Shahzad G. Raja

Impact of off-pump coronary artery bypass surgery on postoperative bleeding: current best available evidence.

Abstractu2003 Cardiopulmonary bypass (CPB) is a prerequisite for open‐heart surgery, and is a procedure routinely used. CPB exposes blood to artificial surfaces, to mechanical trauma from the pump, to alterations in temperature, and to dilution with fluids, whole blood, plasma products, and drugs, and leads to the activation of platelets, coagulation, and fibrinolysis. Coagulopathy during cardiac surgery with CPB results in impairment in hemostasis and subsequently higher morbidity and mortality. Recent advances in surgical techniques and postoperative management have aimed at reducing postoperative morbidity and mortality. Off‐pump coronary artery bypass (OPCAB) surgery is one such advance that attempts to avoid the deleterious effects of extracorporeal circulation by performing myocardial revascularization without CPB. Emerging evidence from several randomized controlled trials (RCTs) as well as large registries such as the Society of Thoracic Surgeons (STS) database suggests that OPCAB reduces the postoperative morbidity and mortality. This review article attempts to evaluate the current best available evidence from RCTs on the impact of OPCAB on postoperative bleeding and transfusion requirements.

Impact of off-pump coronary artery bypass surgery on graft patency: current best available evidence.

Abstractu2003 For more than three decades cardiac surgeons have been used to perform delicate coronary anastomoses on cardiopulmonary bypass (CPB). However, the price of a still and bloodless field is ultimately paid by the patients in the form of sequelae of negative effects of CPB including blood trauma, activation of a series of inflammatory responses, nonpulsatile flow, and possible embolization of air or debris. In an attempt to avoid these deleterious effects of CPB, off‐pump coronary artery bypass surgery (OPCAB) has been rediscovered and refined. Although abundant evidence is available to suggest that excellent results can be achieved when CPB is avoided, concerns have been raised about quality of anastomosis and graft patency rates after OPCAB surgery. We are currently practicing in an era of evidence‐based medicine that mandates the prospective randomized controlled trial (RCT) as the most accurate tool for determining a treatment benefit compared with a control population. This review article attempts to evaluate the current best available evidence from RCTs on the impact of OPCAB surgery on graft patency.

Impact of stentless aortic valves on left ventricular function and hypertrophy: current best available evidence.

Abstractu2002 Past four decades have seen a gradual evolution in aortic valve replacement surgery. The ideal valve substitute should combine central flow, low transvalvular gradient, low thrombogenicity, durability, easy availability, resistance to infection, freedom from anticoagulation, and easy implantability. Although there are several types of valves available to replace the diseased aortic valve—autograft, allograft, xenograft, mechanical, and bioprosthetic valves—none is ideal. On one end of the spectrum is the pulmonary autograft, which comes closest to achieving these goals, but creates a double valve procedure for single valve disease, while on the other end are the mechanical valves and stented tissue valves, which allow easy “off the shelf” availability as well as easy implantability but are limited by the potential drawback of causing intrinsic obstruction to some extent because of the space occupied by the stent and sewing ring. Stentless xenograft aortic valves have been developed as a compromise between these ends of the valve spectrum. Stentless aortic valves have been reported to provide more physiologic hemodynamic behavior and cause more timely and thorough regression of ventricular hypertrophy. This review article attempts to evaluate current best available evidence from randomized controlled trials to assess the impact of stentless aortic valves on left ventricular function and hypertrophy.

Impact of modified ultrafiltration on morbidity after pediatric cardiac surgery.

Cardiopulmonary bypass is a double-edged sword. Without it, corrective cardiac surgery would not be possible in the majority of children with congenital heart disease. However, much of the perioperative morbidity that occurs after cardiac surgery can be attributed to a large extent to pathophysiologic processes engendered by extracorporeal circulation. One of the challenges that has confronted pediatric cardiac surgeons has been to minimize the consequences of cardiopulmonary bypass. Ultrafiltration is a strategy that has been used for many years in an effort to attenuate the effects of hemodilution that occur when small children undergo surgery with cardiopulmonary bypass. Over the past several years, a modified technique of ultrafiltration, commonly known as modified ultrafiltration, has been used with increasing enthusiasm. Multiple studies have been undertaken to assess the effects of modified ultrafiltration on organ function and postoperative morbidity following repair of congenital heart defects. This review attempts to evaluate current available scientific evidence on the impact of modified ultrafiltration on organ function and morbidity after pediatric cardiac surgery.

Impact of off‐pump coronary artery bypass surgery on postoperative renal dysfunction: Current best available evidence (Review Article)

SUMMARY:u2003 Renal dysfunction is a serious complication after coronary artery bypass surgery with cardiopulmonary bypass. Cardiopulmonary bypass‐related non‐pulsatile flow, hypothermia, haemolysis, systemic inflammatory reactions and emboli are mentioned as possible causes for this postoperative renal dysfunction. In an attempt to avoid these deleterious effects of cardiopulmonary bypass, off‐pump coronary artery bypass surgery has been rediscovered. Resurgence of interest in off‐pump coronary artery bypass surgery is associated with the expectation that avoiding deleterious effects of the cardiopulmonary bypass leads to better outcomes and possibly decreased costs and resource use. We are currently practising in an era of evidence‐based medicine that mandates the prospective randomized controlled trial as the most accurate tool for determining a treatment benefit compared with a control population. The present review article attempts to evaluate the current best available evidence from randomized controlled trials on the impact of off‐pump coronary artery bypass surgery on postoperative renal dysfunction.

Efficacy and Safety of Drug‐Eluting Stents: Current Best Available Evidence

Abstractu2003 The development of drug‐eluting coronary stents has proved to be a quantum advance in interventional cardiology, rivaling the impact of stenting itself. Drug‐eluting coronary stents deliver effective local concentrations of antiproliferative drugs (thus avoiding systemic toxicities), without substantially modifying the technique of percutaneous coronary intervention. Studies involving several different stent platforms and antiproliferative drug coatings have recently demonstrated dramatic reductions in restenosis rates, compared to conventional bare metal stents. Although the clinical benefits of drug‐eluting stents are increasingly evident, important concerns about their long‐term safety and costs have been raised. Furthermore, drug‐eluting stents are being claimed to replace coronary artery bypass surgery in the near future. This review article evaluates the current best available evidence on the efficacy and safety of drug‐eluting stents with a focus on the impact of this “revolutionary” new technology on the practice of coronary artery bypass surgery.

Off-Pump Coronary Revascularization preserves Renal Function in patients with Preoperative Non-Dialysis dependent renal dysfunction - A Prospective, Randomized Study

The off-pump coronary artery bypass operation (OPCAB) is a relatively new surgical procedure, which avoids the use of cardiopulmonary bypass and is intuitively considered renoprotective in patients with preoperative normal renal function. However, no prospective, randomized study has been done so far to show whether these benefits may also apply to patients with preoperative non-dialysis dependent renal dysfunction. This first ever prospective, randomized, controlled trial was performed in 50 patients (45 men, mean age 51.2±4.8 yrs) with preoperative nondialysis dependent renal insufficiency, undergoing first-time elective coronary artery bypass grafting. Patients were randomly assigned to conventional revascularization with cardiopulmonary bypass (on-pump) or beating heart revascularization (off-pump). Glomerular and tubular functions were assessed upto 48 hrs postoperatively. There were no deaths, strokes or myocardial infarctions in either group. Glomerular function as assessed by creatinine clearance and the urinary microalbumin/creatinine ratio was significantly worse in the on-pump group (p=0.0003 and p=0.008, respectively). Renal tubular function was also significantly impaired in the on-pump group as assessed by the increased N- acetyl glucosaminidase activity (p=0.021). Six patients in the on-pump group developed acute renal failure requiring renal support compared with one in the off-pump group although statistically the comparison was not significant (p=0.098). This study suggests that off-pump coronary artery bypass surgery reduces the likelihood of acute renal failure in patients with preoperative non-dialysis dependent renal dysfunction and thus shortens postoperative intensive care and length of hospital stay.

Comment: acute myocardial infarction after sildenafil citrate ingestion:

1. Kubiak DW, Szumita PM, Fanikos JR. Extensive prolongation of aPTT with argatroban in an elderly patient with improving renal function, normal hepatic enzymes, and metastatic lung cancer. Ann Pharmacother 2005;39:1119-23. Epub 10 May 2005. DOI 10.1345/aph.1G020 2. Product information. Argatroban. Research Triangle Park, NC: GlaxoSmithKline Beecham, February 2002. 3. Gosselin RC, Dager WE, King JH, Janatpour K, Mahackian K, Larkin EC, et al. Effect of direct thrombin inhibitors, bivalirudin, lepirudin, and argatroban on prothrombin time and INR values. Am J Clin Pathol 2004;121:593-9. 4. Sheth SB, Dicicco RA, Hursting MJ, Montaguet T, Jorkasky DK. Interpreting the international normalized ratio (INR) in individuals receiving argatroban and warfarin. Thromb Haemost 2001;85:435-40. 5. Hursting MJ, Zehnder JL, Joffrion JL, Becker JC, Knappenberger GD, Schwarz RP. The international normalized ratio during concurrent warfarin and argatroban anticoagulation: differential contributions of each agent and effects of the choice of thromboplastin used. Clin Chem 1999;45:409-12. 6. Product information. Coumadin (warfarin). Wilmington, DE: Du Pont Pharmaceuticals, revised 11/99, reviewed 7/2000. 7. Kearon C, Johnston M, Moffat K, McGinnis J, Ginsberg JS. Effect of warfarin on activated partial thromboplastin time in patients receiving heparin. Arch Intern Med 1998;158:1140-3. 8. Harder S, Graff J, Klinkhardt U, von Hentig N, Walenga JM, Watanabe H, et al. Transition from argatroban to oral anticoagulation with phenprocoumon or acenocoumarol: effects on prothrombin time, activated partial thromboplastin time, and ecarin clotting time. Thromb Haemost 2004; 91:1137-45. 9. Schünemann HJ, Munger H, Brower S, O’Donnell M, Crowther M, Cook D, et al. Methodology for guideline development for the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004;126(3 suppl):174S-8S.