Simon Schopka

Cardiac decompression on extracorporeal life support: a review and discussion of the literature.

Extracorporeal life support is a worldwide expanding technology for patients in critical cardiogenic shock. The device is usually attached to the femoral vessels using percutaneous techniques. Despite sufficient extracorporeal circulatory support, an unclear number of patients develop high end-diastolic pressures leading to left ventricular distension and pulmonary edema, and ventricular thrombus formation may evolve. This article discusses the strategies to prevent ventricular distension by conservative, interventional, and surgical means, also illustrated by case presentations.

Early experiences with miniaturized extracorporeal life-support in the catheterization laboratory

OBJECTIVES Cardiocirculatory arrest during different types of interventions in the catheterization laboratory (cath-lab) requires mechanical cardiopulmonary resuscitation (CPR) to restore spontaneous circulation. However, mechanical chest compression leads to interruption of the procedure and can severely compromise the success of the percutaneous coronary intervention (PCI) or transcatheter aortic valve implantation (TAVI). Alternatives to mechanical chest compression are rare and mostly uncommon. The use of extracorporeal assistance for cardiopulmonary resuscitation (E-CPR) can be life-saving, but, up to now, it is not commonly and rapidly available in hospitals with cardiac-catheter laboratories but without cardiac-surgery departments. Here, we report our early experiences in using miniaturized extracorporeal membrane oxygenation (ECMO) systems for E-CPR in the cath-lab. We characterize the emergency uses and the bridging function of these simplified ECMO devices. METHODS Patients who developed cardiocirculatory arrest during PCI and TAVI procedures were treated with E-CPR using percutaneous veno-arterial extracorporeal life-support. To provide extracorporeal life-support, we used two types of miniaturized ECMO systems that can act independently from wall their connection points for power and oxygen supply and are suitable for use in the cath-lab. RESULTS Between 2006 and 2011, E-CPR was used in 10 PCI and 4 TAVI patients. The mean age was 73.6 ± 8.8 years. In all patients, E-CPR could be established using percutaneous veno-arterial vessel access. On extracorporeal assistance, the return of beating heart circulation could be rapidly re-established in all patients. In the PCI group, the procedure was successfully completed in all patients while on ECMO. Two patients in the TAVI group were bridged on ECMO to surgical aortic valve replacement. In the clinical follow-up, seven patients (50%) survived to hospital discharge. CONCLUSIONS Miniaturized ECMO systems can be safe and highly effective in restoring circulation and gas exchange in patients with cardiocirculatory failure in the cath-lab. Additionally, the PCI and TAVI procedures can be finished successfully on ECMO, otherwise the patients can be bridged to cardiac surgery. Especially for patients in need of cardiac surgery, patient transfer to extracorporeal assistance can be more easily processed.

Current Strategies in Cardiovascular Biomaterial Functionalization

Prevention of the coagulation cascade and platelet activation is the foremost demand for biomaterials in contact with blood. In this review we describe the underlying mechanisms of these processes and offer the current state of antithrombotic strategies. We give an overview of methods to prevent protein and platelet adhesion, as well as techniques to immobilize biochemically active molecules on biomaterial surfaces. Finally, recent strategies in biofunctionalization by endothelial cell seeding as well as their possible clinical applications are discussed.

Minimizing the risk of perioperative stroke by clampless off-pump bypass surgery: a retrospective observational analysis

ObjectivesStroke is a devastating complication after coronary artery bypass grafting, occurring in 1.4% to 4.3% of patients. A major cause of stroke is cerebral embolization of aortic atheromatous debris or calcified plaques. This report analyzes the incidence of stroke in patients treated according to the clampless concept, i.e. avoiding side-clamping of the aorta, by means of off-pump coronary artery bypass surgery (OPCAB) in combination with the HEARTSTRING device.MethodsDuring a period of 43 months (2005-2008), 412 consecutive patients were treated with the above-mentioned method by one single surgeon. A minimum of one proximal aortal anastomosis was performed in each patient. Altogether, 542 proximal anastomosis were applied, each created by means of the HEARTSTRING device.ResultsThe mean age of patients was 67+9.7 years, the predicted mortality 5.2% (logistic EuroSCORE) and the observed mortality 1.9%. Histories of preoperative neurological disorders or cerebrovascular diseases were documented in 15% of patients. The overall incidence of postoperative stroke was 0.48% in contrast to 1.3% according to the stroke risk score.ConclusionsIn accordance to previously published data, our results show that avoiding aortic side-clamping during OPCAB reduces postoperative stroke rates. The HEARTSTRING device is a safe option for creating proximal aortic anastomosis.

Ablation of atrial fibrillation with the Epicor system: a prospective observational trial to evaluate safety and efficacy and predictors of success

BackgroundHigh intensity focused ultrasound (HIFU) energy has evolved as a new surgical tool to treat atrial fibrillation (AF). We evaluated safety and efficacy of AF ablation with HIFU and analyzed predictors of success in a prospective clinical study.MethodsFrom January 2007 to June 2008, 110 patients with AF and concomitant open heart surgery were enrolled into the study. Main underlying heart diseases were aortic valve disease (50%), ischemic heart disease (48%), and mitral valve disease (18%). AF was paroxysmal in 29%, persistent in 31%, and long standing persistent in 40% of patients, lasting for 1 to 240 months (mean 24 months). Mean left atrial diameter was 50 ± 7 mm. Each patient underwent left atrial ablation with the Epicor system prior to open heart surgery. After surgery, the patients were treated with amiodarone and coumadin for 6 months. Follow-up studies including resting ECG, 24 h Holter ECG, and echocardiography were obtained at 6 and 12 months.ResultsAll patients had successful application of the system on the beating heart prior to initiation of extracorporeal circulation. On average, 11 ± 1 ultrasound transducer elements were used to create the box lesion. The hand-held probe for additional linear lesions was employed in 83 cases. No device-related deaths occurred. Postoperative pacemaker insertion was necessary in 4 patients. At 6 months, 62% of patients presented with sinus rhythm. No significant changes were noted at 12 months. Type of AF and a left atrial diameter > 50 mm were predictors for failure of AF ablation.ConclusionAF ablation with the Epicor system as a concomitant procedure during open heart surgery is safe and acceptably effective. Our overall conversion rate was lower than in previously published reports, which may be related to the lower proportion of isolated mitral valve disease in our study population. Left atrial size may be useful to determine patients who are most likely to benefit from the procedure.

Extracorporeal membrane oxygenation by single-vessel access in adults: advantages and limitations.

Veno-venous extracorporeal membrane oxygenation (vvECMO) conventionally requires the cannulation of two vessels. Here we report our initial experience with the “Wang-Zwische” (WZ) double-lumen cannula. In a group of n = 36 patients single venous cannulation for vvECMO was performed. A retrospective analysis was executed. A comparison of flow characteristics to standard two-vessel cannulation was performed. Mean age of the patient population was 48 ± 15 years (body mass index [BMI] 32 ± 13 kg/m2). In n = 32 patients (89%) the cannula was implanted percutaneously under echo or fluoroscopic guidance in less than 30 minutes. Nine patients were partially mobilized on extracorporeal membrane oxygenation (ECMO) support. Oxygenation (partial arterial oxygen tension [PaO2]/fraction of inspired oxygen [FiO2]) improved significantly in all patients from 66 mm Hg (interquartile range [IQR] 58–87 mm Hg) before ECMO to 117 mm Hg (IQR 95–195 mm Hg, p = 0.001) after 24 hours. In seven patients (19%) nonfatal adverse events occurred, including three dislocations, two partial cannula thrombosis, one ventricular perforation, and one retroperitoneal hemorrhage. The negative pressures for drainage at a flow of 2.5 L/min were significantly lower in a standard (S) two-vessel approach compared with a WZ approach (S: −9 mm Hg; IQR −3 to −24 mm Hg, vs. WZ: −23 mm Hg; IQR −4 to −40 mm Hg; p = 0.04). The WZ cannula offers sufficient gas exchange in addition to certain advantages over standard cannulation, including facilitated cannulation in selected patients and improved mobilization.

Recellularization of biological heart valves with human vascular cells: in vitro hemocompatibility assessment.

Coverage of cardiovascular bioprostheses with autologous endothelium is used for the purpose of improving blood compatibility. The aim of our study was to analyze endothelialization potential of glutaraldehyde-fixed heart valves, cellular functions of seeded endothelial cells (EC), and the impact of a two-stage seeding protocol using human vascular fibroblasts (FB) and EC from saphenous veins (HSVEC) on cellular functional properties in vitro. Adherence and morphology of adhered cells were assessed by scanning electronic microscopy and immunohistochemistry. Reproducible, complete surface coverage with EC was established on decellularized and glutaraldehyde-fixed bovine pericardium. Analyzing functional properties of cells directly adhered to biomaterial revealed nonproliferative cells, which were capable of inflammatory stimulation in terms of TNF-induced increase in interleukin-6 secretion and adhesion of inflammatory cells. Furthermore, EC showed sustained antithrombotic properties quantified by platelet adhesion onto EC and prostacyclin secretion by EC. Preseeding with vascular fibroblasts using a two-stage seeding protocol induced EC proliferation and improved inflammatory and anti-thrombotic functions. Cardiovascular biomaterials differ significantly in their potential to allow for adhesion of human EC. Successfully endothelialized biomaterial, however, revealed cellular properties which are likely to be favorable to improving performance of biomaterials. Two-stage seeding adds regenerative potential and improves cell functions of adherent EC.

Impact of cardiopulmonary bypass on acute kidney injury following coronary artery bypass grafting: a matched pair analysis.

BackgroundPostoperative Acute Kidney Injury (AKI) after coronary artery bypass grafting (CABG) is a common complication associated with significant morbidity and mortality. Cardiopulmonary bypass (CPB) is accepted to contribute to the occurrence of AKI and is of particular importance as it can be avoided by using the off-pump technique. However the renoprotective properties of off-pump (CABG) are controversial. This analysis evaluates the impact of cardiopulmonary bypass on renal function.MethodsA matched-pair analysis of 1428 patients undergoing coronary artery bypass grafting was conducted. The patients were stratified according to their preoperative renal function and to risk factors for postoperative AKI. The development of the glomerular filtration rate (GFR) from before surgery until hospital discharge was analyzed. Incidence of AKI were analyzed. Furthermore the impact of CPB duration on postoperative GFR was assessed.ResultsThe occurrence of AKI increases the risk of thirty-day mortality (odds ratio of 4.3). The postoperative GFR decreases significantly after coronary artery bypass grafting but does not differ between onpump and offpump CABG (60.2 ± 24.5 vs 60.7 ± 24.8; p = 0.54). No difference regarding the incidence (26.6% vs 25%) and severity of AKI between cardiopulmonary bypass and the off-pump technique could be found. Duration of cardiopulmonary bypass does not correlate with the decline in postoperative glomerular filtration rate (Pearson Product Moment Correlation; p > 0.050).ConclusionNeither the mere use nor duration of cardiopulmonary bypass proofed to be a risk factor for developing postoperative AKI in CABG patients with a comparable preoperative risk profile for postoperative renal dysfunction. Furthermore, the severity of postoperative AKI is not affected by the use of cardiopulmonary bypass.

Single‐Center Experience With Extracorporeal Life Support in 103 Nonpostcardiotomy Patients

Extracorporeal membrane oxygenation (ECMO) has been successfully used to support patients with cardiac arrest failing to respond to conventional cardiopulmonary resuscitation (CPR). Preimplant factors being indicative for success are unknown up to now. The study describes single center experience with special focus on differences between survivors and nonsurvivors. Between 2002 and 2009, 103 patients were supported within the scope of CPR by means of ECMO. Besides primary diagnosis, duration, and outcome, pH, lactate, mean arterial pressure, aspartate aminotransferase, bilirubin, catecholamine dosage, and oxygenation ratio before ECMO, after 2 h, 1 day, and at explantation were analyzed. One hundred three patients (51.2 ± 16 years, 35 women, 68 men) were analyzed. Primary cardiac failure led to CPR in 54%. Duration of support was 4.8 ± 0.6 days. Twenty-nine (28.1%) patients survived to hospital discharge. On ECMO support, pH, lactate, and mean arterial pressure improved significantly. Catecholamine dosage was significantly reduced after ECMO implantation. Demographic data and primary diagnosis revealed no significant influence on outcome. pH, lactate, creatinine, and bilirubin differed significantly between survivors and nonsurvivors in the course of ECMO support. ECMO support during CPR reliably improves the circulatory and respiratory situation. Considering observed survival critical patient selection is mandatory. Although there are several significant differences between surviving patients and patients with fatal outcome, patient selection turns out to be difficult as clinically relevant factors show only limited predictive value. Future research should focus on better defining a population that may be best of all suited for the use of ECMO support in CPR.

Cell-type specific evaluation of biocompatibility of commercially available polyurethanes

The biocompatibility of different commercially available poly(ether)urethane (PUR), medically used as main component for pump chambers of implantable ventricular assist devices (VAD), was evaluated. We investigated the influence of the PUR manufacturing process in an in vitro cytotoxicity screening assay. Human saphenous vein endothelial cells (HSVEC) and a mouse fibroblast cell line (L929) were cultivated with different PUR specimens. Tissue-cultured polystyrole (TCP) was used as a reference. The cytotoxic effect was evaluated by morphology (phase contrast microscopy), cell viability (mitochondrial acitvity), cell growth kinetics, and proliferation (incorporation of (3)H-methyl-thymidine) tests. Fibronectin-coating guaranteed the adhesion of both cell types onto the reference material. Sterilization procedure of test materials did not affect adhesion properties. L929 completely covered the surfaces of Tecothane, Carbothane, and Mecora specimens, whereas HSVEC formed an imperfect monolayer onto the PUR. The mitochondrial activity was reduced in all cell types attached to PUR. In addition, proliferation of cells was not observed when using these materials. Commercially available PUR provided an unfavorable support for colonization of patient-derived HSVEC, which demanded a surface modification.