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

Improved myocardial ischemia detection by combined physical and mental stress testing

The hypothesis that addition of mental stress to physical exercise would modify the circulation response to stress and improve noninvasive detection of myocardial ischemia was tested in a randomized, crossover radionuclide angiocardiographic study. Compared with physical exercise or mental stress alone, combined stress led to higher heart rates and rate-pressure products in early stress stages, to more pronounced symptoms, and to a better discrimination of subjects with and without coronary artery disease by radionuclide angiography.

Effects of sublingual nitroglycerin on the gas exchange response to exercise in stable angina pectoris

To quantitate changes in gas exchange variables that occur after administration of sublingual nitroglycerin in patients with stable angina pectoris, a randomized double-blind 2-period crossover study was performed with continuous expired gas exchange analysis and progressive exercise using individualized ramp treadmill protocols. Significant reductions in minute ventilation and respiratory rate were observed at 5 minutes of exercise during nitroglycerin therapy. Gas exchange variables i.e., minute ventilation, carbon dioxide production and oxygen uptake were significantly increased at the onset of angina after nitroglycerin administration. When techniques for optimizing the assessment of cardiopulmonary function were used, significant improvements in gas exchange variables were demonstrated in stable angina pectoris after administration of sublingual nitroglycerin.

Ischemia in collateral-dependent myocardium: effects of nifedipine and diltiazem in man

It has recently been shown that ischemia in collateral-dependent myocardium may develop at a very variable threshold in anginal patients; accordingly, the aim of this study was to assess whether nifedipine and diltiazem can increase blood flow to collateralized myocardium in man. Nine patients with complete coronary occlusion filled by collaterals, with no other coronary stenosis, normal left ventricular function, and reproducibly positive exercise tests were studied. They underwent exercise tests off therapy and after acute randomized administration of nifedipine (10 mg sublingually), diltiazem (120 mg orally), and nitroglycerin (0.5 mg sublingually), the latter a drug known to increase blood flow to collateralized myocardium. Following nifedipine, time to 1 mm ST segment depression increased significantly (from 430 +/- 176 to 576 +/- 205 seconds, p < 0.01), while heart rate and rate-pressure product remained unchanged (115 +/- 16 vs 121 +/- 17 beats/min and 199 +/- 29 vs 204 +/- 44 beats/min.mm Hg.10(2), respectively, p = NS for both). Similarly, diltiazem significantly increased time to ischemic threshold from baseline to 638 +/- 125 seconds (p < 0.01), but did not change heart rate and rate-pressure product at 1 mm ST segment depression. Submaximal rate-pressure products were significantly lowered by both nifedipine and diltiazem. Nitroglycerin not only significantly improved time to ischemic threshold (from baseline to 666 +/- 76 seconds, p < 0.01), but also increased heart rate (from baseline to 137 +/- 16 beats/min, p < 0.01) and rate-pressure product (from baseline to 242 +/- 48 beats/min.mm Hg.10(2), p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Propionyl-L-carnitine: a new compound in the metabolic approach to the treatment of effort angina

The effects of propionyl-L-carnitine on exercise tolerance of 12 patients with stable exertional angina were assessed in a double-blind, placebo-controlled, cross-over protocol using serial exercise tests. Compared to placebo, propionyl-L-carnitine significantly increased total work from 514 +/- 199 to 600 +/- 209 W (P less than 0.05) (17%) and prolonged exercise time and time to ischemic threshold from 515 +/- 115 to 565 +/- 109 sec (P less than 0.05) (10%) and from 375 +/- 102 to 427 +/- 93 sec (P less than 0.01) (14%), respectively. ST segment depression at the highest common work level was significantly reduced from 0.19 +/- 0.08 to 0.15 +/- 0.08 mV (P less than 0.05) (21%). No significant changes in heart rate, systolic blood pressure, and rate-pressure product at rest, at the highest common work level, on appearance of the ischemic threshold, or at peak exercise were observed after propionyl-L-carnitine treatment. No side effects were observed under propionyl-L-carnitine treatment. This study shows that propionyl-L-carnitine can significantly improve exercise tolerance in patients with stable angina. Our data seem to confirm that propionyl-L-carnitine most likely exerts its protective action via the metabolic pathway.

Clinical evaluation of cardiac function by ambulatory ventricular scintigraphic monitoring (VEST): validation and study of the effects of nitroglycerin and nifedipine in patients with and without coronary artery disease

Global left ventricular function and ECGs were continuously monitored by radionuclide ambulatory ventricular function monitoring (VEST) and validated against multigated blood pool analysis (MUGA) and left ventriculography in 26 subjects (study 1). Ejection fraction by VEST (Y) showed good correlation with Y = 5.5 +/- 0.79 X (r = 0.91), Y = 1.7 +/- 0.86 X' (r = 0.91), and Y = 11.6 + 0.68 X" (r = 0.82) to sitting and supine MUGA and left ventriculography, respectively. In study 2 left ventricular function and ECGs were evaluated at rest and during exercise without any drug (control), with nitroglycerin, and with nifedipine in 21 patients with coronary disease (group I) and six normal subjects (group II). In group I abnormal ejection fraction responses (exercise increase less than or equal to 6%) during the control exercise period were found in 15 patients (71%), ST segment abnormalities in seven (33%), and chest pain in four (18%). Control exercise increased end-diastolic volume (100 to 112 +/- 8%) and end-systolic volume (53 +/- 15% to 63 +/- 22%) and decreased the ejection fraction (47 +/- 15% to 43 +/- 21%). The ejection fraction during exercise increased after nitroglycerin (50 +/- 22%) or nifedipine (54 +/- 21%) (p less than 0.05). In group II the ejection fraction was unchanged between rest and exercise with or without nitroglycerin or nifedipine. Thus combined radionuclide and ECG monitoring by VEST could detect changes in left ventricular function at rest and during exercise over a prolonged period and demonstrated that nitroglycerin and nifedipine improved cardiac function in the ischemic setting with an increased ejection fraction in the upright position.

Prevalence and extent of right ventricular dysfunction after myocardial infarction--relation to location and extent of infarction and left ventricular function

In view of today's efforts to preserve myocardial function in acute myocardial infarction, the prevalence and extent of persistent right ventricular dysfunction was analysed in a prospective study of 127 patients admitted with a first myocardial infarction without thrombolysis. Right ventricular ejection fraction measured at hospital discharge by radionuclide angiocardiography was related to the location of infarction as judged electrocardiographically, its size as estimated enzymatically, and by the simultaneously measured left ventricular ejection fraction. Two opposite patterns of right and left ventricular function were observed in relation to the location of infarction: the right ventricular ejection fraction was significantly depressed in inferior, but not in anterior, infarction and the reverse was true for left ventricular ejection fraction (P less than 0.001 between infarct locations for both right ventricular ejection fraction and left ventricular ejection fraction). There were significant correlations between peak levels of creatine kinase and left ventricular ejection fraction for anterior (r = 0.76, P less than 0.001) and inferior (r = 0.57, P less than 0.001) infarction, while peak levels of creatine kinase and right ventricular ejection fraction correlated only in inferior infarction (r = 0.45, P less than 0.01). There was no overall correlation for left ventricular ejection fraction and right ventricular ejection fraction (r = 0.28, P NS), despite the fact that right ventricular ejection fraction was lower in patients with severely reduced left ventricular ejection fraction than in those with normal left ventricular function (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Propionyl carnitine in stable effort angina

The aim of this study was to investigate the anti-ischemic activity of propionyl carnitine (PC) in 18 informed, volunteer male patients, aged 37-70, suffering from a typical stable effort angina. The study design was randomized, balanced, crossover, and double blinded. The study lasted 75 days. In the first 15 days of washout the patients performed two maximal symptom-limited bicycle tests to verify the repeatability of the parameters examined. Then one group received PC for 30 days 500 mg three times a day, and the other group received placebo (PL) three times a day. At the end of 30 days the groups exchanged treatments. At the end of each period, 2 hours after the last oral administration, the patients performed a maximal symptom-limited bicycle exercise test with increased loads of 10 watts/min. No significant differences were observed between the two tests performed during the wash-out period, for a 1 mm ST-segment depression time, for the time to the end of exercise, and for the rate x pressure product at the same experimental time. The oral administration of PC in coronary patients increased both the 1 mm ST-segment depression time and the time to the end of exercise. Furthermore, the drug reduced the ischemic depression of ST at maximal common work and at maximal work. After PC, the rate x pressure product was not significantly different in relation to placebo at submaximal and maximal exercise. Thus PC seems to have an antiischemiclike effect, probably related to its metabolic activity.

Nitrates: why and how should they be used today? Current status of the clinical usefulness of nitroglycerin, isosorbide dinitrate and isosorbide-5-mononitrate

Nitrates are highly effective both in terminating acute attacks of angina pectoris and in the prophylaxis of symptomatic and asymptomatic myocardial ischemia. Preload reduction by venodilatation is the prevailing mechanism of nitrates in patients with chronic stable angina and is the unique feature distinguishing them from beta and calcium-channel blockers. Nitrates dilate coronary arteries not only in pre- and poststenotic vessels, but also in eccentric lesions. In patients with endothelial dysfunction, nitrates seem to be the physiological substitute for endothelium-derived relaxing factor. During the past decade, however, there has been substantial evidence of a clinically relevant loss of the anti-ischemic effects ("nitrate tolerance"). Many studies with oral dosing of isosorbide dinitrate or isosorbide-5-mononitrate at least three times daily have proven nitrate tolerance in patients with coronary artery disease and/or congestive heart failure. Complete loss of anti-ischemic effects after repetitive, continuous patch attachments has also been found. As we first showed in 1983, intermittent therapy with once-daily ingestion of high-dose sustained-release isosorbide dinitrate was successful in preventing the development of tolerance. Similarly, tolerance to isosorbide-5-mononitrate also does not develop when it is ingested once daily. It is now generally accepted that a daily low-nitrate interval is required to prevent tolerance development. Although the minimal patch-free interval required to prevent tolerance needs further investigation, a 12-h patch-free interval should prevent tolerance in most patients. The prolonged duration of action of once-daily high-dosage administration of sustained-release formulations, the improved patient compliance with a single daily administration, and the increased likelihood of maximal anti-ischemic effects are important reasons for recommending high single daily doses of isosorbide dinitrate or isosorbide-5-mononitrate.

Complementary mechanisms of atenolol and diltiazem in the clinical improvement of patients with stable angina

The combination of atenolol with diltiazem has been shown to be useful in the treatment of patients with coronary artery disease. Eighteen patients with proven coronary artery disease, stable angina, and no previous myocardial infarction were studied before and after treatment with atenolol (100 mg/day) (9 patients) or diltiazem (180 mg/day) (9 patients). Ischemic threshold at stress test, pressure-rate product at ischemic threshold, direct oxygen consumption at ischemic threshold, and exercise ejection fraction were determined. There was a slight increase in the duration of exercise, maximal oxygen consumption, and ischemic threshold after treatment with each drug. Double product at ischemic threshold decreased from 20.9 to 19.8 (p = NS) with atenolol but increased from 20.1 to 21.9 (p = NS) with diltiazem. Conversely oxygen consumption at ischemic threshold increased with atenolol to nearly significant values from 17.2 to 23.6 (p = 0.067) but not with diltiazem (16.2 to 22.3; p = 0.16). Before treatment, exercise ejection fraction increased less than 10% or decreased from its resting values in all patients but 1 with atenolol and 1 with diltiazem, but exercise ejection fraction increased significantly after treatment with atenolol (60.6 to 67.5; p = 0.02) but not with diltiazem. This improvement was due to a significant reduction in end systolic volume (103.8 to 78.6; p = 0.019), despite a similar increase in heart rate and blood pressure in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and hemodynamic effects of long-term administration of gallopamil in patients with coronary artery disease and normal or impaired left ventricular function

The hemodynamic and clinical profiles of gallopamil, a new calcium antagonist, were evaluated in 20 patients with severe coronary artery disease in a placebo-controlled, single-blind study. The patients were divided into 2 groups depending on baseline ejection fraction (greater than 45 or less than or equal to 45%) and underwent nuclear ventriculography, both at rest and during bicycle exercise under electrocardiographic monitoring, after 3 weeks of therapy (50 mg 3 times daily) and the 1-week run in and washout placebo periods. The mean anginal weekly frequency per patient was significantly reduced, from 3.4 to 0.5 (p less than 0.001). The left ventricular ejection fraction, cardiac volumes, ejection and filling indexes at rest and for the same workload were not altered in the population as a whole or in each of the 2 groups. The rate pressure product during exercise was reduced for the same workload from 18.0 +/- 5.0 X 10(3) to 16.8 +/- 4.7 X 10(3), while the regional ejection fraction in ischemic regions was not significantly changed. Individual variations of ventriculographic parameters in both groups were not related to basal values. Gallopamil increased the total duration of exercise from 432 +/- 201 to 537 +/- 188 s (p less than 0.001). Six patients did not complain of angina and their exercise was interrupted because of muscular weakness. The hemodynamic and clinical responses did not differ when the results in the population as a whole and in each of the 2 groups were compared. Gallopamil was effective and well tolerated, even in patients with very depressed cardiac function.

Chronic stable angina monotherapy. Nifedipine versus propranolol

A placebo-controlled, double-blind, crossover study was conducted to determine the effects of nifedipine (60 to 90 mg per day) monotherapy and propranolol (240 mg per day) monotherapy on symptoms, angina threshold, and cardiac function in patients with chronic stable angina. Following a two-week placebo period, patients were randomly assigned to receive either nifedipine or propranolol for a five-week treatment period, after which they crossed over to the alternative regimen. All 21 patients were men with chronic stable angina pectoris, 13 of whom had symptoms both at rest and on exertion. New York Heart Association functional class improved in patients taking either nifedipine or propranolol, and nitroglycerin consumption decreased with both treatments compared with placebo. Nifedipine significantly delayed the onset of chest pain and 1 mm of ST-segment depression during bicycle exercise; increases with propranolol were smaller and not statistically significant. Nine patients had a preferential clinical response to nifedipine compared with six patients to propranolol; this was unrelated to the presence or absence of pain at rest or to any baseline hemodynamic finding. Nifedipine and propranolol were equally effective in relieving exertional ischemia as shown by improvement in radionuclide ejection fraction at identical work loads. Exercise wall motion, assessed by a semiquantitative wall motion score, also improved with both drugs. Propranolol treatment decreased exercise cardiac output by 14 percent (p = 0.01) through its effect on heart rate. In contrast, nifedipine treatment had no effect on cardiac output. Thus, nifedipine is more effective on several measurements than propranolol when administered as single drug therapy in stable angina and has the advantage of preserving cardiac output during exercise.

Effect of bisoprolol on cardiac performance in coronary heart disease

The effects of 5 and 10 mg bisoprolol once daily for 7 days on exercise ECG, myocardial perfusion and left ventricular function in 25 patients with stable coronary heart disease have been assessed in a double-blind, randomized, parallel group trial design. ST-segment depression during exercise was reduced by 56% by 5 mg bisoprolol and by 64% after 10 mg; the difference between the dose levels was significant. Heart rate, systolic and diastolic blood pressure and the rate-pressure product were reduced to similar extent both at rest and during exercise by both doses. Left ventricular thallium-201 scintigrams indicated a significant reduction in myocardial perfusion defects after 10 mg bisoprolol compared to baseline; however, the difference between the two active treatments was not significant. Left atrial and left ventricular diameters obtained by one-dimensional echocardiography, and the calculated shortening fraction, remained unchanged after bisoprolol, and so gave no evidence of a negative inotropic action. It is concluded that 5 mg bisoprolol was effective in once-a-day treatment of angina pectoris due to coronary heart disease, and a further improvement can be expected on increasing the dose to 10 mg.

Intravenous nifedipine for control of hypertension in patients after coronary artery bypass graft surgery

A study was undertaken to assess the use of intravenous nifedipine in controlling hypertension in patients following coronary artery surgery. A combined hemodynamic and metabolic assessment was carried out in 15 patients on data recorded at six sequential time intervals: (1) baseline, (2) control of blood pressure, (3) 30 minutes after control of blood pressure, (4) 1.5 hours after control of blood pressure, (5) 3.5 hours after control of blood pressure, and (6) 30 minutes after discontinuing nifedipine. Coronary sinus and great cardiac vein blood flows were measured by the continuous thermodilution technique using the Baim coronary sinus flow catheter. Intravenous nifedipine was run initially at an average rate of 1.82 microg/kg/min. It took an average time of 12 minutes to lower the blood pressure to less than 130 mmHg systolic. There were highly significant decreases in systolic, mean, and diastolic blood pressures (P < .001), associated with significant decreases in systemic vascular resistance (P < .001) and left ventricular stroke work index (P < .05). There was an increase in cardiac output at 30 and 90 minutes of infusion (P < .05), and the stroke volume was increased 90 minutes after starting nifedipine (P < .05). The increase in heart rate was not significant. There was no significant effect on conduction times as measured by PR and QRS intervals on the ECG. However, the QTc interval was decreased after 3.5 hours (P < .05). There was an increase in right atrial pressure at 90 minutes and again 30 minutes after stopping nifedipine. (P < .05). The pulmonary artery pressure also was increased after stopping the infusion (P < .05). The pulmonary capillary wedge pressure, pulmonary vascular resistance, and right ventricular stroke work index remained unchanged. Coronary sinus and great cardiac vein flows were maintained despite a decrease in perfusion pressure, suggesting that nifedipine is a potent coronary vasodilator. Indeed, coronary vascular resistance was significantly decreased (P < .05). Myocardial oxygen consumption remained unchanged. The lactate extraction indicated that myocardial metabolism remained aerobic regionally and globally. Thus, the results suggest that blood pressure was easy to control and that there were no adverse effects on atrioventricular conduction, cardiac performance, regional and global myocardial oxygen utilization, or lactate extraction.

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.

Haemodynamic effects of nifedipine in patients undergoing coronary artery bypass surgery

Forty patients scheduled for elective aortocoronary bypass surgery were entered in a double-blind study set up to compare the haemodynamic effects of 20 mg nifedipine (n = 20) and placebo (n = 20), both administered with the premedication. Global left ventricular function was normal in all patients. Anaesthesia was induced and maintained with standardized doses of fentanyl, flunitrazepam, and pancuronium together with 50% N2O. Cardiovascular responses to anaesthesia, intubation, skin incision, sternal retraction, and aortic manipulation were investigated. Throughout the study nifedipine produced a marked decrease in systemic vascular resistance. The reduction of left ventricular afterload was associated with an increase in cardiac index. In contrast to other reports, we observed no severe hypotension after nifedipine administration. Mean arterial pressure in patients from the nifedipine group was lower than in the placebo group only prior to anaesthesia. Since no negative drug interactions between nifedipine and the anaesthetic agents were observed, we conclude that the established cardiovascular benefit of nifedipine should be continued during anaesthesia.

Effect of nifedipine on left ventricular function in patients with angina pectoris

Calcium channel blocking agents function as negative inotropic agents when they are administered in vitro directly to the myocardium. In patients with coronary artery disease, however, such direct effects are attenuated by a number of other factors, including decreased afterload and resultant reflex sympathetic stimulation, increased coronary blood flow with improved myocardial perfusion, and protection of mitochondria. Nifedipine has not been observed to cause significant left ventricular depression in patients with angina pectoris; this is primarily due to peripheral arteriolar vasodilatation, which reduces impedance of left ventricular ejection. In addition, the relief of myocardial ischemia by nifedipine plays a major role in improving systolic and diastolic function. The clinical response to calcium channel blockers may differ in patients with idiopathic dilated cardiomyopathy, for whom the factor of fluctuating ischemia is less important.

[Calcium antagonists in heart failure?]

Although beneficial acute hemodynamic effects of calcium antagonists in heart failure have been reported, their use in this setting is still controversial because of the negative inotropic effects produced by these agents. The direct actions of calcium antagonists, that is direct depression of myocardial contractility and coronary and peripheral vasodilation, are modulated by systemic hypotension-induced baroreceptor activation of autonomic reflexes. Thus, at clinically relevant dosages, the baroreceptor-mediated cardiac stimulatory effects may counterbalance or override the direct negative-inotropic effects, as usually observed with nifedipine or diltiazem. By contrast, with verapamil significant depression of contractility may occur. Newer calcium antagonists with higher vasoselectivity such as nisoldipine or felodipine may be particularly interesting in the setting of congestive heart failure because of pronounced arterial vasodilatation and their additional effects on coronary blood flow, LV-regional wall motion and diastolic function and peripheral blood flow distribution with negligible myocardial effects. Due to their marked vasodilatating properties, newer derivatives may be advantageous in the treatment of heart failure due to coronary artery disease and hypertension. Although limited data concerning long-term efficacy are available, preliminary studies suggest long-term benefit in selected patients. It appears that verapamil should not be used for vasodilator therapy of severe heart failure, since deterioration of LV function may occur.

Comparison of nifedipine alone with propranolol alone for stable angina pectoris including hemodynamics at rest and during exercise

The effects of nifedipine (60 to 90 mg/day) and propranolol (240 mg/day) on symptoms, angina threshold and cardiac function were compared in a placebo-controlled, double-blind, crossover study. Five-week treatment periods with nifedipine and propranolol were compared with 2 weeks of placebo treatment in 21 men with chronic stable angina pectoris, 13 of whom had symptoms both at rest and on exertion. Compared with placebo, New York Heart Association functional class improved in patients equally with nifedipine (p = 0.001) and propranolol (p = 0.006). Frequency of chest pain decreased with nifedipine (p = 0.001) and propranolol (p = 0.01), and nitroglycerin consumption similarly decreased with both treatments. Nifedipine significantly delayed the onset of chest pain (p = 0.01) and 1 mm of ST-segment depression (p = 0.002) during bicycle exercise; smaller increases with propranolol were not statistically significant. A preferential clinical response to nifedipine (9 patients) or propranolol (6 patients) was unrelated to the presence or absence of pain at rest or to any baseline hemodynamic finding. Nifedipine and propranolol were equally effective in relieving exertional ischemia as shown by improvements in ejection fraction at identical workloads, from 0.48 +/- 0.11 to 0.58 +/- 0.12 (p less than 0.001) and 0.56 +/- 0.14 (p less than 0.001), respectively. Exercise wall motion, assessed by a semiquantitative wall motion score, also improved with both drugs. Propranolol treatment decreased exercise cardiac output by 14% (p = 0.01) through its effect on heart rate. In contrast, nifedipine treatment had no effect on cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute hemodynamic effects of nifedipine during supine exercise in patients with prior myocardial infarction

Twelve male patients age 36-66, 8 on clinical doses of beta blocker, with old transmural myocardial infarction underwent rest and matched workload exercise before and 30 min after 20 mg sublingual nifedipine during cardiac catheterization. For the group, resting heart rate, aortic pressure, pulmonary wedge pressure, systemic vascular resistance, cardiac index, and left ventricular ejection fraction were normal. Exercise duration was 12.5 +/- 1.5 min. Comparing exercise before and after nifedipine, heart rate, cardiac index, and mean velocity circumferential fiber shortening increased, while mean aortic pressure, systemic vascular resistance, pulmonary wedge pressure, right atrial pressure, left ventricular end-diastolic volume and left ventricular end-systolic volume decreased with no significant change in double product, pulmonary arteriolar resistance and left ventricular ejection fraction. Therefore, for the range of left ventricular dysfunction in this study group and with 8 patients concurrently on beta blocker, nifedipine 20 mg s.l. produced significant improvement in hemodynamics at rest and exercise.

Alterations in myocardial perfusion during exercise after isosorbide dinitrate infusion in patients with coronary disease: assessment by thallium-201 scintigraphy

We studied the effect of intravenous isosorbide dinitrate (ISDN) on myocardial perfusion of patients with coronary artery disease, by using exercise thallium-201 (TI-201) myocardial scintigraphy. A control study was conducted initially to assess regional myocardial perfusion rate. Left ventricular myocardium was divided into six parts: anterior, lateral, apical, inferior, posterior, and septal segments. The segmental myocardial perfusion was characterized according to TI-201 initial uptake index (IUI) of relative distribution and redistribution index (RDI) of TI-201 washout. The normal limit of IUI and RDI was established from the data of 17 persons with normal coronary arteries, and then the IUI less than or equal to 84% and the RDI greater than or equal to 1.12 was defined as abnormal. Based on IUI and RDI, each segment was characterized into three types: A type = IUI less than or equal to 84%, RDI greater than or equal to 1.12; B type = IUI less than or equal to 84%, RDI less than 1.12; and C type = IUI greater than 84%, RDI less than 1.12. ISDN was given as a dose of 0.1 mg/kg/hr, and then treadmill testing was repeated for the same duration of exercise time using the same protocol as in the control period. The segments of A type showed a significant improvement in IUI and RDI after receiving ISDN infusion, while the B and C type segments showed no change. It was also shown that the improvement of IUI and RDI of the A type segments was not as marked in multivessel disease as in cases of single-vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of the haemodynamic effects of nifedipine, nisoldipine and nitrendipine in man

Nifedipine (10 mg), nisoldipine (10 mg) and nitrendipine (20 mg) were given orally to 8 normal volunteers in a placebo controlled, double blind, crossover study. Blood pressure (BP), pulse (P) and systolic time intervals (STI) were recorded at time 0, 30, 60, 90, 120 min after drug administration. Adverse effects were also recorded. There was a fall in BP, pre-ejection time (PEP), PEP/LVET (left ventricular ejection time) and electro-mechanical systole index (QS2 index), and a rise in LVET index in response to the three active drugs compared with placebo. All active drugs, but not placebo, were associated with adverse effects.

Localization of exercise-induced myocardial ischemia with single view and biplanar radionuclide ventriculography: validation in single vessel coronary disease

The ability of single view and biplanar radionuclide ventriculography (RVG) to determine the location of myocardial ischemia during maximal graded supine bicycle exercise was assessed in 50 patients with chest pain, no prior myocardial infarction, and a single coronary stenosis of greater than or equal to 50% luminal diameter narrowing at coronary angiography. A biplane collimator was used so that both right anterior oblique (RAO) gated first-pass and left anterior oblique (LAO) equilibrium RVG could be performed at rest and exercise. Results were compared with those obtained using 4-view 201Tl myocardial scintigraphy in the same patients. Regional wall motion abnormalities (WMA) and 201Tl perfusion defects were detected and assigned to individual coronary vessels by agreement between at least two of three independent observers, who read all studies blinded along with those from control subjects with chest pain but no angiographically significant coronary artery disease. When scintigraphic abnormalities were detected, both biplanar RVG (36/39 = 92%) and 201Tl (25/25 = 100%) were more frequently correct in predicting the stenosed vessel than single view LAO RVG (24/32 = 75%) (P less than 0.05). At RVG only inferior WMA, in the RAO view, predicted right coronary stenosis. Only posterolateral WMA, in the LAO view, predicted left circumflex stenosis. Thus biplanar, but not single view, LAO exercise RVG is a reasonable alternative to exercise 201Tl for localizing exercise-induced ischemic abnormalities to individual coronary stenoses.

Important differences between short- and long-term hemodynamic effects of amiodarone in patients with chronic ischemic heart disease at rest and during ischemia-induced left ventricular dysfunction

To assess and compare the hemodynamic profile of short-and long-term amiodarone administration in the same set of patients and to investigate hemodynamic mechanisms responsible for the antianginal effect of this drug, 10 patients with documented coronary artery disease and stable angina pectoris were studied. Simultaneous right heart catheterization and equilibrium radionuclide angiocardiography were performed at rest and during exercise before therapy (control), after a 5 minute intravenous infusion of 7.5 mg/kg of amiodarone and after 21.0 +/- 4.3 days of peroral therapy (10 days 800 mg/day, 7 days 400 mg/day and then 200 mg/day). After acute drug administration, ejection fraction, stroke index and systolic blood pressure decreased, whereas heart rate, left and right ventricular filling pressures and systemic vascular resistance increased. These effects were reversed after long-term therapy; all measured values returned to control levels except for heart rate, which decreased below the control value, and right atrial pressure, which remained slightly elevated. Amiodarone drug levels decreased from 4.8 +/- 1.8 after intravenous infusion to 1.2 +/- 0.6 mg/liter after long-term therapy. After adjustment for hemodynamic changes at rest, there were still significant reductions in heart rate, mean arterial pressure and rate-pressure product during exercise. It is concluded that the marked negative inotropic effect of amiodarone administered acutely in the dose applied calls for cautious use of this drug when administered intravenously. In contrast, long-term oral amiodarone therapy seems hemodynamically safe, even in patients with moderately depressed left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in exercise capacity and associated changes in hemodynamics and left ventricular function after the addition of metoprolol to nifedipine in patients with stable exertional angina

In 10 men with stable exertional angina, the changes in exercise capacity, hemodynamics, and left ventricular (LV) function were measured after 20 mg sublingual nifedipine (N) and again after adding 100 mg oral metoprolol (M). Nifedipine alone did not significantly improve exercise workloads (+18%) and duration (+21%), but the addition of metoprolol increased both parameters by a further 37 and 32%, respectively (both p less than 0.005 vs. N). After nifedipine the onset of angina was slightly delayed (5.14 +/- 2.41 min placebo (P), 6.00 +/- 2.31 min N, p less than 0.1) and occurred at higher workloads (36 +/- 17 W P, 43 +/- 8 W N, p less than 0.1). After the addition of metoprolol, the onset of angina was delayed substantially more (9.57 +/- 2.22 min, p less than 0.001 vs. P and N) and occurred at much higher workloads (62 +/- 20 W, p less than 0.001 vs. P and N). At rest (R) and during exercise (E), nifedipine decreased systemic vascular resistance (-36% R, -27% E, both p less than 0.001) and mean arterial pressure (-18% R, -21% E, both p less than 0.001), and increased heart rate (+15% R, +11% E, both p less than 0.001), Pulmonary artery wedge pressure on exercise increased less (22 +/- 7 mmHg P, 13 +/- 5 mmHg N, p less than 0.001). After adding metoprolol, the major change was a reduced heart rate (-25% vs. N at R and E, both p less than 0.001), and arterial pressure was unaltered. Pulmonary artery wedge pressure on exercise increased to 18 +/- 5 mmHg (p less than 0.05 vs. N). Exercise LV ejection fraction and volume did not change significantly after adding metoprolol despite marked improvement in angina. In this acute exercise study in patients with stable exertional angina, metoprolol added to nifedipine markedly improved exercise capacity by preventing the increase in heart rate seen with nifedipine. In our patients with relatively normal LV function at rest, the combination was safe and produced no deleterious effects on LV function.

Regional left ventricular contraction abnormality during early systole in patients with angina pectoris. Assessment with radionuclide ventriculography

To determine the presence and prevalence of regional contraction abnormalities in patients with angina pectoris, radionuclide ventriculography gated to an electrocardiogram was carried out in 22 control subjects (group 1) and in 22 patients with angina pectoris (group 2) with isolated stenosis of the left anterior descending coronary artery. No patients had had previous myocardial infarctions. A computer program subdivided the left ventricle into four regions at a geometric centre, and time-activity curves (30-40 ms/frame) of the global, septal, apical, and lateral regions were computed. There was no significant difference in the ejection fraction in the global or in any of the regions between the two groups. End systole in each region occurred close to global end systole in both groups. In the global region the percentage stroke volume ejected during the first third of systole was not significantly less in group 2 than in group 1. Regional analysis of the segments perfused by the stenosed vessel showed that the percentage stroke volume ejected during the first third of systole in group 2 was significantly less in the septal region and in the apical region compared with that in group 1. In contrast, in the normally perfused lateral region, there was no significant difference in the percentage stroke volume at the first third of systole between the two groups. This indicates that early contraction abnormalities are present in the region perfused by the stenosed vessel in patients with angina pectoris without previous myocardial infarction. Thus analysing the regional change in left ventricular volume during ejection in patients with coronary artery disease can show localised areas of contraction abnormalities during early systole that are not apparent when ventricular contraction is assessed as a whole.

Randomized, placebo-controlled study of the effect of verapamil on exercise hemodynamics in coronary artery disease

At cardiac catheterization, 16 patients with coronary artery disease (14 men and 2 women) were allocated by a random, double-blind method to intervention with placebo (saline solution) or verapamil (0.2 mg/kg total by bolus and by 10-minute infusion). In all patients, resting and exercise (3 minutes with a bicycle at 150 kg X m/min) hemodynamic values were obtained during a control period and after intervention. Subsequent left ventriculography and coronary arteriography revealed a mean ejection fraction of 52 and 53% and the mean number of diseased vessels (3-vessel scale) of 2.1 and 1.5 in the placebo and verapamil groups, respectively. In both groups of patients, exercise induced significant increased heart rate, mean arterial pressure, left ventricular end-diastolic pressure and cardiac index. Verapamil increased the heart rate and decreased the mean arterial pressure at rest and the arterial pressure during exercise. It did not affect exercise-induced increases in left ventricular end-diastolic pressure or cardiac index. These results support a role for peripheral mechanisms mediating the antianginal effects of verapamil.

Relation between radionuclide angiographic regional ejection fraction and left ventricular regional ischemia in awake dogs

Multigated equilibrium radionuclide angiography was used to quantitate global and regional ejection fraction (EF) in 26 awake dogs 10 minutes after distal and then proximal occlusion of the left anterior descending (LAD) or left circumflex (LC) coronary artery. Changes in global and regional EF were correlated with simultaneous measurements of the extent of acute left ventricular (LV) ischemia measured by radioisotope-labeled microspheres. The extent of ischemia, defined as the percentage of LV mass with greater than 25% reduction in blood flow from normal regional flow, was linearly related to the percent change in global EF after LAD (r = 0.84) and LC (r = 0.77) occlusions. The extent of ischemia also correlated with regional EF (r = 0.47 to 0.88 for LAD and r = 0.41 to 0.69 for LC occlusions). In 24 of 25 LAD occlusions and in all 20 LC occlusions that produced a measurable ischemic zone, the maximal percent change in regional EF exceeded the percent change in global EF. Two LAD occlusions and 2 LC occlusions reduced regional EF but not global EF. Thus, global and regional EF decreased in direct proportion to the extent of acute myocardial ischemia; regional ischemia produced greater changes in regional than in global EF.

Clinical applications of slow channel blocking compounds

The slow-channel blockers constitute a structurally diverse group of drugs with varying mechanisms of action, propensities for site of greatest cardiovascular activity, and clinical efficacy. They share however the property of blocking the slow inward channel in heart muscle and of inhibiting calcium fluxes in smooth muscle. Their in vivo and in vitro actions must be distinguished. The overall actions represent a balance of direct and autonomically-mediated reflex actions interacting with the compounds' varying degrees of intrinsic non-competitive sympathetic antagonism. A knowledge of the pharmacodynamic differences between these drugs allows the physician to select the most appropriate agent for a given clinical situation. The central role of calcium in the cellular processes in the heart and the vascular system forms the basis for the utility of this class of drugs in a wide variety of cardiovascular disorders. Current intensive experimental and clinical investigations are likely to further define the roles of nifedipine, verapamil and diltiazem and their congeners in cardiovascular therapeutics. The prospect of development of newer compounds with greater selectivity of action is real. As pointed out by Braunwald (1982 a,b), with further clarification of the mechanisms of actions of these compounds and elucidation of the role of calcium fluxes throughout the body, more specific and potent agents may be developed. The apparent efficacy of the nifedipine congener nimodipine, in the treatment of cerebral vasospasm associated with subarachnoid hemorrhage (Allen et al., 1983) may simply be the first of a large number of 'specific' or targeted slow channel blockers. The development of such compounds may offer further therapeutic possibilities in the control of a variety of cardiocirculatory diseases.