Madhav Swaminathan

Recommendations for Evaluation of Prosthetic Valves With Echocardiography and Doppler Ultrasound. A Report From the American Society of Echocardiography's Guidelines and Standards Committee and the Task Force on Prosthetic Valves, Developed in Conjunction With the American College of Cardiology Cardiovascular Imaging Committee, Cardiac Imaging Committee of the American Heart Association

A Report From the American Society of Echocardiography’s Guidelines and Standards Committee and the Task Force on Prosthetic Valves, Developed in Conjunction With the American College of Cardiology Cardiovascular Imaging Committee, Cardiac Imaging Committee of the American Heart Association, the European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography and the Canadian Society of Echocardiography, Endorsed by the American College of Cardiology Foundation, American Heart Association, European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography, and Canadian Society of Echocardiography

The association of lowest hematocrit during cardiopulmonary bypass with acute renal injury after coronary artery bypass surgery

BACKGROUND Acute renal injury is a common serious complication of cardiac surgery. Moderate hemodilution is thought to reduce the risk of kidney injury but the current practice of extreme hemodilution (target hematocrit 22% to 24%) during cardiopulmonary bypass (CPB) has been linked to adverse outcomes after cardiac surgery. Therefore we tested the hypothesis that lowest hematocrit during CPB is independently associated with acute renal injury after cardiac surgery. METHODS Demographic, perioperative, and laboratory data were gathered for 1,404 primary elective coronary bypass surgery patients. Preoperative and daily postoperative creatinine values were measured until hospital discharge per institutional protocol. Stepwise multivariable linear regression analysis was performed to determine whether lowest hematocrit during CPB was independently associated with peak fractional change in creatinine (defined as the difference between the preoperative and peak postoperative creatinine represented as a percentage of the preoperative value). A p value of less than 0.05 was considered significant. RESULTS Multivariable analyses including preoperative hematocrit and other perioperative variables revealed that lowest hematocrit during CPB demonstrated a significant interaction with body weight and was highly associated with peak fractional change in serum creatinine (parameter estimate [PE] = 4.5; p = 0.008) and also with highest postoperative creatinine value (PE = 0.06; p = 0.004). Although other renal risk factors were significant covariates in both models, TM50 (an index of hypotension during CPB) was notably absent. CONCLUSIONS These results add to concerns that current CPB management guidelines accepting extreme hemodilution may contribute to postoperative acute renal and other organ injury after cardiac surgery.

The effect of aprotinin on outcome after coronary-artery bypass grafting.

BACKGROUND Aprotinin has recently been associated with adverse outcomes in patients undergoing cardiac surgery. We reviewed our experience with this agent in patients undergoing cardiac surgery at Duke University Medical Center. METHODS We retrieved data on 10,275 consecutive patients undergoing surgical coronary revascularization at Duke between January 1, 1996, and December 31, 2005. We fit data to a logistic-regression model predicting each patients likelihood of receiving aprotinin on the basis of preoperative characteristics and to models predicting long-term survival (up to 10 years) and decline in renal function, as measured by increases in serum creatinine levels. RESULTS A total of 1343 patients (13.2%) received aprotinin, 6776 patients (66.8%) received aminocaproic acid, and 2029 patients (20.0%) received no antifibrinolytic therapy. All patients underwent coronary-artery bypass grafting, and 1181 patients (11.5%) underwent combined coronary-artery bypass grafting and valve surgery. In the risk-adjusted model, survival was worse among patients treated with aprotinin, with a main-effects hazard ratio for death of 1.32 (95% confidence interval [CI], 1.12 to 1.55) for the comparison with patients receiving no antifibrinolytic therapy (P=0.003) and 1.27 (95% CI, 1.10 to 1.46) for the comparison with patients receiving aminocaproic acid (P=0.004). As compared with the use of aminocaproic acid or no antifibrinolytic agent, aprotinin use was also associated with a larger risk-adjusted increase in the serum creatinine level (P<0.001) but not with a greater risk-adjusted incidence of dialysis (P=0.56). CONCLUSIONS Patients who received aprotinin had a higher mortality rate and larger increases in serum creatinine levels than those who received aminocaproic acid or no antifibrinolytic agent.

Impact of Mitral Valve Regurgitation Evaluated by Intraoperative Transesophageal Echocardiography on Long-Term Outcomes After Coronary Artery Bypass Grafting

Background—It is unclear if mild or moderate mitral valve regurgitation (MR) should be repaired at the time of coronary artery bypass grafting (CABG). We sought to determine the long-term effect of uncorrected MR, measured by intraoperative transesophageal echocardiography (TEE), in CABG patients. Methods and Results—Between May 1999 and September 2003, data were gathered for 3264 consecutive patients who underwent isolated CABG and had MR graded by intraoperative TEE. MR was graded on the following 5 levels: none, trace, mild, moderate, and severe. Patients who had severe MR or who underwent mitral valve surgery were eliminated from the analysis. The remaining patients were combined into the following 3 groups: none or trace, mild, and moderate MR. Preoperative and follow-up data were 99% complete. The median length of follow-up was 3.0 years. Multivariable analysis controlling for important preoperative risk factors was performed to determine predictors of death and death/hospitalization for heart failure. Increasing MR was a risk factor for death [hazard ratio (HR), 1.44; P<0.001] and death/heart failure hospitalization (HR, 1.34; P<0.01). When patients with moderate MR were eliminated from the analysis, mild MR was a risk factor for death (HR, 1.34; P=0.011) and death/hospitalization for heart failure (HR, 1.34; P<0.001). Conclusions—Even mild MR, identified by intraoperative TEE, predicts worse outcomes after CABG. Revascularization alone did not eliminate the negative long-term effects of mild MR. CABG patients with uncorrected mild or moderate MR are at increased risk for death and heart-failure hospitalization; consideration for surgical repair or more aggressive medical management and follow-up is warranted.

Basic Perioperative Transesophageal Echocardiography Examination: A Consensus Statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists

Scott T. Reeves, MD, FASE, Alan C. Finley, MD, Nikolaos J. Skubas, MD, FASE, Madhav Swaminathan, MD, FASE, William S. Whitley, MD, Kathryn E. Glas, MD, FASE, Rebecca T. Hahn, MD, FASE, Jack S. Shanewise, MD, FASE, Mark S. Adams, BS, RDCS, FASE, and Stanton K. Shernan, MD, FASE, for the Council on Perioperative Echocardiography of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists, Charleston, South Carolina; New York, New York; Durham, North Carolina; Atlanta, Georgia; Boston, Massachusetts

Survival Prognosis and Surgical Management of Ischemic Mitral Regurgitation

BACKGROUND Ischemic mitral regurgitation (IMR) has an adverse prognosis, but survival characteristics and management are controversial. This study reviewed a 20-year series of IMR patients managed with multiple approaches to assess and refine surgical strategies. METHODS Patients having surgery for primary coronary disease from 1986 to 2006 were divided into group 1 (no IMR; bypass grafting only; n = 16,209), group 2a (IMR; bypass only; n = 3,181), group 2b (IMR; mitral repair; n = 416), and group 2c (IMR; mitral replacement; n = 106). Cox proportional hazards modeling adjusted for baseline differences, and therapeutic adequacy was quantified by area under each survival curve expressed as a percentage of group 1. RESULTS Group 2 patients were older than group 1 patients and had worse baseline characteristics. Group 2a had less severe MR and group 2b had the most comorbidity. Assuming group 1 provided the best adjusted outcome at a given baseline risk, group 2a achieved 97.7%, 2b achieved 93.7%, and 2c achieved 79.1% of potential survival (hazard ratio 1.1, 1.4, and 1.6, respectively; p < 0.003). Most of the survival difference was perioperative. CONCLUSIONS Worse baseline risk is a major factor reducing long-term survival in IMR. Current algorithms in which mild to moderate IMR is managed with bypass only (group 2a) generally produced good late results. In patients with moderate and severe IMR, repair achieved 93.7% of full survival potential; valve replacement was less satisfactory, primarily owing to higher operative mortality. Future therapeutic refinement, emphasizing reparative procedures and better perioperative care, could enhance the surgical prognosis of IMR.

Inhaled nitric oxide after left ventricular assist device implantation: A prospective, randomized, double-blind, multicenter, placebo-controlled trial

BACKGROUND Used frequently for right ventricular dysfunction (RVD), the clinical benefit of inhaled nitric oxide (iNO) is still unclear. We conducted a randomized, double-blind, controlled trial to determine the effect of iNO on post-operative outcomes in the setting of left ventricular assist device (LVAD) placement. METHODS Included were 150 patients undergoing LVAD placement with pulmonary vascular resistance ≥ 200 dyne/sec/cm(-5). Patients received iNO (40 ppm) or placebo (an equivalent concentration of nitrogen) until 48 hours after separation from cardiopulmonary bypass, extubation, or upon meeting study-defined RVD. For ethical reasons, crossover to open-label iNO was allowed during the 48-hour treatment period if RVD criteria were met. RESULTS RVD criteria were met by 7 of 73 patients (9.6%; 95% confidence interval, 2.8-16.3) in the iNO group compared with 12 of 77 (15.6%; 95% confidence interval, 7.5-23.7) who received placebo (p = 0.330). Time on mechanical ventilation decreased in the iNO group (median days, 2.0 vs 3.0; p = 0.077), and fewer patients in the iNO group required an RVAD (5.6% vs 10%; p = 0.468); however, these trends did not meet statistical boundaries of significance. Hospital stay, intensive care unit stay, and 28-day mortality rates were similar between groups, as were adverse events. Thirty-five patients crossed over to open-label iNO (iNO, n = 15; placebo, n = 20). Eighteen patients (iNO, n = 9; placebo, n = 9) crossed over before RVD criteria were met. CONCLUSIONS Use of iNO at 40 ppm in the perioperative phase of LVAD implantation did not achieve significance for the primary end point of reduction in RVD. Similarly, secondary end points of time on mechanical ventilation, hospital or intensive care unit stay, and the need for RVAD support after LVAD placement were not significantly improved.

Serum Cystatin C– Versus Creatinine-Based Definitions of Acute Kidney Injury Following Cardiac Surgery: A Prospective Cohort Study

BACKGROUND The primary aim of this study was to compare the sensitivity and rapidity of acute kidney injury (AKI) detection by cystatin C level relative to creatinine level after cardiac surgery. STUDY DESIGN Prospective cohort study. SETTINGS & PARTICIPANTS 1,150 high-risk adult cardiac surgery patients in the TRIBE-AKI (Translational Research Investigating Biomarker Endpoints for Acute Kidney Injury) Consortium. PREDICTOR Changes in serum creatinine and cystatin C levels. OUTCOME Postsurgical incidence of AKI. MEASUREMENTS Serum creatinine and cystatin C were measured at the preoperative visit and daily on postoperative days 1-5. To allow comparisons between changes in creatinine and cystatin C levels, AKI end points were defined by the relative increases in each marker from baseline (25%, 50%, and 100%) and the incidence of AKI was compared based on each marker. Secondary aims were to compare clinical outcomes among patients defined as having AKI by cystatin C and/or creatinine levels. RESULTS Overall, serum creatinine level detected more cases of AKI than cystatin C level: 35% developed a ≥25% increase in serum creatinine level, whereas only 23% had a ≥25% increase in cystatin C level (P < 0.001). Creatinine level also had higher proportions meeting the 50% (14% and 8%; P < 0.001) and 100% (4% and 2%; P = 0.005) thresholds for AKI diagnosis. Clinical outcomes generally were not statistically different for AKI cases detected by creatinine or cystatin C level. However, for each AKI threshold, patients with AKI confirmed by both markers had a significantly higher risk of the combined mortality/dialysis outcome compared with patients with AKI detected by creatinine level alone (P = 0.002). LIMITATIONS There were few adverse clinical outcomes, limiting our ability to detect differences in outcomes between subgroups of patients based on their definitions of AKI. CONCLUSIONS In this large multicenter study, we found that cystatin C level was less sensitive for AKI detection than creatinine level. However, confirmation by cystatin C level appeared to identify a subset of patients with AKI with a substantially higher risk of adverse outcomes.

Hypocarbia in the ventilated preterm infant and its effect on intraventricular haemorrhage and bronchopulmonary dysplasia

Objective:  To examine the relationship between PaCO2 levels in ventilated very preterm infants and (i) the incidence of severe intraventricular haemorrhage (IVH) and periventricular leukomalacia (PVL); and (ii) bronchopulmonary dysplasia (BPD).

Impact of Early Renal Recovery on Survival After Cardiac Surgery-Associated Acute Kidney Injury

BACKGROUND Cardiac surgery-associated acute kidney injury (CSA-AKI) is a major postoperative complication. Although some early recovery is common, its effect on long-term outcomes is unclear. We tested the hypothesis that early renal recovery after CSA-AKI is independently associated with improved long-term survival. METHODS Data were examined for 10,275 consecutive patients undergoing isolated coronary artery bypass grafting from 1996 to 2005. Patients with CSA-AKI were identified, defined as a peak postoperative creatinine level exceeding 50% above baseline. Renal recovery was characterized using postoperative creatinine values. The recovery variable with the strongest association with 1-year survival was selected and validated internally. The independent association of early renal recovery with long-term survival during a 10-year follow-up was assessed with Cox proportional hazards modeling. RESULTS CSA-AKI occurred in 1113 patients (10.8%). The renal recovery variable with the strongest association with 1-year survival was the percentage decrease in creatinine 24 hours after its peak value (PD24; C index, 0.72; p=0.002). Cox proportional hazards analysis showed a significant negative association between PD24 and long-term mortality (0.82 hazard ratio for each 10% change). CONCLUSIONS Early recovery of renal function is associated with improved long-term survival after CSA-AKI. This variable is clinically useful because it occurs immediately after the peak creatinine level and simultaneously helps define the severity of AKI and the magnitude of recovery. Given the high risk of death associated with postoperative AKI, early renal recovery seems to offer a distinct survival benefit and may represent an important therapeutic focus.