Plasma concentrations and hemodynamic effects of intravenous, sublingual, and aerosolized nitroglycerin in patients undergoing cardiac catheterization.

Intravenous, sublingual, or aerosolized nitroglycerin was administered to 19 patients with coronary artery disease during clinically indicated cardiac catheterization. Eight blood samples were collected over 15 min from each patient, and analyzed for content of nitroglycerin, 1,2-glycerol dinitrate, and 1,3-glycerol dinitrate. Simultaneously, heart rate (HR), systolic blood pressure (SBP), and left ventricular end-diastolic pressure (LVEDP) were recorded. Plasma concentrations of nitroglycerin were highest after intravenous injection and lowest after sublingual tablets. Metabolite concentrations were highest after intravenous injection at early time-points; at later time-points, no between-group differences could be detected. SBP was minimally affected by intravenous nitroglycerin but was significantly reduced by sublingual and aerosolized formulations. Minor fluctuations in HR were observed in association with all three formulations. LVEDP was reduced by all three formulations of nitroglycerin but most rapidly by the intravenous form. Overall, no differences were detected in hemodynamic responses caused by sublingual and aerosolized nitroglycerin. Efficacy of sublingual and aerosolized nitroglycerin in patients undergoing cardiac catheterization is equivalent.

Haemodynamic effects of intracoronary neuropeptide Y in dogs: resistance to alpha adrenergic blockade.

STUDY OBJECTIVE: Neuropeptide Y is a peptide isolated from brain and neural tissue around human coronary arteries. It has been shown to produce coronary vasoconstriction and myocardial ischaemia. The purposes of this study were (a) to determine whether the vasoconstriction induced by neuropeptide Y was mediated by alpha adrenergic receptors in vivo, and (b) to determine the time course of the effect and whether it was reproducible with a second administration. DESIGN: Neuropeptide Y (200 micrograms over 2 min) was given by intracoronary injection on two occasions 1 h apart to group I dogs (control). In group II the second dose was preceded by treatment with the alpha blocker phenoxybenzamine (4-10 mg.kg-1). The time course and magnitude of the effect was studied in the two groups to determine the effects of alpha blockade and of repeated neuropeptide Y dosage. EXPERIMENTAL MATERIAL: 14 mongrel dogs (n = 7 per group) were anaesthetised with chloralose for a left thoracotomy to measure coronary blood flow, aortic pressure, left ventricular pressure, and heart rate. MEASUREMENTS AND MAIN RESULTS: Reproducible prolonged increases in coronary vascular resistance occurred after the first [33(SD 18)%] and second [34(17)%] doses of neuropeptide Y. At this infusion rate mean aortic pressure increased with each dose by 21% and coronary blood flow decreased by 7%. In group II dogs, phenoxybenzamine given intravenously 20 min after the first dose of neuropeptide Y reduced mean aortic pressure by 15-20 mm Hg. In this group neuropeptide Y also caused reproducible increases in coronary vascular resistance before (36%) and after (46%) alpha blockade. CONCLUSIONS: Neuropeptide Y constricts coronary arteries in vivo by mechanisms that do not require intact alpha adrenergic receptors, and the coronary vasoconstriction was prolonged and reproducible.

Effect of peripheral cardiopulmonary bypass on left ventricular size, afterload and myocardial function during elective supported coronary angioplasty.

Although cardiopulmonary bypass support has been increasingly used for high risk coronary angioplasty, few data exist regarding its effects on left ventricular function. Accordingly, in 20 patients changes in left ventricular size, afterload and myocardial function were assessed by continuous hemodynamic monitoring and simultaneous two-dimensional echocardiography during cardiopulmonary bypass-supported high risk angioplasty. The cross-sectional left ventricular area during bypass support remained unchanged during diastole, whereas during systole it decreased (from 29.6 +/- 11.4 to 27.6 +/- 10.4 cm2, p less than 0.05). Global left ventricular function expressed as fractional area change remained unchanged from baseline to bypass support but decreased during balloon inflation (from 0.27 +/- 0.11 to 0.17 +/- 0.09, p less than 0.001). The end-systolic meridional wall stress decreased during bypass support (from 141 +/- 75 to 110 +/- 58 x 10(3) dynes/cm2, p less than 0.02). Regional myocardial function was assessed by a wall motion score (0 = normal, 1 = hypokinesia, 2 = akinesia and 3 = dyskinesia). Regions supplied by a stenotic (greater than or equal to 50% diameter) vessel deteriorated during bypass support (score from 0.9 +/- 0.8 to 1.06 +/- 0.8, p less than 0.01), whereas regions supplied by a nonstenotic vessel did not. Regions supplied by the target vessel deteriorated further during balloon inflation (score from 0.7 +/- 0.6 to 1.7 +/- 0.75, p less than 0.001). Thus, although left ventricular size and global function remain unchanged and afterload decreases during bypass support, myocardial dysfunction in regions supplied by a stenotic vessel may occur. Furthermore, regional and global left ventricular dysfunction still occur with angioplasty balloon inflation during cardiopulmonary bypass support.

Hemodynamic and metabolic effects of venoarterial cardiopulmonary support in coronary artery disease.

Coronary angioplasty was performed on 14 high-risk patients supported with venoarterial partial cardiopulmonary bypass. Hemodynamic, metabolic and physiologic parameters were monitored to assess the effect of cardiopulmonary support in conscious patients. Cardiopulmonary support caused a decrease in systolic (45 +/- 17 to 27 +/- 14 mm Hg, p less than 0.001), diastolic (23 +/- 12 to 14 +/- 8 mm Hg, p less than 0.005) and mean (29.7 +/- 13.2 to 18 +/- 9 mm Hg, p less than 0.001) pulmonary artery pressures. Aortic systolic (129 +/- 18 to 106 +/- 17 mm Hg, p less than 0.001), mean (89 +/- 19 to 84 +/- 19 mm Hg, p less than 0.05) and pulse (64 +/- 17 to 37 +/- 16 mm Hg, p less than 0.00001) pressures also decreased. Heart rate and aortic diastolic pressures were unchanged. End-systolic wall stress (122 +/- 48 x 10(3) to 96 +/- 44 x 10(3) dynes/cm2, p less than 0.001) and left ventricular end-diastolic diameter (5.7 +/- 0.8 to 5.5 +/- 0.9 cm, p less than 0.05) were reduced during partial cardiopulmonary bypass. After initiation of cardiopulmonary support, normal lactate extraction across the coronary circulation was diminished or converted to lactate production (38 +/- 23 to 2 +/- 29%, p less than 0.005). There was a marked reduction in hematocrit (41 +/- 4 to 28 +/- 5%, p less than 0.0001) and platelet count (259,000 +/- 57,600/ml to 145,900 +/- 46,000/ml, p less than 0.0001) after bypass. Cardiopulmonary bypass successfully supported all patients during balloon inflation, for an optimal angioplasty result.(ABSTRACT TRUNCATED AT 250 WORDS)