Mid-Ventricular Hypertrophic Obstructive Cardiomyopathy Complicated by an Apical Aneurysm, Presenting as Ventricular Tachycardia

69-year-old woman presented to the emergency department with palpitations and dizziness of half an hour duration. The patient's history included dyslipidemia under atorvastatin. The patient was hemodynamically stable. The 12-lead surface electrocardiogram demonstrated sustained ventricular tachycardia (VT) with a left ventricular origin and north-west axis at 200 beats/min (Fig. 1A). Cardioversion with intravenous procainamide administration revealed sinus rhythm with left-axis deviation and deep T-wave inversion in the anterior leads (Fig. 1B). Two-dimensional (Fig. 1D and E), contrast (Fig. 1F), and 3-dimensional (Fig. 1G and H) echocardiography revealed mid-ventricular hypertrophy with an apical aneurysm, and an intraventricular flow velocity of 4 m/s (Fig. 1I). Coronary arteriography demonstrated normal coronary arteries, while left ventriculography (Fig. 1C) revealed mid-ventricular obliteration with an abrupt drop in intraventricular pressure from 280 mmHg to 160 mmHg, measured with the pig-tail catheter.

Fig. 1.

A: Presenting electrocardiogram showing ventricular tachycardia at 200 beats/min. B: Electrocardiogram revealing sinus rhythm with deep T-wave inversion in the anterior leads after intravenous procainamide administration. C: Left ventriculography demonstrating mid-ventricular obliteration. D and E: Two-dimensional echocardiography. F: Contrast echocardiography. G and H: Three-dimensional echocardiography, showing left mid-ventricular hypertrophy with an apical aneurysm. I: Intraventricular flow velocity of 4 m/s.

Mid-ventricular obstructive hypertrophy cardiomyopathy comprises a rare subtype of hypertrophic cardiomyopathies (HCM), accounting for only 1% of cases.1) It is characterized by the presence of a pressure gradient between the apical and basal chambers of the left ventricle (LV). The mid-cavity obstruction is the result of the mid-systolic muscular apposition of the septum and LV free wall producing distinct proximal and distal chambers, resembling an "hourglass" shape.2) Furthermore, LV apical aneurysms are present in up to 2% of patients with HCM, and are associated with intramural thrombus and sustained monomorphic VT.3),4)

Our patient received an implantable cardioverter-defibrillator and was discharged with explicit instructions and medication. This case demonstrates multiple complications and peculiarities of HCM.