Ares K. Menon

Low stroke rate and few thrombo-embolic events after HeartMate II implantation under mild anticoagulation

OBJECTIVES Bleeding and thrombo-embolism are two of the most threatening adverse events associated with the use of continuous flow left ventricular assist devices (LVADs) in the treatment of severe heart failure. We analysed our LVAD patients treated with the HeartMate II (HM II) device by following a low anticoagulation regimen. METHODS Between 2008 and February 2011, we implanted 40 HM II LVADs in our institution. Intention to treat was bridge to transplant in 25, destination therapy in 9, bridge to candidacy in 5 cases and bridge to recovery in 1 case. Heparin was started only after 24 h postoperatively, and Phenprocumon (Phen) was started after removal of all chest drains. International normalized ratio (INR) target in the years 2008-2009 was 2.5, and 2.0-2.5 since 2010. Acetyl salicylic acid (ASA) was prescribed 50-100 mg/day only in patients <55 years or in case of severe atherosclerotic disease of the right coronary artery. All data were analysed consecutively concerning thrombo-embolic and bleeding events. RESULTS Fifty-two percent of the patients were in INTERMACS level 1 or 2 at the time of implantation. The mean age was 58 ± 11 years, and the mean days under LVAD was 241 days (maximum: 1052 days). The survival rate was 87.5% after 30 years and 75% in the long term. Early postoperatively, no strokes or thrombo-embolic events occurred. In the long term, two patients suffered from ischaemic strokes, but recovered well. In both of these index events, the INR was lasting below 1.4. One of these two patients developed pump thrombosis additionally. Only three patients (ASA + Phen) developed gastrointestinal bleeding (7.5%). Two patients were withdrawn from Phen + ASA because of multiple angiodysplasia. CONCLUSIONS Compared with the literature, even a mild anticoagulation protocol does not increase the risk of thrombotic events, but reduces bleeding events in the use of an HM II LVAD.

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

BACKGROUND Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome. METHODS Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively. RESULTS In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B. CONCLUSIONS The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.

Left ventricular geometry and cardiac function during minimally invasive coronary artery bypass grafting

BACKGROUND This investigation was designed to study the changes in function and geometry of the left ventricle during two critical steps of minimally invasive direct coronary artery bypass procedures: placement of an epicardial stabilizer and occlusion of the left anterior descending coronary artery. METHODS Between February 1997 and January 1998, 28 patients underwent bypass grafting with the left internal thoracic artery to the left anterior descending coronary artery (minimally invasive direct coronary artery bypass technique). Transesophageal echocardiography was used for determination of fractional area change and to assess left ventricular (LV) diameters in two dimensions and at the apex. RESULTS Placement of the epicardial stabilizer resulted in a small decrease in LV end-systolic and end-diastolic dimensions; cardiac function remained unchanged. Subsequent occlusion of the left anterior descending coronary artery caused a moderate decline in cardiac index and fractional area change, an increase in LV diameters, and the development of hypokinetic segments within the LV myocardium. CONCLUSIONS The use of an epicardial stabilizer provides a safe and effective means to stabilize the operative field during minimally invasive direct coronary artery bypass procedures. Monitoring of LV function by transesophageal echocardiography enhances the safety of such procedures and is highly recommended.

What Is the Significance of Perioperative Release of Macrophage Migration Inhibitory Factor in Cardiac Surgery

Cardiac surgery is associated with release of the pleiotropic cytokine macrophage migration inhibitory factor (MIF). The trigger for MIF release has not yet been elucidated. Owing to its intrinsic antioxidative activity, MIF might reduce oxidative stress and protect from myocardial ischemia and reperfusion (I/R) injury. In the present study, patients scheduled for elective cardiac surgery (n=46) were randomized to undergo coronary artery bypass grafting either conventionally with cardiopulmonary bypass and cardioplegic arrest-induced I/R (cCABG) or in an off-pump procedure (OPCAB) with minimized I/R. We report that only patients who underwent cCABG exhibited a postoperative increase of MIF (p=0.024), while both groups showed an increase in interleukin-6. MIF release appears to be primarily mediated by I/R and to a lesser extent by inflammation. Endogenous peroxidase activity (p=0.021) and serum levels of thioredoxin (p=0.003) were significantly higher in patients who underwent cCABG after surgery. Interestingly, perioperative MIF release was associated with an enhanced antioxidant capacity and a significantly reduced postoperative incidence of atrial fibrillation (p=0.018) and acute kidney injury (p=0.048). The present study highlights the role of MIF increase during cardiac surgery in response to oxidative stress. Based on current observations, we hypothesize that intraoperative MIF secretion is due to I/R and enhances the antioxidant capacity in patients during cardiac surgery.

The importance of intraoperative selenium blood levels on organ dysfunction in patients undergoing off-pump cardiac surgery: a randomised controlled trial.

Introduction Cardiac surgery is accompanied by an increase of oxidative stress, a significantly reduced antioxidant (AOX) capacity, postoperative inflammation, all of which may promote the development of organ dysfunction and an increase in mortality. Selenium is an essential co-factor of various antioxidant enzymes. We hypothesized a less pronounced decrease of circulating selenium levels in patients undergoing off-pump coronary artery bypass (OPCAB) surgery due to less intraoperative oxidative stress. Methods In this prospective randomised, interventional trial, 40 patients scheduled for elective coronary artery bypass grafting were randomly assigned to undergo either on-pump or OPCAB-surgery, if both techniques were feasible for the single patient. Clinical data, myocardial damage assessed by myocard specific creatine kinase isoenzyme (CK-MB), circulating whole blood levels of selenium, oxidative stress assessed by asymmetric dimethylarginine (ADMA) levels, antioxidant capacity determined by glutathionperoxidase (GPx) levels and perioperative inflammation represented by interleukin-6 (IL-6) levels were measured at predefined perioperative time points. Results At end of surgery, both groups showed a comparable decrease of circulating selenium concentrations. Likewise, levels of oxidative stress and IL-6 were comparable in both groups. Selenium levels correlated with antioxidant capacity (GPx: r = 0.720; p<0.001) and showed a negative correlation to myocardial damage (CK-MB: r = −0.571, p<0.001). Low postoperative selenium levels had a high predictive value for the occurrence of any postoperative complication. Conclusions OPCAB surgery is not associated with less oxidative stress and a better preservation of the circulating selenium pool than on-pump surgery. Low postoperative selenium levels are predictive for the development of complications. Trial registration ClinicalTrials.gov NCT01409057

Successful combined procedure of HeartMate II left ventricular assist device implantation and minimally invasive transapical aortic valve replacement

Left ventricular assist device (LVAD) implantation is an accepted treatment for patients with end-stage heart failure, either as a bridge to transplantation or destination therapy. The newer continuous-flow LVAD HeartMate II LVAD (Thoratec Corp, Pleasanton, Calif) represents the current generation of devices and received CE mark and Food and Drug Administration approval, resulting in approximately 3500 implantations in patients worldwide. Severe aortic valve regurgitation remains a strict contradiction to the use of LVADs. We present a combined treatment with implantation of a HeartMate II LVAD after successful transapical aortic valve replacement in a 51year-old patient with end-stage heart failure and severe aortic regurgitation. Transapical transcatheter aortic valve implantation (TA-AVI) was introduced to clinical use byWalther and colleagues in 2007, after the first implantation in humans by Cribier and colleagues in 2002. TA-AVI reflects an alternative operative strategy to treat aortic valve disease in patients with advanced age and severe comorbidities, who present a high risk for open surgery with cardiopulmonary bypass (CPB).

Special Treatment and Wound Care of the Driveline Exit Site after Left Ventricular Assist Device Implantation.

OBJECTIVE Despite good results following implantation of left ventricular assist devices (LVADs), infections of the driveline and device pocket remain a major problem for patients on long-term support. We present the data from heart failure patients treated with a Thoratec HeartMate-II LVAD (Thoratec Corporation, Pleasanton, California, United States). METHODS From January 2008 to April 2011, in our institution, 40 heart failure patients (NYHA IV) were supported with a HeartMate-II LVAD. The driveline maintenance of 17 patients consisted of the use of Octenidine for the wound dressing, whereas merbromin was additionally used for local irrigation in 31 patients. The data concerning driveline infections were analyzed retrospectively. RESULTS In our study, 95% of the entire cohort was free from infections of the system. Two patients in the conventional group (11.8%) developed a driveline infection at a mean of 130.5 days during 3,416 patient-days (0.21 infection/patient-years). In the Merbromid group (Co. New FaDem SRL Farmaceutici & Chimici, Giugliano, Campania, Italy), all patients were free from any driveline infections during the observation period. In a log-rank comparison, the difference reached statistical significance (p = 0.043). CONCLUSION During our observation period, fewer infections were noted with merbromin treatment. A multicenter setting in a larger cohort should be performed to confirm these findings, although a (double-) blinded setting might be difficult to achieve.

Feasibility and efficacy of bypassing the right ventricle and pulmonary circulation to treat right ventricular failure: an experimental study

BackgroundRight ventricular failure (RVF) and -support is associated with poor results. We aimed for a new approach of right - sided assistance bypassing the right ventricle and pulmonary circulation in order to better decompress the right ventricle and optimize left ventricular filling.MethodsFrom a microaxial pump (Abiomed), a low resistance oxygenator (Maquet and Novalung) and two cannulas (28 and 27 Fr) a system was set up and evaluated in an ovine model (n = 7). Connection with the heart was the right and left atrium. One hour the system was operated without RVF and turned of again. Then a RVF was induced and the course with the system running was evaluated. Complete hemodynamic monitoring was performed as well as echocardiography, flow measurement and blood gas analysis.ResultsThe overall performance of the system was reliable. Without RVF no relevant changes of hemodynamics occurred; blood gases were supra normal. In RVF a cardiogenic shock developed (MAP 35 ± 13 mmHg, CO 1,1 ± 0,7 l/min). Immediately after starting the system the circulation normalized (significant increase of MAP to 85 ± 13 mmHg, of CO to 4,5 ± 1,9). Echocardiography also revealed right ventricular recovery. After stopping the system, RVF returned.ConclusionsBypassing the right ventricle and pulmonary circulation with an oxygenating assist device, which may offer the advantages of enhanced right ventricular decompression and augmented left atrial filling, is feasible and effective in the treatment of acute RVF. Long time experiments are needed.

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.

Ultrasound-assisted treatment of sternocutaneous fistula in post-sternotomy cardiac surgery patients

OBJECTIVES Using an ultrasonic debridement system (low frequency, 25 kHz), we aimed to completely remove bacterial biofilms and preserve vital sternal tissue and to compare this procedure with conventional surgical therapy. METHODS In this retrospective study, we evaluated 37 consecutive patients (25 males) between April 2011 and June 2013 in whom sternocutaneous fistula (SCF) was treated with the ultrasound-assisted wound (UAW) system (Group A, n = 18) or with conventional surgical therapy (Group B, n = 19). Treatment in Group A consisted of a complete dissection of the SCF followed by a multistep UAW debridement session after an interval of 3 days. Our final step in both groups was secondary wound closure with a musculocutaneous flap. RESULTS Patients in both groups were categorized as high risk with respect to several of the known SCF risk factors. In both groups, a similar variety of bacteria were isolated: 61% were gram-positive species, 16.5% were gram-negative species and 10.5% were Candida albicans. Time to secondary wound closure following eradication was significantly shorter in Group A (10 ± 5.4 vs 15 ± 7.1 days in Group B, P = 0.012). Postoperative antibiotic treatment time (16 ± 9.3 vs 22 ± 10.7 days in Group B, P = 0.078) showed a trend in favour of Group A, but the mean hospitalization time (22 ± 12.0 vs 26 ± 14.3 days in Group B, P = 0.34) did not differ between groups. Recurrence of SCF tended to be less frequent in Group A (6 vs 21% in Group B, P = 0.46). In Group B, one infection-related death was noted. The mean follow-up time was 8 ± 2.7 (Group A) and 10 ± 5.7 (Group B) months. CONCLUSIONS Ultrasonic debridement is a promising adjunct to SCF treatment. In combination with adequate surgical and antimicrobial therapy, we documented good mid-term results in our trial group.