Comparison of central and peripheral haemodynamic effects of dilevalol and atenolol in essential hypertension

A new non-imaging echo-Doppler cardiac output device that works on the principle of attenuated compensation volume flow (ACVF), has been used to assess the cardiovascular effects of atenolol and dilevalol in 24 patients with essential hypertension. Compared with the baseline, one month of atenolol reduced systemic mean arterial blood pressure (12 mmHg; P less than 0.01), heart rate (-24 bpm; P less than 0.001), aortic velocity integral (-2.1 cm/sec; P less than 0.01) without a change in cardiac output or systemic vascular resistance. Dilevalol reduced systemic mean arterial pressure (-12 mmHg; P less than 0.01) and heart rate (-13 bpm; P less than 0.01), without a change in cardiac output or aortic velocity integral; systemic vascular resistance fell (-149 dyne/sec; P less than 0.01). Thermography and skin thermal clearance techniques were used to assess the effects of each compound on the peripheral circulation; both compounds reduced skin temperature and thermal clearance but the changes were more marked for atenolol than dilevalol. These results suggest that the mechanism of action of dilevalol is, in part, different from atenolol and would be compatible with a direct vasodilator action on the peripheral vasculature.

Pharmacodynamic monitoring during acute intervention in ischaemic heart disease using a new echo-Doppler device

1. We have utilised a new non-imaging echo-Doppler cardiac output device, using the principle of attenuated compensated volume flow (ACVF), to assess the cardiovascular effects of atenolol and buccal nitroglycerin (NTG) in a placebo-controlled study of 30 patients with coronary disease. 2. Atenolol (4 mg i.v.) reduced heart rate, cardiac output and time-averaged mean aortic velocity (P less than 0.01) and increased systemic vascular resistance (P less than 0.01). 3. Buccal NTG (5 mg) reduced systemic mean arterial pressure (P less than 0.01), cardiac stroke volume (P less than 0.05) and stroke length (P less than 0.01). 4. Thus although both drugs reduced time-averaged aortic velocity (an index of cardiac performance), the concomitant reduction in cardiac stroke length and tachycardia suggested sub-optimal cardiac filling for buccal NTG, whereas for atenolol (with the associated increased systemic vascular resistance but unchanged stroke length) attenuation of sympathetic stimulation at cardiac beta-adrenoceptors. 5. The ACVF method of cardiovascular monitoring should prove useful in human pharmacodynamic studies.

Haemodynamic dose-response effects of UK-52,046 in ischaemic disease with or without impaired left ventricular function

1. The haemodynamic effects of a new cardioselective postsynaptic alpha 1-adrenoceptor antagonist UK-52,046, were evaluated in 25 patients with stable coronary disease, with or without impaired left ventricular function. At rest the haemodynamic effects to two dose-response regimens were determined. In an initial eight patients 0.125, 0.125 and 0.25 micrograms kg-1 were administered peripherally at 15 min intervals; the haemodynamic measurements were determined between 10 to 15 min after each dose. In a further 17 patients, the dose regimen was doubled yielding a cumulative dose-regimen of 0.25, 0.5 and 1.0 micrograms kg-1. The exercise effects were determined by comparison of measurements during 4 min of supine sub-maximal bicycle exercise at a fixed workload before and after drug treatment. 2. At rest, the lower dose regimen of UK-52,046 significantly reduced systemic mean arterial blood pressure (-5 mm Hg; P less than 0.05) and increased cardiac index (+0.2 l min-1 m-2, P less than 0.01). The higher dose regimen of UK-52,046 reduced systemic mean arterial blood pressure (-7 mm Hg; P less than 0.01), pulmonary artery occluded pressure (PAOP) (-2 mm Hg, P less than 0.01) and vascular resistance index (-314 dyn s cm-5 m2; P less than 0.05) with an increase in heart rate (+7%, P less than 0.05) and cardiac index (+0.2 l min-1 m-2, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

An exercise hemodynamic comparison of verapamil, diltiazem, and amlodipine in coronary artery disease

A prospective, randomized study compared the effects of equivalent intravenous doses of three slow calcium-channel blockers (verapamil, diltiazem, and amlodipine) on rest and exercise haemodynamics in 30 ischemic heart disease patients. Following a stable control period during which rest and exercise (supine bicycle) hemodynamics were assessed, equivalent hypotensive doses of each compound were administered over 20 minutes and rest/exercise parameters were assessed 10 minutes later. At rest all agents similarly reduced systemic blood pressure; the fall in systemic vascular resistance and the increase in cardiac indices was ranked: amlodipine greater than diltiazem greater than verapamil. The heart rate increase for amlodopine differed from verapamil and diltiazem (+19.4% vs. +1.5% vs. -7%; p less than 0.01). On exercise, similarly greater falls in the systemic vascular resistance index followed amlodipine, compared with verapamil and diltiazem (p less than 0.05). Only amlodipine significantly reduced the exercise pulmonary artery occlusion pressure (PAOP). Exercise cardiac stroke volume improved after diltiazem and amlodipine. In terms of cardiac performance, both amlodipine and diltiazem produced an improvement, whereas verapamil depressed cardiac pumping activity. Thus, hemodynamic differences between slow-calcium-channel blocking drugs may be demonstrated in humans. These differences would be compatible with a predominant peripheral vascular site of action for amlodipine, in contrast with mixed cardiac and peripheral sites for diltiazem and verapamil.

Haemodynamic and radionuclide effects of amlodipine in coronary artery disease

1. The haemodynamic and radionuclide effects of a new long-acting slow-calcium channel blocking agent, amlodipine, were evaluated in 32 patients with coronary artery disease. 2. Haemodynamic measurements in 24 patients were made at rest and 10 to 15 min after 20 mg i.v. amlodipine. Amlodipine significantly reduced systemic arterial blood pressure and vascular resistance index with an increased heart rate and augmented cardiac index. Cardiac stroke volume index rose and stroke work fell without change in pulmonary artery occluded pressure (PAOP). 3. The exercise effects were determined by comparison of measurements during 4 min of supine bicycle exercise at a fixed workload before and after drug treatment. During dynamic exercise, amlodipine reduced systemic arterial pressure and vascular resistance index. Exercise cardiac index, stroke volume index and heart rate were higher. The left ventricular filling pressure was significantly reduced. 4. Radionuclide parameters were studied in 16 patients at rest and on exercise; ejection fraction was unaltered following amlodipine. 5. Pre-therapy haemodynamic values correlated with response following amlodipine for resting mean blood pressure, systemic vascular resistance and exercise PAOP. 6. Thus, the immediate impact of amlodipine in stable coronary artery disease was to reduce left ventricular afterload and thereby improve cardiac pumping performance.

The treatment of mild to moderate hypertension with ACE inhibitors

The efficacy and safety of quinapril were evaluated in patients with mild to moderate hypertension [sitting diastolic blood pressure (DBP) of 95-115 mm Hg] in seven large, multicenter studies and in one large, single-center study. In double-blind trials, 1,367 patients were treated with quinapril and 820 patients were treated with comparative therapies (enalapril, captopril, chlorthalidone, or placebo). The usual effective dosage of quinapril was 10-40 mg/day, with some patients receiving up to 80 mg/day. Diuretics were added optionally for nonresponders in some studies. Quinapril was equally safe and effective administered either once daily (o.d.) or twice daily and was significantly more effective in lowering blood pressure than was placebo. Quinapril and enalapril administered o.d. were similarly effective in producing clinically and statistically significant reductions in resting blood pressure 24 h after dosing. Quinapril in o.d. doses was as effective as captopril administered two or three times daily. Quinapril was well tolerated; the incidence of adverse events was similar to that for placebo and was comparable to or less than that reported for captopril or enalapril. Quinapril in o.d. doses (10-40 mg/day) is safe and effective as first-line therapy for the treatment of mild to moderate hypertension. Diuretics can be safely added for patients who are not controlled by quinapril alone.

The efficacy of amlodipine in myocardial ischemia

Calcium antagonists are among the most potent and efficacious drugs used in the treatment of angina pectoris. Amlodipine, a new member of this family of dihydropyridines, has a unique pharmacokinetic profile with high bioavailability and an extended period of pharmacodynamic activity. In formal randomized, double-blind, placebo-controlled trials with exercise tests carried out 24 hours after administration, amlodipine was significantly more effective than the placebo and comparable in efficacy with the calcium antagonist diltiazem and the beta-blocking drug nadolol. In addition to extending exercise capacity in patients with angina pectoris, amlodipine significantly reduces ECG evidence of myocardial ischemia. Amlodipine has also been found to be effective in reducing the anginal attack rate in patients with vasospastic angina. From the evidence available, it is concluded that once-daily treatment with amlodipine in the dose range of 5 to 10 mg is effective in improving exercise capacity and reducing anginal attack rate in patients with chronic stable angina pectoris and also those with vasospastic angina.

Nitrate therapy for left ventricular failure complicating acute myocardial infarction: a haemodynamic comparison of intravenous, buccal, and transdermal delivery systems

The haemodynamic effects of three different methods of nitrate administration [intravenous (i.v.) isosorbide dinitrate (ISDN) and buccal and transdermal nitroglycerin (NTG)] were evaluated in 36 patients with acute left ventricular failure due to a recent myocardial infarction. Similar reductions in pulmonary artery occluded pressure (p less than 0.01) followed all three regimens without change in heart rate and cardiac and stroke volume indices. Significant reductions in systemic arterial pressure and vascular resistance followed both ISDN and buccal NTG but not transdermal NTG. A disadvantage of the buccal NTG delivery was an abrupt and, on occasion, inappropriate reduction in blood pressure. The more gradual and controlled reduction of systemic blood pressure with substantial falls in pulmonary artery occluded pressure following ISDN infusion suggest that in the context of myocardial infarction this method of nitrate delivery may have safety advantages; however, when invasive haemodynamic monitoring facilities are not available, transdermal delivery may offer a practical alternative.

Hemodynamic assessment of nicardipine alone and with atenolol in coronary artery disease using a modified echo-Doppler device

We have used a modified noninvasive echo-Doppler cardiac output device, based on the principle of attenuated compensation volume flow, to assess the cardiovascular effects of the slow-calcium antagonist nicardipine in coronary disease. The dose-response effects of 2.5, 5.0 and 10.0 mg intravenous nicardipine were determined in 8 patients with angina. Dose-related decreases were seen in systemic mean arterial pressure (p less than 0.01) after administration of nicardipine. Cardiac pumping indexes were improved, as evident from linear increases in cardiac stroke volume (p less than 0.001), stroke length (p less than 0.01) and time-averaged mean velocity (p less than 0.01). The echo-Doppler device was also used to assess beta-blocking/nicardipine combination therapy in patients with angina. When nicardipine was given after the cardioselective beta blocker atenolol the reduction in heart rate and cardiac output after atenolol was reversed compared with a group that received atenolol followed by placebo. Cardiac performance improved and the 35% reduction in systemic vascular resistance was associated with markedly increased cardiac index (p less than 0.01), augmentation of time-averaged mean velocity (p less than 0.01) and cardiac stroke length (p less than 0.05). These data are consistent with previous invasive studies of nicardipine, either alone or when combined with beta blockade in coronary disease. The data also suggest that nicardipine/beta-blocking combination is safe in patients with coronary heart disease and that the echo-Doppler method of cardiovascular monitoring will prove useful in human pharmacodynamic studies.

Clinical pharmacotherapeutics of doxazosin

Doxazosin is the latest in a series of highly selective postsynaptic alpha 1-adrenoceptor inhibitors. It is readily absorbed, with high bioavailability and a relatively long plasma half-life, neither of which property is influenced by age. This accounts for the prolonged pharmacologic activity of doxazosin following a single oral dose. Its prime pharmacodynamic activity resides in its ability to counter sympathetic vasoconstriction of the systemic arteriolar resistance vessels and venous capacitance system, which enables the drug to target the major pathophysiologic abnormality in hypertension, i.e., the generalized systemic arteriolar constriction. The widespread vasodilation induced by doxazosin relieves both cardiac preload and afterload and, consequently, reduces left ventricular wall stress and myocardial oxygen consumption. In hypertension, doxazosin reduces blood pressure both at rest and during exercise by reduction of systemic vascular resistance without precipitating substantial reflex cardiac stimulation. The effects are maximal on the standing blood pressure between two and four hours after ingestion; due to doxazosin's relatively slow absorption, postural hypotension is infrequent. Its antihypertensive activity is maintained over 24 hours following a single oral dose, and the optimal dose range is 2 to 8 mg once daily. The antihypertensive efficacy of doxazosin has been shown to be comparable with that of other alpha-adrenoceptor inhibitors, beta-blocking drugs, diuretics, calcium antagonists, and angiotensin-converting enzyme inhibitors. In contrast to other conventional antihypertensive drugs, a unique feature of alpha-adrenoceptor-inhibiting drugs, including doxazosin, is their ability to reduce the plasma concentrations of triglycerides, total cholesterol, and low-density lipoprotein cholesterol and to increase high-density lipoprotein cholesterol concentration. This contrasts with the opposite effect on lipid levels induced by hydrochlorothiazide and atenolol seen in comparative studies. Side effects show no predilection for any organ system, and the overall incidence of such effects compares well with those of other commonly used antihypertensive drugs. This unique combination of antihypertensive efficacy and favorable effect on blood lipid levels indicates that once-daily treatment with doxazosin holds considerable promise in the treatment of hypertension, both from the point of view of its antihypertensive efficacy and also from its primary preventative potential.

Therapeutic targets and expectations for the treatment of heart failure

Drug therapy for heart failure holds considerable promise. Direct support of cardiac pumping activity with positive inotropic drugs provides a specific correction for the failing myocardium. Vasodilatation of the systemic arteriolar resistance and venous capacitance systems affords a different but equally rational remedy. Volume and pressure load on the heart is reduced and this augments the pharmacodynamic effects of drugs with positive inotropic activity. For this reason, drugs possessing both pharmacodynamic attributes are an important development in heart failure. The precise clinical targets at which heart failure therapy must be aimed are: (i) relief of symptoms and improvement in quality of life; (ii) reduced risk of morbid events, particularly ventricular arrhythmias; and (iii) extension of survival. Whilst the pathophysiological targets for drug intervention are the same at all stages of the syndrome, expectations of benefit are likely to depend on the stage at which therapy is instituted. In early or mild heart failure, when the patient is not markedly impaired by symptoms, the most that can be expected from treatment is a marginal improvement in quality of life but a major improvement in survival expectancy. In contrast, treatment of severe heart failure may be expected to improve the quality of life substantially by relieving the oppressive symptoms of the advanced syndrome, but only a relatively small increase, if any, in survival. Nevertheless, when the syndrome is terminal, improvement in quality of life carries a clinical priority far in excess of prolonged survival.

Effects of nicorandil on left ventricular hemodynamics and volume at rest and during exercise-induced angina pectoris

The hemodynamic effects of nicorandil (20 mg) were compared with placebo in a double-blind study of 20 patients with angiographically proved coronary artery disease at rest before and 7, 15, 30 and 60 minutes after oral dosing. The impact of the drug on left ventricular (LV) hemodynamics and volume during exercise-induced angina was determined by repeating exercise 60 minutes after drug administration, at the same work load that reliably induced angina during control predrug exercise. At rest, nicorandil reduced all components of systemic arterial pressure without change in cardiac or stroke volume indexes or heart rate. Pulmonary artery occluded pressure was reduced without change in LV ejection fraction or systemic vascular resistance index. Effects were evident at 7 minutes and peaked at 30 minutes with attenuation at 60 minutes. Compared with control supine bicycle exercise, the drug (at 60 minutes) reduced mean systemic arterial pressure and LV filling pressure without change in cardiac stroke volume indexes and heart rate. There was a smaller increase in LV ejection fraction. These data suggested greatest impact on LV function during exercise when substantial decreases in filling pressure occurred at maintained cardiac pumping indexes.

A comparison of the efficacy and safety of quinapril with that of enalapril in the treatment of mild to moderate essential hypertension

This twenty-eight-week double-blind study in patients with mild to moderate essential hypertension showed quinapril (10, 20, and 40 mg/day) to be similarly effective to enalapril at the same doses in producing clinically significant reductions in sitting DBP. Hydrochlorothiazide could be safely added to quinapril therapy in nonresponders. Quinapril and enalapril were well tolerated. Both agents can safely be administered as first-line therapy.

Comparative effects of atenolol and cicloprolol on cardiac performance in coronary heart disease

Cicloprolol is a new cardioselective beta-blocking agent with partial agonist activity (intrinsic sympathomimetic activity, ISA). Its haemodynamic profile was compared with that of atenolol (cardioselective; no ISA) in a comparative dose-response study of 24 ischaemic patients with diminished cardiac reserve. Following a stable control period, equivalent intravenous (i.v.) beta-blocking boluses of atenolol (1, 1, 2, and 4 mg) or cicloprolol (0.025, 0.025, 0.05, and 0.1 mg/kg) were randomly administered and haemodynamics and left ventricular ejection fraction were determined at rest and during bicycle exercise. At rest, atenolol reduced heart rate (HR) and cardiac index; diastolic blood pressure (DBP), systemic vascular resistance index (SVRI), and pulmonary artery occluded pressure (PAOP) increased without change in mean arterial pressure (MAP). Cicloprolol increased left ventricular ejection fraction, reduced its end-diastolic volume, and tended to reduce filling pressure without change in other variables. During exercise, atenolol reduced ejection fraction and increased SVRI; in contrast, cicloprolol did not significantly alter these parameters. Attenuation of exercise tachycardia and cardiac index increase was similar after each agent. Thus, the cardiac performance assessed from left ventricular stroke index or ejection fraction/filling pressure relationships was less depressed after cicloprolol as compared with atenolol. The relevance of such haemodynamic differences to exercise ability or quality of life during sustained therapy warrants examination.

A comparison of doxazosin and enalapril in the treatment of mild and moderate essential hypertension

The antihypertensive efficacy and safety of doxazosin, a selective alpha 1-adrenoceptor antagonist, were compared with that of the angiotensin-converting enzyme inhibitor enalapril in an 18-week double-blind, parallel-group trial. Sixty-seven hypertensive patients entered the three-phase study, which involved a 4-week placebo washout period, a 10-week titration period with doxazosin, 1 to 16 mg, or enalapril, 10 to 40 mg once daily followed by a 4-week maintenance period. The target response was a standing diastolic blood pressure less than or equal to 90 mm Hg. In the 62 efficacy evaluable patients the mean final daily dose of doxazosin was 5.6 mg and 25.5 mg for enalapril. The percentages of therapeutic successes were 74% in the doxazosin- and 81% in the enalapril-treated groups; the proportions in whom standing diastolic blood pressure less than or equal to 90 mm Hg were 55% and 61%, respectively. Both sitting and standing blood pressures were significantly reduced at all visits during the 14-week treatment period in both groups. Twelve patients receiving doxazosin reported 14 adverse events and nine patients administered enalapril reported 19 adverse events; therapy was stopped in three patients in each group because of side effects. The overall assessment of efficacy was excellent or good for 71% of the doxazosin-treated and 67% of the enalapril-treated patients, respectively. Toleration of therapy was excellent or good for 91% of the doxazosin-treated and 88% of the enalapril-treated patients, respectively. No clinically significant changes were observed in the serum lipids, plasma biochemistry, or hematologic profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacotherapeutic stature of doxazosin and its role in coronary risk reduction

In hypertension the primary pathophysiologic abnormality is a generalized increase in the peripheral vascular resistance as a result of concentric narrowing of the systemic arterioles, as a result of alpha 1-receptor stimulation. Such stimulation is attenuated by the selective alpha 1-inhibitor doxazosin. The pharmacologic attributes of doxazosin are translated into direct relaxation of the peripheral arteriolar resistance vessels and venous capacitance system, particularly those with a high alpha-adrenoceptor population. The direct effects of such vascular dilatation are immediately beneficial to the heart in reducing systemic and pulmonary vascular pressures that reduce left ventricular wall stress and myocardial oxygen consumption. In clinical studies doxazosin has been found to have a plasma half-life of 19 to 22 hours, of which a single daily dose is sufficient to control hypertension. The antiatherogenic changes in the blood lipid profile resulting from long-term treatment with doxazosin can also be expected to advance its primary prevention potential in hypertensive patients, which is in marked contrast to the potentially disadvantageous changes in the blood lipid profile that follow treatment with beta-blockers and thiazide diuretics. The therapeutic efficacy of doxazosin has been confirmed, irrespective of hypertension severity, age and race of the patient, or the presence of renal impairment or diabetes mellitus. Its side-effect profile is not substantially different from that of placebo or other antihypertensive drug treatment. Given its unique actions regarding antihypertensive efficacy, together with favorable effects on blood lipids, doxazosin probably holds more promise for the prevention of precocious coronary heart disease in hypertensive patients than any other currently available antihypertensive agent.

Drug therapy of chronic heart failure

Chronic heart failure is an irremediable terminal syndrome. The inability of the heart to pump sufficient blood to meet the demands of metabolically active tissues is aggravated by reflex increases in peripheral vasoconstriction induced by the sympathoadrenal and renin-angiotensin-aldosterone systems. Vasoconstriction is partially attenuated by atrial natriuretic hormone, prostaglandin, and bradykinin. The aim of therapy is to improve the pumping performance of the heart and reduce arterial and venous constriction in the hope that this will reduce symptoms and improve the quality of life. Many drugs achieve such benefits, at least initially. Inotropic drugs increase cardiac pumping activity, and drugs acting directly on arteries and veins improve cardiac function by reducing afterload and preload. ACE inhibitors suppress angiotensin II formation, reducing its vasoconstrictive action, its ability to increase aldosterone secretion and the consequent salt retention and expansion of plasma volume. Since the proportionate role played by various hemodynamic factors in individual patients is unknown, it is likely that most benefit will be achieved by a combined therapeutic approach.

Sympathetic (alpha-beta) or calcium channel blockade for hypertensive myocardial infarction? A haemodynamic comparison of labetalol and nifedipine

The haemodynamic impact of alpha- and beta-adrenoceptor blockade (labetalol) was compared with that of slow-calcium channel blockade (nifedipine) in 32 patients with sustained elevation of systemic arterial pressure (systolic blood pressure greater than 160; diastolic blood pressure greater than 95 mmHg) following a recent myocardial infarction (6-22 h). Patients with normal (pulmonary artery occluded pressure; (PAOP less than 18 mmHg; n = 16) or impaired (PAOP greater than 18 mmHg; n = 16) left ventricular function were randomized to labetalol (1 mg/kg i.v. 15 min) or nifedipine (20 mg sublingually) and haemodynamic profile was measured over 2 h. Both drugs equally reduced mean systemic arterial pressure (P less than 0.01 versus pretreatment control), and presumably left ventricular afterload; however, the heart rate (P less than 0.01) and cardiac index (P less than 0.01) increased after nifedipine, contrasting with reductions in both variables following labetalol (P less than 0.01). The elevated left ventricular filling pressure was reduced by both labetalol (P less than 0.05) and nifedipine (P less than 0.01) but the reduction was greater following nifedipine (-2 mmHg versus -5 mmHg, P less than 0.05). Thus both compounds were equally effective hypotensive agents. Labetalol consistently reduced cardiac stroke work and double product, important determinants of myocardial oxygen requirements; however, nifedipine afforded some improvement in cardiac performance in patients with left ventricular dysfunction.

Celiprolol in hypertension

Celiprolol is a third-generation, beta-adrenoceptor antagonist with ancillary pharmacologic properties that are potentially advantageous in the treatment of hypertension. Celiprolol provides 24-hour control of blood pressure and in formal clinical trials has been found superior to a placebo and of equal efficacy to other commonly used beta-blocking drugs. It has also been found to be equally as effective as enalapril in lowering the resting blood pressure and superior in controlling the increases in blood pressure and heart rate during exercise. Celiprolol is known to exert a beneficial effect on the atheroprotective components of the risk factors for coronary heart disease, such as cholesterol triglyceride, and fibrinogen. Therefore the primary attributes of beta-blockade are uniquely advanced by celiprolol's ancillary pharmacologic activities.

Circulatory effects of intravenous and oral atenolol in acute myocardial infarction

The hemodynamic dose-response effects of intravenous (0.05 and 0.10 mg/kg) and oral (50 and 100 mg) atenolol were compared in a randomized between-group study of 24 men within seventeen hours of an acute uncomplicated myocardial infarction; 6 subjects were evaluated in each of the four groups. Hemodynamic variables were determined over a one-hour control period, following which the randomized dose of atenolol was administered and measurements repeated at 15 (intravenous therapy only), 30, 60, 90, 120, 180, 240, 300, and 360 minutes. The peak hemodynamic effect was similar and independent of either the dosage or route of administration. In all groups atenolol reduced heart rate and cardiac and stroke volume indices. The pulmonary artery occluded pressure and systemic vascular resistance index were transiently increased. Mean arterial pressure was significantly reduced only in the oral group with the highest pretreatment pressure. Maximum changes developed between fifteen and thirty minutes after intravenous dosing and between two and three hours after oral dosing. However, substantial reductions in cardiac index (-0.6 L/min/m2; p less than 0.05) were already achieved at sixty minutes following oral dosing. The duration of pharmacodynamic activity was for two to three hours following intravenous and for the study duration (four to six hours) after oral dosing. These data confirm the hemodynamic safety of atenolol after acute myocardial infarction.

Hemodynamic comparison of dopexamine hydrochloride and dopamine in ischemic left ventricular dysfunction

The hemodynamic dose-response effects of intravenous dopexamine hydrochloride (0.5 to 2.0 micrograms/kg/min) have been compared with dopamine (2.5 to 10 micrograms/kg/min) in 12 patients with ischemic left ventricular dysfunction in an open randomized crossover study. Both drugs increased cardiac output and decreased systemic vascular resistance. Dopexamine hydrochloride appeared to increase heart rate more than dopamine although this did not reach statistical significance. Dopexamine hydrochloride produced small increases in systolic and decreases in diastolic blood pressure, whereas dopamine had a biphasic effect resulting in a decrease in mean blood pressure at low doses and an increase at the highest dose studied. With increasing dosage, there was a trend toward more vasodilator activity with dopexamine hydrochloride than with dopamine. Dopexamine hydrochloride produced fewer adverse effects than dopamine.

Cardiovascular consequences of heart failure

The cardiac and reflex neuroendocrine consequences of heart failure are reviewed. The mechanisms responsible for the many neuroendocrine reflexes that result as a consequence of heart failure are considered particularly in relation to their pathophysiological interactions. The lack of knowledge regarding quantitative changes occurring in the various circulatory reflexes activated by heart failure and the paucity of knowledge of the immediate and long-term effects of pharmacotherapeutic interventions on these reflexes are highlighted.

Celiprolol and the heart

The introduction of beta-adrenoceptor antagonists was a major advance in the treatment of hypertension and coronary artery disease. However, nonselective beta blockade carries distinct circulatory disadvantages, which accounts for the search for an "ideal" beta-blocking drug for use in this extensive therapeutic field. It is possible to define the desirable cardiodynamic profile of a beta-blocking drug. How far does celiprolol meet this function? What questions should we address in attempting to evaluate the effects of celiprolol on the heart? In contrast to propranolol, in the normal heart, celiprolol does not depress left ventricular pumping function. There is little information on the effects of celiprolol on left ventricular function in the hypertensive patient. However, we now know that most patients with hypertension already have advancing coronary artery disease. It is reasonable, therefore, to examine the effects of celiprolol on left ventricular function in patients with coronary disease because these can not only be used to evaluate the possible efficacy of the drug in patients with angina pectoris, but also to extrapolate to their clinical effectiveness in most patients with hypertension. Celiprolol does not depress left ventricular pumping function at rest or during exercise, in contrast to other beta-adrenoceptor antagonists that reduce both heart rate and left ventricular activity. Moreover, celiprolol possesses anti-ischemic properties equivalent to those of atenolol. It does not appear to aggravate the atherogenic profile of the lipids as much as some other cardioselective beta-blocking drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemodynamic dose-response effects of a transdermal nitrate delivery system in acute myocardial infarction with and without left heart failure

The haemodynamic effects of a transdermal nitroglycerin delivery system (NTG-TTS) were investigated in 67 patients with a recent myocardial infarction. The study objectives were to define the dose-response effects of NTG-TTS and to examine the influence of baseline haemodynamic status on subsequent response. Therefore, patients with normal cardiac function [pulmonary artery occluded pressure (PAOP) less than 18 mm Hg, n = 40] and those with acute heart failure (PAOP greater than 18 mm Hg, n = 27) were studied after one of three regimens (TTS-10, TTS-20, or TTS-40) with the intention of securing 10 evaluable patients in each group. In patients with acute heart failure, all three doses reduced the left ventricular filling pressure with a modest decrease in systemic arterial pressure; cardiac index and heart rate were unaltered. The systemic vascular resistance was significantly reduced from 120 min. In patients with normal left ventricular function, there were small but significant reductions in systemic arterial pressure and vascular resistance with limited increases in heart rate; the cardiac stroke work index was reduced. These results are compatible with actions of NTG-TTS mainly on capacitance vessels; PAOP fell with limited impact on systemic arterial pressure and vascular resistance index. This mode of nitrate delivery resulted in a low incidence of hypotension and side-effects; comparison with other delivery methods in myocardial infarction seems indicated.

Is the measurement of cardiac output useful in clinical practice?

The derivation of the "cardiac output" in man is fraught with difficulties whatever principle of measurement is used. The theories underlying the principles involved are sound; the problem arises in their application to the measurement in man. Of equal moment are the immense practical difficulties in applying the techniques available. Together these difficulties frequently give rise to unacceptable errors in the derivation of the "cardiac output". There is no "gold standard" of measurement; all methods have inherent difficulties in their application to man. If intense attention is paid to the practice of any one of the techniques available, then it is possible to reduce the variability of the measurement to acceptable proportions, but the conditions necessary to obtain such narrow ranges of variability in the human subject rarely obtain in routine clinical practice. These realizations apply to the techniques available at present, and it is difficult to imagine that there will be further development of the invasive methods available which would negate these. In contrast, it is possible that refinement of some of the non-invasive techniques now being introduced will allow reasonably reliable measurement of the cardiac output with greater facility than is possible at present. Finally, this brings into question the whole objective of the utility of measurement of cardiac output in practice. Frequently it is measured without due deference to its usefulness. Doubtless there are situations in which the measurement of cardiac output may be of scientific, if not of individual clinical benefit, for example the influence of drugs in hypertension and heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular failure complicating acute myocardial infarction--problems and potential of nonthrombolytic therapy

Despite recent advances, problems in the treatment of acute myocardial infarction still remain. In the earliest stages of the syndrome thrombolysis holds substantial if not absolute promise but many patients present too late for it to be effective. In these latter individuals and those in whom thrombolysis was not successful, the major mortality risk is concentrated in those with left ventricular failure. Many drugs, including diuretics, vasodilators, ACE inhibitors and positive inotropes, singly or in combination, may be used to manipulate the circulation and correct partially or completely the abnormal circulatory profile. Despite such haemodynamic efficacy the impact of drug therapy on the high morbidity and mortality risk of patients with acute myocardial infarction complicated by left ventricular failure is still unknown.

Haemodynamic dose-response actions of cicloprolol in left ventricular dysfunction due to ischaemic heart disease

Cicloprolol is a cardioselective beta-1 partial agonist; its haemodynamic and radionuclide (nuclear stethoscope) effects were determined in 22 patients with impaired left ventricular function due to coronary artery disease. Following a 20 min stable control period, the effects of four doses of cicloprolol (0.025, 0.025, 0.05 and 0.1 mg/kg at 10 min intervals) were measured at rest 5-10 min after each intravenous injection. The effects of the cumulative 0.2 mg/kg dosage were assessed during supine bicycle exercise and compared with a control exercise period. At rest there were significant increases in systolic arterial without change in mean blood pressure. The heart rate and cardiac index were unchanged. There was a significant increase in left ventricular ejection fraction with a reduction in filling pressure and volume. Patients with resting heart rate below 75 beats/min and with ejection fraction greater than 35% showed the greatest improvement. During supine bicycle exercise, ejection fraction was increased compared to control (31 +/- 2 to 36 +/- 2; P less than 0.01), cardiac volume reduced and exercise tachycardia attenuated. These data suggest that cicloprolol may be of value where beta-blockade is considered in the presence of underlying left ventricular dysfunction due to ischaemic heart disease.

Comparative hemodynamic dose-response effects of five slow calcium channel-blocking agents in coronary artery disease

A prospective, randomized study compared the hemodynamic effects of equivalent doses of five slow calcium channel blockers (verapamil, diltiazem, nicardipine, nisoldipine, and amlodipine) in 50 patients with ischemia. After a stable control period, dose-response curves were constructed for each drug with hemodynamics measured 10 minutes after intravenous boluses. Each drug reduced mean systemic arterial pressure (P less than 0.01) and systemic vascular resistance index (P less than 0.01). The heart rate increased after nicardipine, nisoldipine, and amlodipine (P less than 0.01) but was unchanged after verapamil and reduced after diltiazem (P less than 0.01). The left ventricular filling pressure increased after amlodipine (P less than 0.05) and verapamil (P less than 0.01) but was unchanged with the other compounds. Cardiac index increased substantially after the dihydropyridines (P less than 0.01), with little change after verapamil or diltiazem. Cardiac double product fell only after verapamil and diltiazem. These studies provide quantitation of the comparative actions of acute intravenous calcium channel blockade in coronary disease.

Immediate effects of bumetanide on systemic haemodynamics and left ventricular volume in acute and chronic heart failure

1 The haemodynamic and radionuclide effects of i.v. bumetanide (25 micrograms kg-1) were prospectively studied in 24 patients with angiographically documented coronary artery disease and either acute exercise-induced (Group I, n = 12) or chronic (Group II, n = 12) heart failure. 2 Bumetanide at rest increased systemic arterial blood pressure and vascular resistance index; cardiac index and pulmonary artery occluded pressure (PAOP) were reduced at an unchanged heart rate in all patients. The left ventricular ejection fraction fell in patients with normal resting left ventricular filling pressure without change in those with chronic heart failure. The cardiac volumes were unchanged in either group. 3 During constant-load supine bicycle exercise, there were similar effects on systemic arterial pressures, vascular resistance index and PAOP; however the cardiac index was maintained at a reduced left ventricular filling pressure and unchanged ejection fraction and volumes. 4 These data demonstrate immediate mild pressor and vasoconstrictor actions of bumetanide which appear independent of the state of cardiac function; they suggest that any immediate improvement in patient symptomatology following bumetanide may be consequent on the reduction in PAOP; short-term reductions in volume may not occur.

Drug therapy and quality of life in angina pectoris

Quality of life is impaired in patients with angina pectoris because of their symptoms, impaired activity, and anxiety. These various factors reduce enjoyment of life, but their components and interrelationships are difficult to measure in the individual. There is no consensus on the best methods of measurement of quality of life; many general instruments have been proposed but none that specifically concern angina pectoris. Despite the absence of such quantitative information, there is no doubt that antianginal drugs benefit the majority of patients and, despite their side effects, advantageously change the relationship between the factors that add up to "quality of life." How the relief of symptoms, both organic and psychologic, interact and how far they are offset by the negative aspects of treatment in the patient with angina pectoris remain to be defined. Past and present trials give encouragement that instruments will be developed that are relevant, valid, reproducible, and sufficiently sensitive to convincingly measure the different impacts on quality of life of the patient with angina pectoris.

First-line treatment of left ventricular failure complicating acute myocardial infarction: a randomised evaluation of immediate effects of diuretic, venodilator, arteriodilator, and positive inotropic drugs on left ventricular function

A prospective randomised trial compared the immediate haemodynamic effects of intravenous diuretic (frusemide), venodilator (isosorbide dinitrate), arteriolar dilator (hydralazine), and positive inotropic stimulation (prenalterol) as first-line therapy for acute left ventricular (LV) failure following myocardial infarction. Forty-eight patients with transmural myocardial infarction and a pulmonary artery occluded pressure (PAOP) of greater than 20 mm Hg were studied within 18 h of admission to a coronary care unit. Both frusemide (-4 mm Hg; p less than 0.01) and isosorbide dinitrate (-6 mm Hg; p less than 0.01) reduced LV filling pressure without change in cardiac index and heart rate. Although both hydralazine and prenalterol increased cardiac index (p less than 0.01), the reduction in LV filling pressure (-2 mm Hg; p less than 0.05) was less than with frusemide and isosorbide dinitrate, and was associated with an increased heart rate (+8 and +13 beats min-1; p less than 0.01). These data suggest that in acute heart failure following myocardial infarction the four treatment modalities could be ranked in descending order of potential benefit as follows: venodilatation (isosorbide dinitrate)--decrease of LV pressure/work; diuretic therapy (frusemide)--decrease of LV pressure/work offset by a transient pressor effect; arteriolar dilatation (hydralazine)--decrease of LV pressure/work and of PAOP, but offset by tachycardia; and positive inotropic therapy (beta 1-agonist prenalterol)--tachycardia and augmented LV afterload. Combination of the former and latter agents, because of their differing modes of action, should offer haemodynamic advantages over monotherapy and deserves further evaluation.

Coronary artery disease risk factor management in the hypertensive patient

Recent advances in understanding the relation of risk factors to coronary artery disease (CAD) have initiated a change in the approach to managing the hypertensive patient. Reduction of elevated blood pressure still remains a major therapeutic priority. However, the risk of cardiovascular morbidity is also related to hypercholesterolemia, hyperuricemia, hyperglycemia, hyperfibrinogenemia and obesity; all aggravate the risk of CAD in the patient with high blood pressure. Life-style is also important: cigarette smoking, high alcohol consumption and lack of physical exercise all predispose to precocious atheromatous CAD. Thus, the most favorable prognosis in terms of reducing CAD risk is accomplished by reducing elevated systemic arterial pressure while simultaneously improving all other risk factors. The method by which blood pressure is lowered is an important consideration. The ancillary metabolic activities of antihypertensive drugs now available differ widely. Diuretics and beta blockers, for example, have potentially adverse metabolic effects, whereas agents such as selective alpha 1-adrenoceptor inhibitors appear to beneficially affect several metabolic cofactors influencing the CAD risk profile. The impact of such drug-induced metabolic changes on overall prognosis of the hypertensive patient remains to be clarified. In the absence of other contraindications, however, it is sensible to use drugs that do not increase the metabolic predilection to precocious CAD.

Role of cardioselectivity and intrinsic sympathomimetic activity in beta-blocking drugs in cardiovascular disease

The significance of ancillary properties of beta blockers continues to be the focus of considerable clinical investigation. Beta 1-selective blocking agents, such as acebutolol, inhibit cardiac beta 1 receptors, but have less influence on bronchial and vascular beta 2 receptors. Certain beta 1-selective blocking drugs, including acebutolol, have intrinsic sympathomimetic activity (ISA), also termed partial agonist activity. This property produces slight cardiac stimulation, which can be blocked by propranolol. Drugs with mild or moderate ISA have proven to be as clinically effective as beta blockers lacking this property. Additionally, drugs with ISA possess potential therapeutic benefits, particularly for patients with coronary artery disease. The hemodynamic influences of cardioselectivity and ISA on left ventricular function, heart rate, cardiac output, left-sided heart filling pressure and myocardial oxygen consumption in patients with coronary artery disease are now clearly defined.

Nifedipine following acute myocardial infarction--dependence of response on baseline haemodynamic status

The haemodynamic effects of nifedipine (20 mg sublingually) were studied in 40 patients with acute myocardial infarction within 18 h of the onset of symptoms. To determine the influence of preload and afterload on the haemodynamic response to nifedipine, patients were prospectively stratified equally into four groups of 10 patients based on systemic blood pressure level (less than or greater than 160/100 mm Hg) and level of left ventricular filling pressure [pulmonary artery-occluded pressure (PAOP) less than or greater than 18 mm Hg]. In all groups, nifedipine reduced systemic arterial pressure (p less than 0.01) and vascular resistance index (p less than 0.01); heart rate (p less than 0.01) and cardiac index (p less than 0.01) were increased. PAOP was reduced by nifedipine only in those hypertensive patients in whom it was initially raised; in these patients cardiac stroke volume index also increased (p less than 0.01). In hypertensive patients with normal PAOP the cardiac stroke work index was reduced. In patients with normal systemic and pulmonary arterial pressures, nifedipine had no beneficial effects on cardiac function. These data suggested that haemodynamic criteria may allow selection of patients for nifedipine therapy following myocardial infarction; clear advantages were evident only in hypertensive patients in both the presence and the absence of left ventricular failure.

A haemodynamic and radionuclide assessment of diltiazem in coronary heart disease

To obtain multiple dose-response haemodynamic and radionuclide data on i.v. diltiazem, 12 ischaemic patients were studied during routine catheterization. At rest, following a 20 min stable control period, the effects of four doses (0.0625, 0.0625, 0.125 and 0.25 mg kg-1 diltiazem at 5 min intervals) were measured in the 3-5 min following i.v. injection. The exercise effects of the cumulative 0.5 mg kg-1 dosage were assessed by comparing a control and post drug period of supine bicycle exercise. The increase in plasma diltiazem levels correlated linearly with the administered dose and achieved therapeutic levels. There were significant dose-related reductions in systemic arterial blood pressure and vascular resistance index; the heart rate fell and cardiac stroke index increased. The calculated double-product (heart rate X systolic blood pressure) was significantly reduced. The left ventricular filling pressures, ejection fraction and cardiac volumes were unaltered. During supine bicycle exercise, the systemic diastolic blood pressure, heart rate and calculated double-product were reduced without change in other parameters. Over the dose range 0.0625-0.5 mg kg-1, diltiazem acutely increased cardiac stroke index and reduced resting heart rate. These haemodynamic data, taken together with its described coronary vasodilator activity suggest that its role in acute vasospastic angina and during angiographic procedures ought to be explored further.

Efficacy of a new calcium antagonist PN 200-110 (isradipine) in angina pectoris

Angina pectoris is one of the major syndromes against which to test the therapeutic effectiveness of any new calcium antagonist. An interim analysis of the efficacy and safety of a new dihydropyridine calcium antagonist (PN 200-110 [isradipine]) in patients with confirmed coronary artery disease is reported. The study was carried out in 3 centers; 50 patients of an anticipated 96 have completed the double-blind comparative phases in 3 separate studies. Preliminary results from the placebo-controlled study indicate that PN 200-110 was significantly more effective than placebo in reducing the anginal attack rate and glyceryl trinitrate consumption in the 15 patients so far enrolled. Dose-response comparisons against nifedipine in 21 patients and against isosorbide dinitrate in 14 patients demonstrate that PN 200-110 has a similar antianginal efficacy profile to both drugs. No significant change in any of the monitored safety factors was noted in any of the patients taking PN 200-110. The side-effects profile compared favorably with that of nifedipine. These interim results suggest that PN 200-110 will prove to be an effective and safe drug for the treatment of angina pectoris.

Comparative haemodynamic dose-response effects of dobutamine and amrinone in left ventricular failure complicating acute myocardial infarction

The comparative haemodynamic dose-response effects of intravenous (i.v.) amrinone and dobutamine were evaluated in 20 male patients with haemodynamic (pulmonary artery occluded pressure (PAOP) greater than 20 mm Hg) and radiographic left heart failure following a recent myocardial infarction. Following a 1-h control period, 10 patients were each randomised to amrinone (800, 1,600, or 3,200 micrograms/kg/h) or dobutamine (200, 400, or 800 micrograms/kg/h) sequentially infused for 30 min at each dose level; haemodynamic parameters were recorded at the end of each infusion period. Amrinone reduced systemic arterial blood pressure and vascular resistance index with a moderately increased heart rate; PAOP (-10 mm Hg; p less than 0.01) fell substantially without change in cardiac or stroke work indices. Dobutamine increased systemic arterial blood pressure, heart rate, and stroke work index at an unchanged PAOP; cardiac index (+0.7 L/min/m2; 25%; p less than 0.01) increased. Systemic vascular resistance index was significantly reduced by both drugs. Thus, dobutamine increased cardiac index at an unchanged PAOP; myocardial stroke work increased. Amrinone had lesser effect on cardiac pumping but reduced PAOP (preload) at an unchanged stroke work. The implications of these differential actions for the clinical therapy of myocardial infarction deserves further evaluation.

A rest and exercise haemodynamic evaluation of a new cardio-selective beta-adrenoceptor blocker celiprolol alone and in combination with nitroglycerine in ischaemic heart disease

The symptomatic benefits of combining beta-adrenoceptor blockers and nitrates in angina pectoris are well recognised. Their actions on cardiac haemodynamics and volumes when combined have been poorly characterized. Accordingly this study investigated a new cardioselective beta-adrenoceptor blocking agent celiprolol and buccal nitroglycerine in 24 patients with angiographically documented coronary artery disease. Following a control period, with confirmed stable haemodynamics, three groups (n = 8/group) of prospectively matched patients, were studied following intravenous celiprolol (8 mg), buccal nitrate (10 mg) or their combination. Haemodynamics and left ventricular ejection fraction (nuclear probe) were determined following each intervention. The actions of each regimen on the haemodynamics of exercise-induced angina were compared by exercise testing in the control state and following each regimen. At rest, celiprolol did not alter haemodynamic parameters. Nitrate therapy reduced left ventricular filling pressure (pulmonary artery occluded pressure--PAOP) and volumes; the ejection fraction and heart rate increased. Combination therapy resulted in a highly significant reduction in left ventricular preload and afterload (PAOP and mean arterial blood pressure) at an increased left ventricular ejection fraction and reduced cardiac volumes; there was a trend to reduce cardiac double product (HR X SBP). During exercise celiprolol reduced systolic blood pressure, heart rate and cardiac index; systemic vascular resistance index increased. Nitrate therapy reduced blood pressure and PAOP, and increased ejection fraction. Combination therapy reduced all components of the triple product (heart rate, systolic blood pressure and PAOP) without affecting the other haemodynamic or radionuclide parameters. These data suggest improvements in cardiac function from the combination of celiprolol and nitrate therapy which were not achieved by either agent when used as monotherapy; they afford an interesting insight into the manner in which such widely utilised therapeutic modalities interact in coronary artery disease.

A haemodynamic dose finding study with a new slow-calcium channel blocker (amlodipine) in coronary artery disease

The haemodynamic dose-response effects of a new long-acting slow-calcium channel blocking agent, amlodipine were evaluated in 20 patients with angiographically confirmed coronary heart disease. At rest, following a control saline period, four i.v. doses of the drug (cumulative dosage 1.25, 2.5, 5 and 10 mg) were administered to ten patients and haemodynamics determined in the ten to 15 minutes following injection. Effects on circulatory parameters were only evident following the maximum cumulative dosage. Accordingly in a further ten patients, the regimen was doubled (cumulative i.v. dosage 2.5, 5, 10 and 20 mg). In each study the haemodynamic effects during constant load supine bicycle exercise were evaluated by comparison of values during the control exercise period and following the final cumulative dosage. On the higher regimen, amlodipine significantly reduced resting systolic, diastolic and mean (p less than 0.01) systemic arterial pressure and systemic vascular resistance index (p less than 0.01). Heart rate (p less than 0.01), stroke volume index (p less than 0.01) and cardiac index (p less than 0.01) increased; pulmonary artery occluded pressure was unchanged. During constant load bicycle exercise, the mean arterial pressure was significantly reduced (p less than 0.01), and the heart rate and cardiac index increased (p less than 0.01). Thus the immediate impact of amlodipine in stable coronary artery disease was to reduce left ventricular afterload and augment cardiac pumping performance. The minimum effective i.v. dosage appeared to be 10 mg. Amlodipine appears sufficiently promising to warrant longer-term studies in ischaemic heart disease.

Comparative haemodynamic effects of intravenous lignocaine, disopyramide and flecainide in uncomplicated acute myocardial infarction

A prospective study evaluated the comparative haemodynamic effects of three Class I antiarrhythmics (lignocaine Class 1B, disopyramide Class 1A and flecainide Class 1C) in 30 patients with uncomplicated acute myocardial infarction. Three groups, each of 10 patients, were allocated to lignocaine (Group I) 1.5 mg kg-1 i.v. loading dose over 10 min followed by infusion at 3 mg kg-1 h-1, disopyramide (Group II) or flecainide (Group III), both administered as a 1.0 mg kg-1 i.v. loading bolus over 10 min followed by a 1.6 mg kg-1 h-1 infusion for 120 min. The plasma levels of each drug were in the described therapeutic range. Lignocaine decreased cardiac index (-0.3 l min-1 m-2 (9%); P less than 0.05) and stroke volume index (-5 ml m-2 (11%); P less than 0.01). Systemic blood pressure, heart rate and systemic vascular resistance index were unchanged. There was a small increase (+3 mm Hg (30%); P less than 0.01) in pulmonary artery occluded pressure (PAOP). Both disopyramide and flecainide increased systemic blood pressure; the maximum increases for mean blood pressure were +10 mm Hg (11%) and +4 mm Hg (4%) respectively. Both drugs reduced cardiac index (-0.5 l min-1 m-2 (16%): -0.4 l min-1 m-2 (11%)) and stroke volume index (-11 ml m-2 (25%): -5 ml m-2 (11%)). There were increases in heart rate (+13: +5 beats min-1) pulmonary artery occluded pressure (+2: +3 mm Hg) and systemic vascular resistance index (+696: +275 dyn s cm-5 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

A haemodynamic study of the effects of combined slow-calcium channel blockade (nisoldipine) and beta-blockade (metoprolol) in coronary heart disease

The interaction of a new slow-calcium blocker (nisoldipine) and the beta-blocker metoprolol was evaluated in 16 patients with stable angina. Haemodynamic parameters were determined in a control rest and exercise period. Patients were then randomised equally to nisoldipine (4-8 micrograms/kg) or metoprolol (10 mg) and the haemodynamics of monotherapy assessed; finally the second drug was administered and the effects of combination determined. At rest nisoldipine reduced systemic blood pressure and vascular resistance (P less than 0.01); heart rate, cardiac and stroke volume indices increased (P less than 0.01) at an unchanged pulmonary artery occluded pressure. Metoprolol alone reduced heart rate (P less than 0.05) and increased the pulmonary artery occluded pressure (P less than 0.05). Combination therapy reduced systemic blood pressure and vascular resistance (P less than 0.01); cardiac index and pulmonary artery occluded pressure increased (P less than 0.01) at an unchanged heart rate. The effect of combination was influenced by the order of administration; an improvement in cardiac performance was particularly evident when nisoldipine was added to metoprolol. The interaction during dynamic exercise was similar to that at rest. Thus these data indicated the haemodynamic safety of concurrent nisoldipine/metoprolol therapy; the addition of nisoldipine to metoprolol appeared to offset in part the cardiodepressant properties of beta-blockade.

The role of transdermal nitroglycerin in the treatment of coronary heart disease

Nitroglycerin has long been a mainstay of the treatment of ischemic cardiac pain. The introduction of transdermal formulations and in particular the development of controlled methods of delivery have been responsible for the renaissance of clinical interest in this simple and effective treatment. The pathophysiologic abnormality accompanying myocardial ischemia affords a natural theater for the exhibition of the therapeutic utility of these preparations and methods. The means whereby nitrates induce relaxation of vascular smooth muscle are not entirely clear, but their pharmacodynamic activities are perfectly plain. In the doses used in clinical practice, nitrates exert their predominant hemodynamic effects and therapeutic benefits through their peripheral vasodilator activities. This is particularly marked in veins, although in higher doses nitrates also dilate the larger systemic and coronary arteries. Criticisms of the efficacy of transdermal formulations of nitrates in the treatment of angina pectoris have arisen largely from uncritical acceptance of a small number of studies of questionable methodologic validity. Large-scale general practice studies have invariably found that transdermal nitrate delivery systems improve the quality of life in ambulant patients: anginal attacks are reduced with a minimum of side effects. The widespread acceptance of this novel form of drug delivery has stimulated its application in other therapeutic avenues. The efficacy of transdermal nitroglycerin in the suppression of silent ischemic attacks has been demonstrated. The maintenance of benefit initiated by intravenous nitroglycerin in patients with unstable angina also broadens the use of this method of nitrate delivery. In patients with acute myocardial infarction, whether complicated by left ventricular failure or not, the nitrates, and transdermal nitroglycerin in particular, appear to hold considerable promise. Improvement of hemodynamic abnormalities may cause reduction in infarct size and fewer life-threatening arrhythmias. Even survival may be extended. The utility of transdermal nitrates in the treatment of severe chronic heart failure is less certain. But the use of higher doses and an interval regimen of administration may hold promise for such patients. Naturally, more information is required before the overall therapeutic profile of this new method of controlled nitroglycerin delivery across the whole spectrum of coronary heart disease can be fully described. Fortunately, the high level of efficacy and safety of transdermal nitroglycerin demonstrated in the majority of reported studies encourages the pursuit of such an important therapeutic target.

Late intervention studies with beta-blocking drugs in myocardial infarction: a critical appraisal

Immense therapeutic effort has been devoted to testing the secondary preventative value of beta-blocking drugs in survivors of acute myocardial infarction. The failure to demonstrate a universally statistically significant benefit is ascribable to major inadequacies of design and technical errors in the majority of trials. Moreover, even in the very few trials in which survival benefit has been demonstrated, the ultra-selection of patients eventually included severely limits the general clinical application of their result. The specific subgroups of patients who derive most benefit and as importantly those that are disadvantaged by these drugs are ill-defined. Lack of comparative trials and absence of dose-response information also pose insuperable problems in attempting secondary prevention with beta-blocking drugs in practice. When to start these drugs to achieve maximum benefit and when to stop them to avoid long-term adverse reactions are major outstanding problems. The consequences of missed therapy are also unknown. Lack of a clinically discernible endpoint of success in the individual patient means that the physician's role is relegated to one of faith. Data so for available is insufficient to afford a rational change in therapeutic practice. However, these extensive studies have advanced understanding. They have clearly defined the design faults which must be avoided in future trials. They have made us aware that many post-infarct patients may not need beta-blocking drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic, haemodynamic and radionuclide studies with nicardipine in coronary artery disease

Pharmacokinetic, haemodynamic and radionuclide studies explored the acute pharmacokinetic and pharmacodynamic actions of nicardipine in patients with coronary heart disease. Nicardipine infusion resulted in dose-related reductions in systolic and diastolic blood pressure and an increased heart rate. Pharmacodynamic activity was evident between 12 and 24 min following 5 and 10 mg i.v. nicardipine but by 3-6 min following the higher doses of 15 and 20 mg; hypotensive activity persisted for up to 2 h. Post-infusion nicardipine concentrations declined biexponentially; however the limited data precluded formal compartmental analysis. Plasma clearance ranged from 5-12 ml/min/kg, and appeared lower than previously reported volunteer data. The haemodynamic actions of nicardipine (10 mg infusion over 10 min) in 6 patients undergoing diagnostic catheterization were reductions in systolic, diastolic and mean systemic arterial pressure and systemic vascular resistance index. Heart rate and stroke volume index increased, and there was a small but statistically significant increase in pulmonary artery occluded pressure. Radionuclide parameters were measured in 20 patients with stable angina, at rest and during supine bicycle exercise, before and 3-5 min after nicardipine 10 mg intravenously. The left ventricular ejection fraction increased by 4% at rest but not during exercise. The left ventricular rest and exercise ejection and filling rates both increased with a concurrently reduced left ventricular ejection time. There was a highly significant inverse relationship between baseline exercise ejection fraction and the response to nicardipine; ejection fraction increased with low initial values but was either unchanged or fell with higher initial values.(ABSTRACT TRUNCATED AT 250 WORDS)

A single-blind randomized comparison of the 24-h antianginal efficacy of celiprolol versus atenolol

The effects of once-daily dosing with celiprolol 200 mg, celiprolol 400 mg, and atenolol 100 mg have been studied in 19 male patients with chronic stable angina pectoris. All three treatments improved angina attack rates and treadmill exercise performance equally. Celiprolol appears to be as efficacious as atenolol as an antianginal agent during long-term therapy.

Celiprolol in the treatment of hypertension: a comparison with propranolol

A randomized double-blind study compared the antihypertensive efficacy of single daily oral doses of celiprolol 200 or 400 mg to twice daily doses of propranolol 40 or 80 mg in 58 patients with uncomplicated essential hypertension (supine diastolic blood pressure range 95-114 mm Hg). Before treatment there was no significant difference in patient characteristics or in the average systolic or diastolic blood pressures or heart rates between the two groups. Sixty-five percent of the celiprolol group and 56% of the patients randomized to propranolol achieved blood pressure control on the lowest dose of each drug. The mean reductions in the systolic and diastolic pressures at the end of the 4 week titration period were -14/-13 mm Hg for the celiprolol group and -11/-12 mm Hg for the propranolol group. Continued treatment with the same doses of celiprolol and propranolol for a further 8 weeks resulted in blood pressure reductions of -18/14 mm Hg and -8/-9 mm Hg, respectively. In 64% of patients taking celiprolol and in 54% of those taking propranolol the prospective target reduction in supine diastolic blood pressure was achieved, namely a reduction to below 90 mm Hg or a reduction lower after propranolol than after celiprolol; celiprolol reduced the heart rate by an average of 6 bt/min and propranolol by 13 bt/min after 12 weeks treatment (p 0.01). Adverse reactions assessed by patient-volunteered information were similar in character and frequency for both drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in haemodynamic response to beta-blocking drugs between stable coronary artery disease and acute myocardial infarction

Theoretically the increased sympathoadrenal activity following acute myocardial infarction might augment the haemodynamic impact of beta-adrenoceptor blockade. To evaluate this question 32 haemodynamic studies were performed to compare the effects of equivalent beta-blocking doses of propranolol (8 mg i.v.) and pindolol (0.8 mg i.v.) in patients with a recent acute myocardial infarction (A.M.I.) or stable coronary artery disease (and a presumptive low sympathetic state). In stable coronary artery disease there were clear differences between the haemodynamic impact of propranolol and pindolol. Propranolol decreased both heart rate (delta HR -7 beat/min) and cardiac index (delta CI -0.4 l/min/m2), with an increased pulmonary artery occluded pressure (delta PAOP +4 mmHg) and systemic vascular resistance index (delta SVRI +358 dyn X s X cm-5 m2). However an equivalent beta-blocking dose of pindolol increased PAOP (delta PAOP +3 mmHg) leaving other variables unchanged. These differential actions of propranolol and pindolol have previously been ascribed to the intrinsic sympathomimetic activity (I.S.A.) of pindolol maintaining cardiac pumping function in a low sympathetic state. In contrast following myocardial infarction, both drugs reduced cardiac index to a significantly greater extent compared with stable coronary artery disease (delta CI propranolol -0.81/min/m2; pindolol -0.4 l/min/m2; p less than 0.05); propranolol also reduced the systemic arterial blood pressure (delta systolic -10 mmHg; delta mean -5 mmHg; p less than 0.05). The haemodynamic relevance of the I.S.A. of pindolol appeared attenuated following A.M.I. These data are compatible with experimental evidence of sympathetic nervous activation following coronary occlusion; the resulting hyperadrenergic state appears to condition an augmented haemodynamic response to beta-blocking drugs irrespective of their ancillary pharmacological properties.(ABSTRACT TRUNCATED AT 250 WORDS)