OBJECTIVETo analyze the clinical and angiographic characteristics of mid-ventricular hypertrophic obstructive cardiomyopathy (MV-HOCM).

METHODSMV-HOCM was diagnosed in 5 patients [3 males, mean age: 16 - 73 (44 ± 22) years]. Left ventricular catheterization and angiography were performed in all patients, and the pressures were recorded in the left ventricular apical chamber, basal chamber, outflow tract and ascending aorta.

RESULTSOf five patients with MV-HOCM, chest discomfort occurred in four patients and syncope in two patients. All patients presented systolic murmur and asymmetric left ventricular hypertrophy. The thickness of ventricular septum was 19 - 31 (23.8 ± 5.4) mm, the dimension of left ventricle was 35 - 55 (43.4 ± 7.4) mm and the LVEF was 53% - 70% (64.2% ± 6.9%). Electrocardiogram showed left ventricular hypertrophy with Q waves in all patients, ventricular tachycardia in 1 patient and complete left bundle branch block in 1 patient. Mid-ventricular obstruction was found in all patients and the pressure gradient in mid-ventricle was 45 - 102 (68.6 ± 24.1) mm Hg (1 mm Hg = 0.133 kPa). Coronary angiogram documented muscular bridge presented in 1 patient and coronary artery disease in 1 patient. Left ventricular apical aneurysm was seen in 2 patients.

CONCLUSIONMV-HOCM was a distinguished subtype of hypertrophic obstructive cardiomyopathy, and left cardiac catheterization and angiography examinations are necessary for confirming diagnosis and guiding related therapy.