Borut Gersak

Sutureless aortic valve replacement: a systematic review and meta-analysis.

BACKGROUND Sutureless aortic valve replacement (SU-AVR) has emerged as an innovative alternative for treatment of aortic stenosis. By avoiding the placement of sutures, this approach aims to reduce cross-clamp and cardiopulmonary bypass (CPB) duration and thereby improve surgical outcomes and facilitate a minimally invasive approach suitable for higher risk patients. The present systematic review and meta-analysis aims to assess the safety and efficacy of SU-AVR approach in the current literature. METHODS Electronic searches were performed using six databases from their inception to January 2014. Relevant studies utilizing sutureless valves for aortic valve implantation were identified. Data were extracted and analyzed according to predefined clinical endpoints. RESULTS Twelve studies were identified for inclusion of qualitative and quantitative analyses, all of which were observational reports. The minimally invasive approach was used in 40.4% of included patients, while 22.8% underwent concomitant coronary bypass surgery. Pooled cross-clamp and CPB duration for isolated AVR was 56.7 and 46.5 minutes, respectively. Pooled 30-day and 1-year mortality rates were 2.1% and 4.9%, respectively, while the incidences of strokes (1.5%), valve degenerations (0.4%) and paravalvular leaks (PVL) (3.0%) were acceptable. CONCLUSIONS The evaluation of current observational evidence suggests that sutureless aortic valve implantation is a safe procedure associated with shorter cross-clamp and CPB duration, and comparable complication rates to the conventional approach in the short-term.

Low Rate of Atrial Fibrillation Recurrence Verified by Implantable Loop Recorder Monitoring Following a Convergent Epicardial and Endocardial Ablation of Atrial Fibrillation

Implantable Loop Recorder Monitoring Outcomes for the Convergent AF Procedure. Objective: Evaluate long‐term outcomes in patients undergoing the Convergent procedure (CP) for the treatment of atrial fibrillation (AF).

European experience of the convergent atrial fibrillation procedure: Multicenter outcomes in consecutive patients

BACKGROUND The objective of this collaborative, multicenter, European effort was to evaluate the outcomes of the convergent procedure for the treatment of persistent and long-standing persistent atrial fibrillation (AF) in consecutive patients at 4 European centers. METHODS Outcomes of consecutive patients, undergoing the convergent procedure at 4 European centers, were evaluated in this study. Epicardial ablation was performed before endocardial ablation. Convergent procedure outcomes were recorded by interrogation of implanted loop recorders or Holter monitors. Rhythm status and required interventions (antiarrhythmic drugs, cardioversions, and repeat ablations) were quantified 6 and 12 months after the procedure. Outcomes, monitoring type, and patient baseline characteristics were analyzed and reported. RESULTS Seventy-three consecutive patients presenting with persistent AF (30.1%) or long-standing persistent AF (69.9%) underwent the convergent procedure between January 2010 and December 2011. At 6 months, 82% (56/68) were in sinus rhythm. At 12 months, 80% (53/66) were in sinus rhythm; single-procedure maintenance of sinus rhythm without postblanking period interventions was 76% (50/66); 52% (34/66) were in sinus rhythm and not receiving antiarrhythmic drugs. CONCLUSIONS This multicenter European collaborative effort demonstrated that the convergent procedure is a safe and efficacious treatment option for persistent and long-standing persistent AF.

Sutureless, rapid deployment valves and stented bioprosthesis in aortic valve replacement: recommendations of an International Expert Consensus Panel.

OBJECTIVES After a panel process, recommendations on the use of sutureless and rapid deployment valves in aortic valve replacement were given with special respect as an alternative to stented valves. METHODS Thirty-one international experts in both sutureless, rapid deployment valves and stented bioprostheses constituted the panel. After a thorough literature review, evidence-based recommendations were rated in a three-step modified Delphi approach by the experts. RESULTS Literature research could identify 67 clinical trials, 4 guidelines and 10 systematic reviews for detailed text analysis to obtain a total of 28 recommendations. After rating by the experts, 12 recommendations were identified and degree of consensus for each was determined. Proctoring and education are necessary for the introduction of sutureless valves on an institutional basis as well as for the individual training of surgeons. Sutureless and rapid deployment should be considered as the valve prosthesis of first choice for isolated procedures in patients with comorbidities, old age, delicate aortic wall conditions such as calcified root, porcelain aorta or prior implantation of aortic homograft and stentless valves as well as for concomitant procedures and small aortic roots to reduce cross-clamp time. Intraoperative transoesophageal echocardiography is highly recommended, and in case of right anterior thoracotomy, preoperative computer tomography is strongly recommended. Suitable annular sizes are 19-27 mm. There is a contraindication for bicuspid valves only for Type 0 and for annular abscess or destruction due to infective endocarditis. Careful but complete decalcification of the aortic root is recommended to avoid paravalvular leakage; extensive decalcification should be avoided not to create annular defects. Proximal anastomoses of concomitant coronary artery bypass grafting should be placed during a single aortic cross-clamp period or alternatively with careful side clamping. Available evidence suggests that the use of sutureless and rapid deployment valve is associated with (can translate into) reduced early complications such as prolonged ventilation, blood transfusion, atrial fibrillation, pleural effusions and renal replacement therapy, respectively, and may result in reduced intensive care unit and hospital stay in comparison with traditional valves. CONCLUSION The international experts recommend various benefits of sutureless and rapid deployment technology, which may represent a helpful tool in aortic valve replacement for patients requiring a biological valve. However, further evidence will be needed to reaffirm the benefit of sutureless and rapid deployment valves.

The Convergent Procedure: A Multidisciplinary Atrial Fibrillation Treatment

BACKGROUND Persistent atrial fibrillation (AF) and long-standing persistent AF (LSPAF) are difficult to treat. Epicardial surgical and percutaneous catheter ablations have lower success rates in these patients. The convergent procedure, an endoscopic transdiaphragmatic ablation procedure with conventional percutaneous endocardial ablation, is examined. METHODS Twenty-eight patients with persistent AF or LSPAF underwent the convergent procedure. All underwent combined surgical epicardial radiofrequency ablation and electrophysiological transseptal endocardial ablation to electrically isolate the 4 pulmonary veins, to exclude the posterior left atrium, to ablate the coronary sinus, and to confirm block at the cavotricuspid isthmus. Follow-up was with 24-hour Holter monitoring at 3 months, and 24-hour or 7-day monitoring at 6 and 12 months. RESULTS The mean duration of the procedure was 187 minutes (102 surgical ablation minutes; 85 endocardial ablation minutes). The mean total fluoroscopy time was 35.1 minutes. Two patients developed symptomatic pericardial effusions requiring percutaneous drainage, and 1 patient has demonstrated phrenic nerve paresis. There were no deaths. At 3 months, 87% were in sinus rhythm, and 43% were free of AF and antiarrhythmic medications (AADs). At 6 months, 76% were free from AF and AADs. CONCLUSION The convergent procedure effectively combines surgical and electrophysiological AF expertise to provide a viable treatment option to patients with persistent AF or LSPAF. Long-term follow-up is under way.

Beat-to-beat repolarisation variability in body surface electrocardiograms.

The repolarisation variability in body surface electrocardiograms has been evaluated by beat-to-beat QT interval variability. Interpolated R-peak time and template T-wave matching algorithms were used to determine the characteristic time points of the R-wave and T-wave, respectively. The T-wave time can be determined accurately and robustly by searching for the best match between a template T-wave and measured T-waves. The authors studied 5 min multichnnel ECG recordings (35 channels) measured in 20 healthy subjects. A QT variability of 2.24±0.79 ms was obtained (1.15±0.30 ms, if linear detrend was used), which is significantly lower than that reported in several other studies. To explore this discrepancy, the sensitivity of the template matching algorithm to periodic and random noise on the ECG was estimated by a simulation study. The results showed that the repolarisation variability depended on selection of the appropriate lead, the signal-to-noise ratio and the effectiveness of baseline correction. Lead II of a standard 12-lead ECG is a reasonable choice for QT variability analysis; however, precordial leads V3-V6 could be better with regard to the amplitude of the T-wave. Poor signal-to-noise ratios can lead to unrealistic values for repolarisation variability.

Assessment of Cardiac Autonomic Regulation and Ventricular Repolarization after Off-Pump Coronary Artery Bypass Grafting

BACKGROUND Altered autonomic regulation precipitates cardiac arrhythmias and increases the risk of sudden cardiac death. This risk is further increased by changes in ventricular repolarization. Autonomic regulation is deranged in patients after myocardial on-pump revascularization. We aimed to clarify how off-pump coronary artery bypass grafting (CABG) affects postoperative cardiac autonomic regulation and ventricular repolarization within 4 weeks after CABG. METHODS Forty-two patients (mean age, 61.9 +/- 9.3 years; mean EURO score 2.6 +/- 1.9) were electively admitted for off-pump CABG. The electrocardiographic and respiratory waveform recordings were performed in the afternoon in the supine position for 10 minutes. Autonomic modulation was assessed using heart rate variability analysis. Power spectra were computed from 5-minute stable RR intervals using Fourier Transform analysis. Total power of spectra was defined in the range of 0.01 to 0.40 Hz, high-frequency power within 0.15 to 0.40 Hz, and low-frequency power within 0.04 to 0.15 Hz. Normalized power was defined as a ratio of power in each band/total power. The high- and low-frequency power as well as their normalized values indicated cardiac vagal and sympathetic modulation, respectively. Ventricular repolarization was assessed using QT interval, QT interval variability, and QT-RR interdependence analysis. QT intervals were determined from the beginning of the 5-minute segments. QT interval variability was evaluated by a T-wave template-matching algorithm. Pearson correlation between length of RR and QT interval was applied to study QT-RR characteristics. The results were tested for significance using the Fisher exact test, nonpaired t test, and analysis of variance; a P <.05 was considered significant. RESULTS The frequency of arrhythmic events and heart rate increased from the fourth to the seventh postoperative day and returned to preoperative levels 4 weeks after CABG. Heart rate variability measures indicating autonomic modulation remained depressed even 4 weeks after the procedure. QT variability index increased from -1.2 +/- 0.5 to -0.8 +/- 0.4 on the fourth day after the operation (P <.05) and returned to -1.0 +/- 0.5 4 weeks after CABG (P = not significant). QT-RR correlation decreased from 0.41 to 0.23 (P <.05) and remained significantly impaired as long as 4 weeks after CABG. CONCLUSIONS Observed faster heart rates until 1 week after off-pump CABG imply excessive adrenergic activation, which is comparable to on-pump CABG procedure rates. The results indicate profound autonomic derangement and loss of rate-dependent regulation after off-pump CABG even 4 weeks after operation. Restituted repolarization as assessed by QT variability index 4 weeks postoperatively corresponded with decreased frequency of rhythm disturbances 4 weeks after CABG. The loss of coupling between QT and RR intervals shows increased electrical instability postoperatively, which may serve as an additional promoter for postoperative arrhythmias, especially at higher heart rates.

A technique for aortic valve replacement on the beating heart with continuous retrograde coronary sinus perfusion with warm oxygenated blood

The protection of ventricular myocardium in aortic valve operations is always an issue because those hearts do not tolerate global ischemia well. A technique of aortic valve replacement is described involving continuous retrograde coronary sinus perfusion with warm oxygenated blood used in 34 patients to date without any complications. This technique maintains a beating heart throughout the procedure.

Computer simulation and spatial modelling in heart surgery

In this work, three dimensional modelling and computer simulation of heat transfer on generally-shaped nonhomogeneous bodies is proposed and described. The complexity of the calculation is estimated and the potential use of high performance parallel computers is discussed. The method is focused on applications in medicine. As an example, a numerical algorithm for the parallel computer simulation of heart cooling procedures during surgery is presented. On the basis of simulated results, two different methods of cooling are compared.

Multichannel ECG measurement system

Multichannel ECG is an important instrumentation for experimental and clinical electrophysiology. Both the software and the front-end design issues are described for a 128 channel system which can record the signals up to 100 seconds. The basic analysis and presentation of the acquired ECG signals are also given with examples of body surface potential maps. Thanks to the frequency response of the front-end down to 0.05 Hz, the system can show high resolution isointegral maps of ST segment shift. The system is modular and can be modified for different number of channels, sample-rate, bandwidth and quantization resolution.