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Madhav Swaminathan

Publications and source records attributed to Madhav Swaminathan.

At least 19 recordsLinked to original sources
PubMed2006

Case report: optimizing intraoperative detection of pulmonary embolism using contrast-enhanced echocardiography.

PURPOSE: Perioperative pulmonary embolism (PE) is associated with significant morbidity and mortality. Intraoperatively, the clinical management of patients with PE can be enhanced by the use of transesophageal echocardiography (TEE) to visualize emboli, assess pulmonary artery (PA) anatomy, and monitor the function of the right ventricle. However, the sensitivity of intraoperative TEE to detect thromboemboli is reported to be below 50%. In this report, we describe the use of contrast-enhanced TEE (CE-TEE) to improve the visualization of PE. CLINICAL FEATURES: A 44-yr-old female with chronic thrombo-embolic pulmonary hypertension was scheduled for pulmonary thromboendarterectomy. The precardiopulmonary bypass TEE exam demonstrated signs of PA obstruction and right ventricle dysfunction, but the borders of the thrombus in the right PA were only minimally visualized. Perflutren lipid microspheres, composed of octafluoropropane encapsulated in an outer lipid shell, were injected as a 0.3 mL iv bolus, while visualizing the right PA with harmonic ultrasound imaging. The CE-TEE image clearly visualized a large mobile thrombus along with a distinct pattern consistent with pulmonary flow obstruction. The postcardiopulmonary bypass CE-TEE confirmed thrombus evacuation and absence of PA flow abnormalities. CONCLUSION: Contrast-enhanced-TEE may decrease operator dependency and increase the sensitivity necessary to detect central, surgically accessible PE.

Adult↗
PubMed2006

Reimplantation technique (David operation) for multiple sinus of valsalva aneurysms.

Sinus of Valsalva aneurysms are relatively uncommon, and surgical repair is indicated at the time of diagnosis whether or not symptoms are present. This generally entails closure using a patch technique because usually only one sinus is involved. We report here the successful treatment of multiple sinus of Valsalva aneurysms using a David reimplantation valve-sparing root replacement.

Aortic Aneurysm↗
PubMed2006

Symmetry aortic connector devices and acute renal injury: a comparison of renal dysfunction after three different aortocoronary bypass surgery techniques.

Although the pathogenesis of acute renal injury after cardiac surgery is multifactorial, atherosclerosis of the ascending aorta and embolic burden are strong independent predictors. Use of the Symmetry aortic connector device (ACD) for proximal anastomosis of coronary grafts may reduce ascending aortic atheroembolism. Therefore, we tested the hypothesis that off-pump coronary artery bypass (OPCAB) surgery performed using an ACD is associated with less postoperative renal dysfunction compared with conventional OPCAB or on-pump coronary artery bypass graft (CABG) surgery. Three-thousand-three-hundred consecutive patients undergoing non-emergent aortocoronary bypass surgery were retrospectively divided into three groups by surgical procedure; Group A: OPCAB with ACD (n = 124), Group B: standard OPCAB (n = 313), Group C: on-pump CABG (n = 2863). Postoperative peak fractional change in creatinine compared with baseline was used as a measure of renal outcome. Multivariable analysis did not identify ACD use as an independent predictor of postoperative peak fractional change in creatinine (P = 0.71), although the relationships of several known renal risk factors with postoperative peak fractional change in creatinine were confirmed. We could not find evidence that OPCAB surgery using ACDs reduces acute renal injury compared with standard OPCAB or CABG surgery.

Acute Kidney Injury↗
PubMed2005

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.

Aged↗
PubMed2005

Association of genetic polymorphisms with risk of renal injury after coronary bypass graft surgery.

BACKGROUND: Post-cardiac surgery renal dysfunction is a common, serious, multifactorial disorder, with interpatient variability predicted poorly by preoperative clinical, procedural, and biological markers. Therefore, we tested the hypothesis that selected gene variants are associated with acute renal injury, reflected by a serum creatinine level increase after cardiac surgery. METHODS: One thousand six hundred seventy-one patients undergoing aortocoronary surgery were studied. Clinical covariates were recorded. DNA was isolated from preoperative blood; mass spectrometry was used for genotype analysis. A model was developed relating clinical and genetic factors to postoperative acute renal injury. RESULTS: A race effect was found; therefore, Caucasians and African Americans were analyzed separately. Overall, clinical factors alone account poorly for postoperative renal injury, although more so in African Americans than Caucasians. When 12 candidate polymorphisms were assessed, 2 alleles (interleukin 6 -572C and angiotensinogen 842C) showed a strong association with renal injury in Caucasians (P < 0.0001; >50% decrease in renal filtration when they present together). Using less stringent criteria for significance (0.01 > P > 0.001), 4 additional polymorphisms are identified (apolipoproteinE 448C [4], angiotensin receptor1 1166C, and endothelial nitric oxide synthase [eNOS] 894T in Caucasians; eNOS 894T and angiotensin-converting enzyme deletion and insertion in African Americans). Adding genetic to clinical factors resulted in the best model, with overall ability to explain renal injury increasing approximately 4-fold in Caucasians and doubling in African Americans (P < 0.0005). CONCLUSION: In this study, we identify genetic polymorphisms that collectively provide 2- to 4-fold improvement over preoperative clinical factors alone in explaining post-cardiac surgery renal dysfunction. From a mechanistic perspective, most identified genetic variants are associated with increased renal inflammatory and/or vasoconstrictor responses.

Acute Kidney Injury↗
PubMed2005

Preoperative statin therapy does not reduce cognitive dysfunction after cardiopulmonary bypass.

OBJECTIVE: The purpose of this study was to determine if patients receiving statin therapy before coronary artery bypass grafting surgery would have less cognitive dysfunction after cardiopulmonary bypass as a consequence of a diminished inflammatory response. DESIGN: Retrospective observational study of patients undergoing coronary artery bypass grafting surgery. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: Four hundred forty patients undergoing coronary artery bypass grafting surgery with cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thirty-five percent of patients received statins in the preoperative period. Multivariable analysis revealed no effect of preoperative statin therapy on cognitive function (p = 0.67). Post hoc analysis revealed that statin therapy at hospital discharge was associated with less improvement in cognitive performance at 6 weeks after surgery (p = 0.011). No significant differences were found between statin therapy groups in either range or maximum value of any of the cytokines (p > 0.05). CONCLUSIONS: Preoperative statin therapy did not decrease the inflammatory response to cardiopulmonary bypass or the cognitive dysfunction commonly seen after cardiac surgery.

C-Reactive Protein↗
PubMed2005

The impact of intraoperative echocardiography on clinical outcomes following adult cardiac surgery.

Over the past 30 years, intraoperative echocardiography has become an invaluable diagnostic tool and monitor of cardiac performance for the management of cardiac surgical patients. The essential information provided by intraoperative echocardiography regarding hemodynamic management, cardiac valve function, congenital heart lesions, and great vessel pathology has contributed to its widespread popularity. Numerous investigations have been conducted in an attempt to specifically demonstrate a beneficial impact of intraoperative echocardiography in cardiac surgery. However, there is a relative paucity of data derived from prospective trials in which the use of intraoperative echocardiography has been randomized among various cardiac surgical patient populations to formally ascertain, rather than simply infer, its putative impact on perioperative decision-making and clinical outcomes. Ironically, the popularity of intraoperative echocardiography has imposed ethical limitations on performing randomized trials in patient populations for whom significant benefit has been previously inferred. Nonetheless, significant evidence has been published to support its almost universal acceptance as an important perioperative diagnostic tool and monitor for cardiac surgical patients. This review focuses on the impact of intraoperative echocardiography on clinical outcomes in the more common adult cardiac surgical scenarios, including coronary artery bypass graft surgery, mitral and aortic valve surgery, and in evaluating the intrathoracic aorta.

Aorta, Thoracic↗
PubMed2004

Preliminary report on the interaction of apolipoprotein E polymorphism with aortic atherosclerosis and acute nephropathy after CABG.

BACKGROUND: Renal dysfunction is a serious complication of cardiac surgery that is highly associated with short- and long-term adverse outcome. While the apolipoprotein E (APOE) epsilon4 allele has been linked to the occurrence of both postcardiac surgery acute renal injury (epsilon4 favorable) and ascending aortic arteriosclerosis (epsilon4 unfavorable), the role of epsilon4 in the relationship between these two conditions is unknown. We hypothesized that patients with and without the epsilon4 allele (E4/non-E4) would have different associations between atheroma burden and postoperative renal dysfunction. METHODS: Ascending, arch, and descending aorta atheromatous burden and APOE status were evaluated for 130 coronary bypass patients. Multivariable analyses were performed for aortic regions to assess the relationship of atheroma burden and APOE epsilon4 status with peak in-hospital postoperative serum creatinine. All p < 0.05 were considered significant. RESULTS: We found an interaction between E4 status (E4/non-E4; 24/106) and atheroma burden, with a much greater predicted peak in-hospital postoperative serum creatinine for increases in ascending aorta atheroma load for non-E4 patients versus E4 patients (beta coefficient -0.13; p = 0.002). We also confirmed the association between ascending aorta atheroma and peak creatinine (beta coefficient 0.11; p = 0.0008), after controlling for E4 status, preoperative creatinine, and the E4-atheroma interaction. CONCLUSIONS: Equivalent ascending aortic atheroma burden is associated with a greater susceptibility to postoperative renal injury among patients undergoing cardiac operation who lack the APOE epsilon4 allele. Findings may be attributable to APOE-related differences in inflammation, susceptibility to atheroma detachment (eg, during operative aortic manipulation), or renal vulnerability to embolic injury.

Acute Kidney Injury↗
PubMed2004

Predictors of inotrope use during separation from cardiopulmonary bypass.

OBJECTIVE: To identify the demographic, clinical, and echocardiographic features that predict the use of inotropic support at separation from cardiopulmonary bypass (CPB). DESIGN: Retrospective study of consecutive patients undergoing coronary artery bypass graft (CABG) surgery. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: One thousand nine patients undergoing either CABG or combined CABG and valve surgery with CPB in whom an intraoperative transesophageal echocardiography (TEE) examination was performed. INTERVENTIONS: Inotropic support was defined as the use of dopamine >/=5 microg/kg/min; any dose of epinephrine, norepinephrine, dobutamine, and milrinone; or the insertion of an IABP during separation from CPB. Support was implemented by the anesthesia care team as clinically indicated. Comprehensive TEE examinations were conducted before CPB in all patients according to published guidelines and subsequently reviewed by a single, independent operator. MEASUREMENTS AND MAIN RESULTS: Inotropic support was used in a total of 394 patients (39%) at separation from CPB. The study identified 6 significant, independent predictors of inotrope use: (1) Wall Motion Score Index, (2) combined CABG and mitral valve repair or replacement surgery, (3) left ventricular ejection fraction <35%, (4) reoperation, (5) moderate-to-severe mitral regurgitation, and (6) aortic cross-clamp time. CONCLUSIONS: Incorporating data from a comprehensive intraoperative TEE examination, the authors identified 6 reproducible factors that independently predict the use of inotropic support at separation from CPB.

Cardiopulmonary Bypass↗
PubMed2003

Mitral valve surgery and acute renal injury: port access versus median sternotomy.

BACKGROUND: Many outcomes and complications of minimally invasive and conventional cardiac surgery await comparison. Patients undergoing mitral valve surgery commonly sustain renal injury. Using peak postoperative fractional change of serum creatinine as a marker of renal injury, we tested the hypothesis that mitral valve surgery with port access minithoracotomy (Port) and conventional surgery with a median sternotomy (MS) incision are associated with different degrees of acute renal injury. METHODS: We evaluated data from all isolated mitral valve operations by a single surgeon between 1990 and 2000 (MS = 90, Port = 227). We also performed a secondary analysis of mitral valve surgeries performed by both MS and Port approaches in a concurrent period from 1996 to 2002 (MS = 93, Port = 240). Univariable and multivariable tests were used to determine the association of surgical technique with peak postoperative creatinine (CrmaxPost) and peak postoperative fractional change in creatinine (%deltaCr); p less than 0.05 was considered significant. RESULTS: In our analysis that accounted for the date of surgery, we observed a highly significant independent association between surgical approach and %deltaCr, indicating a greater risk of acute renal injury in the MS group (F value 13.33; p = 0.0003). Similar findings were noted in the secondary (time-concurrent) analysis of %deltaCr (F value 12.65; p = 0.0176). CONCLUSIONS: We present retrospective evidence of reduced acute renal injury associated with the port access technique in mitral valve surgery patients. Our findings suggest that a port access minithoracotomy approach to mitral valve surgery may be preferable to conventional methods for patients with high renal risk.

Acute Kidney Injury↗
PubMed2003

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.

Acute Disease↗
PubMed2003

Renal dysfunction after vascular surgery.

PURPOSE OF REVIEW: The purpose of this review is to focus on the static incidence of renal dysfunction, the lack of evidence of benefit of traditional renoprotective strategies, and newer techniques that may provide an insight into the mechanisms of acute perioperative renal injury associated with vascular surgery. RECENT FINDINGS: Recent studies that have investigated the long-term results of aortic surgery still report a significant incidence of postoperative renal dysfunction. This finding remains consistent in several reports. However, less invasive techniques such as endovascular repair seem to be associated with reduced inflammation and postoperative renal dysfunction. The possible association between genetic heterogeneity and renal dysfunction in vascular surgical patients is an exciting new area of research. SUMMARY: Renal dysfunction after major vascular surgery remains a significant problem. New insights into the mechanisms of acute renal injury and less invasive techniques of vascular repair may help reduce the incidence of renal dysfunction in this patient population. The lack of a truly 'renoprotective' agent has hampered our efforts in preventing this major complication of vascular surgery.

Journal Article↗