Myocardial protection by intracoronary nicardipine administration during percutaneous transluminal coronary angioplasty

Nicardipine or nitroglycerin in patients with failed percutaneous coronary angioplasty: effect on myocardial diastolic function

OBJECTIVE

To evaluate whether intracoronary vasodilators can improve diastolic function in 32 patients with failed percutaneous transluminal coronary angioplasty (PTCA).

DESIGN

Clinical trial.

SETTING

Single-institution, academic hospital.

PARTICIPANTS

Failed PTCA patients undergoing emergency coronary artery bypass grafting surgery.

INTERVENTIONS

Patients were divided into 2 groups: group A received 0.1 mg of intracoronary nicardipine, and group B received 20 microg of intracoronary nitroglycerin. Both drugs were administrated via a coronary dilatation perfusion catheter inserted in the catheterization laboratory by the cardiologist. Subsequently, they were continuously infused via the side port of the introducer of the pulmonary artery catheter and titrated to keep systolic blood pressure at about two thirds of the control value. Transesophageal echocardiography (Power Vision/6000, 9-mm 5MHZ Probe; Toshiba, Elmsford, NY) was used in this study.

MEASUREMENTS AND MAIN RESULTS

Left ventricular ejection fraction, cardiac index, tissue Doppler imaging velocity of the left ventricle and mitral annulus, and troponin levels were measured before and after administration of the 2 vasodilators and after cardiopulmonary bypass. Diastolic dysfunction was found preoperatively in all the patients and responded only to intracoronary nicardipine. Ea of mitral annulus velocity significantly increased in group A patients from 7.5 +/- 0.02 to 11.8 +/- 0.01 (p < 0.005) and decreased in group B patients from 8.0 +/- 0.03 to 7.5 +/- 0.02 after nicardipine or nitroglycerin administration. Left ventricular ejection fraction and cardiac index increased significantly (p < 0.005) only after nicardipine administration. Troponin levels were significantly lower in group A than in group B patients (p < 0.005).

CONCLUSION

Intracoronary nicardipine improves diastolic function and myocardial flow velocity in patients with failed PTCA undergoing emergency coronary artery bypass graft surgery.

Nicardipine to control mean arterial pressure after cardiothoracic surgery in infants and children

Nicardipine is the first intravenously administered dihydropyridine calcium channel blocker. Its primary physiologic action includes vasodilatation with limited effects on the inotropic and dromotropic function of the myocardium. Several previous reports document its use in adult patients for pharmacologic control of blood pressure. The current report describes the use of nicardipine to control mean arterial pressure (MAP) in nine infants and children after cardiothoracic surgical procedures. The patients ranged in age from 6 days to 9 years (mean, 3.3 +/- 4.1 years) and in weight from 4.1 to 49 kg (mean, 15.3 +/- 14.4). The surgical procedures included aortic coarctation repair (three), repair of tetralogy of Fallot (two), arterial switch for transposition of the great vessels (two), pulmonary valvotomy (one), and aortic valvotomy (one). The target systolic blood pressure was 90 mm Hg in patients younger than 4 years of age and < or = 110 mm Hg in patients 5 years of age or older. The nicardipine infusion was started at 5 microg/kg/min in all patients. The target blood pressure was achieved within 15 minutes in eight of nine patients. One patient required an initial infusion rate of 10 microg/kg/min to achieve the target blood pressure. The maintenance infusion rate varied from 2.5 to 5.5 mcg/k/min (mean 3.0 +/- 1.1). The duration of the infusion varied from 30 to 42 hours (mean, 37.4 +/- 4.2). In the nine patients, nicardipine was infused for a total of 337 hours. No adverse effects such as excessive hypotension were noted. Nicardipine is an effective agent for controlling MAP after cardiothoracic surgical procedures in infants and children.

Effects of nicardipine and nitroglycerin on perioperative myocardial ischemia in patients undergoing coronary artery bypass surgery

Perioperative myocardial ischemic episodes are predictive of adverse cardiac outcomes after coronary artery bypass surgery. We compared the efficacy of continuous infusions of nicardipine (group NIC) and nitroglycerin (group NTG) in reducing the frequency and severity of myocardial ischemic episodes. Patients received either a nicardipine infusion, 0.7 to 1.4 microg/kg/min (n = 30), nitroglycerin infusion, 0.5 to 1 microg/kg/min (n = 30), or neither medication (group C; n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes were considered as ST segment depressions or elevations of 1 mm or greater from baseline, each at J + 60 milliseconds and lasting 1 minute or greater, using a two-channel Holter monitor. Only nicardipine significantly decreased the duration (3.2 +/- 1.2 min/h) and the area under the ST time curve (AUC; 5.7 +/- 15.7 AUC/h) of 1-mm or greater myocardial ischemic episodes compared with group C (17.2 +/- 5.6 min/h and 30.1 +/- 49 AUC/h, respectively) during the intraoperative postbypass period. A trend toward lower frequency, duration, and area under the ST time curve of myocardial ischemic episodes was observed in group NIC compared with group NTG. Cardiac indices and mixed venous oxygen saturations were significantly greater, whereas systemic pressures were less in group NIC compared with group NTG for the same period. These results suggest that nicardipine, but not nitroglycerin, decreased the duration and area under the ST time curve of myocardial ischemic episodes shortly after coronary revascularization. Larger studies are required to verify the efficacy of nicardipine in reducing the severity of myocardial ischemia during cardiac surgery.

Antiischemic effects of nicardipine and nitroglycerin after coronary artery bypass grafting

BACKGROUND

We assessed the efficacy of a continuous infusion of nicardipine and nitroglycerin in reducing the incidence and severity of perioperative myocardial ischemia during elective coronary artery bypass grafting procedures in a prospective, randomized, controlled study.

METHODS

Patients received either nicardipine infusion (0.7 to 1.4 microg x kg(-1) x min(-1); n = 30) or nitroglycerin (0.5 to 1 microg x kg(-1) x min(-1); n = 30) or neither medication (n = 17) after aortic occlusion clamp release and for 24 hours postoperatively. Myocardial ischemic episodes (MIE) were considered to have occurred with ST-segment depressions or elevations of at least 1 mm and at least 2 mm (for both depressions or elevations), each at J + 60 ms and lasting at least 1 minute, using a two-channel Holter monitor.

RESULTS

Only nicardipine significantly decreased the duration (p = 0.02) of the 1-mm or greater minutes per hour (3.2 +/- 1.2 minutes per hour) and eliminated the number (p = 0.02) of the 2-mm or greater minutes per hour (zero minutes per hour) when compared with control patients (17.2 +/- 5.6 minutes per hour and 0.17 minutes per hour, respectively) during the intraoperative postbypass period.

CONCLUSIONS

Our results suggest that nicardipine lessened the severity of myocardial ischemia shortly after coronary revascularization and could be considered as an alternative to standard antiischemic therapy.

Antiischemic effect of intracoronary diltiazem on myocardial ischemia during PTCA

To evaluate the effect of intracoronary diltiazem on myocardial ischemia during percutaneous transluminal coronary angioplasty (PTCA), 38 patients were randomly assigned to receive inactive placebo (n = 19; group C) or a low dose (1 mg, n = 10; group D1), or a high dose (2 or 3 mg, n = 9; group D2) of diltiazem in a double-blind manner. The agent was administered directly into the coronary artery via a balloon catheter following a control balloon inflation. Chest pain score (maximum, 10) and the magnitude of ischemic ST elevation on standard and intracoronary electrocardiograms (ECGs) during a balloon inflation were assessed in the control and posttreatment periods. After the administration of diltiazem, the chest pain score was significantly decreased in group D1 (control: 5.1 +/- 3.6, posttreatment: 3.8 +/- 3.1, P < 0.01) and group D2 (3.4 +/- 2.5 vs 2.5 +/- 2.0, P < 0.01), but not in group C (4.1 +/- 3.1 vs 3.7 +/- 3.3, difference not significant). The magnitude of ST elevation relative to the control on standard and intracoronary ECGs was significantly smaller in groups D1 and D2 than in group C (standard ECG; D1: 51.8 +/- 10.6% of control, D2: 41.6 +/- 28.7% vs C: 93.3 +/- 15.6% and intracoronary ECG; D1: 47.1 +/- 11.7% of control, D2: 27.5 +/- 26.9% vs C: 94.6 +/- 29.3%, all P < 0.01). Although systolic blood pressure decreased slightly in groups D1 and D2, there was no significant correlation between the change in ST elevation and the change in the rate-pressure product. Pretreatment with a small dose of intracoronary diltiazem attenuated myocardial ischemia during PTCA and this pretreatment may enable us to perform balloon inflation for a longer period.

Role of calcium channel blockers in reducing acute ischaemia and preventing restenosis in PTCA

Calcium channel blockers (calcium antagonists) are widely used before, during and after percutaneous transluminal coronary angioplasty (PTCA). When administered during PTCA, calcium channel blockers may be beneficial in decreasing regional ischaemia in patients with proven or suspected variant angina, as a result of their cardioprotective effects, their ability to enhance collateral flow, and their antispastic effects at the epicardial level. More recently, the agents have also proven to be effective in patients who have developed "no-reflow' phenomenon during PTCA. Preliminary findings suggest that calcium channel blockers may also have potential benefits when administered after angioplasty. The combined results of 5 studies, evaluating a total of 919 patients, showed a trend towards angiographic reduction in restenosis. These observations are of interest but may be due to reporting bias. In conclusion, calcium channel blockers are effective in reducing ischaemia induced by PTCA. These agents may, thus, be appropriate in high risk patients. Further large studies examining the effects of calcium channel blockers on restenosis are required to confirm the observations available to date.

Nicardipine: applications in anesthesia practice

Nicardipine is the first intravenously administered dihydropyridine calcium channel blocker. Its primary physiologic actions include vasodilatation with limited effects on the inotropic and dromotropic function of the myocardium. Nicardipine has been used to control blood pressure intraoperatively in response to tracheal intubation and in the postoperative period. Various patient populations have been included such as major vascular and cardiovascular surgery. It has also been used as an agent for controlled hypotension. Preliminary experience suggests that nicardipine provides safe and effective control of perioperative blood pressure. The basic pharmacology and physiology of the most recently released calcium channel antagonist, nicardipine, is reviewed, and its applications in clinical anesthesia and interaction with other anesthetic drugs are discussed.

SIN-1 has no direct myocardial anti-ischemic action

Anti-ischemic drugs may develop their cardiac activity via peripheral (reduction in preload and/or afterload) or cardiac (coronary vasculature, myocardial cell metabolism) effects. The aim of the study was to investigate whether SIN-1, the active metabolite of molsidomine, develops a direct myocardial anti-ischemic property. Three groups of seven patients each were treated with 0.4 mg SIN-1 administered via either the intracoronary (IC) or intravenous (IV) route, or with placebo in a double-blind randomized investigation. SIN-1 had no influence on either the ischemic parameters in the surface electrocardiogram (ECG) or the intracoronary ECG. There was also no change in peripheral or central hemodynamics or in the severity of angina following this low IC or IV dosage. There is no evidence of a direct myocardial anti-ischemic response of SIN-1. The well known anti-ischemic activity of SIN-1 or molsidomine has to be attributed to the proven peripheral and cardiac vascular responses.

Similar antiischemic effects of intracoronary atenolol and nifedipine during brief coronary occlusions in humans

To compare the antiischemic effects of intracoronary administration of a beta blocker, atenolol, and of a calcium antagonist, nifedipine, on the clinical and electrocardiographic signs of myocardial ischemia induced by balloon occlusion of the coronary artery, we studied 32 consecutive patients undergoing routine PTCA. In each patient at least three balloon inflations were performed: the first served to verify the occurrence of ischemia (ST segment depression/elevation greater than 1.5 mm); the second was used as a control occlusion; the third was performed after the patients were assigned to receive either atenolol 1.0 mg IC (group 1, N = 16) or nifedipine V = 0.2 mg IC (group 2, N = 16). In a control population of 10 patients, the time to return to baseline of the ECG tended to be progressively shorter during the three consecutive inflations, but the other clinical and ECG parameters did not change significantly. In group 1 and group 2, two patients did not show ECG signs of ischemia at the third inflation; the time to ischemia increased in group 1 (+76%, p less than .001) and group 2 (+85%, p less than .01; NS group 1 versus group 2); ST segment displacement at 30 seconds decreased in group 1 (-38%, p less than .01) and group 2 (-36%, p less than .01; NS group 1 versus group 2).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Influence of balloon size and stenosis morphology on immediate and delayed elastic recoil after percutaneous transluminal coronary angioplasty

After successful coronary angioplasty, the minimal luminal diameter of the dilated coronary artery segment is generally smaller than the diameter of the largest balloon catheter at the maximal inflation pressure. The determinants of this phenomenon were studied in 28 patients. Biplane angiograms were obtained after intracoronary administration of isosorbide dinitrate (1 mg) before, immediately and 24 h after coronary angioplasty. Balloon and coronary luminal diameters were measured by automated contour detection. Immediately after the procedure, the difference between inflated balloon diameter and minimal luminal diameter averaged 0.93 +/- 0.43 mm for the entire group and was greater both in eccentric stenoses (1.13 +/- 0.39 vs. 0.70 +/- 0.36 mm; p less than 0.01) and after angioplasty with an oversized balloon (1.20 +/- 0.37 vs. 0.71 +/- 0.33 mm; p less than 0.005). At 24 h, the balloon - minimal luminal diameter difference was unchanged at the group level (0.86 +/- 0.38 mm, but the minimal luminal diameter increased significantly in the subgroup of coronary segments dilated with an oversized balloon (1.97 +/- 0.37 vs. 1.81 +/- 0.28 mm; p less than 0.05). Thus, the difference between the minimal diameter of a dilated coronary segment immediately after a successful coronary balloon angioplasty procedure and the maximal diameter of the inflated balloon catheter is dependent both on eccentricity of the stenosis and on the balloon/artery diameter ratio. Moreover, the increase in minimal luminal diameter 24 h after angioplasty performed with an oversized balloon suggest that in addition to elastic recoil partly reversible factors related to vessel barotrauma are involved.

Effect of gallopamil on myocardial ischaemia during percutaneous transluminal coronary angioplasty

This report summarises selected preliminary results from an ongoing study designed to investigate the effect of the calcium antagonist gallopamil on myocardial ischaemia during percutaneous transluminal coronary angioplasty (PTCA). To date, 12 adult males with coronary artery disease and significant proximal stenosis of the left anterior descending coronary artery (LAD) have been randomly assigned to gallopamil or placebo under double-blind conditions. Patients with recent myocardial infarction, apparent collateralisation of the LAD, myocardial failure, sinoatrial or atrioventricular block, severe hepatic disease or renal failure were excluded from the study. PTCA was performed using at least 2 balloon inflations, each of 2 minutes' duration. Gallopamil 0.4 mg or placebo (normal saline) were administered during the 10-minute interval between the 2 inflations. Blood samples were taken simultaneously from the coronary sinus and the femoral artery before and immediately after each inflation. Lactate concentration and the relative amount of activated neutrophils were selected for trend analysis. Furthermore, ECG changes were analysed by calculating the sum of the absolute ST-segment deviations (80 msec after J point, maximal T deviation) of leads I, II, III, V2, V4 and V6. In the presence of gallopamil, the degree of ST-segment/T-wave changes induced by balloon inflation was reduced. Additionally, gallopamil attenuated myocardial lactate release and appeared to prevent the increase in activated neutrophils observed during control inflations. These preliminary results suggest a beneficial effect from intracoronary administration of gallopamil during PTCA, achieved by attenuation of the ischaemic reaction during coronary occlusion.

Protective effects of pretreatment with intracoronary nifedipine on myocardial ischemia and dysfunction

To assess whether pretreatment with intracoronary nifedipine protects the myocardium against acute ischemia induced by coronary occlusion, 18 patients were studied during coronary angioplasty of the left anterior coronary artery. After a control occlusion of 60 seconds, 0.1 mg nifedipine was injected and occlusion was repeated for 60 seconds. Before and during the occlusion period, pulmonary capillary pressure was measured and the intracoronary epicardial ECG was recorded. After intracoronary administration of nifedipine, the onset of the rise in diastolic filling pressure was delayed from 23 to 38 seconds (p less than 0.01) and the changes at 60 seconds of occlusion were reduced from 14 to 11 mmHg (p less than 0.05). Nifedipine delayed the appearance of ischemic ST-segment elevation in the intracoronary ECG from 11 to 21 seconds (p less than 0.01) and diminished the changes at 60 seconds of occlusion from 1.8 to 1.2 mV (p less than 0.05). These findings suggest that pretreatment with intracoronary nifedipine protects the myocardium against some of the mechanical and electrocardiographic consequences of regional ischemia during acute coronary occlusion.

Myocardial protection by intravenous diltiazem during angioplasty of single-vessel coronary artery disease

The possible cardioprotective effect of diltiazem during ischemia caused by percutaneous transluminal coronary angioplasty was tested. Electrocardiograms and myocardial lactate, hypoxanthine and urate production were determined in 26 patients with a stenosis in the left anterior descending artery without angiographically demonstrable collaterals. Measurements took place before angioplasty, after each of 4 occlusions and 15 minutes after the last balloon inflation. Patients were randomly given placebo or DL-diltiazem (0.4 mg/kg as a bolus intravenously, followed by an infusion of 15 mg/hr). During angioplasty the ST-segment elevation for the anterior wall leads V2, V4 and V6, and the intracoronary lead was similar for both groups, as was lactate release. Diltiazem significantly reduced cardiac hypoxanthine release immediately after angioplasty from 63 to 88% (p less than 0.05). The drug diminished urate production after the last dilatation by 82% (p less than 0.05). In conclusion, intravenous infusion of diltiazem reduced cardiac adenosine triphosphate breakdown during angioplasty as shown by diminished hypoxanthine and urate production. In contrast, diltiazem was unable to attenuate ST-segment elevation and lactate release.

Clinical pharmacology, pharmacokinetics, and hemodynamic effects of nicardipine

The dihydropyridine derivatives constitute a distinct subcategory of calcium channel blockers that have marked peripheral vascular effects with minimal or no electrophysiologic actions when administered to intact animals or humans. These dihydropyridine derivatives are structurally similar to nifedipine, the most widely studied dihydropyridine. The derivatives have varying affinities for different regional circulations, and there may be an important relationship between structure and activity of these compounds with respect to the predilection of the site of their action in vascular tissue. It is possible that such differences may be of clinical significance. As a class, the dihydropyridines exert reasonably distinct hemodynamic changes that may be of particular importance in the treatment of hypertension, cardiac failure, and regurgitant valvular lesions. Nicardipine hydrochloride is a newer agent that has undergone extensive evaluation in recent years. Pharmacologically and electrophysiologically, it resembles other dihydropyridines. Unlike nifedipine, however, it can be administered by both the intravenous and oral routes. There are additional differences between its properties and those of other calcium channel blockers. For example, nicardipine appears to produce a greater increase in coronary sinus blood flow than other calcium channel blockers. The clinical significance of this finding is unclear. In addition, nicardipine appears to increase myocardial contractility, even in patients with severe congestive cardiac failure. Nicardipine produces a dose-dependent decrease in blood pressure and systemic vascular resistance with increases in heart rate, left ventricular dP/dt, LV ejection fraction, cardiac output, and stroke work index, but no significant change in LV end-diastolic pressure. Clearly, the drug has negligible venodilator actions.(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.

Effects of long-term combined dosing with nicardipine and propranolol on coronary hemodynamics, myocardial metabolism, and exercise tolerance in patients with angina pectoris: comparison with monotherapy

To determine whether the association of nicardipine with propranolol had additive effects on myocardial metabolism, 16 patients with angina pectoris were studied invasively before and after 1 month of therapy with a combination of nicardipine and propranolol and compared to a group of 42 patients treated with nicardipine (n = 17) or propranolol (n = 25) alone. When data were compared at a fixed heart rate (atrial pacing), mean blood pressure was reduced with combined treatment from 96 +/- 19 to 76 +/- 13 mm Hg (p less than 0.003). Myocardial oxygen uptake and coronary sinus flow decreased significantly from 20 +/- 9 to 14 +/- 6 ml/min (p less than 0.015) and from 152 to 111 ml/min (p less than 0.05), respectively. The arterio-coronary sinus difference in oxygen content also decreased (13.3 to 12.5 ml/dl; p less than 0.0025), suggesting an improved balance between oxygen supply and demand. Such changes in coronary blood flow and myocardial oxygen uptake were not observed in the group of patients assigned to monotherapy. Lactate uptake rose and the abnormal glutamine production, which worsened with propranolol monotherapy, improved with nicardipine and propranolol (-2.0 to -1.4 mumol/min; p less than 0.05 vs propranolol). The superiority of nicardipine and propranolol over propranolol monotherapy was maintained during a pacing stress test. Thus the combination of nicardipine with a beta blocker had greater oxygen-sparing effects and restored aerobic metabolism better than either drug alone, allowing optimal use of the coronary reserve.

Calcium channel antagonists. Part V: Second-generation agents

Second-generation agents include new dihydropyridines, such as amlodipine, felodipine, isradipine, nicardipine, nimodipine, nisoldipine, and nitrendipine. Verapamil-like agents include tiapamil, gallopamil, and anipamil. Among the diphenylalkylamines, bepridil is of special interest. New preparations of existing agents include slow-release formulations of nifedipine, verapamil, and diltiazem. From all these agents will be selected those that are longer-acting and provide higher vascular selectivity.