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(Circulation. 1999;100:807-812.)
© 1999 American Heart Association, Inc.
Clinical Investigation and Reports |
Ventricular Pacing With Premature Excitation for Treatment of Hypertensive-Cardiac Hypertrophy With Cavity-Obliteration
From the Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
Correspondence to David A. Kass, MD, Halsted 500, Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21287. E-mail dkass{at}bme.jhu.edu
Background—Hypertensive left ventricular hypertrophy with supranormal systolic ejection and distal cavity obliteration (HHCO) can result in debilitating exertional fatigue and dyspnea. Dual-chamber pacing with ventricular preactivation generates discoordinate contraction, which can limit cavity obliteration and thereby increase potential ejection reserve. Accordingly, we hypothesized that pacing may improve exercise tolerance long-term in this syndrome.
Methods and Results—Dual-chamber pacemakers were implanted in 9
patients with exertional dyspnea caused by HHCO. Intrinsic atrial rate
was sensed, and ventricular preactivation was achieved by
shortening the atrial-ventricular delay. Pacing was on or
off for successive 3-month periods (randomized, double-blind,
crossover design), followed by 6 additional pacing-on months.
Metabolic exercise testing, quality-of-life assessment, and
rest and dobutamine-stress
echocardiographic/Doppler data were obtained. After
3 months of pacing-on, exercise duration rose from 324±133 to 588±238
s (mean±SD; P=0.001, with 7 of 9 patients improving
30%), and maximal oxygen consumption increased from 13.6±2.9 to
16.7±3.3 mL of O2 · min-1 ·
kg-1 (P<0.02). Both parameters
were little changed from baseline during the pacing-off period.
Improved exercise capacity persisted at 1-year follow-up. Clinical
symptoms and activities of daily living improved during the pacing-on
period and stayed improved at 1 year, but they were little changed
during the pacing-off period. Despite similar basal values, stroke
volume (P<0.001) and cardiac output
(P<0.02) increased with dobutamine
stimulation 2 to 3 times more after 1 year of follow-up as compared
with baseline.
Conclusions—Long-term dual-chamber pacing can improve exercise capacity, cardiac reserve, clinical symptoms, and activities of daily living in patients with HHCO. This therapy may provide a novel alternative for patients in whom traditional pharmacological treatment proves inadequate.
Key Words: pacing • hypertension • exercise • hypertrophy • heart failure
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