Myocardial ischemia induced by rapid atrial pacing causes troponin T release detectable by a highly sensitive assay: insights from a coronary sinus sampling study.

Objectives: The purpose of this study was to assess whether: 1) very small increases in troponin T, measured by a new highly sensitive cardiac troponin T (hs-cTnT), may reflect ischemia without necrosis; and 2) serial changes can discriminate ischemia from other causes of cardiac troponin T (cTnT) release.

Background: A new hs-cTnT assay offers greater sensitivity than current assays.

Methods: Nineteen patients referred for diagnostic catheterization underwent cannulation of the coronary sinus (CS).

The effect of acute hypoxemia on coronary arterial dimensions in patients with coronary artery disease.

Objectives: To assess the influence of acute hypoxemia on the dimensions of diseased and nondiseased coronary arterial segments in humans.

Methods: In 18 subjects (age 53 +/- 8 years) with known or suspected coronary artery disease, quantitative coronary angiography was performed before and after being randomly assigned to breathing (1) an inspired oxygen concentration (fraction of inspired oxygen, FIO2) of 21% (room air, RA) for 20 min (n = 4, controls) or (2) an FIO2 of 15 and 10% for 10 min each (corresponding to altitudes of 2,500 and 5,500 m, respectively; n = 14).

Results: In the control subjects, no hemodynamic, oximetric or angiographic variable changed.

Inaccuracies of oximetry in identifying the location of intracardiac left-to-right shunts in adults.

Although oximetric analysis of blood from the right heart chambers is the most commonly used method for assessing the presence of intracardiac left-to-right shunting, it sometimes provides misleading information because a patient with a left-to-right shunt in only 1 location sometimes manifests a significant oxygen step-up (1) in >1 chamber or (2) in a chamber other than that in which the shunt is actually located. This study was performed (1) to assess the frequency with which oximetric data provide such misleading results and (2) to determine which variables (if any) may contribute to the occurrence of such erroneous oximetric results. Accordingly, we analyzed oximetric data from 168 patients (61 men, 107 women, 14 to 76 years of age) with a proved left-to-right shunt at only 1 site and oximetric evidence of significant oxygen step-up.

Predictors of coronary artery disease in patients with left bundle branch block undergoing coronary angiography.

Patients with left bundle branch block (LBBB) and concomitant coronary artery disease (CAD) have a worse prognosis than those with LBBB without CAD. In addition, subjects with CAD and concomitant LBBB have a higher cardiovascular mortality than those with a similar extent of CAD but without LBBB. Because the presence of LBBB makes the noninvasive identification of CAD problematic, patients with LBBB often are referred for coronary angiography to assess the presence and severity of CAD.

Theodore E. Woodward award: cardiovascular complications of cocaine abuse.

As cocaine abuse has become widespread, it has been associated with various cardiovascular complications, including angina pectoris, myocardial infarction, and sudden cardiac death. Cocaine's principal effects on the cardiovascular system are mediated via alpha-adrenergic stimulation and include (a) an increase in the determinants of myocardial oxygen demand (heart rate and systemic arterial pressure) and (b) a concomitant decrease in myocardial oxygen supply (caused by vasoconstriction of the epicardial coronary arteries). Cocaine-induced coronary arterial vasoconstriction is enhanced at sites of atherosclerotic narrowing.

Percutaneous coronary interventions: guidelines, short- and long-term results, and comparison with coronary artery bypass grafting.

An ever-growing number of patients are being referred for coronary revascularization in an attempt to reduce morbidity or to reduce mortality. Multiple randomized trials comparing percutaneous and surgical coronary revascularization have been performed. The decision to proceed with percutaneous or surgical revascularization should be based ona thorough understanding of the short- and long-term risks and benefits of each procedure in conjunction with the individual patient's coronary arterial anatomy and clinical risk profile.

Intra-aortic balloon counterpulsation.

Intra-aortic balloon counterpulsation (IABP) is sometimes used in critically ill patients with cardiac disease. By increasing diastolic arterial pressure and decreasing systolic pressure, it reduces left ventricular afterload. IABP may be beneficial in subjects with cardiogenic shock, mechanical complications of myocardial infarction, intractable ventricular arrhythmias, or advanced heart failure or those who undergo "high-risk" surgical or percutaneous revascularization, but the evidence to support its use in these patient groups is largely observational.