A case of hypertrophic cardiomyopathy with mid-ventricular obstruction (MVO) — Dramatic long-term improvement with a DDD pacemaker as assessed by diastolic paradoxical jet flow velocity

Abstract

A 68-year-old woman complaining of exertional chest and back pain was referred to our hospital for a preoperative evaluation for gastric cancer. She had been treated with a β-blocker since 2002 after being diagnosed with hypertrophic obstructive cardiomyopathy (HOCM) at another hospital. The frequency of her chest and back pain episodes during stair climbing and rapid walking had increased in the previous year. Based on the studies below, a permanent DDD pacemaker with an AV delay of 80 ms was implanted at a heart rate setting of 60/min. Surgery for gastric cancer was performed uneventfully 2 months later. Continuous-waveDoppler imaging (Fig.1A)demonstratedbloodflow from the apex to the base of the left ventricle during early systole (white arrowheads) followed by high-speed blood flowduring diastole, forming biphasicwaves. The latter part of thewave is generally known as diastolic paradoxical jet flow (yellowarrows). The blood flow from the base to the apex showed triphasic waves, in which E-waves [E], A-waves [A], and high-speed bloodflow [H]were observed in the diastolic, presystolic, and early systolic phases, respectively. Color Doppler imaging of the apical four-chamber view (Fig. 1B) revealed so-called diastolic paradoxical jet flow from the apex to the base of the left ventricle (shown in blue) during diastole, with the vortex flows forming a mosaic pattern. Furthermore, as her main complaint was chest and back pain during stair climbing and rapid walking, a hemodynamic assessment was performed during exertion. After the administration of isoproterenol, the patient's heart rate increased to 110/min, and chest pain developed. In addition, her diastolic paradoxical jet flow velocity was elevated to 544 cm/s (Fig. 1C, yellow arrows), and the maximal pressure gradient increased to 119 mmHg, as estimated by continuous-wave Doppler imaging. Immediately after the start of pacing in VVI mode at a heart rate of 115/min, her diastolic paradoxical jet flow velocity decreased to less than 200 cm/s (Fig. 1D, yellow arrows). At 20 months after surgery, she is doing well without any complaints. Her diastolic paradoxical jet flow velocity was 159 cm/s at the last follow-up (Fig. 1E, yellow arrows), and her maximal pressure gradient was 10.1 mmHg, as estimated by continuous-wave Doppler imaging. The coronary cine angiogram revealed normal epicardial coronary arteries. A left ventriculogram confirmed mid-ventricular obstruction combined with an apical aneurysm, which seemed to be enlarged compared with that seen in 2002. During cardiac catheterization, simultaneous pressure measurements at the apex and base of the left ventricle demonstrated a maximal pressure gradient of 162 mmHg in the control conditions (Fig. 2, 1). Using an AV sequential pacemaker with electrodes placed in the right atrium and the right ventricle, her maximal pressure gradient was decreased from 162 mmHg to 116 mmHg (Fig. 2,2) and 20 mmHg (Fig. 2, 3) as the atrioventricular (AV) conduction delay was shortened to 120 ms and then to 70 ms, respectively. It should also be noted that the pressure gradient detected between the apex