Effect of nitrates on left ventricular size and function during exercise: comparison of sublingual nitroglycerin and nitroglycerin paste

Exercise Dynamics in Secondary Mitral Regurgitation: Pathophysiology and Therapeutic Implications

Secondary mitral valve regurgitation (MR) remains a challenging problem in the diagnostic workup and treatment of patients with heart failure. Although secondary MR is characteristically dynamic in nature and sensitive to changes in ventricular geometry and loading, current therapy is mainly focused on resting conditions. An exercise-induced increase in secondary MR, however, is associated with impaired exercise capacity and increased mortality. In an era where a multitude of percutaneous solutions are emerging for the treatment of patients with heart failure, it becomes important to address the dynamic component of secondary MR during exercise as well. A critical reappraisal of the underlying disease mechanisms, in particular the dynamic component during exercise, is of timely importance. This review summarizes the pathophysiological mechanisms involved in the dynamic deterioration of secondary MR during exercise, its functional and prognostic impact, and the way current treatment options affect the dynamic lesion and exercise hemodynamics in general.

Nitroglycerin ointment effective for seven hours in severe angina pectoris

The efficacy and tolerability of nitroglycerin (NTG) ointment were studied in 80 male patients with severe angina pectoris. Two symptom-limited exercise tests were performed on successive days after application of an ointment containing 15 mg NTG or a placebo (P) ointment. The patients were assigned to 4 groups. The study was conducted in a double-blind, cross-over manner. The total amount of work performed was higher in all groups on NTG (46-70%) compared to P ointment. The difference was statistically significant (p less than 0.001) at all points of time from 0.5 to 7 hours. The ST segment depression in ECG at the end of the exercise test was slightly greater on P than on NTG, but the difference was statistically significant only in the 3-hour group (p less than 0.01). The frequencies of headache and dizziness were 35% and 16%, respectively, on NTG. Eight patients (10%) reported that headache was severe enough to prevent regular use of NTG ointment. NTG ointment is effective, has a long duration of action and is relatively well tolerated by patients with severe angina pectoris.

Treatment of congestive heart failure

The past decade has improved our understanding of the pathophysiological mechanisms underlying the congestive heart failure syndrome. The same decade has seen a considerable expansion in modes of therapy for this syndrome. A review of the present forms of treatment is given.

Antianginal effects of nitroglycerin during exercise-induced angina: hemodynamic and left ventricular function changes related to indexes of myocardial oxygen consumption

In 14 patients during exercise, intravenous nitroglycerin improved anginal threshold and increased workload compared with control subjects. At similar workloads, the decreased left ventricular volumes suggested decreased myocardial oxygen consumption due to peripheral unloading. At maximal exercise with nitroglycerin (50 +/- 17 to 79 +/- 15 watts), rate-pressure product and end-diastolic volumes were higher with less ischemia, suggesting myocardial supply was improved by nitroglycerin.

Prolonged hemodynamic effect of a slow-release nitroglycerin ointment

Nitroglycerin (NTG) ointment has been shown to be effective in the treatment of angina pectoris and congestive heart failure. Its duration of action is usually 4 to 6 hours. This study presents data that show that a new slow-release NTG ointment produces hemodynamic improvement over at least 24 hours. Twenty patients with coronary artery disease were tested with serial gated equilibrium radionuclide ventriculography before and at various stages of continuous, once-a-day use of slow-release NTG ointment and 4 days after cessation of therapy. NTG ointment significantly (p less than 0.005) decreased left ventricular end-diastolic and end-systolic volumes both at rest (23% and 33%) and during handgrip exercise (22% and 32%) when examined after continuous usage of at least 24 hours. Ejection fraction increased 21% at rest, from 0.42 +/- 0.15 to 0.51 +/- -0.18, p less than 0.0005). The ratio of peak systolic pressure to end-systolic volume increased 85% at rest (p less than 0.05) and 54% during exercise (p less than 0.01). All values had returned to baseline 4 days after cessation of treatment. Thus, slow-release NTG ointment may be useful in the treatment of angina pectoris and congestive heart failure on a once-a-day basis.

Assessment of the end-systolic pressure-volume relationship in human beings with the use of a time-varying elastance model

The analysis of left ventricular end-systolic pressure-volume relationships in human beings has been hindered by the lack of a practical method of serial volume assessment and by an imprecise definition of end-systole. Modifications of the end-systolic relationship that have been used to circumvent these problems have included the use of single-point end-systolic pressure-volume ratios, the use of peak systolic pressure/minimum ventricular volume points for end-systolic points, and the use of end-ejection as a marker for end-systole. To assess the correlation between the parameters generated by these modifications with the slope (Emax) and volume intercept (VO) of the end-systolic line as defined by Sagawa's model of time-varying elastance, simultaneous measurement of left ventricular pressure and gated radionuclide volume was made in 26 patients under various loading conditions and pressure-volume diagrams were constructed for each loading condition from 32 simultaneous pressure-volume coordinates. Two pressure-volume diagrams were recorded in 14 patients and three pressure-volume diagrams were recorded in 12 patients. Emax and VO were determined in all patients from the slope and volume intercept of the isochronic pressure-volume line with the maximum time-varying elastance as described by Sagawa's model and were designated true Emax and true VO, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of left ventricular function by radionuclide angiography during exercise in normal subjects and in patients with chronic coronary heart disease

Radionuclide angiography permits evaluation of left ventricular performance during exercise. There are several factors that may affect the results in normal subjects and in patients with chronic coronary heart disease. Important among these are the selection criteria: age, sex, level of exercise, exercise end points, ejection fraction at rest and effects of pharmacologic agents. An abnormal ejection fraction response to exercise is not a specific marker for coronary heart disease but may be encountered in other cardiac diseases. In addition to the diagnostic considerations, important prognostic data can be obtained. Further studies are needed to determine the prognostic implications of anatomic findings versus the functional abnormalities induced by exercise in patients with coronary artery disease.

Cutaneous administration of nitroglycerin: a review

Chronic administration of nitroglycerin may have important therapeutic effects in patients with angina, acute myocardial infarction, congestive heart failure and peripheral vascular disease. Because of unpredictable oral absorption and short duration of action, topical preparations provide an alternative mode of administration. New controlled release transdermal preparations appear to produce constant plasma nitroglycerin concentrations of 0.2-0.3 ng/ml that persist for up to 24 hours. Additional clinical trials of the therapeutic response to this drug form are necessary, particularly in regard to the relative hemodynamic efficacy and side-effect profile of sustained vs. fluctuating plasma nitroglycerin concentrations.

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.

Exercise 2-dimensional echocardiography. Quantitation of left ventricular performance in patients with severe angina pectoris

To assess the feasibility and reproducibility of exercise 2-dimensional (2-D) echocardiography for quantitating left ventricular size and performance, 25 patients with angina pectoris due to severe coronary artery disease and 10 normal subjects were studied before and after the administration of nitroglycerin. In 18 (72%) of the 25 patients, suitable biapical 2-D echocardiograms for quantitative analysis were recorded during upright bicycle exercise. Left ventricular volume (Simpson's rule), ejection fraction (EF), and wall motion score (10 segments graded 0 to 3, normal to dyskinetic) were measured at rest, and at peak exercise (control), 30 minutes later at rest, after nitroglycerin at rest, and at peak exercise. EF increased during control exercise in the normal subjects from 57 +/- 16 to 71 +/- 22% (p less than 0.01), but was unchanged in the patients during exercise before nitroglycerin. In 7 patients (39%), marked increases in EF (greater than 0.05 units) during exercise occurred after nitroglycerin administration. The wall motion score increased significantly in the patients during control exercise, from 2.6 +/- 3.4 to 5.6 +/- 4.5, but was less at maximal exercise after nitroglycerin (3.4 +/- 4.0, p less than 0.001). Intra- and interobserver variability in these measurements was acceptable. Thus, quantitation of left ventricular performance during exercise by biapical 2-D echocardiography can be accomplished in a high proportion of patients with coronary artery disease (CAD) and can be used to assess the effects of therapeutic interventions.

The acute hemodynamic effects of intravenous verapamil in coronary artery disease. Assessment by equilibrium-gated radionuclide ventriculography

The acute hemodynamic effects of an i.v. bolus of verapamil, 0.1 mg/kg or 0.06-0.075 mg/kg, were examined by serial radionuclide studies in 46 patients with coronary artery disease. In 20 patients with ejection fractions (EFs) greater than 35% (group 1A), verapamil, 0.1 mg/kg given over 1-11/2 minutes, had a biphasic effect: first, a transient decrease in EF accompanied by increased left ventricular (LV) volumes and cardiac output equivalents; then, an overshoot of EF to values above control, accompanied by a decrease in peripheral vascular resistance and a drastic decrease in LV volumes, while cardiac output equivalent remained slightly elevated. In eight patients with EFs less than 35% (group 1B), only the first effect on EF was noted. In 10 patients with EFs greater than 35% (group 2), verapamil, 0.06-0.075 mg/kg, exerted qualitatively similar but milder effects on hemodynamic function. Finally, verapamil, 0.1 mg/kg given more slowly, over 2-21/2 minutes, produced no significant changes in EF or LV volumes in another eight patients (group 3). The acute effects of verapamil are thus both time-related and dose-dependent. They are also related to the baseline functional reserve of the left ventricle. This study documents that verapamil exerts a depressant effect on LV function. However, the transient nature of this depression and the quick recovery to normal or above-normal values indicate that verapamil, in the doses used in this study, is safe to use intravenously in patients with coronary artery disease.

The transdermal administration of nitrates: an overview

Nitroglycerin has been the mainstay of the medical management of angina pectoris for over 100 years. The long-held clinical impression of the efficacy of nitroglycerin has now been clearly documented in controlled clinical trials designed to evaluate objective response to antianginal agents. Advances in scientific methodology and improved experimental design have contributed to continuing interest in nitrates. Newer uses of nitroglycerin and other nitrates in congestive heart failure and acute myocardial infarction are the result of a developing understanding of the pharmacology of nitrates.

Radionuclide angiographic assessment of global and segmental left ventricular function at rest and during exercise after coronary artery bypass graft surgery

Left ventricular ejection fraction (LVEF) was measured by radionuclide angiography at rest and during supine bicycle exercise before and 3 months after coronary artery bypass graft surgery (CABG) in 20 patients with chronic stable angina. The right anterior oblique gated first-pass technique was used to assess LVEF response to maximal exercise (Wmax), while the left anterior oblique equilibrium-gated technique was used to assess LVEF and relative LV volume changes during graded submaximal exercise. Mean LVEF was unchanged at rest after CABG by both the first-pass (60 +/- 12% vs 60 +/- 12%) and equilibrium-gated (61 +/- 13% vs 62 +/- 13%) measurements. At Wmax, mean first-pass LVEF was significantly higher postoperatively than preoperatively (63 +/- 17% vs 53 +/- 17%; p less than 0.01) with a higher Wmax (750 +/- 182 vs 590 +/- 202 kpm/min; p less than 0.001) and higher rate-pressure product (302 +/- 59 vs 222 +/- 57 units; p less than 0.001). Similarly, equilibrium-gated LVEF levels during graded exercise, using stepwise regression analysis, were significantly higher postoperatively than preoperatively (p less than 0.001); at the highest graded work load, they averaged 63 +/- 19% postoperatively and 53 +/- 17% preoperatively, with higher work loads (500 +/- 190 vs 417 +/- 155; p less than 0.05) and higher rate-pressure products (271 +/- 55 vs 207 +/- 53; p less than 0.001). The increase in exercise LVEF after surgery was due to a marked decrease in the ratio, relative to resting values, of counts-based end-systolic volumes during submaximal exercise (preoperatively 1.91 +/- 1.04; postoperatively 1.14 +/- 0.46; p less than 0.01). The five subjects in whom LVEF decreased significantly during exercise postoperatively all had one or more blocked or stenosed grafts. This study documents, by two independent radionuclide techniques, an improved LVEF during exercise at an increased maximal work capacity and rate-pressure product 3 months after successful CABG.

Verapamil in stable effort angina: effects on left ventricular function evaluated with exercise radionuclide ventriculography

A double blind placebo-controlled study was performed in 12 patients with stable angina pectoris to evaluate the effects of oral verapamil (320 mg/day) on left ventricular function, as measured at rest and during exercise with gated equilibrium radionuclide ventriculography. On verapamil, patients had a lower heart rate-blood pressure product at each work load than with placebo. Anginal threshold increased by 28 +/- 19 watts (p less than 0.005), and maximal exercise capacity increased by 20 +/- 14 watts (p less than 0.001) with verapamil, but the rate-pressure product at the onset of angina and at maximal exercise was unchanged. Left ventricular ejection fraction at rest during verapamil therapy was the same as with placebo therapy. On exercise during placebo therapy, the ejection fraction decreased from 40 +/- 9 to 35 +/- 11 percent (p less than 0.025) because end-systolic volume increased disproportionately compared with end-diastolic volume. On exercise during verapamil therapy, the ejection fraction did not decrease (44 +/- 8 versus 45 +/- 12 percent) and was significantly higher at identical work loads than on placebo because of a smaller increase in end-systolic volume. Oral verapamil is effective treatment for effort angina and may prevent the decrease in left ventricular ejection fraction due to exercise-induced ischemia.

Effect of nitrate on determinants of myocardial oxygen consumption during exercise

We evaluated the effects of isosorbide dinitrate on some of the major determinants of myocardial oxygen demand during upright exercise in ten normal subjects. In addition to heart rate and systolic blood pressure, we assessed left ventricular size and performance by echocardiography. Compared to the control study, heart rate was significantly faster after the nitrate administration at rest (67 +/- 14 versus 83 +/- 21 beats/minute), but there was no difference in heart rate at any stage during exercise. Systolic blood pressure also was significantly lower at rest after nitrate (104 +/- 8 versus 92 +/- 2 mm Hg) but was similar to control after 6 minutes of exercise. Echocardiographic end-diastolic dimension was decreased at rest post-nitrate (45.3 +/- 4.7 versus 40.2 +/- 4.2 mm) and remained significantly reduced during exercise by an analysis of variance. We conclude that a major beneficial effect of nitrates on myocardial oxygen demand during upright exercise is a decrease in left ventricular size which reduces wall tension.

Noninvasive assessment of load reduction in chronic congestive heart failure patients

Therapy with phentolamine can improve the condition of patients with congestive heart failure due to the inotropic effect of this drug as well as its vasodilating action. Therefore, 8 patients with volume-overloaded left ventricles due to aortic insufficiency and mitral insufficiency received 50 mg of phentolamine 4 times a day for 2 weeks. Peak and end systolic wall stress were estimated using a noninvasive echocardiographic technique. The peak systolic wall stress in this group was 133 X 10(3) dynes/sq cm, which is similar to the reported normal value. However, the end systolic wall stress was 89 X 19(3) dynes/sq cm, which is much higher than the reported normal values. After PO administration of phentolamine, the end systolic stress was normalized while the peak systolic stress was reduced below normal. As a result of therapy with phentolamine, the ejection fraction, the percentage of change in the minor axis, and the velocity of circumferential fiber shortening significantly increased. Thus, PO administration of phentolamine can improve left ventricular function in patients with mitral insufficiency and aortic insufficiency.

Response of the left ventricle to stress: effects of exercise, atrial pacing, afterload stress and drugs

A variety of tests are being utilized today to diagnose the presence of ischemic heart disease, assess the prognosis of myocardial and valvular heart disease and evaluate the effects of various pharmacologic agents on cardiac performance. This review summarizes the current evidence regarding the response of left ventricular performance and size to atrial pacing, afterload stress and various forms of exercise. The responses in normal persons and in subjects with coronary heart disease is reviewed and, when applicable, the effects of various pharmacologic agents on exercise performance in these patient groups are examined.