Relief of left ventricular outflow tract obstruction following inadvertent left ventricular apical pacing in a patient with hypertrophic cardiomyopathy

Impact of Right Atrial-Left Ventricular Dual-Chamber Permanent Pacing in Patients With Severely Symptomatic Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

Effective alternatives to surgical myectomy for patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM) remain unestablished. Dual-chamber (DDD) pacing was evaluated in these patients using right atrial (RA) and epicardial left ventricular (LV) leads.

METHODS AND RESULTS

In 6 patients with HOCM refractory to medical therapy and conventional RA-right ventricular (RV) DDD pacing, we implanted DDD pacemakers using RA and epicardial LV leads. The baseline intraventricular pressure gradient before pacemaker implantation was 103+/-44 mmHg. The pressure gradient decreased significantly to 8+/-16 mmHg by temporary RA-LV DDD pacing (p=0.006), while it decreased only to 68+/-25 mmHg by temporary RA-RV pacing (NS). It was nearly eliminated to 1+/-2 mmHg (p=0.027) 3 months after RA-LV DDD pacemaker implantation. LV end-diastolic pressure, cardiac index and systolic aortic pressure did not change significantly. New York Heart Association class improved in all patients (p=0.023). Brain and atrial natriuretic peptide concentrations, respectively 516+/-286 and 143+/-34 pg/ml at baseline, decreased significantly to 230+/-151 and 93+/-44 pg/ml 3 months after implantation (p=0.027 and 0.028).

CONCLUSION

RA-LV DDD pacemaker implantation is a useful option for patients with symptomatic HOCM.

Early results of AV sequential pacing on left ventricular outflow obstruction after Senning procedure

Dual chamber pacing was shown to decrease left ventricular outflow tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy 30 years ago. We report early results of AV sequential pacing from the LV apex in a patient with transposition of the great arteries who is post-Senning procedure. LVOT obstruction resulted from septal deviation and systolic anterior motion of the mitral valve. Pacing was indicated for sinus node dysfunction. AV sequential pacing with a short optimal AV interval of 60 ms demonstrated a 45% reduction in the degree of LVOT obstruction. This article suggests that LVOT obstruction after the Senning procedure can be palliated by asynchronous septal contraction induced by AV sequential pacing, even if the activation is from LV apex, and avoid or postpone surgery in selected situations.

Hypertrophic cardiomyopathy: evaluation and treatment of patients at high risk for sudden death

Hypertrophic cardiomyopathy (HCM) is a heritable disease characterized by LV hypertrophy with markedly variable clinical, morphological, and genetic manifestations. It is the most common cause of sudden death in otherwise healthy young individuals. HCM patients often have disabling symptoms and are prone to arrhythmias. Frequently, there is associated LV systolic and diastolic dysfunction, LV outflow obstruction, and myocardial ischemia. Over the past decade, progress has been made in identifying patients who are at high risk for sudden death, in elucidating potential mechanisms of sudden death, and in defining therapeutic algorithms that may improve prognosis. It has also been possible to determine the genetic defect in some of the patients and to correlate clinical findings with the molecular defects. An exciting development has been the use of dual chamber pacemaker as an alternative to cardiac surgery to improve symptoms and relieve LV outflow obstruction.