Objective: To analyze the clinical and angiographic characteristics of mid-ventricular hypertrophic obstructive cardiomyopathy (MV-HOCM).
Methods: MV-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.
Results: Of 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.
Conclusion: MV-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.