Author + information
- Received February 14, 1992
- Revision received December 29, 1992
- Accepted January 4, 1993
- Published online July 1, 1993.
- Howard L. Haber, MD1,
- Christopher L. Simek, MD,
- James D. Bergin, MD, FACC,
- Alberto Sadun, PhD,
- Lawrence W. Gimple, MD, FACC,
- Eric R. Powers, MD, FACC and
- Marc D. Feldman, MD, FACC∗,1
- ↵∗Address for correspondence: Marc D. Feldman, MD, Box 158, Division of Cardiology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908.
Objectives. We hypothesized that bolus intravenous nitroglycerin would be an afterload-reducing agent in patients with excessive initial afterload for their level of left ventricular systolic function. Conversely, bolus intravenous nitroglycerin should be a preload-reducing in patients without excessive initial afterload.
Background. Although nitroglycerin has both preload- and afterload-reducing actions, methods to predict its predominant site of action in an individual patient have not been previously described.
Methods. Left ventricular pressure-volume relations were recorded with micromanometer and conductance catheters during bolus injection of intravenous nitroglycerin in 27 patients with both normal left ventricular systolic function and varying degrees of congestive heart failure. Preload was determined by end-diastolic volume, afterload by effective arterial elastance, left ventricular systolic function by end-systolic elastance and coupling of afterload and ventricular function by the ratio of effective arterial elastance to end-systolic elastance (EaEesratio). An EaEesratio >1 was defined as excessive afterload for the level of ventricular function.
Results. Patients with an initial EaEesratio <1 (Grouup 1) constituted a group of normotensive patients with intact ventricular function who exhibited a perdominant reduction im preload in response to intravenous nitroglycerin. Those with an initial EaEesratio >1 and normal or mildly depressed ventricular function (Group 2a) constitude a group of patients, most of whom were hypertensive, who exhibited a predominant afterload reduction. Finally, those with an initial EaEesratio >1 and abnormal ventricular function (Group 2b) constituted a group of patients with clinical congestive failure who exhibited both preload and afterload reduction but a predominant afterload reduction because stroke volume increased.
Conclusions. Patients with normal arterial elastance and ventricular function respond to nitroglycerin with a predominant preload reduction, whereas patients with either excessive arterial elastance or abnormal ventricular function respond with a predominant afterload reduction.
↵1 This study was supported by a fellowship to Dr. Haber from the American Heart Association, Virginia Affiliate, Inc. (VA-91-F-61) and a FIRST Award (R29HL47046-01) to Dr. Feldman from the National Heart, Lung, and Blood Institute of the National Institutes of Health, Bethesda, Maryland.
☆ This study could not have been performed without the support of Robert Owen, BS, Ian J. Sarembock, MB, ChB, MD and the entire staff of the cardiac catheterization laboratory.
- Received February 14, 1992.
- Revision received December 29, 1992.
- Accepted January 4, 1993.