiographically. Among patients with MVO, both LVPG and LVET were greater in patients with the spike-and-half-dome pattern than in patients with the spike-and-dip pattern (113 ± 34 vs 57 ± 17 mm Hg, respectively [p < 0.0001]; 318 ± 19 vs 281 ± 27 ms, respectively [p = 0.0033]), but echocardiographic parameters revealed no significant differences between the two types of MVOs. The pattern of continuous-wave Doppler recordings of the left ventricle in patients with the spike-and-half-dome pattern was identical to that of patients with IHSS, but that of patients with the spike-and-dip pattern exhibited concavity from the onset of systole to the point of maximal velocity.
Conclusions: Two specific patterns for the diagnosis of patients with MVO were identified by CPT. These patterns may be strongly related to differences in ejection dynamics.