Coronary artery bypass grafting in patients with mild renal insufficiency

Off-pump versus on-pump complete coronary artery bypass grafting: Comparison of the effects on the renal damage in patients with renal dysfunction

BACKGROUND

We aimed to compare off-pump technique with on-pump technique on renal function in patients with nondialysis-dependent renal dysfunction who underwent coronary artery bypass grafting.

METHODS

The 94 patients with renal dysfunction undergoing isolated coronary artery bypass grafting were retrospectively analyzed. No patient was receiving dialysis. Patients were randomly assigned to conventional revascularization with cardiopulmonary bypass and beating heart. Both groups were compared in terms of renal dysfunction parameters and dialysis requirement. The logistic regression models were constructed to identify risk factors associated with dialysis requirement.

RESULTS

Renal dysfunction requiring dialysis developed in 9 patients in the on-pump group. The measures analysis of variance was performed on the data that showed worsening of renal function in the on-pump group compared with the off-pump group. Cardiopulmonary bypass is significant as independent predictor for the development of postoperative dialysis.

CONCLUSION

These results suggest that off-pump coronary revascularization offers a superior renal protection and has a significantly lower risk for renal complications in patients with nondialysis-dependent renal dysfunction when compared with conventional coronary revascularization with cardiopulmonary bypass.

Does mild renal failure affect coronary flow reserve after coronary artery bypass graft surgery?

INTRODUCTION

There are only a limited number of studies on the link between mild renal failure and coronary artery disease. The purpose of this study is to investigate the effects of mild renal failure on the distal vascular bed by measuring the coronary flow reserve (CFR) in transthoracic echocardiography after coronary artery bypass grafting (CABG).

METHODS

The study included 52 consecutive patients (12 women and 40 men) who had undergone uncomplicated CABG. The patients were divided into 2 groups. Group 1 included patients with a preoperative glomerular filtration rate (GFR) of 60-90 (mild renal failure), and group 2 included those with a GFR >90. The CFR measurements were carried out through a second harmonic transthoracic Doppler echocardiography.

RESULTS

The mean age was 60.08 ± 1.56 years in group 1 and 60.33 ± 1.19 in group 2. The mean preoperative CFR was 1.79 ± 0.06 in group 1 and 2.05 ± 0.09 in group 2. The mean postoperative CFR was 2.09 ± 0.08 in group 1 and 2.37 ± 0.06 in group 2. There was a statistically significant difference between the 2 groups as to preoperative creatinine clearance, preoperative estimated GFR, postoperative day 7 creatinine clearance, postoperative month 6 creatinine clearance, postoperative day 7 estimated GFR, postoperative month 6 estimated GFR, preoperative CFR, and postoperative CFR (P < .05). CFR was found to be unaffected by the choice of on-pump or off-pump technique (P = .907). After bypass surgery, there was a significant increase in the mean postoperative CFR, when compared with the mean preoperative CFR (P = .001).

CONCLUSION

In our study, we detected a decrease in CFR in patients with mild renal failure. We believe that in patients undergoing CABG for coronary artery disease, mild renal failure can produce adverse effects due to deterioration of the microvascular bed.

Postoperative outcomes in patients with chronic renal failure undergoing coronary artery bypass grafting in madani heart center: 2000-2010

INTRODUCTION

Renal failure predisposes patients to adverse outcome after coronary artery bypass grafting (CABG). Renal dysfunction is a predictor of increased morbidity and mortality after CABG, whether it is dialysis-dependent or not.

METHODS

In a retrospective study from April 2000 to December 2010, seventy-six patients (60 male and 16 female with the mean age of 58.57±7.93 years) with different categories of chronic renal failure undergoing CABG in Shahid Madani Hospital, were studied. The cardiac disease leading to the operation was coronary artery disease (CAD) in all patients. Patients demographic, surgical and laboratory data were gathered from hospital records. Data were then analyzed.

RESULTS

Mean hospital stay was 10.16±7.16 days. The preoperative mortality rate was 10.5% (15% in non dialysis and 5.6% in dialysis dependant patients with no significant difference). Morbidity rate was 28.9% (respectively 30% and 27.8% in dialysis and non dialysis patients with no significant difference) including in-hospital myocardial infarction (MI) (10.5%), in-hospital stroke (2.6%), in-hospital bleeding (21.1%) and in-hospital infection, pneumonia, (5.3%). Mean creatinine and blood urea nitrogen (BUN) levels were significantly increased after surgery (p<0.001). Postoperative hemodialysis rate was 33.3%.

CONCLUSION

Chronic renal failure whether dialysis-dependant or not increases in-hospital mortality and morbidity in patients undergoing CABG. For CRF patients not on dialysis with a creatinine 2.5 gm/dL, there is a strong likelihood of postoperative dialysis.

The scope of coronary heart disease in patients with chronic kidney disease

Chronic kidney disease (CKD) affects approximately 13% of the U.S. population and is associated with increased risk of cardiovascular complications. Once renal replacement therapy became available, it became apparent that the mode of death of patients with advanced CKD was more likely than not related to cardiovascular compromise. Further observation revealed that such compromise was related to myocardial disease (related to hypertension, stiff vessels, coronary heart disease, or uremic toxins). Early on, the excess of cardiovascular events was attributed to accelerated atherosclerosis, inadequate control of blood pressure, lipids, or inflammatory cytokines, or perhaps poor glycemia control. In more recent times, outcome research has given us further information that relates even lesser degrees of renal compromise to an excess of cardiovascular events in the general population and in those with already present atherosclerotic disease. As renal function deteriorates, certain physiologic changes occur (perhaps due to hemodynamic, inflammatory, or metabolic changes) that decrease oxygen-carrying capacity of the blood by virtue of anemia, make blood vessels stiffer by altering collagen or through medial calcinosis, raise the blood pressure, increase shearing stresses, or alter the constituents of atherosclerotic plaque or the balance of thrombogenesis and thrombolysis. At further levels of renal dysfunction, tangible metabolic perturbations are recognized as requiring specific therapy to reduce complications (such as for anemia and hyperparathyroidism), although outcome research to support some of our current guidelines is sorely lacking. Understanding the process by which renal dysfunction alters the prognosis of cardiac disease might lead to further methods of treatment. This review will outline the relationship of CKD to coronary heart disease with respect to the current understanding of the traditional and nontraditional risk factors, the role of various imaging modalities, and the impact of coronary revascularization on outcome.

Low dose nesiritide and the preservation of renal function in patients with renal dysfunction undergoing cardiopulmonary-bypass surgery: a double-blind placebo-controlled pilot study

BACKGROUND

Renal insufficiency is associated with increased morbidity and mortality after cardiopulmonary bypass cardiac surgery. B-type natriuretic peptide is a cardiac hormone that enhances glomerular filtration rate and inhibits aldosterone. Cystatin has been shown to be a better endogenous marker of renal function than creatinine.

METHODS AND RESULTS

We performed a double-blinded placebo-controlled proof of concept pilot study in patients (n=40) with renal insufficiency preoperatively (defined as an estimated creatinine clearance of <60 mL/min determined by the Cockroft-Gault formula), undergoing cardiopulmonary bypass cardiac surgery. Patients were randomized to placebo (n=20) or i.v. low dose nesiritide (n=20; 0.005 microg/Kg/min) for 24 hours started after the induction of anesthesia and before cardiopulmonary bypass. Patients in the nesiritide group had an increase of plasma B-type natriuretic peptide and its second messenger cGMP with a decrease in plasma cystatin levels at the end of the 24-hour infusion. These changes were not observed in the placebo group. There was a significant activation of aldosterone in the placebo group at the end of the 24-hour infusion, but not in the nesiritide group. At 48 and 72 hours, there was a decrease in estimated creatinine clearance and an increase in plasma cystatin as compared with end of the 24-hour infusion in the placebo group. In contrast, renal function was preserved in the nesiritide group with no significant change in estimated creatinine clearance and a trend for plasma cystatin to increase as compared with end of the 24-hour infusion.

CONCLUSION

This proof of concept pilot study supports the conclusion that perioperative administration of low dose nesiritide is biologically active and decreases plasma cystatin in patients with renal insufficiency undergoing cardiopulmonary bypass cardiac surgery. Further studies are warranted to determine whether these physiological observations can be translated into improved clinical outcomes.

Creatinine clearance but not serum creatinine alone predicts long-term postoperative survival after lower extremity revascularization

BACKGROUND

Renal insufficiency is a well-described risk factor for perioperative morbidity and shortened survival after major vascular procedures. Due to the potential inaccuracy of serum creatinine levels alone in measuring kidney function, our aim was to determine whether estimated creatinine clearance more consistently predicted long-term survival.

METHODS

A retrospective review of one institution's vascular registry was performed. Logistic regression analysis was conducted to determine independent predictors of 1-, 2- and 3-year postoperative mortality. Creatinine clearance was estimated as [140 - age (years)] x weight (kg)/72 x serum creatinine (mg/dl), multiplied by 0.85 for women.

RESULTS

A total of 252 consecutive patients underwent infrainguinal bypass procedures between August 1999 and May 2000. Demographics included average age 68 years, 65% male, 74% diabetic, 12% dialysis-dependent, 23% history of congestive heart failure, 12% history of stroke and 20% serum creatinine >2 mg/dl. One-year mortality was 16% (n = 40), 2-year mortality was 25% (n = 64), and 3-year mortality was 35% (n = 88). There was no difference in serum creatinine values between survivors and non-survivors at 1 year (1.8 vs. 1.9, p = 0.80), 2 years (1.8 vs. 2.0, p = 0.62) or 3 years (1.8 vs. 2.0, p = 0.24), and creatinine >2 mg/dl did not predict long-term adverse outcomes. In contrast, reduced creatinine clearance (< or =60 ml/min) was an independent predictor of mortality regardless of dialysis status (1 year: OR = 2.53, p = 0.014; 2 years: OR = 2.46, p = 0.004; 3 years: OR = 2.45, p = 0.001), and creatinine clearance was higher for survivors versus non-survivors at all 3 time points (1 year: 70.2 vs. 49.5, p = 0.003; 2 years: 72.3 vs. 51.2, p < 0.0001; 3 years: 74.7 vs. 52.6, p < 0.0001). Other independent predictors of mortality included a history of stroke (1 year: OR = 3.28, p = 0.008; 2 years: OR = 2.55, p = 0.025; 3 years: OR = 2.35, p = 0.038) and congestive heart failure (1 year: OR = 2.86, p = 0.006; 2 years: OR = 2.54, p = 0.005; 3 years: OR = 2.13, p = 0.017).

CONCLUSIONS

Independent of dialysis status, a decreased creatinine clearance, but not elevated serum creatinine alone, is an independent predictor of mortality after lower extremity arterial reconstruction. Determination of creatinine clearance should replace serum creatinine in the preoperative risk evaluations of patients undergoing major vascular surgical procedures.

Does off-pump coronary artery bypass grafting really preserve renal function?

It is well known that the use of cardiopulmonary bypass (CPB) influences renal function and occasionally results in renal failure following cardiac surgery. Coronary artery bypass grafting (CABG) without CPB may avoid this and preserve the perioperative renal function. The present study enrolled 52 patients undergoing CABG without CPB (OPCAB group) and matched them for renal function and prognostic variables with 53 patients undergoing conventional CABG (CABG group). Perioperative renal function and early clinical results were assessed. The OPCAB group had significantly less increase in creatinine levels (0.16 +/- 0.05 vs 0.45 +/- 0.06 mg/dl; p = 0.01) and greater creatinine clearance (81.6 +/- 7.3 vs 56.3 +/- 4.8ml/min; p = 0.01) postoperatively. Postoperative recovery of free water clearance was more prompt in the OPCAB group. The duration of intubation and intensive care unit stay was significantly shorter, and the creatine kinase-MB release and blood transfusion requirements were significantly less in the OPCAB group. The OPCAB technique preserved glomerular filtration rate and prevented the increase in creatinine levels. The results suggest that the technique enables earlier patient recovery and gives superior renal protection compared with conventional CABG.

Outcome of cardiac surgery patients with complicated intensive care unit stay

Risk stratification has become an essential element in the practice of cardiac surgery. Several studies have identified preoperative risk factors for adverse outcome. However, outcome is mostly defined by 30-day mortality and morbidity. These data reflect poorly the benefit for the patient. Long-term survival, quality of life, and functional status should be included in a more global analysis of the outcome, particularly in patients with complicated ICU stay. By reviewing the recent data reported in the literature, we can identify a number of preoperative predictive factors for complicated ICU stay, including advanced age, chronic obstructive pulmonary disease, preoperative low ejection fraction, previous myocardial infarction, reoperation, renal failure, combined surgery (coronary artery bypass grafting plus valve surgery), low hematocrit, and neurologic impairment. Short- and long-term outcomes are dependent on the type of postoperative complication. Unfortunately, data regarding the long-term outcome in these situations are very scarce.

The pharmacokinetics and tolerability of an intravenous infusion of the new hydroxyethyl starch 130/0.4 (6%, 500 mL) in mild-to-severe renal impairment

Hydroxyethyl starches (HES) are almost exclusively excreted glomerularly, in part after hydrolysis by amylase. HES 130/0.4 (Voluven; Fresenius Kabi Deutschland GmbH, Bad Homburg, Germany) was developed to improve pharmacokinetics whereas preserving the efficacy of volume effect. We studied the dependency of pharmacokinetics of HES 130/0.4 on renal function. Nineteen volunteers with stable, non-anuric renal dysfunction, ranging from almost normal creatinine clearance (CL(cr)) to severe renal impairment (mean CL(cr): 50.6 mL. min(-1). 1.73 m(-2)), were given a single infusion of 500 mL 6% HES 130/0.4 over 30 min. HES plasma concentrations were determined until 72 h, urinary excretion until 72-96 h. CL(cr) had been obtained at least twice before and twice after dosing. Standard pharmacokinetic calculations and regression analysis were performed. Area under the time concentration curve (AUC(0-inf)) clearly depended on renal function comparing subjects with CL(cr) < 50 with those with CL(cr) > or =50 (ratio 1.73). Peak concentration (C(max), 4.34 mg/mL) as well as terminal half-life (16.1 h, model independent) were not affected by renal impairment. At CL(cr) > or =30, 59% of the drug could be retrieved in urine, versus 51% at CL(cr) 15-<30. The mean molecular weight of HES in plasma was 62,704 d at 30 min, showing lower values with increased renal impairment (P = 0.04). Pre-dose amylase concentrations inversely correlated with baseline CL(cr). Residual HES plasma concentrations after 24 h were small in all subjects (< or =0.6 mg/mL). We conclude that HES 130/0.4 (500 mL 6%) can be safely administered to patients even with severe renal impairment, as long as urine flow is preserved, without plasma accumulation.

IMPLICATIONS

Dependency of the pharmacokinetics of hydroxyethyl starch 130/0.4 on renal function was studied. The area under the time concentration curve increased moderately with more severe renal dysfunction; however, small plasma concentrations were observed after 24 h. Terminal half-life and peak concentration remained unaffected by renal impairment.

Coronary revascularization improves long-term prognosis in diabetic and nondiabetic end-stage renal disease

To test the hypothesis that coronary revascularization improves long-term prognosis in patients with hemodialysis, 80 of 121 patients (66%) on maintenance hemodialysis who had undergone initial coronary angiography had bypass surgery, catheter angioplasty, or both between 1983 and 1999. Multivessel disease was more frequent (p=0.01) and the duration of hemodialysis therapy was shorter (p=0.01) in patients with diabetes (n=61), than in nondiabetic patients (n=60). Of the patients who underwent revascularization, complete revascularization was achieved in 75% of those with diabetic nephropathy (30/40) and 83% in a similar number of nondiabetic patients (33/40). The 5-year survival rate from initiation of hemodialysis was 79% in diabetic and 96% in non-diabetic patients (p<0.01), exceeding published Japanese (53% vs 70%) and US (26% vs 60%) survival rates. When survival was studied from the date of revascularization, predictors of outcome were age and achievement of complete revascularization. Surprisingly, diabetes was not a predictor of survival outcome. Complete revascularization improves long-term survival in both diabetic and nondiabetic patients.