Haemodynamic effects of glyceryl trinitrate during continuous 24 hour infusion in patients with heart failure

Drug therapy before coronary artery surgery: nitrates are independent predictors of mortality and beta-adrenergic blockers predict survival

We conducted this study to evaluate whether there is an association between preoperative drug therapy and in-hospital mortality in patients undergoing coronary artery graft surgery. We collected data on 1593 consecutive patients undergoing coronary artery surgery. The relative risk of in-hospital mortality was determined by logistic regression with in-hospital mortality as the dependent variable, and independent variables that included known risk factors and preoperative cardioactive or antithrombotic drug treatment, i.e., age; left ventricular function; left main coronary artery disease; urgent priority; gender; previous cardiac surgery; concurrent cardiovascular surgery; chronic lung disease; creatinine concentration; hemoglobin concentration; diabetes; hypertension; cerebrovascular disease; recent myocardial infarction; prior vascular surgery; number of arteries bypassed; and regular daily treatment with beta-blockers, aspirin within 5 days, calcium antagonists, angiotensin converting enzyme (ACE) inhibitors, digoxin, or warfarin. In-hospital mortality was 3.3%. The relative risk of in-hospital mortality (with 95% confidence intervals of the relative risk) associated with the following drug treatments was: nitrates 3.8 (1.5-9.6), beta-blockers 0.4 (0.2-0.8), aspirin within 5 days 1.0 (0.5-1.9), calcium antagonists 1.1 (0.6-2.1), ACE inhibitors 0.8 (0.4-1.5), digoxin 0.7 (0.2-1.8), and warfarin 0.3 (0.1-1.6). We conclude that in-hospital mortality is positively associated with preoperative nitrate therapy and negatively associated with beta-adrenergic blocker therapy. A significant association between in-hospital mortality and the preoperative use of calcium antagonists, ACE inhibitors, aspirin, digoxin, and warfarin was not confirmed.

IMPLICATIONS

We examined the association between common drug treatments for ischemic heart disease and short-term survival after cardiac surgery using a statistical method to adjust for patients' preoperative medical condition. Death after surgery was more likely after nitrate therapy and less likely after beta-blocker therapy.

Impact of intravenous nitroglycerin on pulsed Doppler indexes of left ventricular filling in acute anterior myocardial infarction

BACKGROUND

Restrictive transmitral Doppler flow patterns are associated with heart failure in acute myocardial infarction (AMI).

METHODS AND RESULTS

The objective of this study was to evaluate the effect of intravenous nitroglycerin on the transmitral pulsed Doppler patterns in patients with anterior AMI. Twenty-four patients with anterior AMI were randomly assigned to receive incremental intravenous nitroglycerin or placebo over a 16-minute period with change to the other arm after a washout period. Left ventricular filling was assessed with transmitral pulsed Doppler echocardiography. According to the baseline E/A ratio, patients were divided into a restrictive group (n = 17, E/A ratio > or =21.4) and a nonrestrictive group (n = 7, E/A <1.4). In the restrictive group after administration of nitroglycerin the E/A ratio decreased (1.9+/-0.7 to 1.1+/-0.2, P < .001), E-wave peak velocity decreased (71+/-10 to 60+/-9 cm/s, P < .01), and A-wave peak velocity increased (39+/-9 to 58+/-8 cm/s, P < .01 ). In the nonrestrictive group there were no significant changes after nitroglycerin infusion in the E/A ratio (1.1+/-0.2 to 0.8+/-0.1, not significant), peak E-wave velocity (55+/-4 to 47+/-6 cm/s), and peak A-wave velocity (49+/-8 to 52+/-8 cm/s). Deceleration time increased significantly in both groups after administration of nitroglycerin. Placebo did not result in significant changes in hemodynamic or Doppler parameters in either group.

CONCLUSIONS

Intravenous nitroglycerin administration was associated with reversal of restrictive left ventricular diastolic filling pattern on pulsed wave Doppler in patients with anterior AMI.

Nitric oxide and nitrovasodilators: similarities, differences, and interactions

The endothelium functions as a semipermeable membrane separating the blood from the body and allowing the transport of macromolecules from the blood to the interstitial space. The endothelium secretes a number of diffusible substances. These include endothelium-derived relaxing factor (EDRF), endothelium-derived hyperpolarizing factor (EDHF), and prostacyclin, in addition to vasoconstrictors including endothelin, angiotensin, and endothelium-derived contracting factor. EDRF is now known to be nitric oxide, or a closely related molecule, which affects signaling by stimulation of soluble guanylate cyclase, causing increased intracellular levels of cyclic guanosine monophosphate (cGMP), in turn leading to relaxation of vascular smooth muscle as well as a variety of additional effects that include altered function of platelets and cardiac myocytes. Nitric oxide can be made available to cellular elements in two ways: by endogenous synthesis via one or more of the three nitric oxide synthases now known to exist in mammalian species; or by exogenous administration of pharmacologic sources of nitric oxide, usually as organic nitrate vasodilators that can be metabolically converted to biologically activated nitric oxide. This process appears to require free sulfydryl groups. The metabolic machinery necessary to convert organic nitrates to a biologically active form exists mainly in the vasculature and not in the myocardium. Numerous studies have demonstrated that the presence of coronary artery disease is associated with interruption of the endogenous production of nitric oxide. Under these circumstances, exogenous nitrates still produce coronary vasodilation as well as relaxation of vascular smooth muscle in the periphery. Other articles in this supplement will focus on the vascular effects of nitric oxide and nitrovasodilators; this article will conclude with a brief discussion of the role of the nitric oxide pathway in the control of cardiac autonomic responsiveness and the potential role of cytokines and the nitric oxide pathway to impair the ability of the myocardium to respond to catecholamines or other stimuli with a normal increase in contractile function.