Navid Madershahian

Statins for prevention of atrial fibrillation after cardiac surgery: a systematic literature review

OBJECTIVE To determine the strength of evidence of preoperative statin therapy for prevention of atrial fibrillation after cardiac surgery. METHODS A meta-analysis was performed of randomized controlled trials and observational trials reporting the impact of preoperative statin therapy on the incidence of any type and new-onset atrial fibrillation after cardiac surgery. Unadjusted and adjusted treatment effects (odds ratio, 95% confidence intervals) were pooled using a random-effects model, and publication bias was assessed. RESULTS Thirteen studies were identified (3 randomized controlled trials, 10 observational trials) that reported the incidence of postoperative atrial fibrillation in 17,643 patients having cardiac surgery with (n = 10,304; 58%) or without (n = 7339; 42%) preoperative statin use. New-onset atrial fibrillation was reported in a total of 7855 patients. Postoperative incidence rates for any or new-onset atrial fibrillation were 24.6% and 29.9%, respectively. Preoperative statin use resulted in a 22% and 34% unadjusted odds reduction for any atrial fibrillation (odds ratio, 0.78; 95% confidence interval, 0.67-0.90) or new-onset atrial fibrillation (odds ratio, 0.66; 95% confidence interval, 0.51-0.84) after surgery (P < .001). Relevant publication bias and an unequal distribution of confounding variables favoring patients treated with statins were identified. Nevertheless, the beneficial actions of statins on atrial fibrillation persisted after pooled analysis of risk-adjusted treatment effects from randomized controlled trials and observational trials (any atrial fibrillation-odds ratio, 0.64; 95% confidence interval, 0.48-0.87; new-onset atrial fibrillation-odds ratio, 0.66; 95% confidence intervals, 0.48-0.89; P < .01). CONCLUSION Our meta-analysis provides evidence that preoperative statin therapy is associated with a reduction in the incidence of atrial fibrillation after cardiac surgery.

Application of ECMO in Multitrauma Patients With ARDS as Rescue Therapy

Abstract  Background: Despite recent advances in critical care management, the mortality of acute respiratory distress syndrome (ARDS) remains high. The final rescue therapy for patients with severe hypoxia refractory to conventional therapy modalities is the extracorporeal gas exchange. Methods: We report the management of three polytraumatized patients with life‐threatening injuries, severe blunt thoracic trauma, and consecutive ARDS treating by extracorporeal membrane oxygenation (ECMO). Two patients suffered a car accident with severe lung contusion and parenychmal bleeding. Bronchial rupture and mediastinal emphysema was found in one of them. Another patient developed ARDS after attempted suicide with multiple fractures together with blunt abdominal and thoracic trauma. Results: All patients were placed on ECMO and could be rapidly stabilized. They were weaned from ECMO after a mean of 114 ± 27 hours of support without complications, respectively. Mean duration of ICU stay was 37 ± 23 days. Conclusions: Quick encouragement of ECMO for the temporary management of gas exchange may increase survival rates in trauma patients with ARDS.

Minimally invasive transapical aortic valve implantation and the risk of acute kidney injury.

BACKGROUND The new technique of minimally invasive transapical aortic valve implantation (TAP-AVI) deals with high-risk patients and despite the absence of cardiopulmonary bypass it might lead to renal impairment. The aim of this study was to estimate the risk of the development of acute kidney injury (AKI) after TAP-AVI and to identify possible risk factors with regard to the morbidity and mortality of the patients. METHODS Data of 30 consecutive patients undergoing TAP-AVI were recorded and followed up for 8 weeks. Postoperative AKI has been defined according to RIFLE criteria. Two patients on chronic hemodialysis have been followed up. RESULTS Of 28 patients, AKI occurred in 16 patients (57%). Statistical analysis revealed no influence on the risk of developing AKI caused by the dose of applicated contrast medium (p = 0.09), the patients age (p = 0.5), or the existence of diabetes (p = 0. 16). Analysis concerning the relationship between a preexisting coronary heart disease and AKI showed a tendency to be associated with a higher risk of the development of AKI (70% preexisting congenital heart disease in the AKI group versus 50%; p = 0.28). Only a preoperative serum creatinine greater than 1.1 mg/dL was a strong predictor for developing AKI (p < 0.01). Length of stay in the intensive care unit and the complete length of hospital stay revealed no difference with regard to postoperative development of AKI though statistical analysis showed a trend to a higher mortality in the AKI group (27% vs 6%); univariate analysis did not reach statistical significance (p = 0.13). CONCLUSIONS The TAP-AVI seems to be a feasible procedure for high-risk patients with a clear risk of developing AKI. Patients at risk should be identified and, if indicated, already preoperatively treated in collaboration with the attending nephrologists.

Postprocedural Atrial Fibrillation After Transcatheter Aortic Valve Implantation Versus Surgical Aortic Valve Replacement

BACKGROUND Transcatheter aortic valve implantation (TAVI) represents an alternative option for elderly patients with severe aortic valve stenosis who are denied surgical aortic valve replacement (SAVR) because of high perioperative risk. The impact of TAVI on postprocedural atrial fibrillation is undefined. METHODS In a single-center analysis, we assessed clinical data, preoperative risk scores (Society for Thoracic Surgeons score, logistic European System for Cardiac Operative Risk Evaluation), preprocedural electrocardiograms, and 72-hour postprocedural rhythm monitoring of 170 patients undergoing TAVI (n=84) or SAVR (n=86). In a subanalysis, transapical (n=43) and transfemoral TAVI (n=41) were compared. RESULTS Expectedly, TAVI patients were significantly older, presented with more severe symptoms, had higher Society for Thoracic Surgeons score, higher logistic European System for Cardiac Operative Risk Evaluation score, and revealed more frequently intermittent atrial fibrillation compared with SAVR patients. Despite this more compromised health state, prevalence of postprocedural atrial fibrillation was significantly lower in the TAVI group (6.0%, versus 33.7% after SAVR, p<0.05). More than two thirds of TAVI patients but no SAVR patient with atrial fibrillation in preprocedural electrocardiograms had stable sinus rhythm during 72-hour postprocedural monitoring. Notably, no atrial fibrillation was observed after transfemoral TAVI. Whereas atrial fibrillation onset in the SAVR group predominantly occurred on postoperative day 3, atrial fibrillation onset after transapical TAVI was obtained within the first 24 hours after the intervention. CONCLUSIONS Our results indicate that TAVI, compared with SAVR, reduces the risk of periprocedural atrial fibrillation. Furthermore, preprocedural atrial fibrillation may be converted into sinus rhythm particularly after transfemoral TAVI, suggesting an impact of decreased intracardiac pressures in the absence of adverse periprocedural factors that might promote atrial fibrillation.

In vivo application of tissue-engineered blood vessels of bacterial cellulose as small arterial substitutes: proof of concept?

BACKGROUND Tissue-engineered blood vessels (TEBVs) represent an innovative approach for overcoming reconstructive problems associated with vascular diseases by providing small-caliber vascular grafts. This study aimed to evaluate a novel biomaterial of bacterially synthesized cellulose (BC) as a potential scaffold for small-diameter TEBV. METHODS Small-diameter blood vessels with a supramolecular fiber network structure consisting of tubular hydrogels from biodesigned cellulose were created using Gluconacetobacter strains and Matrix reservoir technology. BC tubes (length: 100 mm, inner diameter: 4.0-5.0 mm) were applied to replace the carotid arteries of 10 sheep for a period of 3 mo to gain further insights into (a) functional (in vivo) performance, (b) ability of providing a scaffold for the neoformation of a vascular wall and (c) their proinflammatory potential, and the (d) technical feasibility of the procedure. RESULTS Preoperative analysis revealed a bursting strength of the grafts of approximately 800 mm Hg and suture retention strength of 4-5 N. Postexplantation analysis showed a patency rate of 50% (n = 5) and physiological performance of the patent grafts at 4, 8, and 12 wk postoperatively, compared with native arteries. Histologic analysis revealed a neoformation of a vascular wall-like structure along the BC scaffold consisting of immigrated vascular smooth muscle cells and a homogeneous endothelialization of the inner graft surface without signs of prothrombogenic or inflammatory potential. Scanning electron microscopy revealed a confluent luminal endothelial cell layer and the immigration of vascular smooth muscle cells into the BC matrix. CONCLUSIONS BC grafts provide a scaffold for the neoformation of a three-layered vascular wall exhibit attractive properties for their use in future TEBV programs for cardiovascular surgery.

Outcomes after peripheral extracorporeal membrane oxygenation therapy for postcardiotomy cardiogenic shock: a single-center experience

BACKGROUND We assessed the short-term outcomes and predictors of 30-d mortality in patients requiring temporary, peripheral extracorporeal membrane oxygenation (ECMO) for postcardiotomy cardiac failure. METHODS The data were retrospectively obtained using our institutional patient database. All patients who had received peripheral ECMO support after surgery for acquired heart disease from 2006 to 2010 were included in the present study. The demographic and perioperative variables of the 30-d survivors and nonsurvivors were compared using the chi-square and t-test, and multivariate logistic regression analysis was performed to identify the predictors of 30-d all-cause mortality. RESULTS A total of 77 patients with a mean age of 60 ± 13 years were included in the present analysis. Successful weaning from peripheral ECMO was achieved in 62% after 79 ± 57 h of ECMO support. The overall 30-d mortality rate was 70%, and mortality was reduced to 52% in the patients in whom ECMO support could be weaned successfully. Age (per year) at ECMO implantation was the only independent preoperative predictor of 30-d mortality (odds ratio 1.09, 95% confidence interval 1.03-1.15; P = 0.003). In addition, greater lactate levels after 24 h of ECMO therapy, a longer duration of ECMO support, and the presence of any ECMO-related or gastrointestinal complications were independent predictive factors for 30-d mortality (P < 0.05). CONCLUSIONS ECMO therapy provides a valuable therapeutic strategy for postcardiotomy myocardial failure but is still limited by high complication rates with fewer than 30% of patients discharged from the hospital. Patient age appears to be an essential preoperative predictor for mortality, and the blood lactate level is a relevant marker for the assessment of efficient ECMO support.

The Impact of Intraaortic Balloon Counterpulsation on Bypass Graft Flow in Patients with Peripheral ECMO

Abstract  Objective: Numerous reports have been performed to investigate the hemodynamic effects of intraaortic balloon pumping (IABP) and nonpulsatile circulatory extracorporeal membrane oxygenation (ECMO), but studies on its impact on coronary artery bypass graft flow during concomitant use of IABP and ECMO are lacking. The aim of this study was to assess the impact of additional IABP support on the degree of blood flow increase in bypass grafts in high‐risk patients with nonpulsatile femoral venoarterial ECMO. Methods: In six emergency coronary artery bypass graft patients (mean age = 66.3 ± 2.1 years, gender = five males and one female, ejection fraction = 25.0 ± 3.0%) requiring mechanical circulatory support with ECMO hemodynamic parameters and bypass graft flows were measured with and without IABP counterpulsation. A transit time flowmeter was used for intraoperative graft flow and pulsatility index (PI) measurements. Patients provided their control values. Results: The average value of the mean arterial pressure recorded prior to IABP was 63.6 + 2.9 mmHg and during IABP support 67.8 + 2.9 mmHg (p < 0.0001). IABP augmented the mean bypass graft flow from 46.8 ± 9.6 mL/min to 56.4 ± 12.1 mL/min (p < 0.005), resulting in a 17% increase. The difference in the PI was not statistically significant (2.6 ± 0.2 with IABP, 2.6 ± 0.3 without IABP). Conclusions: We conclude that IABP‐induced pulsatility significantly improves coronary bypass graft flows during nonpulsatile peripheral ECMO.

Logistic risk model predicting postoperative renal failure requiring dialysis in cardiac surgery patients

OBJECTIVE Renal failure requiring dialysis represents a serious complication following cardiac surgery. This study was designed to determine the incidence and predictors of renal failure requiring dialysis in a contemporary patient population. We also aimed to create a model based on these risk factors that could serve as a tool for the prediction of renal failure requiring dialysis. METHODS Between October 2007 and June 2009, 2511 consecutive patients (mean age 69 ± 12 years, 68% male) underwent on-pump cardiac surgery at our institution. The main outcome investigated was postoperative renal failure requiring temporary or permanent dialysis. Other postoperative parameters included in the analysis were hospital mortality, major morbidity, length of hospital stay, and discharge condition. Predictors of renal failure requiring dialysis were determined using multivariate regression models. The discriminatory power was evaluated by calculating the area under the receiver-operating-characteristic (ROC) curves (c-statistic). RESULTS Renal failure requiring dialysis occurred in 3.9% (n = 98) of patients. Hospital mortality among patients with dialysis-dependent renal failure was 37.8% compared with a mortality rate of 1.3% in patients without this complication (p<0.001). Multivariate analysis revealed pulmonary hypertension (odds ratio (OR) = 8.1), preoperative renal dysfunction (creatinine >2.0 mg dl⁻¹) (OR=4.6), cardiopulmonary bypass (CPB) time >120 min (OR=3.9), peripheral vascular disease (OR = 3.1), previous myocardial infarction (OR=3.0), atrial fibrillation (OR = 2.8), age > 75 years (OR = 2.6), New York Heart Association (NYHA) class IV (OR = 2.5), and diabetes (OR = 2.0) as independent predictors for postoperative renal failure requiring dialysis. A logistic equation including the coefficients of the regression analysis accurately predicted individual patients risk for the occurrence of renal failure requiring dialysis (area under the ROC curve: 0.829, 95% confidence interval 0.78-0.86). CONCLUSIONS Renal failure requiring dialysis remains a serious complication, particularly in patients with pulmonary hypertension and previous renal dysfunction. Our logistic risk model allows the prediction of renal failure requiring dialysis, based on the individual presentation of risk factors and, therefore, helps to determine the perioperative risk in cardiac surgery patients.

Pre-ischaemic exogenous surfactant reduces pulmonary injury in rat ischaemia/reperfusion

The optimal timing of exogenous surfactant application to reduce pulmonary injury and dysfunction was investigated in a rat lung ischaemia and reperfusion injury model. Lungs were subjected to flush perfusion, surfactant instillation, cold ischaemia (4°C, 4 h) and reperfusion (60 min). Animals received surfactant before (group 1) or at the end (2) of ischaemia, or during reperfusion (3) or not at all (4). Control groups included “worst case” without Perfadex and surfactant (5), “no injury” without (6) or with surfactant (7), and ischaemia with pre-ischaemic surfactant (8). Intra-alveolar oedema and blood–air barrier injury were estimated by light and electron microscopic stereology. Perfusate oxygenation and pulmonary arterial pressure (Ppa) were determined during reperfusion in groups 1 to 4. Intra-alveolar oedema was almost absent in groups 1, 6, 7 and 8, pronounced in 2, 3 and 4, and severe in 5. Blood–air barrier injury was moderate in groups 1 and 8, slightly pronounced in 2, 3 and 4, extensive in 5 and almost absent in 6 and 7. Perfusate oxygenation was significantly higher in group 1 compared with groups 2 to 4. Ppa did not differ between the groups. In conclusion, exogenous surfactant attenuates intra-alveolar oedema formation and blood–air barrier damage and improves perfusate oxygenation in the rat lung, especially when applied before ischaemic storage.

Renal impairment and transapical aortic valve implantation: impact of contrast medium dose on kidney function and survival

OBJECTIVE Patients undergoing transapical aortic valve implantation (TA-AVI) are usually over 80 years old and have a high prevalence of chronic kidney disease. However, transcatheter valve therapies require the use of contrast injections with the risk of nephrotoxicity. The aim of this study was to evaluate post-operative kidney function and survival in patients with pre-existing renal impairment with regard to the amount of contrast media used during TA-AVI. METHODS From January 2008 to March 2011, 50 patients (52% females, mean age 80.7 ± 5.3 years) with a serum creatinine level of >1.3 mg/dl were investigated. Patients receiving a dose of <100 ml of a contrast agent (low-dose group, n = 24) were separated from those who received >100 ml of a contrast agent (high-dose group, n = 26). An acute contrast-induced nephropathy (CIN) was defined as a serum creatinine increase of 0.5 mg/dl or by >25% of a baseline value within 48 h from contrast medium administration. Patients in both groups had similar characteristics in terms of age, sex, body mass index and comorbidities. RESULTS The median pre-contrast creatinine was 1.67 (1.37-1.83) mg/dl in the low-dose group and 1.51 (1.26-1.98) mg/dl in the high-dose group (P = 0.76). The post-contrast creatinine at 48 h was 1.53 (1.33-2.05) and 2.29 (1.67-2.86) mg/dl in the groups receiving low- and high-dose contrast agents, respectively (P = 0.007). CIN occurred in 41.7% (n = 10) of patients in the low-dose contrast group and in 69.2% (n = 18) in the high-dose contrast group (P = 0.046). Haemodialysis is necessary for 16.7% of the low-dose group and 38.5% of the high-dose group (P = 0.12). Trends towards longer intensive care unit and hospital stay were seen in patients with an extensive use of contrast media [4.3 (2.5-6.5) vs. 5 (3-7.8) days and 12 (9-14.3) vs. 13 (9-18) days, P = 0.091 vs. P = 0.546, respectively]. Regarding death, 3-month and 3-year mortality were significantly higher in the high-dose group (8.3 vs. 30.8%, P = 0.036 and 25 vs. 61.5%, P = 0.004, respectively). CONCLUSIONS Our results indicate a possible association between higher CIN and mortality rate and the extensive use of contrast media during TA-AVI among high-risk patients with pre-existing renal impairment.