Left ventricular decompression in veno-arterial extracorporeal membrane oxygenation.

BACKGROUND: Despite the survival benefit of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for treatment of refractory cardiogenic shock, it can also have potentially deleterious effects of left ventricular overload and pulmonary edema. The objective of this review was to investigate the current evidence on the incidence, diagnosis, risk factors, prevention, and interventions for left ventricular overload in adult and pediatric VA-ECMO patients. METHODS: Five electronic databases, including MEDLINE, EMBASE, PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Database of Systematic Reviews, were searched for original published studies from their dates of inception to January 2018. All types of adult and pediatric studies that investigated LV overload in VA-ECMO and were published in the English language were reviewed. Exclusion criteria included abstracts and conference presentations. RESULTS: The reported incidence and sequelae of LV overload in VA-ECMO are highly variable, with presentations ranging from pulmonary arterial diastolic pressures of greater than 25 mmHg and LV distention on echocardiography, to severe pulmonary edema, LV thrombosis, and refractory ventricular arrhythmias. Currently, there are no standardized diagnostic criteria or guidelines for the type and timing of intervention for LV overload. Techniques for LV decompression have included direct surgical LV venting with catheter insertion via sternotomy or a minimally invasive incision; percutaneous catheterization via a transaortic, transseptal, or transpulmonary approach; ventricular assist devices; and intra-aortic balloon pumps. CONCLUSIONS: Left ventricular volume distention is a significant problem in VA-ECMO patients, with sequelae including myocardial ischemia, severe pulmonary edema, and intracardiac thrombosis. Further research is required on its incidence, diagnostic criteria, and risk factors, as well as the optimal timing and method for LV decompression, given the diversity of surgical and percutaneous techniques that are available.

Implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: an updated systematic review and meta-analysis of outcomes and complications.

BACKGROUND: Since the introduction of the implantable cardioverter-defibrillator (ICD) in patients with hypertrophic cardiomyopathy (HCM), the incidence of sudden cardiac death (SCD) has been significantly reduced. Given its widespread use, it is important to identify the outcomes associated with ICD use in patients with HCM. The present paper is a systematic review and meta-analysis of the rates of appropriate and inappropriate interventions, mortality, and device complications in HCM patients with an ICD. METHODS: We conducted a systematic review and meta-analysis on 27 studies reporting outcomes and complications after ICD implantation in patients with HCM. ICD interventions, device complications, and mortality were extracted for analysis. RESULTS: A total of 3,797 patients with HCM and ICD implantation were included (mean age, 44.5 years; 63% male), of which 83% of patients had an ICD for primary prevention of SCD. The cardiac mortality was 0.9% (95% CI: 0.7-1.3) per year and non-cardiac mortality was 0.8% (95% CI: 0.6-1.2) per year. Annualized appropriate intervention rate was 4.8% and annualized inappropriate intervention was 4.9%. The annual incidence of lead malfunction, lead displacement and infection was 1.4%, 1.3%, and 1.1%, respectively. CONCLUSIONS: ICD use in patients with HCM produces low rates of cardiac and non-cardiac mortality, and an appropriate intervention rate of 4.8% per year. However, moderate rates of inappropriate intervention and device complications warrant careful patient selection in order to optimize the risk to benefit ratio in this select group of patients.

Neurologic Complications of Extracorporeal Membrane Oxygenation: A Review.

OBJECTIVE: To review the evidence on neurologic complications in adult extracorporeal membrane oxygenation (ECMO) patients with regard to incidence, pathophysiology, risk factors, diagnosis, monitoring techniques, prevention, and management. DESIGN: Literature review. SETTING: Observational studies and case reports from a variety of institutions. PARTICIPANTS: Adult ECMO patients. INTERVENTIONS: Six electronic databases were searched from their dates of inception to October 2016. MEASUREMENTS AND MAIN RESULTS: The range of neurologic complications reported in adult ECMO patients included stroke, intracranial hemorrhage, and brain death. Due to a lack of standardized reporting, their true incidence may have been underestimated significantly. A variety of pathophysiologic mechanisms and risk factors have been proposed. Some of these are specific to venoarterial ECMO, whereas others may be more relevant to venovenous ECMO (eg, rapid correction of hypercarbia). With regard to diagnosis and monitoring, clinical examination alone can be challenging and insufficiently sensitive, particularly for the confirmation of brain death. Computed tomography is the main imaging modality for acute neurologic assessment because magnetic resonance imaging is not feasible in these patients. Options for neuromonitoring are limited, although cerebral near-infrared spectroscopy may be useful. There are very limited data to guide the management of specific complications such as intracranial hemorrhage, which remains a leading cause of mortality in ECMO patients. CONCLUSIONS: ECMO can be lifesaving and is being used increasingly for severe respiratory and/or cardiac failure. However, it remains associated with significant neurologic morbidity and mortality. Greater research clearly is needed to determine the best approach to the assessment and management of neurologic complications in this rapidly growing patient population.

Recirculation in venovenous extracorporeal membrane oxygenation.

Despite the increasing use of venovenous extracorporeal membrane oxygenation (ECMO) to treat severe respiratory failure, recirculation remains a common complication that may result in severe hypoxemia and end-organ damage. The present review, therefore, examines updated evidence for the causes, measurement, and management of recirculation. Six electronic databases were searched from their dates of inception to January 2016, and 38 relevant studies were selected for analysis. This review revealed that, currently, recirculation is typically calculated from measurement of blood oxygen saturations, although limited evidence suggests that oxygen content may provide a more accurate measure. Dilutional ultrasound may play an additional role in dynamic quantitative monitoring of recirculation, but further human studies are required to validate its clinical use. Although cannula configuration appears to be a key contributor to recirculation in addition to factors such as ECMO flow rate, there are insufficient comparative clinical studies to recommend an optimal cannulation technique for minimizing recirculation. Existing evidence suggests that the dual-lumen cannula may have a low recirculation fraction, but only if correctly positioned. This review underscores the need for more robust clinical and laboratory studies to effectively evaluate and address the persistent problem of recirculation.

Development of a Mock Extracorporeal Membrane Oxygenation Circuit to Assess Recirculation.

A limitation of veno-venous extracorporeal membrane oxygenation (VV-ECMO) is the recirculating of newly oxygenated blood back to the VV-ECMO circuit. We compared cannulation strategies for combating recirculation utilizing a mock circulation loop (MCL) with ultrasonic flow probes and pressure transducers ensuring that the MCL was run at physiological hemodynamic parameters. Mean recirculation percentages were lower (ANOVA, F = 14.25; p = 0.0001) with the Wang-Zwische dual lumen cannula (4.00 ± 1.77, n = 7) than both the femoro-jugular (15.23 ± 7.00, n = 8) and the femoro-femoral cannulation configurations (13.49 ± 1.44, n = 8).

Video-assisted thoracoscopic surgery versus open thymectomy for thymoma: a systematic review.

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) thymectomy is an increasingly utilized alternative to traditional open approaches for the resection of thymomas. Recent studies have suggested comparable survival and oncological efficacy as well as reduced perioperative morbidity when using the VATS approach. This current systematic review thus aimed to critically evaluate existing evidence for the efficacy and safety of VATS versus open (transsternal or transthoracic) thymectomy for thymomas. METHODS: Six electronic databases were searched from their date of inception to April 2015. Relevant studies were identified using specific eligibility criteria and data were extracted and analyzed based on predefined primary and secondary endpoints. RESULTS: Fourteen comparative observational studies with a total of 1,061 patients were obtained for qualitative assessment, data extraction and analysis. Five-year overall survival and 10-year recurrence-free survival was similar or higher in patients undergoing VATS compared to open thymectomy. On average, the VATS group also demonstrated reduced intraoperative blood loss (131.8 vs. 340.5 mL), shorter hospital stays (7.0 vs. 9.8 days), and lower rates of postoperative pneumonia (1.9% vs. 4.1%). The mean rate of conversion from VATS to open thymectomy was relatively low (3.1%), while 30-day mortality remained low in both the VATS and open groups (0 vs. 0.3%). CONCLUSIONS: The current evidence suggests that VATS thymectomy for thymoma has at least equal if not superior oncological efficacy and survival outcomes, as well as reduced perioperative complications, compared to open surgery. Further adequately powered studies and future randomized trials are required to confirm these findings.

Ministernotomy or minithoracotomy for minimally invasive aortic valve replacement: a Bayesian network meta-analysis.

BACKGROUND: Establishing the relative merits of ministernotomy (MS) and minithoracotomy (MT) approaches to minimally invasive aortic valve replacement (MIAVR) is difficult given the limited available direct evidence. Network meta-analysis is a Bayesian approach that can combine direct and indirect evidence to better define the benefits and risks of MS and MT. METHODS: Electronic searches were performed using six databases from their inception to June 2014. Relevant studies utilizing a minimally invasive approach for aortic valve replacement were identified. Data were extracted and analyzed according to predefined clinical endpoints. Both traditional and Bayesian meta-analysis approaches were conducted. RESULTS: Compared to full sternotomy, MT was associated with longer cardiopulmonary bypass (CPB) duration (WMD, 9.99; 95% CI, 3.91, 16.07; I(2)=55%; P=0.001) and cross-clamp duration (WMD, 7.64; 95% CI, 2.86, 12.42; P=0.002; I(2)=74%). When compared to MS using network meta-analysis, no significant difference in duration was detected. Postoperative outcomes including 30-day mortality, stroke, and reoperation for bleeding and wound infection were comparable between MS and MT using both traditional and Bayesian meta-analysis techniques. CONCLUSIONS: The current evidence demonstrates that MIAVR via MS or MT is a safe and efficacious alternative to conventional median sternotomy. MT may be associated with longer CPB and cross-clamp durations, but has similar post-operative outcomes compared to MS. An individualized approach tailored to both the patient and surgical team is likely to provide optimal outcomes.

Venoarterial extracorporeal membrane oxygenation for cardiogenic shock and cardiac arrest: a meta-analysis.

OBJECTIVE: To evaluate the effect of extracorporeal membrane oxygenation (ECMO) on survival and complication rates in adults with refractory cardiogenic shock or cardiac arrest. DESIGN: Meta-analysis. SETTING: University hospitals. PARTICIPANTS: One thousand one hundred ninety-nine patients from 22 observational studies. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Observational studies published from the year 2000 onwards, examining at least 10 adult patients who received ECMO for refractory cardiogenic shock or cardiac arrest were included. Pooled estimates with 95% confidence intervals were calculated based on the Freeman-Tukey double-arcsine transformation and DerSimonian-Laird random-effect model. Survival to discharge was 40.2% (95% confidence intervals [CI], 33.9-46.7), while survival at 3, 6, and 12 months was 55.9% (95% CI, 41.5-69.8), 47.6% (95% CI, 25.4-70.2), and 54.4% (95% CI, 36.6-71.7), respectively. Survival up to 30 days was higher in cardiogenic shock patients (52.5%, 95% CI, 43.7%-61.2%) compared to cardiac arrest (36.2%, 95% CI, 23.1%-50.4%). Concurrently, complication rates were particularly substantial for neurologic deficits (13.3%, 95% CI, 8.3-19.3), infection (25.1%, 95%CI, 15.9-35.5), and renal impairment (47.4%, 95% CI, 30.2-64.9). Significant heterogeneity was detected, although its levels were similar to previous meta-analyses that only examined short-term survival to discharge. CONCLUSIONS: Venoarterial ECMO can improve short-term survival in adults with refractory cardiogenic shock or cardiac arrest. It also may provide favorable long-term survival at up to 3 years postdischarge. However, ECMO also is associated with significant complication rates, which must be incorporated into the risk-benefit analysis when considering treatment. These findings require confirmation by large, adequately controlled and standardized trials with long-term follow-up.

Comparing energy sources for surgical ablation of atrial fibrillation: a Bayesian network meta-analysis of randomized, controlled trials.

Simplified maze procedures involving radiofrequency, cryoenergy and microwave energy sources have been increasingly utilized for surgical treatment of atrial fibrillation as an alternative to the traditional cut-and-sew approach. In the absence of direct comparisons, a Bayesian network meta-analysis is another alternative to assess the relative effect of different treatments, using indirect evidence. A Bayesian meta-analysis of indirect evidence was performed using 16 published randomized trials identified from 6 databases. Rank probability analysis was used to rank each intervention in terms of their probability of having the best outcome. Sinus rhythm prevalence beyond the 12-month follow-up was similar between the cut-and-sew, microwave and radiofrequency approaches, which were all ranked better than cryoablation (respectively, 39, 36, and 25 vs 1%). The cut-and-sew maze was ranked worst in terms of mortality outcomes compared with microwave, radiofrequency and cryoenergy (2 vs 19, 34, and 24%, respectively). The cut-and-sew maze procedure was associated with significantly lower stroke rates compared with microwave ablation [odds ratio <0.01; 95% confidence interval 0.00, 0.82], and ranked the best in terms of pacemaker requirements compared with microwave, radiofrequency and cryoenergy (81 vs 14, and 1, <0.01% respectively). Bayesian rank probability analysis shows that the cut-and-sew approach is associated with the best outcomes in terms of sinus rhythm prevalence and stroke outcomes, and remains the gold standard approach for AF treatment. Given the limitations of indirect comparison analysis, these results should be viewed with caution and not over-interpreted.

Biatrial ablation vs. left atrial concomitant surgical ablation for treatment of atrial fibrillation: a meta-analysis.

AIMS: Surgical ablation performed concomitantly with cardiac surgery has emerged as an effective curative strategy for atrial fibrillation (AF). Left atrial (LA) lesion sets for ablation have been suggested to reduce procedural times and post-surgical bradycardia compared with biatrial (BA) lesions. Given the inconclusive literature regarding BA vs. LA ablation, the present meta-analysis sought to assess the current evidence. METHODS AND RESULTS: Electronic searches were performed using six databases from their inception to December 2013, identifying all relevant randomized trials and observational studies comparing BA vs. LA surgical ablation AF patients undertaking cardiac surgery. In 10 included studies, 2225 patient results were available for analysis to compare BA (n = 888) vs. LA (n = 1337) ablation. Sinus rhythm prevalence was higher in the BA cohort compared with the LA cohort at 6-month and 12-month follow-up, but similar beyond 1 year. Permanent pacemaker implantations were higher in the BA cohort, but 30-day and late mortality, neurological events, and reoperation for bleeding were similar between BA and LA groups. CONCLUSIONS: Biatrial and LA ablations produced comparable 30-day and late mortality but LA was associated with significantly reduced permanent pacemaker implantation rates. Biatrial ablation appeared to be more efficacious than LA ablation in achieving SR at 1 year, but this difference was not maintained beyond 1 year. Trends appear to be driven by the preferential selection of long-standing and persistent AF patients for the BA approach. Future randomized studies of adequate follow-up are required to validate risks and benefits of BA vs. LA surgical ablation.

Durability of continuous-flow left ventricular assist devices: a systematic review.

BACKGROUND: Left ventricular assist devices (LVADs) are becoming an increasingly viable alternative therapy for heart failure, either as a bridge to heart transplantation (BTT) or destination therapy (DT). The latter has become increasingly popular in recent years, in the face of a donor organ shortage and a rise in elderly patients ineligible for heart transplants. For these patients in particular, device durability is a key contributor to survival, morbidity, and quality of life. This systematic review aimed to assess the long-term durability of current continuous-flow LVADs. METHODS: Six electronic databases were searched from their dates of inception to August 2014 for original studies reporting on patients receiving continuous-flow LVADs. LVAD failure was defined as device malfunction necessitating exchange or explantation, or causing patient mortality. Pooled averages were calculated for outcomes and rates of device failure were reconstructed from digitized graph curves using the software, WebPlotDigitizer v3.3. RESULTS: Twelve retrospective observational studies with a total of 5,471 patients were included for analysis. The mean duration of LVAD support was 504.7 (range, 303-568) days, and the overall weighted incidence of device failure was 3.9% (range, 1-11.3%). On average, pump thrombosis was the most common cause of device failure (50.5%), followed by lead or cable damage (21.7%), mechanical pump failure (11.6%), device-related infection (11.1%), and surgical complications from implantation (2.5%). Long-term device failure rates at 2-, 6-, 12-, 18- and 24-months post-implantation were 0.5%, 1.8%, 2.9%, 4.5% and 6.5%, respectively. CONCLUSIONS: With the expected rise in LVAD usage for end-stage heart failure, particularly as a DT, the steady minority of patients experiencing device failure is likely to increase. Further investigation is required into the incidence and mechanism of major causes of failure, as well as design improvements that may address these complications. There is currently a lack of guidelines and large randomized studies reporting on the etiology and outcomes of LVAD failure.

A meta-analysis of minimally invasive versus conventional sternotomy for aortic valve replacement.

Minimally invasive aortic valve replacement (AVR) is increasingly used as an alternative to conventional AVR, despite limited randomized evidence available. To assess the evidence base, a systematic search identified 50 comparative studies with a total of 12,786 patients. A meta-analysis demonstrated that minimally invasive AVR is associated with reduced transfusion incidence, intensive care stay, hospitalization, and renal failure, and has a mortality rate that is comparable to conventional AVR. The evidence quality was mostly very low. Given the inadequate statistical power and heterogeneity of available studies, prospective randomized trials are needed to assess the benefits and risks of minimally invasive AVR approaches.

Surgical ablation for treatment of atrial fibrillation in cardiac surgery: a cumulative meta-analysis of randomised controlled trials.

INTRODUCTION: Concomitant surgical ablation is a treatment modality for patients with atrial fibrillation (AF) undergoing cardiac surgery, however, its efficacy and clinical outcomes are not well established. The present study is the first cumulative meta-analysis of randomised controlled trials (RCT) on clinical outcomes of surgical ablation versus no ablative treatment in all patients with cardiac surgery. METHODS: Electronic searches were performed using six databases from their inception to October 2013, identifying all relevant RCTs comparing surgical ablation versus no ablation in patients with AF undertaking cardiac surgery. Data were extracted and analysed according to predefined clinical endpoints. RESULTS: Sixteen relevant RCTs were identified for the present study. Higher prevalence of sinus rhythm in the surgical ablation group was evident at all ≥ 12 month follow-up (OR, 6.72; 95% CI 4.88 to 9.25; p<0.00001). There were no significant differences between surgical ablation versus no ablation in terms of mortality (OR, 1.05; 95% CI 0.66 to 1.68; p=0.83), pacemaker implantations (OR, 0.88; 95% CI 0.51 to 1.51; p=0.64), and neurological events (OR, 0.86; 95% CI 0.37 to 2.04; p=0.74). Cumulative meta-analysis demonstrated that these trends have remained consistent over the years, with recent studies narrowing the CIs of the summary estimates. CONCLUSIONS: The evaluation of the current randomised trials demonstrates that concomitant surgical ablation and cardiac surgery is safe and effective at restoring sinus rhythm.