The purpose of this investigation was to establish normal values of RR variability for middle-aged persons and compare them with values found in patients early and late after myocardial infarction. We hypothesized that presence or absence of coronary heart disease, age, and sex (in this order of importance) are all correlated with RR variability.

The Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO-I) trial was designed to test whether thrombolytic strategies achieving more complete, early, sustained coronary artery patency would lead to further reductions in mortality in patients with acute myocardial infarction. An angiographic substudy within GUSTO-I provided a unique opportunity to examine the relation between mortality and degrees of patency among the regimens.

Prolonged postoperative recovery caused by a low cardiac output state occurs in some patients after complete repair of tetralogy of Fallot. Biventricular systolic function is usually well preserved in these patients. The contribution of impaired diastolic function, particularly of the right ventricle, has not been studied in detail; therefore, we performed a prospective study of right ventricular diastolic function in this patient group.

Early defibrillation is the single most important factor for improving out-of-hospital ventricular fibrillation resuscitation rates. To achieve the earlier response times required for survival, typically < 6 minutes from time of collapse, it will be necessary to equip a far wider network of first responders (firefighters, police, and other individuals with responsibility for public safety) with small, lightweight, and inexpensive automatic external defibrillators (AEDs). An important step in reducing the size and cost of AEDs will be to improve defibrillation efficacy. Because biphasic waveform defibrillation has had a favorable impact on implantable cardioverter-defibrillators (ICDs), there are reasons to believe that biphasic waveforms would also improve transthoracic defibrillators. Our purpose, therefore, was to examine the efficacy of two different low-energy biphasic truncated waveforms referenced to a standard damped sine waveform for transthoracic defibrillation in humans.

Adenosine administered intravenously terminates supraventricular tachycardias (SVT) involving the AV node as part of the reentrant circuit. Dipyridamole increases interstitial myocardial levels of this nucleoside. This study was designed to determine whether intravenous dipyridamole increases coronary sinus plasma adenosine concentrations ([Ado]cs) in humans to levels sufficient to alter electrophysiological parameters and terminate SVT.

Left ventricular (LV) hypertrophy, as measured by M-mode echocardiography, is an independent predictor of mortality and/or morbidity from coronary heart disease (CHD). LV global and segmental systolic dysfunction also have been associated with myocardial ischemia and cardiovascular morbidity and mortality. Echocardiographic data, especially two-dimensional, have not been available previously from multicenter-based studies of the elderly. This report describes the distribution and relation at baseline of echocardiographic LV mass and global and segmental LV wall motion to age, sex, and clinical disease category in the Cardiovascular Health Study (CHS), a cohort of 5201 men and women (4850 white) 65 years of age and older.

Patients with essential hypertension have abnormal endothelium-dependent vascular relaxation, largely related to reduced bioactivity of nitric oxide (NO). The purpose of the present investigation was to determine whether this defect is due to a deficit at the specific intracellular signal-transduction pathway level or is a consequence of a more generalized endothelial abnormality.

Continuous positive airway pressure (CPAP) can improve cardiac function in patients with congestive heart failure (CHF). We hypothesized that this effect might be related to CPAP-induced increases in intrathoracic pressure, which would reduce left ventricular transmural pressure (LVPtm) during systole, thereby decreasing left ventricular afterload.

Symptom-limited incremental exercise tests are used to estimate the severity of cardiovascular disease and the patient's daily activity. However, there is a need for objective parameters for submaximal exercise. To test the hypothesis that a decrease in maximal exercise capacity can be estimated by oxygen uptake (VO2) kinetics, we measured the time constant of VO2 both during the onset of constant work rate exercise at 50 W and during recovery from this exercise and compared it with data obtained during maximal exercise in patients with cardiovascular disease and in normal subjects.

Angiopeptin is a cyclic octapeptide analogue of somatostatin that has been shown to limit myointimal thickening of arteries in balloon injury models and to restore the vasodilating response to acetylcholine. A randomized, double-blind placebo controlled trial was conducted to assess the effect of angiopeptin in restenosis prevention after percutaneous transluminal coronary angioplasty (PTCA).

The placement of stents in coronary arteries has been shown to reduce restenosis in comparison to balloon angioplasty. However, clinical use of intracoronary stents is impeded by the risk of subacute stent thrombosis and complications associated with the anticoagulant regimen. To reduce these complications, the hypothesis that systemic anticoagulation is not necessary when adequate stent expansion is achieved was prospectively evaluated on a consecutive series of patients who received intracoronary stents.

Despite remarkable advances in the treatment of acute myocardial infarction, substantial early patient mortality remains. Appropriate choices among alternative therapies and the use of clinical resources depend on an estimate of the patient's risk. Individual patients reflect a combination of clinical features that influence prognosis, and these factors must be appropriately weighted to produce an accurate assessment of risk. Prior studies to define prognosis either were performed before widespread use of thrombolysis or were limited in sample size or spectrum of data. Using the large population of the GUSTO-I trial, we performed a comprehensive analysis of relations between baseline clinical data and 30-day mortality and developed a multivariable statistical model for risk assessment in candidates for thrombolytic therapy.

The capability of chronic tricyclic antidepressant drug (TAD) treatment to elicit myocardial damage has been a subject of debate. Lack of an adequate noninvasive method to detect such damage has prevented an in-depth study.

Elevated levels of shear stress such as those that occur in stenotic arterial vessels can directly activate and aggregate platelets and thus contribute to the pathogenesis of acute arterial thrombosis. This shear-induced platelet aggregation (SIPA) is mediated by von Willebrand factor binding to platelet membrane glycoprotein (GP) Ib and GPIIb/IIIa. The chimeric Fab fragment of the monoclonal antibody 7E3 (c7E3 Fab) that binds selectively to GPIIb/IIIa is under clinical evaluation in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). This study was undertaken to investigate the effects on ex vivo SIPA of c7E3 Fab administered to patients undergoing PTCA.

Early loss of minimal luminal diameter (MLD) after successful percutaneous transluminal coronary angioplasty (PTCA) is associated with a higher incidence of late restenosis.

Unlike nonselective coronary vasodilators, nitroglycerin (GTN) is said to exert its primary vasodilatory effect on epicardial conductance vessels. Thus, in experimental models of coronary occlusion GTN appears to preferentially direct blood flow to poststenotic zones of ischemia. This phenomenon has, to date, not been tested in humans. Using positron emission tomography we examined the effect of transdermal GTN on global and regional myocardial perfusion in patients with angiographically proven coronary artery disease.

The objectives of this study were to assess the antianginal and anti-ischemic effects of three dose levels of transdermal nitroglycerin patches applied for 12 hours daily for 30 days. The study also assessed the development of tolerance and rebound. Intermittent transdermal nitroglycerin therapy with a patch-free period of 10 to 12 hours each day has documented clinical benefits during the period of patch application, but studies have failed to clearly document prolonged exercise duration for the entire period of patch application. This study was designed to evaluate the efficacy and duration of action of a range of doses of nitroglycerin. The study also permitted the assessment of the maintenance of initial effects, the development of tolerance, and the presence of rebound.

A real-time in vitro system of human platelet thrombosis under arterylike flowing conditions similar to those produced in vivo by angioplasty would be useful for the evaluation of potential antiarterial thrombotic agents in association with in vivo trials. Aspirin, heparin, and the chimeric monoclonal antibody antigen-binding fragment 7E3 (c7E3 Fab) directed against platelet glycoprotein (GP) IIb-IIIa have been used in attempts to delay or prevent thrombotic reocclusion of coronary arteries after angioplasty. We compared the effects of these agents administered in vivo on GPIb-mediated platelet adhesion to von Willebrand factor (vWF)/collagen type I (as in atherosclerotic subendothelium) and on subsequent GPIIb-IIIa-fibrinogen/vWF-mediated platelet aggregation under flowing conditions analogous to those in constricted coronary arteries.