DDD Pacing Therapy Could Serve as a Dual Purpose Treatment in Hypertrophic Obstructive Cardiomyopathy —A Case Report Which Suggests the Importance of Lead Position and the Mechanism—

We treated a patient with hypertrophic obstructive cardiomyopathy (HOCM) who underwent DDD pacing therapy. He suffered from attacks of paroxysmal atrial fibrillation (PAF) complicated by sick sinus syndrome. Initially, we were unable to decrease the left ventricular outflow tract (LVOT) gradient by pacing from the mid-distal portion of the right ventricular (RV) septum. However, by changing the pacing site to the apical portion guided by right ventriculography, it was possible to decrease the LVOT gradient and at the same time reduce the mitral regurgitation. Tissue Doppler imaging (TDI) revealed a marked motion delay of the ventricular septum during DDD pacing. The mechanism of the therapy for HOCM provided by the DDD pacing was clearly confirmed by TDI. Furthermore, a dramatic effect of preventing symptomatic PAF with the use of overdrive pacing in the region of Bachmann's bundle was also observed. This case report provides new insight into DDD pacing therapy for patients with HOCM.