Systemic, left ventricular and coronary hemodynamic effects of intravenous diltiazem in coronary artery disease

Chronic Coronary Disease in Older Adults

The number of older adults age ≥75 with chronic coronary disease (CCD) continues to rise. CCD is a major contributor to morbidity, mortality, and disability in older adults. Older adults are underrepresented in randomized controlled trials of CCD, which limits generalizability to older adults living with multiple chronic conditions and geriatric syndromes. This review discusses the presentation of CCD in older adults, reviews the guideline-directed medical and invasive therapies, and recommends a patient-centric approach to making treatment decisions.

Is myocardial bridge more frequently detected on radial access coronary angiography?

Background

Although the incidence of myocardial bridge (MB) has been defined in different femoral access conventional coronary angiography (FACCA) studies, the frequency of MB on radial access coronary angiography (RACA) is unknown. The aim of this study was to determine the difference in the incidence of MB between patients undergoing RACA and FACCA.

Method

A total of 2500 consecutive patients who underwent RACA and a total of 1455 consecutive patients who underwent FACCA were retrospectively investigated to detect the presence of MB. The incidences of the groups were calculated separately and compared. The clinical and angiographic features of the patients with MB were analyzed.

Results

MB was detected at an incidence of 10.2%, in 255/2500 patients who underwent RACA, and 1.8% in 27/1455 patients who underwent FACCA (p < 0.001). In both RACA and FACCA patients, the most involved coronary artery was the left anterior descending artery (LAD) (86.9% and 93.1%) and the mid-segment (84.9% and 88.9%) was the most affected section. Co-involvement of multiple coronary arteries by MB was 7.8% in patients who underwent RACA and 7.4% in patients who underwent FACCA. Coronary artery disease (CAD) was determined in 111 (35.7%) of the coronary arteries with MB, of which 81.9% were proximal to the MB. No significant CAD was detected in any of the vessels of 69.8% (178/255) of the patients who underwent RACA for different clinical indications.

Conclusion

These data demonstrated that the incidence of myocardial bridge able to be detected on RACA was much higher than FACCA.

Comparison of Antihypertensives after Coronary Artery Surgery

Hypertension following coronary artery bypass grafting is a common problem that may result in postoperative myocardial infraction or bleeding, Hemodynamic effects were compared in 45 hypertensive coronary bypass patients randomized to receive either diltiazem, nitroglycerin, or sodium nitroprusside. Diltiazem was administered as an intravenous bolus of 0.3 mg·kg−1 within 5 min, followed by infusion of 0.1–0.8 mg·kg−1·h−1 in group 1. Nitroglycerin was infused at a rate of 1–3 μg·kg·h−1 in group 2, and sodium nitroprusside was given at a rate of 1–3 μg·kg−1·min−1 in group 3. Hemodynamic measurements were carried out before infusion (T1) and at 30 min (T2), 2 h (T3), and 12 h (T4) after initiation of treatment in the intensive care unit. Mean arterial pressure decreased significantly in all groups. There were no differences among groups at T1 and T2. At T3, heart rate in group 2 was significantly higher than group 1. At T3 and T4, the double product was highest in group 3 (group 1 vs. 3, p < 0.001). These results suggest that the hemodynamic effects of the 3 drugs are similar within the first 30 min. However, after 30 min, diltiazem affords better myocardial performance and more effective control of hypertension.

Effect of Diltiazem on Coronary Artery Flow and Myocardial Perfusion in Patients With Isolated Coronary Artery Ectasia and Either Stable Angina Pectoris or Positive Myocardial Ischemic Stress Test

Isolated coronary artery ectasia (CAE) may be associated with stable or unstable coronary events despite the absence of epicardial coronary stenosis. Impaired coronary flow dynamics and myocardial perfusion have been demonstrated in stable patients with ectatic coronary arteries. We aimed to assess whether epicardial flow and tissue-level perfusion would be improved by diltiazem in myocardial regions subtended by the ectatic coronary arteries in patients with isolated CAE. A total of 60 patients with isolated CAE were identified of 9,780 patients who underwent elective coronary angiography. Patients were randomized to 5 mg of intracoronary diltiazem or saline. Coronary blood flow of the microvascular network was assessed using myocardial blush grade (MBG) technique. The thrombolysis in myocardial infarction (TIMI) flow grade and TIMI frame count (TFC) were used to assess epicardial coronary flow. MBG (from 2.4 to 2.6, p = 0.02), TIMI flow grades (from 2.4 to 2.8, p <0.001), and TFC (from 35 to 26, p <0.001) were significantly improved after diltiazem, whereas no significant change was noticed after saline (from 2.4 to 2.4, p = 0.86 for MBG; from 2.3 to 2.3, p = 0.71 for TIMI flow grade; and from 35 to 33, p = 0.43 for TFC). Diltiazem provided amelioration of the altered coronary flow dynamics, which was suggested as the pathophysiological influence of CAE. In conclusion, the favorable effects of the diltiazem on myocardial perfusion were observed at both epicardial and tissue levels.

SEVERAL ASPECTS OF DILTIAZEM AND ORGANIC NITRATES USAGE IN VARIOUS SEVERITY STABLE ANGINA PATIENTS

Aim. To estimate the effectiveness of Diltiazem (Dlt) and its combination with nitrates in patients with ischemic heart disease (CHD) and arterial hypertension (AH) according to exercise tolerance by functional class (FC) of stable angina (StA).

Material and methods. 30 CHD male patients at the age of 58,8±7,5 with StA II FC (n=11), III FC (n=19) and 1–2 stage AH were included into open randomized placebo-controlled study. Drug therapy: Dlt 90–180 mg bid, isosorbide 5-mononitrate 50 mg qd, trinitrolong 2 mg bid or tid. Effectiveness of the regular drug intake was controlled by repeated exercise tolerance tests (ETT) by treadmill with the value of threshold effort time (ThT). Total duration of treatment was 4 weeks.

Results. At the beginning the ThT was 249,8±23,4 s for III FC and 368,6±14,4 s for II FC patients (p=0,0001). One dose of Dlt increased ThT in 5 hours to 387,3±37,5 s and 533,7±20,3 s in both groups, respectively (p=0,001), with the difference between groups being held. During regular Dlt intake the ThT in III FC angina patients reached 441,1±26,8 s, but in II FC patients in has not changed: 526,1±22,0 s. Additional nitrate intake to III FC group led to even more increase of ThT; in II FC patients there was no improvement. Combination therapy by Dlt and nitrates has not led to differences between III and II FC groups by achieved exercise tolerance. Hemodynamic parameters in both groups has not differ.

Conclusion. For patients with III FC stable angina it is recommended to prescribe Dlt with nitrates because of additional effectiveness of combination that might be linked to the influence on cardiac hemodynamics and to improvement of myocardium metabolism. In II FC stable angina Dlt alone reaches its maximum antiischemic effect so the addition of nitrates is not helpful.

Role of potassium channels in coronary vasodilation

K+ channels in coronary arterial smooth muscle cells (CASMC) determine the resting membrane potential ( Em) and serve as targets of endogenous and therapeutic vasodilators. Em in CASMC is in the voltage range for activation of L-type Ca2+ channels; therefore, when K+ channel activity changes, Ca2+ influx and arterial tone change. This is why both Ca2+ channel blockers and K+ channel openers have such profound effects on coronary blood flow; the former directly inhibits Ca2+ influx through L-type Ca2+ channels, while the latter indirectly inhibits Ca2+ influx by hyperpolarizing Em and reducing Ca2+ channel activity. K+ channels in CASMC play important roles in vasodilation to endothelial, ischemic and metabolic stimuli. The purpose of this article is to review the types of K+ channels expressed in CASMC, discuss the regulation of their activity by physiological mechanisms and examine impairments related to cardiovascular disease.

Diltiazem and regional left ventricular function during graded coronary constriction and propofol anesthesia in the dog

Although calcium channel blockers may preserve function in ischemic myocardium, they may also produce myocardial depression and dysfunction in the presence of decreased coronary flow. This study was designed to examine the issue of possible protection afforded by diltiazem against ischemia-induced myocardial dysfunction during propofol anesthesia. In eight anesthetized and ventilated dogs, regional myocardial (ultrasonic crystals in both left anterior descending [LAD] and left circumflex [LC] perfusion areas) and global ventricular function were evaluated during progressively severe degrees of myocardial ischemia (LAD constriction) before and after intravenous diltiazem (150 micrograms/kg). As coronary flow decreased, heart rate increased, and arterial and coronary perfusion pressures, left ventricular dP/dt, and cardiac output decreased. Systemic vascular resistance was unaffected. Diltiazem without coronary constriction increased heart rate, and decreased diastolic arterial pressures, left ventricular (LV) end-diastolic, coronary perfusion pressures, LV dP/dt max, LAD coronary blood flow, stroke volume, and cardiac output. At all levels of coronary constriction following diltiazem, there were decreases in systolic and diastolic arterial pressures, stroke volume, cardiac output, LV dP/dt, and coronary perfusion pressure. Heart rate increased at critical coronary constriction, and then remained constant relative to the prediltiazem state. The regional muscle effects of the reductions in coronary flow in the LAD perfusion territory included decreased systolic shortening and increased postsystolic shortening before and after diltiazem. Diltiazem did not alter the magnitude of the alterations in systolic or postsystolic shortening brought about by coronary constriction. No changes occurred in the LC area.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic tolerability and anti-ischemic efficacy of high dose intravenous diltiazem in patients with normal versus impaired ventricular function

OBJECTIVES

This study was designed to compare the acute systemic and coronary hemodynamic effects of high doses of intravenous diltiazem in patients with normal versus impaired left ventricular function, investigate the safety of this drug and compare its anti-ischemic potential in these two patient groups during pacing-induced stress.

BACKGROUND

Because coronary hemodynamic effects and negative inotropic properties of diltiazem are dose related, high dose intravenous diltiazem may improve anti-ischemic efficacy but may not be tolerated in patients with impaired cardiac function.

METHODS

High dose intravenous diltiazem, 0.4 mg/kg for 5 min followed by 0.4 mg/kg for 10 min, was administered to 23 normotensive patients with coronary artery disease, 11 (group A) with normal and 12 (group B) with impaired ventricular function (ejection fraction < 45%) during two identical arterial pacing stress tests performed 30 min before (pacing test I) and immediately after diltiazem (pacing test II).

RESULTS

Diltiazem was well tolerated despite high peak plasma levels, 869 +/- 152 micrograms/liter (group A) and 926 +/- 169 micrograms/liter (group B). It resulted in immediate but similar reductions in systemic resistance from 1,321 +/- 136 (control value) to 963 +/- 113 dynes.s.cm-5 (group A) and from 1,267 +/- 106 to 865 +/- 58 dynes.s.cm-5 (group B) and in mean arterial pressure from 107 +/- 3 to 93 +/- 4 mm Hg (group A) and from 103 +/- 4 to 86 +/- 4 mm Hg (group B), at 5 min after diltiazem (all p < 0.05 vs. control value). Diltiazem improved stroke output from 36 +/- 3 (control value) to 46 +/- 4 ml/beat per m2 in group B and from 44 +/- 4 (control value) to 49 +/- 5 ml/beat per m2 in group A, an effect that was significantly greater and more prolonged in group B than in group A. Although neither heart rate nor contractility was affected in either group, left ventricular end-diastolic pressure increased in group A (9 +/- 2 mm Hg to 12 +/- 1 mm Hg, p < 0.05) but not in group B. Despite similar reductions in coronary resistance and improvements in coronary flow, diltiazem consistently reduced myocardial oxygen extraction, but only in group B. Also, the anti-ischemic effects of diltiazem were more pronounced in group B. During pacing test II, myocardial lactate extraction normalized in group B (7 +/- 5% vs. -6 +/- 12% [pacing test I]) but not in group A, contractility indexes improved more and the increase in left ventricular filling pressure was reduced to a greater extent in group B. Moreover, the ischemia-induced increase in arterial pressures, observed in both groups during pacing test I, was prevented in group B but recurred in group A during pacing test II.

CONCLUSIONS

High dose intravenous diltiazem is well tolerated, augments coronary flow and improves left ventricular pump function, particularly in patients with preexisting ventricular dysfunction. As its anti-ischemic effects also appear more pronounced in the latter group, high dose diltiazem may be particularly useful when ventricular function is depressed, for example, during prolonged ischemia at rest.

Perspective: the cellular influences of calcium antagonists on systemic and coronary hemodynamics

Calcium antagonists may have a valuable role in ameliorating the extent and duration of myocardial ischemia following infarction. The precise cellular effects of these agents are being revealed through studies using the model of transient coronary occlusion induced by coronary angioplasty. The class of calcium antagonists is not uniform, and these diverse agents may have a favorable effect on ischemia through one or more of the following mechanisms: direct cardioprotective effects, prevention of calcium accumulation in the mitochondria in ischemic cells, reduction in oxygen consumption or in coronary artery vasoconstriction or coronary spasm, prevention of ischemia-induced arrhythmias, and increased coronary blood flow to ischemic tissue directly or through enhancement of collateral flow. Recent studies of diltiazem, nifedipine, nicardipine, nisoldipine, and amlodipine, as representative agents, are reviewed.

[Changes in myocardial metabolism induced by drugs used during intensive care]

More and more patients with coronary heart disease (CAD) are admitted to intensive care units. The drugs used to treat these patients have various effects on the myocardium which must be known in order to avoid worsening the CAD. This review examines the metabolic effects on the myocardium of the most commonly used drugs in intensive care. The physiology of myocardial oxygen supply is first recalled with regard to the coronary circulation, myocardial oxygen extraction and consumption. Digitalis glycosides do not affect the coronary circulation, but the decrease myocardial oxygen consumption in patients with heart failure, mainly by lowering heart rate. Dihydropyridine calcium blockers (nifedipine, nicardipine) increase coronary blood flow, despite a decrease in arterial blood pressure. Their effects on myocardial oxygen consumption are mediated by a sympathetic reflex. Verapamil decreases the heart rate and myocardial inotropism, and is responsible for coronary vasodilation. The result is a decrease in myocardial oxygen consumption. Diltiazem and bepridil have almost similar effects: they decrease myocardial oxygen consumption and increase blood supply to the heart. It has been recently shown that verapamil was the most depressant calcium channel blocking agent, and that it resulted in the most important decrease in myocardial metabolism. Beta-blocking agents decrease myocardial metabolism, except those with an important intrinsic sympathomimetic activity, such as pindolol. Amiodarone can be considered as an alpha and beta blocking drug: its main effect is to counteract the effects of endogenous catecholamines on myocardial metabolism. The sympathomimetic amines (noradrenaline, adrenaline, isoprenaline, dopamine, dobutamine) increase, to different extents, myocardial oxygen consumption. Vasodilators, such as the nitrates or sodium nitroprusside, decrease cardiac filling pressures, and increase myocardial blood flow, thus lowering myocardial oxygen consumption. Phosphodiesterase inhibitors (amrinone, enoximone) have both an inotropic and a vasodilating effect. They decrease cardiac afterload, and increase blood supply to the myocardium; this compensates for the increase in myocardial oxygen consumption due to the increase in myocardial contractility. Because all the drugs used in intensive care have different effects on myocardial metabolism, their reasoned use should avoid an inappropriate increase in oxygen demand.

Effects of diltiazem and nifedipine on systemic and coronary hemodynamics and ischemic responses during transient coronary artery occlusion in patients

Diltiazem and nifedipine improve coronary blood flow and reduce peripheral determinants of myocardial oxygen demand through activation of similar but distinct cellular mechanisms. To identify differences during myocardial ischemia, systemic and coronary hemodynamics were measured continuously before and during brief periods of left anterior descending coronary balloon occlusion in 23 patients undergoing single-vessel angioplasty. Data were compared for two matched ischemic periods, one control and one "drug" period. In 13 patients, diltiazem, 10 mg (intravenous bolus with continuous 500 mg/min infusion), was given; in 10 patients, nifedipine, 10 mg sublingual, was given and after 15 minutes, ischemia was reinduced. Both drugs significantly reduced systolic and mean arterial pressure (for diltiazem, 108 +/- 15 to 93 +/- 10 mm Hg; and for nifedipine, 117 +/- 20 to 96 +/- 8 mm Hg, both p less than 0.01). Diltiazem significantly reduced heart rate-pressure product (with heart rate unchanged), while both drugs maintained the resting great vein blood flow (for diltiazem, 97 +/- 25 to 91 +/- 34 ml/min; for nifedipine, 115 +/- 49 to 98 +/- 58 ml/min, p = ns) with reduced arterial pressure. Coronary flow during occlusion was unchanged (for control versus diltiazem, 63 +/- 21 versus 59 +/- 14 ml/min; for nifedipine, 66 +/- 33 versus 73 +/- 38 ml/min, both p = ns). Neither drug improved collateral hemodynamics or resistance index during ischemia. Both diltiazem and nifedipine prolonged the time to ischemic ST segment alteration (for diltiazem, 27 +/- 10 to 40 +/- 16 seconds, p less than 0.05; for nifedipine, 24 +/- 14 to 38 +/- 14 seconds, p = ns) during transient coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic and echocardiographic assessment of the effects of diltiazem during transient occlusion of the left anterior descending coronary artery during percutaneous transluminal coronary angioplasty

The effects of diltiazem during transient myocardial ischemia were studied in 17 patients (age 58 +/- 11 years, 12 men, 5 women) undergoing 1-vessel left anterior descending percutaneous transluminal coronary angioplasty (PTCA). After hemodynamic, echocardiographic and electrocardiographic data were obtained during the control ischemic periods, diltiazem (10 mg intravenous bolus with 500 micrograms/min infusion) was given and 15 minutes later ischemia reinduced. Diltiazem reduced mean arterial pressure (113 +/- 16 to 95 +/- 15 mm Hg, p less than 0.05) and heart rate-pressure product (p less than 0.05) with no change in heart rate, pulmonary pressures or coronary (sinus, thermodilution technique) blood flow at rest. After diltiazem, times to ischemia-induced 1.0 mm ST-segment elevation (28 +/- 10 to 42 +/- 17 seconds, p less than 0.05) and new left ventricular wall motion abnormalities (by 2-dimensional echocardiography, 24 +/- 8 to 36 +/- 12 seconds, p less than 0.001) were prolonged without significant augmentation of great cardiac vein flow during coronary occlusion. Left ventricular (LV) ejection fraction decreased from 51 +/- 7 to 41 +/- 12% (p less than 0.05) during control ischemia, but declined less after diltiazem (54 +/- 12 to 47 +/- 14%, difference not significant; 47 +/- 14 vs 41 +/- 12%, p less than 0.01). Diltiazem can attenuate, but not abolish, some of the effects of myocardial ischemia on LV function during transient coronary artery occlusion. These data support the use of diltiazem as a beneficial adjunct that may be used acutely and safely during routine PTCA.

The role of nitrates, beta blockers, and calcium antagonists in stable angina pectoris

Numerous controlled studies have shown that nitrates, beta blockers, and calcium antagonists are effective in the treatment of stable angina pectoris. The pharmacokinetics, pharmacodynamics, and hemodynamic effects of these agents are different, and thus combination therapy offers additive improvement and also counterbalancing of the undesirable side effects of each drug. The choice of therapy depends on the severity of symptoms, associated diseases, compliance, side effects, and status of left ventricular function. The main mechanism of improvement is a decrease in myocardial oxygen consumption, though an increase in coronary blood flow is another potential reason for the use of calcium blockers. This review considers the properties of these drugs, their mechanism of action, and the results of randomized studies.

Regional coronary hemodynamic effects of diltiazem in man

We evaluated the changes in regional coronary hemodynamics induced by diltiazem, 0.25 mg/kg intravenously, in nine patients with 75% to 90% diameter stenosis of the left anterior descending coronary artery (LAD) (group 1) and in 10 patients with 100% occlusion of the LAD and collaterals to the distal LAD (group 2). Although diltiazem induced similar changes in systemic hemodynamics in the two groups, a decrease in anterior coronary vascular resistance (ACVR) and an increase in great cardiac vein flow (GCVF) were observed after administration of diltiazem in all patients in group 1 but in only 6 of 10 patients in group 2 (subgroup 2B). ACVR increased and GCVF decreased after administration of diltiazem in 4 of 10 patients in group 2 (subgroup 2A). Clinico-angiographic characteristics, origin of collaterals, and diltiazem-induced changes in systemic hemodynamics were similar in subgroups 2A and 2B. Thus diltiazem increases coronary flow distal to a stenotic coronary artery but can decrease regional coronary flow and increase regional coronary resistance in a minority of patients with an occluded coronary artery supplied by collaterals, probably through a steal mechanism.

Labetalol in normotensive patients with angina pectoris

Labetalol, an alpha-beta-blocker, has been shown to have vasodilating as well as beta-blocking properties. From the theoretical point of view such a drug is likely to be beneficial in the treatment of angina pectoris. There are very few studies investigating the effects of labetalol in normotensive patients with angina pectoris. The three major controlled trials that have been published show that labetalol reduces angina frequency and prolongs exercise duration. In one study the effects of labetalol in anginal subjects using ambulatory monitoring was performed and showed a reduction in silent ischemia as well as a reduction in angina pectoris. Thus labetalol would appear to be an effective antianginal agent. Further studies are necessary to determine if the anti-anginal effect is entirely due to the beta-receptor-blocking activity of the drug or whether labetalol's vasodilating property has important additional benefit.

Systemic and coronary hemodynamics of labetalol in normotensive patients with ischemic heart disease

The systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade produced by labetalol were assessed in 24 normotensive patients with angina pectoris and an ischemic electrocardiographic response to exercise stress. Both the intravenous (0.5 mg/kg) and oral (200 mg) formulations of labetalol were evaluated. At rest, labetalol produced systemic vasodilation (systemic vascular resistance -16% after intravenous and -8% after oral labetalol, both p less than 0.05) without change in heart rate. Aortic pressure usually was lower and cardiac output preserved or increased. Left ventricular end-diastolic pressure was unchanged. Coronary sinus flow was usually unchanged after either route of administration. Exercise duration was prolonged in 14 of the 20 patients with severe coronary artery disease. During exercise, tachycardia was blunted (-12% after intravenous, -7% after oral labetalol, both p less than 0.05) as was the increase in mean aortic pressure (-12% and -13% intravenous and oral labetalol respectively, both p less than 0.05), left ventricular end-diastolic pressure [-7% and -1%, respectively, both p = not significant (NS)] was unchanged. Coronary sinus flow (-16% and -25%, respectively, both p less than 0.05) was decreased as heart rate and aortic pressure were lower. Cardiac output, systemic vascular resistance, and coronary vascular resistance were similar to control exercise. The hemodynamic effects of intravenous and oral labetalol are, in general, similar. Hemodynamic responses differ from those produced by other beta-blockers and by calcium antagonists.

[Prevention of per- and postoperative myocardial ischemia in non-cardiac surgery by intravenous diltiazem]

A controlled double-blind trial was carried out to assess the efficacy and safety of a continuous intravenous infusion of diltiazem in preventing perioperative myocardial ischaemia in patients with coronary artery disease. Sixty-six patients undergoing non cardiac surgical procedures (vascular surgery, n = 37; other, n = 29) were randomly chosen to receive either diltiazem (group D, n = 32); or placebo (group P, n = 34); there was no difference between these groups in the number of patients in each NYHA class (I: 13/16; II: 14/14; III: 5/4) or having had a previous myocardial infarct (20/22). ECG leads CM5 and CL5 were recorded continuously with an ICR 7200 Holter monitor. After starting recording, either placebo or a loading dose (0.5 mg.kg-1) of diltiazem was given, followed by an infusion of 5 micrograms.kg-1.min-1. Anaesthesia was induced by thiopentone and suxamethonium, and maintained with nitrous oxide (50%), fentanyl and either halothane or droperidol. The number of myocardial ischaemic episodes was significantly (p less than 0.05) lower in group D (2 ST depressions in two patients) than in group P (8 ST depressions in six patients, 2 myocardial infarcts and 1 pulmonary oedema). No conduction disturbance was observed; the lowest cardiac frequency was found in group P (32 b.min-1). Systolic and diastolic arterial blood pressures were lower in group D than in group P, but no difference was found in heart rate and rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of nicardipine on determinants of myocardial ischemia occurring during acute coronary occlusion produced by percutaneous transluminal coronary angioplasty

In 10 patients undergoing percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery (LAD), the clinical, electrocardiographic and hemodynamic effects of acute intravenous calcium channel antagonism with nicardipine (2 mg over 1 minute, followed by a constant infusion of 25 to 50 micrograms/min) were assessed during temporary LAD occlusion. Onset of myocardial ischemia during coronary occlusion was prevented or delayed after administration of nicardipine in 7 of the 10 patients. During infusion of nicardipine and during LAD occlusion, residual great cardiac vein blood flow increased in 9 of 10 patients compared with residual flow during occlusion before nicardipine (10%, p less than 0.05). Nicardipine also decreased mean aortic pressure, but was associated with a reflex-mediated increase in heart rate. Overall, the double product, an index of global myocardial oxygen demand, decreased 7% (p less than 0.05). Thus, nicardipine usually diminished ischemia induced by acute transient coronary occlusion by increasing collateral flow while oxygen demand decreased.

Systemic and coronary hemodynamic effects of combined intravenous diltiazem and nitroglycerin administration

This study evaluated left ventricular (LV) and coronary hemodynamic effects of intravenous nitroglycerin (NTG) in the presence of an intravenous infusion of diltiazem in 15 patients with severe coronary disease. Diltiazem (250 microgram/kg bolus followed by 1.4 micrograms/kg/min infusion) alone decreased mean systemic blood pressure (mean 6%) without changing heart rate or LV end-diastolic pressure. The rate of rise in LV pressure declined slightly (4%), and peripheral resistance decreased (19%). Coronary sinus (CS) and great cardiac vein (GCV) flows were preserved. Addition of NTG (average, 68 micrograms/min) decreased systemic pressure further (7%) as LV end-diastolic pressure declined (5 mm Hg). These pressure changes were accompanied by a 10% increase in heart rate (compared with the heart rate found with diltiazem alone). Peripheral resistance was similar to values after diltiazem alone. The CS and GCV flows did not decrease. The sequence of intravenous drug administration was reversed in three other patients with combination therapy, producing similar effects, regardless of which drug was administered first. Hemodynamic effects of intravenous diltiazem alone and its combination with intravenous NTG seemed potentially favorable for patients with ischemic heart disease.

Systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade (labetalol) in normotensive patients with stable angina pectoris and positive exercise stress test responses

The systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade produced by labetalol were assessed in 12 normotensive patients with angina pectoris and an ischemic electrocardiographic response to exercise stress. When given to the patient at rest, labetalol (0.5 mg/kg intravenously) produced systemic and coronary vasodilation (mean 16% and 13%, respectively, both p less than 0.05); aortic pressure decreased, cardiac output increased and coronary flow and heart rate did not change. Before labetalol treatment, supine bicycle exercise produced angina in all patients. After treatment, exercise duration was prolonged in 8 patients (average 33%). At the same duration of exercise that led to angina during the control period, ST depression in lead V5 was less after labetalol (from 1.2 to 0.4 mm, p less than 0.5). During exercise, tachycardia was blunted (-12%, p less than 0.05) as were the increases in aortic pressure (-12%, p less than 0.05), left ventricular end-diastolic pressure (-7%, difference not significant) and coronary sinus flow (-16%, p less than 0.05). Cardiac output and systemic and coronary vascular resistance were similar to values during control exercise. The hemodynamic effects of labetalol appeared to be beneficial and differed from those of classic beta-adrenergic blocking agents.

The haemodynamic effects of nifedipine, verapamil and diltiazem in patients with coronary artery disease. A review

Of the 3 most widely used calcium antagonists--nifedipine, verapamil and diltiazem--nifedipine is the most potent arterial vasodilator. Increases in cardiac output and coronary blood flow following nifedipine administration result in part from the afterload reduction. Reflex adrenergic stimulation produces an increase in heart rate and masks a direct inhibitory effect on myocardial contractility. The negative inotropic action of nifedipine is observed during intracoronary administration or may be made apparent by concurrent beta-blocker therapy. While verapamil is also a potent vasodilator, negative inotropic and dromotropic properties are more apparent in therapeutically used dosages. Reflex sympathetic activation is also triggered by verapamil, with an offsetting of the negative inotropic effects such that little change in cardiac output results. A decrease in myocardial oxygen consumption, with or without a decrease in coronary sinus blood flow, has regularly been observed following verapamil administration. Reduced oxygen demand appears to be a major mechanism of its antianginal effect. The heart rate X systolic pressure product is decreased both by the fall in arterial pressure and, particularly after oral administration, by a decrease in heart rate. Diltiazem produces similar haemodynamic and electrophysiological effects to those of verapamil but has less potency in inducing arterial dilatation and more of a tendency to slow the heart rate. Diltiazem does not appear to cause significant increases in coronary blood flow or bring about improvement in ejectional and isovolumic indices of myocardial contraction - evidence of its intrinsic negative inotropic effect.

Effects of diltiazem during tachycardia-induced angina pectoris

To investigate the mechanism of relief of angina pectoris by diltiazem administration, 14 patients with effort angina were studied using a protocol to control heart rate. Coronary, systemic and left ventricular (LV) hemodynamic function was assessed at rest and during tachycardia stress (atrial pacing)-induced angina before and during diltiazem infusion. Angina occurred in all patients during tachycardia stress before diltiazem administration. During tachycardia stress at the heart rate that produced angina after diltiazem infusion, pressure-rate product, coronary sinus flow and resistance and ST-segment depression were all similar to findings before diltiazem. Although at the onset of angina, systolic pressure was usually slightly lower after diltiazem infusion (138 +/- 11 vs 128 +/- 11 mm Hg, p less than 0.05), the pacing rate at onset of angina was higher in only 3 patients and the pressure-rate product was higher in only 1 patient. After diltiazem, left ventricular end-diastolic pressure increased less frequently after interruption of pacing. The results suggest that diltiazem favorably alters the relation between myocardial oxygen demand and supply at rest, but during tachycardia, anginal threshold and coronary reserve do not change. Diltiazem's potent antianginal action, shown in previous investigations using exercise-induced angina, is not prominent when heart rate is controlled. The major benefit of diltiazem in patients with stress-induced angina is related to reduction of myocardial oxygen demand rather than improved myocardial oxygen delivery.