R. Autschbach

Inhaled iloprost to control pulmonary artery hypertension in patients undergoing mitral valve surgery: a prospective, randomized-controlled trial

Background: Pulmonary hypertension (PHT) is common in patients undergoing mitral valve surgery and is an independent risk factor for the development of acute right ventricular (RV) failure. Inhaled iloprost was shown to improve RV function and decrease RV afterload in patients with primary PHT. However, no randomized‐controlled trials on the intraoperative use of iloprost in cardiac surgical patients are available. We therefore compared the effects of inhaled iloprost vs. intravenous standard therapy in cardiac surgical patients with chronic PHT.

Modified technique for thoracomyoplasty after posterolateral thoracotomy.

OBJECTIVE Thoracomyoplasty after prior posterolateral thoracotomy (PLT) remains a challenge for the thoracic surgeon. Thoracodorsal artery division after PLT impairs the vascularization supply of the latissimus dorsi muscle (LDM) resulting in muscle mass reduction due to distal atrophy. This makes adequate filling of residual empyema space and/or surgical closure of bronchial stump insufficiency more difficult, and they require alternative surgical procedures. We present an alternative approach using a four-muscle flap technique to include the infraspinatus, the subscapularis and the teres major muscle group, all pedicled from the subscapular artery as a part of a modified thoracomyoplasty technique for closing residual empyema space and bronchial stump insufficiency. METHODS Between 2002 and 2008 we performed the technique in 7 patients with residual empyema space. Three patients had post-tuberculosis syndrome, 2 had postpneumectomy empyema, and 2 had chronic parapneumonic empyema. Three cases were combined with a bronchopleural fistula. All patients underwent a two-stage procedure. First, open window thoracostomy was performed followed by definitive surgical treatment after 3-6 months. In all cases with bronchial insufficiency the stump was covered with a subscapularis muscle flap. The infraspinatus and the teres muscle group were used in combination with a local thoracoplasty. RESULTS Mean age was 68 +/- 7.9 years. Time from open window thoracostomy to thoracomyoplasty averaged 4 +/- 1.3 months. The number of resected ribs ranged between 4 and 8. Mean postoperative stay in the ICU was 3 +/- 2.9 days. The thoracic drains were removed after 5 +/- 2.3 days. Total hospital stay was 15 +/- 7.6 days. No hospital mortality was noted. Minor postoperative complications occurred in 2 cases. Shoulder function without pain allowed abduction up to 90 degrees. Function was decreased by 16 +/- 9 degrees compared to preoperative evaluation. No severe progressive scoliosis was noted. CONCLUSIONS Division of the LDM and its vascular supply after posterolateral thoracotomy results in a reduction of muscle mass. The shoulder girdle muscles offer an adequate alternative to fill residual empyema space with acceptable long-term results and restriction in shoulder motion. In all cases with bronchial fistula, bronchial stump closure with a pedicled subscapular muscle was an effective alternative operative technique.

Influence of aortic dimensions on the hemodynamic performance of small aortic valve prostheses: impact on patient/prosthesis mismatch.

BACKGROUND Since Doppler echocardiography takes no account of pressure recovery, the true hemodynamic burden of aortic valve prostheses remains vague. The purpose of this study was to elucidate the methodological error of Doppler gradient estimation by means of a model demonstrating the different influence of aortic root diameters on net and Doppler gradients, respectively. This matters especially in small valves and the related patient/prosthesis mismatch calculation. METHODS Two bileaflet small aortic valve prostheses (19 mm SJM Regent® and On-X® valve) were tested using a pulsatile circulatory mock loop simulator with two different aortic models: one with statistically normal diameters according to annular size, another one simulating an aortic aneurysm of 50 mm. Doppler and simultaneously recorded net gradients as well as systolic energy losses were obtained for different hemodynamic conditions. RESULTS In all measurements a significant amount of pressure recovery was observed. In cases of aortic aneurysm systolic energy loss increased significantly for each cardiac output at each heart rate ( P < 0.0028), reflected by a significant ( P < 0.0001) increase in net gradients. The corresponding Doppler gradients were unchanged. This indicates significantly less pressure recovery ( P < 0.0001) in the aneurysmatic aorta. CONCLUSIONS Geometry of the ascending aorta considerably alters aortic valve hemodynamic parameters. The hemodynamic function of small aortic valve prostheses, especially with corresponding normal outflow dimensions, is much better than expected from Doppler gradients. Thus, calculation of a patient/prosthesis mismatch can be misleading.

Video-assisted pericardioscopic surgery: refinement of a new technique for implanting epimyocardial pacemaker leads

OBJECTIVE Current alternative approaches for pacemaker lead implantation imply the breach of the pleural space. Recently, the feasibility of experimental lead implantation by rigid endoscopy has been described. The use of flexible endoscopes and a standardised application has not been realised yet. Our main goal was to compare rigid and flexible endoscopy and to establish a standardised protocol for the implementation of a closed-chest subxiphoid approach for epimyocardial lead implantation. METHODS Rigid and flexible endoscopes were used for placement of screw-in pacing leads (4-F). A total of 17 adult pigs (80 kg) were anaesthetised and a 10-mm subxiphoid axial incision performed. The pericardium was opened and entered under endoscopic vision. Epimyocardial electrodes were implanted through the endoscope onto all four chambers. Standard haemodynamic measurements and pacing measurements were carried out. RESULTS Both methods were deployed in the first three individuals. Superior endorsement of rigid endoscopy, due to better orientation and stability, led to its exclusive deployment in the remaining 14 individuals. Access to the implantation sites was quick (<10 min). A plastic cover had to be applied to reduce arrhythmia (VentricularExtraSystoles(bare): 17 ± 2.2 min(-1) vs VentricularExtraSystoles(cover): 5 ± 1.9 min(-1); n = 4). Measured pacing parameters were comparable with classic endocardial-derived thresholds. Post-mortem examination revealed no relevant damage/injury and/or bleeding in the heart and circumjacent tissue. There was no evidence of injury at the implantation sites and the corresponding pericardium. The electrodes showed excellent anchorage inside the myocardial tissue (penetration depths: 3 ± 0.2mm) and resisted high tractive forces. CONCLUSION Flexible endoscopy is not suitable for exclusive deployment inside the pericardial space, whereas rigid endoscopy presented itself as a safe, fast and simple approach for epimyocardial lead implantation using an insulating trocar. Without cover, malignant arrhythmia constrains the implementation of video-assisted pericardioscopic surgery (VAPS). Subxiphoid VAPS permits optimal lead positioning under direct vision without fluoroscopy, without the breach of the pleural space and with a short procedural duration (<60 min). Our standardised minimal-invasive approach allows visualisation and intervention, potentially of all intrapericardial structures.

A core outcome set for all types of cardiac surgery effectiveness trials: a study protocol for an international eDelphi survey to achieve consensus on what to measure and the subsequent selection of measurement instruments

BackgroundCardiovascular disease (CVD) is a major contributor to the burden of disease and the number one cause of death worldwide. From 1990 until today, more people died from coronary heart disease than from any other cause. CVD is regularly treated with minimally or non-minimally invasive off- or on-pump cardiothoracic surgery and several interventions related to the outcome of the surgical procedures have been evaluated in clinical trials, but heterogeneity in outcome reporting hinders comparison of interventions across trials and limits the ability of research synthesis. This problem is encountered with the introduction of core outcome sets (COSs), which should be measured and reported, as a minimum, in all clinical trials for a specific clinical field.Methods/designThis study protocol describes the methods used to develop a COS for all types of cardiac surgery effectiveness trials. We aim to reach consensus on what to measure in an international three-round eDelphi exercise involving adult patients in need or after cardiothoracic surgery, cardiothoracic surgeons, cardiologists, anaesthesiologists, nursing staff and researchers with expertise in this particular field of medical research. Subsequently, outcome measurement instruments (how to measure) will be determined. Recommendations on COS development given by the Core Outcome Measures in Effectiveness Trials (COMET) Initiative and the Outcome Measures in Rheumatology (OMERACT) Initiative were followed.DiscussionThe proposed COS aims to provide methodological guidance for future cardiothoracic surgical trials to ensure the comparability of effects of interventions across studies and enable research synthesis. This does not imply that primary outcomes should always and exclusively be those of the COS. However, to ensure the comparability of results across trials, the outcomes included in this COS should be considered for inclusion besides measuring trial-specific clinical endpoints.

Pulmono-atrial shunt and lung assist to treat right ventricular failure

In right ventricular failure (RVF) a decrease of right ventricular afterload and improvement of left atrial filling could be achieved by a pulmonary artery-left atrial (PA)-shunt. To avoid cyanosis, artificial oxygenation is necessary. In 11 pigs a PA-shunt was created. An interventional lung assist device (ILA) was installed from the femoral artery to vein in 5 pigs (serial in relation to native lung: Group I) and into the PA-shunt in 6 pigs (parallel: Group II). RVF was induced by pulmonary artery banding. Right ventricular performance was determined by pulse contour analysis, pressure - and flow measurements. In both groups a stable RVF was generated. In Group I cardiac output trended to increase but neither right ventricular filling pressures nor arterial pressure changed significantly. The PaO2 decreased significantly. In Group II cardiac output and arterial pressure increased significantly under a shunt flow of 2.3- 2.6 l/min and the animals recovered from cardiogenic shock. In conclusion a PA-shunt with a parallel lung assist can effectively reverse the deleterious effects of RVF.

Delayed sternal closure after total artificial heart implantation

Data represent numbers of patients except as noted. Statistical comparisons were made by 2-tailed t test. RBC, Red blood cell; FFP, fresh-frozen plasma. One of the issues of greatest concern in total artificial heart (TAH) therapy is excessive bleeding in the early postoperative setting. Impaired perfusion, in cases of extended myocardial infarction and cardiogenic shock, and increased filling pressures, in cases of chronic biventricular heart failure, result in hepatic dysfunction and coagulation disorders. It is therefore not surprising that reexploration rates are still high. Although delayed sternal closure (DSC) is a well-established option for the management of refractory bleeding after routine and especially pediatric cardiac surgery, its safety and efficacy have still not been evaluated in the context of TAH therapy.

Survival and quality of life in patients with cardiac resynchronization therapy for severe heart failure and in heart transplant recipients within a contemporary heart failure management program.

BACKGROUND Current treatment of advanced chronic heart failure comprises pharmacologic approaches, multidisciplinary management strategies and device therapy. We sought to compare the outcome after cardiac synchronization therapy (CRT) with the outcome after heart transplantation within a contemporary heart failure management program. METHODS In a cohort study, survival and quality of life were assessed in 105 patients who had received CRT (53% with defibrillator) for severe heart failure and in 112 heart transplant recipients attending a heart failure clinic at a tertiary hospital. For assessment of health-related quality of life the Medical Outcome Short Form 36 (SF-36) was applied to the survivors. A propensity score for receiving transplantation vs CRT was developed using logistic regression and was incorporated into statistical models. RESULTS Severity of heart failure before heart transplantation or CRT was similar. Survival was not different between device recipients and transplant recipients by Kaplan-Meier analysis. Cox regression analysis with time-dependent covariates revealed a significant interaction between treatment and time, which favored transplantation late after intervention. There were no significant differences in 7 of 8 subjective measures of health-related quality of life. The score for physical functioning was higher in the transplantation group; this difference remained of borderline significance after multivariate adjustment. CONCLUSIONS Contemporary management of patients with advanced heart failure including CRT leads to improved survival and quality of life and diminishes the difference in these outcomes between conservative management and heart transplantation within the time-frame studied. Patient selection for heart transplantation requires consideration of these results.

Fluid Dynamics in Rotary Piston Blood Pumps

Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid–structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

Rotary piston blood pumps: past developments and future potential of a unique pump type

ABSTRACT Introduction: The design of implantable blood pumps is either based on displacement pumps with membranes or rotary pumps. Both pump types have limitations to meet the clinical requirements. Rotary piston blood pumps have the potential to overcome these limitations and to merge the benefits. Compared to membrane pumps, they are smaller and with no need for wear-affected membranes and valves. Compared to rotary pumps, the blood flow is pulsatile instead of a non-physiological continuous flow. Furthermore, the risk of flow-induced blood damage and platelet activation may be reduced due to low shear stress to the blood. Areas covered: The past developments of rotary piston blood pumps are summarized and the main problem for long-term application is identified: insufficient seals. A new approach with seal-less drives is proposed and current research on a simplified rotary piston design is presented. Expert commentary: The development of blood pumps focuses mainly on the improvement of rotary pumps. However, medical complications indicate that inherent limitations of this pump type remain and restrict the next substantial step forward in the therapy of heart failure patients. Thus, research on different pump types is reasonable. If the development of reliable drives and bearings succeeds, rotary piston blood pumps become a promising alternative.