Midventricular obstruction associated with chronic systemic hypertension and severe left ventricular hypertrophy.

Midventricular obstruction is an uncommon finding previously defined by catheterization and angiographic techniques in patients with hypertrophic cardiomyopathy. This study describes the clinical and echocardiographic findings of 10 consecutive patients (mean age 73 years) with severe concentric left ventricular (LV) hypertrophy and the unusual finding of a dynamic systolic obstruction located in the midportion of the left ventricle. All patients were known to have chronic hypertension, and none had a history or family history of hypertrophic cardiomyopathy. In each case, a well-defined, high velocity, turbulent jet was identified by Doppler color flow imaging and subsequently confirmed with conventional Doppler techniques. Septal and posterior wall thickness averaged 1.67 and 1.57 cm, respectively. Mean LV mass index was 199 g/m2 and ejection fraction averaged 78%. Peak systolic velocity obtained by continuous-wave Doppler averaged 2.7 m/s and appeared as either a "late-peaking" or a "spike and dome" configuration. Seven of 10 patients gave a history of syncope or severe presyncope at the time of echocardiographic examination. At a mean follow-up of 1 year, syncope or presyncope had resolved in 5 patients in whom medication was adjusted based on the ultrasound study, but persisted in 2 patients in whom diuretic therapy was continued. It is concluded that obstruction to systolic flow can occur at the mid-LV level in some patients with severe concentric LV hypertrophy and avoidance of medication known to lower LV volume may relieve symptoms of transient inadequate cardiac output.