Effect of intravenous and intracoronary nitroglycerin on left ventricular wall motion and perfusion in patients with coronary artery disease

Use of intra-aortic nitroglycerin in the cardiac catheterization laboratory

The purpose of this study was to determine whether nitroglycerin (NTG) injected into the ascending aorta or left ventricle would safely and effectively lower blood pressure in hypertensive patients undergoing cardiac catheterization. Fifty bolus injections of 297 +/- 67 micrograms (mean +/- SD) NTG were given to patients with a systolic blood pressure (SBP) of > or = 140 mm Hg (mean SBP 188 +/- 20.1 mm Hg). An average drop in systolic blood pressure of 36 +/- 16 mmHg (P < 0.001), diastolic blood pressure of 19 +/- 7 mm Hg (P < 0.001), and left ventricular end-diastolic pressure of 4.7 +/- 4 mm Hg (P = 0.001) was well tolerated in each patient. The mean time to response was 11 +/- 3 sec. Intra-aortic injection of NTG is a safe and effective means to treat hypertensive patients in the cardiac catheterization laboratory.

Effects of isosorbide-5-mononitrate on exercise-induced hemodynamic changes in angina pectoris

Hemodynamic effects of isosorbide-5-mononitrate (ISMN) were studied in 14 patients with effort angina pectoris. Hemodynamic and echocardiographic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and 120 minutes after single oral administration of 20 mg of ISMN. Compared with control exercise testing, the ST segment at peak exercise showed less depression after administration of ISMN (p less than 0.001). At rest, systolic and diastolic blood pressure decreased significantly after administration of ISMN (p less than 0.001 and p less than 0.01, respectively). At rest and at peak exercise, pulmonary artery wedge pressure (both p less than 0.001), left atrial volume (both p less than 0.001) and left ventricular end-diastolic volume (both p less than 0.05) decreased, whereas cardiac index, pressure-rate product and systemic vascular resistance did not change significantly after administration of ISMN. Average time to peak plasma ISMN concentration was 90 minutes and average peak plasma concentration was 460 ng/ml with an elimination half-life of 7 hours. These data suggest that the main mechanism of the antianginal action of ISMN is a reduction in left ventricular preload followed by diminution of myocardial oxygen requirements.

Acute hemodynamic effects of propranolol, glycerylnitrate, and exercise in coronary patients with left ventricular dysfunction

Some adverse effects of beta-blockers in heart failure are counteracted by glycerylnitrate. However, the hemodynamics in this condition after giving both drugs are not well known. We examined the drug combination in exercising coronary patients with left ventricular dysfunction. Elevated left ventricular end-diastolic pressure was a measure of dysfunction. A right-heart catheterization with three successive exercise stress tests was done in 40 patients. At repeated exercise without drugs a "warming up" phenomenon was observed, consisting of small but statistically significant reductions in pulmonary capillary wedge pressure, and heart rate. At exercise propranolol reduced heart rate, cardiac output, systemic blood pressure, left ventricular work, and increased arteriovenous oxygen difference. Glycerylnitrate reduced pulmonary capillary wedge pressure at exercise, but, contrary to the findings at rest, it did not increase heart rate or reduce cardiac output. The drug combination resulted in hemodynamics that were similar to those after propranolol alone, except for a lower pulmonary capillary wedge pressure. The drug combination allowed the patients to exercise with the benefits of the beta-blocker, but at a lower ventricular filling pressure. Thus, the potential hazard of giving beta-blockers to patients with left ventricular dysfunction may be reduced by adding glycerylnitrate.

Effect of intracoronary nitroglycerin on myocardial blood flow and distribution in pacing-induced angina pectoris. Quantitative assessment by single-photon emission tomography

Changes in regional coronary flow after administration of intracoronary nitroglycerin were assessed by measuring total coronary blood flow (using coronary sinus flow catheters) and its regional distribution (by quantitative single-photon emission tomography of injected radioactive microspheres). After pacing to angina, 10 patients with coronary artery disease received serial selective left coronary injections of technetium-99m microspheres, 40 micrograms of nitroglycerin, and indium-111 microspheres. Significant changes in coronary flow distribution were determined by subtracting prenitroglycerin from postnitroglycerin tomographic profiles. Perfusion of each myocardial segment was classified as normal mildly, moderately or severely compromised, based on upstream coronary anatomy. The overall increase in coronary flow was 23% in the normal territories and 33%, 44% and 15% (p less than 0.05), in the mildly, moderately and severely compromised territories, respectively, compared with control values. Thus, intracoronary nitroglycerin increased coronary blood flow to all perfusion territories. The increase in distribution of coronary flow was greatest in the mildly and moderately compromised regions and the least in the most severely compromised regions; this is probably a reflection of the underlying coronary reserve.

Comparative effects of nitroglycerin, nifedipine and metoprolol on regional left ventricular function in patients with one-vessel coronary disease

To compare acute effects of nitroglycerin (0.8 mg sublingually), nifedipine (5 ng/kg/min i.v.) and metoprolol (0.15 mg/kg i.v.) on normal, ischemic and scarred myocardial segments in man, we performed simultaneous hemodynamic and radionuclide measurements of left ventricular functions. Sixteen patients with isolated left anterior descending (LAD) disease were studied at rest and during exercise. Nine patients had angina and exercise-induced ischemia (LAD stenosis) and seven patients had previous transmural myocardial infarction and no ischemic changes during thallium imaging (LAD occlusion). The effects of the drugs on regional ejection fraction of the involved anteroseptal region and the normal posterolateral area were compared. Global ejection fraction at rest did not change after nitroglycerin, increased after nifedipine and decreased after metoprolol. In patients with ischemia, the exercise ejection fraction improved after all drugs due to increased regional ejection fraction in ischemic segments: i.e., a regional antiischemic effect evidenced by improved regional function could be demonstrated with all three agents. Regional ejection fraction increased from 35.8 +/- 19.5% to 66.2 +/- 15.2% (+/- SD) after nitroglycerin (p less than 0.001), to 61.7 +/- 8.7% after nifedipine (p less than 0.001), and to 48.4 +/- 7.0% after metoprolol (p less than 0.01). In regions of myocardial scar, regional ejection fraction was not changed after any drug. In normal areas, regional ejection fraction remained unchanged after nitroglycerin and nifedipine, but decreased after metoprolol. Despite similar antiischemic effects of all three drugs, underlying hemodynamic mechanisms were quite different and may provide a rationale for combined forms of treatment. These results may help to select optimal drug combinations to improve myocardial performance in patients with chronic ischemic heart disease.