Martin Strüber

Human cytokine responses to coronary artery bypass grafting with and without cardiopulmonary bypass

BACKGROUND Coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response. This has been attributed to cytokine release caused by extracorporeal circulation and myocardial ischemia. This study compares the inflammatory response after CABG with cardiopulmonary bypass and after minimally invasive direct coronary artery bypass grafting (MIDCABG) without cardiopulmonary bypass. METHODS Cytokine release and complement activation (interleukin-6 and interleukin-8, soluble tumor necrosis factor receptors 1 and 2, complement factor C3a, and C1 esterase inhibitor) were determined in 24 patients before and after CABG or MIDCABG. The maximum body temperature, chest drainage, and fluid balance were recorded for 24 hours after operation. RESULTS Release of interleukin-6, interleukin-8, and tumor necrosis factor receptors 1 and 2 was significantly higher (p < or = 0.005) in the CABG group than the MIDCABG group just after operation. After 24 hours, a significant increase in interleukin-6 was also found in the MIDCABG group (p = 0.001) compared with preoperative value. Body temperature and fluid balance were significantly higher after CABG (p < or = 0.001). CONCLUSIONS Minimally invasive direct coronary artery bypass grafting represents a less traumatizing technique of surgical revascularization. The reduction in the inflammatory response may be advantageous for patients with a high degree of comorbidity.

Methylene blue: The drug of choice for catecholamine- refractory vasoplegia after cardiopulmonary bypass?

OBJECTIVES Vasoplegia is a frequent complication after cardiopulmonary bypass that often requires the application of norepinephrine. In a number of cases, however, vasoplegia is refractory to norepinephrine. The guanylate cyclase inhibitor methylene blue could be an attractive treatment alternative in such cases. This study examines the results of methylene blue therapy for norepinephrine-refractory vasoplegia after cardiopulmonary bypass. METHODS A total of 54 patients with norepinephrine-refractory vasoplegia after cardiopulmonary bypass were treated with methylene blue (2 mg/kg) administered intravenously through a period of 20 minutes. The effects on hemodynamics, norepinephrine dosage, and clinical outcome were evaluated. RESULTS Three patients (5.6%) died during the hospital stay. A clinically relevant increase in systemic vascular resistance and a decrease in norepinephrine dosage were observed in 51 patients within 1 hour after methylene blue infusion. Four patients (7.4%) had no response to methylene blue. No adverse effects related to methylene blue were observed. CONCLUSIONS A single dose of methylene blue seems to be a potent approach to norepinephrine-refractory vasoplegia after cardiopulmonary bypass for most patients, with no obvious side effects. Guanylate cyclase inhibitors could be a novel class of agents for the treatment of norepinephrine-refractory vasoplegia after cardiopulmonary bypass. A controlled clinical trial is now needed to evaluate the role of methylene blue in this situation.

European results with a continuous-flow ventricular assist device for advanced heart-failure patients §

OBJECTIVE The HeartMate II (HM II) LVAD is a small, quiet, continuous-flow, left ventricular assist device (LVAD) for circulatory support in advanced heart-failure patients, with over 2000 implants worldwide. This article reports on the European experience with this device. METHODS The HM II was implanted in 571 patients at 64 European institutions. In 72% of cases (411 patients), implantation has taken place at least 6 months before the closing date of the study (1 August 2008). Patients (19% female, 70% ischaemic aetiology) were on maximum medical therapy, including inotropic support. Body surface area ranged from 1.30 to 2.50 m(2) and age from 14 to 75 years (mean: 51+/-14 years; n=115, 28% over age 60 years). The intention of support was to provide a bridge to transplantation (73%), destination therapy (21%) and a bridge to recovery (6%). Adverse events were documented in the first 53 patients - for obtaining the Conformité Européenne (CE) Mark (group A) - from a European multicentric study (Strüber et al. [Strüber M, Sander K, Lahpor J, Ahn H, Litzler P-Y, Drakos SG, Musumeci F, Schlensak C, Friedrich I, Gustafsson R, Oertel F, Leprince P. HeartMate II left ventricular assist device; early European experience. Eur J Cardiovasc Surg 2008;34(2):289-94.]: 101 patients) and from a single-centre study (UMCU, The Netherlands: 30 patients). RESULTS The mean support duration ranged from 0 to 1019 days with a mean of 236+/-214 days (249 patients: >6 months, 119: 1 year, 12: >2 years; total support time: 293 years). The overall survival to transplantation, recovery or ongoing device support at the end of the study was 69% (284) with an early mortality of 17.5% and late mortality of 13.5%. Of the surviving patients, 23% have been transplanted, 4% had their device removed after recovery of the left ventricle and 42% are still ongoing. Adverse events included bleeding (ranging from 42% in group C to 59% in group A), percutaneous lead infections (A: 0.19, B: 0.61 and C: 0.18 events per patient year), pocket infections (A: 0.08, B: 0.07 and C: 0.09 events per patient year), ischaemic stroke (A: 0.06, B: 0.09 and C: 0.04 events per patient year), haemorrhagic stroke (B: 0.07, C: 0.04 events per patient year) and transient ischaemic attacks (TIAs; A: 0.08, B: 0.02 and C: 0.13 events per patient year). CONCLUSIONS These results support the use of the HM II continuous-flow LVAD for long-term support as a bridge to transplantation and possibly for destination therapy. Future emphasis should focus on minimising adverse events such as infections, bleeding and neurological events.

Flush perfusion with low potassium dextran solution improves early graft function in clinical lung transplantation

OBJECTIVES We have previously demonstrated experimentally an amelioration of reperfusion injury of the lung after preservation using low potassium dextran (LPD) solution compared to Euro-Collins (EC) solution. Now we report on early graft function in 106 lung transplant recipients of LPD or EC preserved grafts. METHODS Initial graft function was assessed by measurement of lung compliance and oxygenation index 2 h after transplantation. Length of stay on the intensive care unit and hours of mechanical ventilation were compared. Correlation of donor oxygenation, ischemic time, type of transplant, recipient age and sex as well as initial lung compliance and oxygenation with early postoperative course were calculated. RESULTS Dynamic lung compliance was significantly (P<0.05) improved in the LPD group. PO(2)/fiO(2) was comparable in both groups (303+/-122 mmHg LPD, 282+/-118 mmHg EC). Mechanical ventilation was used for 321+/-500 h in the EC group and 189+/-365 h in the LPD group (P=0.006). Intensive care therapy was required for 17.2+/-23.7 days in the EC group and 10.4+/-16 days in the LPD group (P=0.012). Significantly higher lung function parameters were obtained in extubated recipients of LPD preserved grafts 2 weeks after TX. Thirty day graft survival was improved in the LPD group (P=0.045). In the EC group, 30 day mortality was 14.2 and 8% in the LPD group. CONCLUSIONS A reduction of perioperative mortality and morbidity suggests that LPD solution has superior early graft function compared to lung preservation using EC solution.

Comparison of inhaled iloprost and nitric oxide in patients with pulmonary hypertension during weaning from cardiopulmonary bypass in cardiac surgery: a prospective randomized trial.

OBJECTIVE The objective of this study was to compare the efficacy of inhaled iloprost and nitric oxide (iNO) in reducing pulmonary hypertension (PHT) during cardiac surgery immediately after weaning from cardiopulmonary bypass (CPB). DESIGN A prospective randomized study. SETTING A single-center university hospital. PARTICIPANTS Forty-six patients with PHT (mean pulmonary artery pressure (mPAP) > or = 26 mmHg preoperatively at rest, after anesthesia induction, and at the end of CPB) scheduled to undergo cardiac surgery were enrolled. INTERVENTIONS Patients were randomly allocated to receive iloprost (group A, n = 23) or iNO (group B, n = 23) during weaning from CPB. MEASUREMENTS AND MAIN RESULTS Heart rate, mean arterial pressure, central venous pressure, pulmonary artery pressure (PAP), pulmonary capillary wedge pressure, and left atrial pressure were recorded continuously. Iloprost and iNO were administered immediately after the end of CPB before heparin reversal. Both substances caused significant reductions in mean PAP (mPAP) and pulmonary vascular resistance (PVR) and significant increases in cardiac output 30 minutes after administration (p < 0.0001). However, in a direct comparison, iloprost caused significantly greater reductions in PVR (p = 0.013) and mPAP (p = 0.0006) and a significantly greater increase in cardiac output (p = 0.002) compared with iNO. CONCLUSIONS PHT after weaning from CPB was significantly reduced by the selective pulmonary vasodilators iNO and iloprost. However, in a direct comparison of the 2 substances, iloprost was found to be significantly more effective.

HeartMate II left ventricular assist device; early European experience

OBJECTIVE The novel axial flow left ventricular assist device HeartMate II was introduced into clinical practice in Europe as part of the pilot study and after CE approval in November 2005. In order to get an overview of the use and performance of the device in Europe a group of investigators was founded to compare the initial results. METHODS In a retrospective analysis of the first 101 consecutive cases in Europe, data were collected with regard to postoperative outcome and severe adverse events and anticoagulation protocols. Results were stratified by intention to treat as a bridge to transplant or as chronic support therapy in heart failure (destination therapy). RESULTS In 70% of patients, the HeartMate II was intended as a bridge to transplant therapy, in 30%, it was used as a destination therapy device. The perioperative mortality post implant was 20% in the bridge to transplant patients and 7% in the destination therapy arm. However, after 1 year a comparable survival was observed in both groups (69% destination therapy, 63% bridge to transplant). Main causes of death were multiple organ failure (n=12) and cerebrovascular accidents (n=5). All, but one cerebrovascular accident occurred in the first 9 days after surgery. Only one other death was reported thereafter and there was no mechanical failure of the device. CONCLUSIONS Even in the early experience the HeartMate II was used as a chronic support device in a substantial number of patients in Europe. Although the total experience is still limited, the incidence of cerebrovascular accidents is very low and the survival beyond the perioperative period is excellent.

Off-bypass coronary bypass grafting via minithoracotomy using mechanical epicardial stabilization.

BACKGROUND Minimally or less invasive surgical coronary revascularization has gained increasing interest along with new techniques and devices designed for easier and safer procedures. Until recently, it appeared questionable whether grafting techniques with avoidance of cardiopulmonary bypass techniques would allow adequate results compared with conventional techniques using cardioplegic arrest. METHODS Since June 1996, minimally invasive direct coronary artery bypass grafting procedures without cardiopulmonary bypass were intended in 24 patients (19 male, 5 female; age, 60.5 +/- 10.5 years) applying a special system (CardioThoracic Systems, Inc) for internal mammary artery access and epicardial surface stabilization approaching through an anterolateral minithoracotomy. Neither video-assisted preparation nor additional pharmacologic stabilization was applied. Concomitant risk factors and associated comorbidity were frequent. RESULTS The procedure was completed in 23 patients, grafting the left anterior descending coronary artery (n = 21) or diagonal branches (n = 3, 1 sequential) as scheduled. In 1 case with internal mammary artery dissection, cardiopulmonary bypass and sternotomy became necessary. Simultaneous carotid endarterectomy was performed in 1 patient. There were two episodes of intraoperative ventricular fibrillation; no other major complications occurred. Postoperative evaluation was obtained in 16 patients (15 by angiography, 1 by Doppler echocardiography) so far and revealed adequate graft function and patency. CONCLUSIONS Using specially designed instruments for internal mammary artery access and epicardial surface stabilization, minimally invasive direct coronary artery bypass grafting procedures via a minithoracotomy avoiding cardiopulmonary bypass techniques may be applied safely and successfully, even in increased risk constellations.

Implantable defibrillator therapy for ventricular tachyarrhythmia in left ventricular assist device patients

Ventricular arrhythmias (VA) occur frequently after permanent left ventricular assist device (LVAD) implantation in end stage heart failure. Left ventricular assist device patients require rhythm control in contrast to patients with biventricular support. However, the rationale for implantable cardioverter‐defibrillator (ICD) utilization in LVAD patients remains unclear. This study investigated the safety and efficacy of primary prevention ICD therapy and the rate of appropriate ICD interventions in LVAD patients.

Acquired von Willebrand syndrome after exchange of the HeartMate XVE to the HeartMate II ventricular assist device

Instead of pulsatile ventricular assist devices an increasing number of nonpulsatile ventricular assist devices are introduced to clinical practice. The different flow characteristics of this new technique lead to alteration in shear stress on blood components, which may affect the coagulation system. Repeated von Willebrand factor analyses were performed in a patient who first was implanted with a pulsatile ventricular assist device (Thoratec HeartMate XVE), which had to be replaced after 405 days with an axial flow device (HeartMate II). During support with the pulsatile ventricular assist device there was no sign of any coagulation disorder. However, on the axial flow device acquired von Willebrand syndrome Type 2 developed. Inhibition of platelet function was also observed, which may be in part due to the von Willebrand syndrome. The HeartMate II axial flow device may induce von Willebrand syndrome, which was not observed in HeartMate XVE pulsatile ventricular assist device. Patients put on continuous flow devices should be screened for acquired von Willebrand syndrome.

Thrombus formation in a HeartMate II left ventricular assist device

doi:10.1016/j.jtcvs.2007.08.048 M ajor limitations of ventricular assist devices have been the high incidence of thromboembolic events, the requirement for systemic anticoagulation, and the mechanical stability and duration of the device. The successful use of axial flow pumps for left ventricular (LV) assistance has been limited by thromboembolic events and pump thrombosis. Therefore, imaging of the devices is crucial. The HeartMate II axial flow pump (Thoratec, Pleasanton, Calif) has shown a low incidence of thromboembolic events and proper long-term mechanical function. Pump thrombosis has not been reported. We report a case of thrombus formation 4 months after HeartMate II implantation.