Sodium bicarbonate versus sodium chloride and oral N-acetylcysteine for the prevention of contrast-induced nephropathy in advanced chronic kidney disease.

INTRODUCTION: Contrast-induced acute kidney injury (CI-AKI) is one of the leading causes of hospital-acquired acute kidney injury. Multiple clinical studies have proposed several preventive strategies. AIMS: To examine the efficacy of sodium bicarbonate compared with sodium chloride and oral N-acetylcysteine (NAC) for preventive hydration after cardiac catheterization. METHODS: We conducted a prospective, single-center trial. Patients with chronic kidney disease (CKD) stage III-IV undergoing cardiac catheterization were allocated to receive either an infusion of 0.9% sodium chloride and oral NAC or 154 mEq/L sodium bicarbonate. MAIN: Outcome measure CI-AKI, defined as an increase of 25% or 0.3 mg/dL or more in plasma creatinine within 2 days of contrast administration. RESULTS: Ninety-three patients were allocated to one of the two groups: 42 patients in the saline plus NAC group and 51 patients in the bicarbonate group. There were no statistically significant differences between the groups in the most important clinical and procedural characteristics. Baseline plasma creatinine levels, estimated glomerular filtration rate, incidence of diabetes mellitus, hypertension, congestive heart failure, and contrast medium volume were similar. Mean plasma creatinine concentration was 1.76 +/- 0.54 mg/dL in the saline and NAC group and 1.9 +/- 1 mg/dL in the bicarbonate group (P = 0.23). The rate of CI-AKI was 9.8% in the bicarbonate group and 8.4% in the saline plus NAC group. No patient required renal replacement therapy. CONCLUSION: Hydration with sodium bicarbonate is not more effective than hydration with sodium chloride and oral NAC for prophylaxis of CI-AKI in patients with CKD stage III-IV undergoing cardiac catheterization.

Symptomatic myocardial bridges: overview of ischemic mechanisms and current diagnostic and treatment strategies.

This review article focuses on the morphological and functional alterations that characterize patients with myocardial bridges (MB) as well as the currently available diagnostic and treatment strategies. Because of incomplete understanding of the pathophysiology of MB, their clinical significance has been the subject of debate for the last quarter century. Investigational tools now available in the cardiac catheterization laboratory have helped clarify why symptoms and signs of ischemia can occur in such patients, especially when the only angiographic finding appears to be systolic compression or milking effect of a coronary vessel. Quantitative coronary angiography and intravascular ultrasound (IVUS) clearly demonstrate that the phasic systolic vessel compression visualized on the angiogram is coupled with a persistent diastolic diameter reduction. Intracoronary Doppler reveals increased flow velocities, retrograde systolic flow, and reduced coronary flow reserve. The clinical diagnosis can be established by significant percent lumen diameter and area narrowing, increased flow velocity, and by characteristic patterns such as the "half moon" phenomenon on IVUS and the early diastolic "finger tip" phenomenon on intracoronary Doppler. Successful medical, interventional, or surgical therapy leads not only to marked improvement or normalization of these alterations but also relief of angina and ischemia.

Effect of aortic valve replacement for aortic stenosis on severity of mitral regurgitation.

BACKGROUND: Surgically addressing moderate mitral regurgitation (MR) at the time of aortic valve replacement (AVR) for aortic stenosis remains uncertain. The purpose of this study was to examine the change in moderate (2+) or moderate-severe (3+) MR after isolated AVR for aortic stenosis to determine preoperative factors predictive of improvement in MR. METHODS: Using an institutional databank of prospectively collected data, all patients undergoing isolated AVR for aortic stenosis with moderate (2+) to moderate-severe (3+) MR between 1994 and 1996 at the Montreal Heart Institute were evaluated. RESULTS: Eighty patients with preoperative and postoperative transthoracic echocardiographic follow-up were identified. Preoperative MR was moderate (2+) in 78 patients (97.5%) and moderate-severe (3+) in 2 patients (2.5%). Mitral regurgitation was classified as rheumatic (32%), ischemic (32%), functional (21%), and myxomatous (15%). At 1-year follow-up transthoracic echocardiography, MR improved by 1 or 2 grades in 29 patients (35%), was unchanged in 44 (55%), and worsened in 7 (10%). On multivariate analysis, isolated ischemic and functional MR were the only preoperative factors predictive of MR improvement after AVR (p = 0.01): 54% of ischemic and 44% of functional MR patients showed improvement in MR after AVR compared with 23% of rheumatic and 17% of myxomatous MR patients. CONCLUSIONS: Etiology of MR was a significant prognostic factor for improvement in MR grade. Since there was little improvement in the rheumatoid and myxomatous group, replacement or repair should strongly be considered. For functional and ischemic mitral regurgitation, a surgical correction should be performed on an individual basis.

Biventricular diastolic filling patterns after coronary artery bypass graft surgery.

OBJECTIVE: We sought to study the evolution of biventricular filling properties after coronary artery bypass grafting. BACKGROUND: The evolution of diastolic function as defined with newer echocardiographic modalities after coronary artery bypass grafting surgery is unknown in patients with preoperative left ventricular diastolic dysfunction. METHODS: Transthoracic echocardiography was performed preoperatively and 48 hours and 6 months after coronary artery bypass grafting in 49 patients (randomized to milrinone [n = 25]) or placebo [n = 24]) with preoperative left ventricular diastolic dysfunction classified according to published criteria. Mild right ventricular diastolic dysfunction was defined as the ratio of early to atrial filling velocity of less than 1 in transtricuspid flow or the velocity of reversed atrial flow of greater than 50% of that of systolic flow in hepatic venous flow or the ratio of tricuspid annulus velocity during early and atrial filling of less than 1 if both the ratio of early to atrial filling velocity and the ratio of systolic to diastolic velocity was greater than 1 in hepatic venous flow. Moderate right ventricular diastolic dysfunction was diagnosed when there was a ratio of early to atrial filling velocity of greater than 1 with a ratio of systolic to diastolic velocity of less than 1. Severe right ventricular diastolic dysfunction was defined as a ratio of early to atrial filling velocity of greater than 1 associated with reversed systolic wave in hepatic venous flow. RESULTS: Moderate and severe left ventricular diastolic dysfunction increased from preoperatively to 48 hours after coronary artery bypass grafting from 8.2% to 53.7% and from 2.0% to 9.7%, respectively (P < .0001, 48 hours vs preoperatively for both), and the patterns at 6 months were similar to those observed preoperatively. Similar evolution over time was found for right ventricular diastolic dysfunction. CONCLUSIONS: In patients with preoperative left ventricular diastolic dysfunction, biventricular filling patterns are impaired initially but return to preoperative status 6 months after coronary artery bypass grafting.