Jan Gummert

Impact of Regular Physical Activity on the NAD(P)H Oxidase and Angiotensin Receptor System in Patients With Coronary Artery Disease

Background—In patients with stable coronary artery disease, physical exercise training (ET) improves endothelial dysfunction. A potential mechanism mediating the enhanced vasomotor function is a reduced breakdown of endothelium-derived nitric oxide by reactive oxygen species (ROS). The aim of the present study was to analyze the impact of ET on sources of ROS generation in the left internal mammary artery of patients with symptomatic coronary artery disease. Methods and Results—In left internal mammary artery rings sampled during bypass surgery from 45 patients randomized to either a training (n=22) or an inactive control (n=23) group, the mRNA expression of NAD(P)H oxidase subunits, NAD(P)H oxidase activity, and ROS production were assessed. In addition, endothelial function, expression of angiotensin II (Ang II) receptor type 1 and 2 (AT1-R and AT2-R), and Ang II-mediated vasoconstriction were determined. ET resulted in a significant lower expression of gp91phox (23.1±0.5 versus 69.1±18.1 arbitrary units, training versus control), p22phox (0.7±0.3 versus 2.0±0.5 arbitrary units), and Nox4 (2.7±1.2 versus 5.4±1.0 arbitrary units). Enzymatic activity (2.1±0.3 versus 4.9±0.4 mU/mg) and ROS generation (0.02±0.01 versus 0.06±0.02 arbitrary units) were significantly lower in the training compared with the control group. On a functional level, ET resulted in improved acetylcholine-mediated vasodilatation and a 49% reduction in Ang II–induced vasoconstriction, accompanied by lower AT1-R (3.7±0.8 versus 16.6±5.7 arbitrary units, training versus control) and higher AT2-R (7.8±2.5 versus 1.6±0.7 arbitrary units) mRNA expression. Conclusions—ET reduces vascular expression of NAD(P)H oxidase and AT1-R, resulting in decreased local ROS generation. These molecular effects converge in a reduced Ang II–mediated vasoconstriction.

Inhibition of Elevated Ca2+/Calmodulin-Dependent Protein Kinase II Improves Contractility in Human Failing Myocardium

Rationale: Heart failure (HF) is known to be associated with increased Ca2+/calmodulin-dependent protein kinase (CaMK)II expression and activity. There is still controversial discussion about the functional role of CaMKII in HF. Moreover, CaMKII inhibition has never been investigated in human myocardium. Objective: We sought to investigate detailed CaMKII&dgr; expression in end-stage failing human hearts (dilated and ischemic cardiomyopathy) and the functional effects of CaMKII inhibition on contractility. Methods and Results: Expression analysis revealed that CaMKII&dgr;, both cytosolic &dgr;C and nuclear &dgr;B splice variants, were significantly increased in both right and left ventricles from patients with dilated or ischemic cardiomyopathy versus nonfailing. Experiments with isometrically twitching trabeculae revealed significantly improved force frequency relationships in the presence of CaMKII inhibitors (KN-93 and AIP). Increased postrest twitches after CaMKII inhibition indicated an improved sarcoplasmic reticulum (SR) Ca2+ loading. This was confirmed in isolated myocytes by a reduced SR Ca2+ spark frequency and hence SR Ca2+ leak, resulting in increased SR Ca2+ load when inhibiting CaMKII. Ryanodine receptor type 2 phosphorylation at Ser2815, which is known to be phosphorylated by CaMKII thereby contributing to SR Ca2+ leak, was found to be markedly reduced in KN-93–treated trabeculae. Interestingly, CaMKII inhibition did not influence contractility in nonfailing sheep trabeculae. Conclusions: The present study shows for the first time that CaMKII inhibition acutely improves contractility in human HF where CaMKII&dgr; expression is increased. The mechanism proposed consists of a reduced SR Ca2+ leak and consequently increased SR Ca2+ load. Thus, CaMKII inhibition appears to be a possible therapeutic option for patients with HF and merits further investigation.

Cardiac Surgery in Germany during 2010: A Report on Behalf of the German Society for Thoracic and Cardiovascular Surgery

All cardiac surgical procedures performed in 79 German cardiac surgical units throughout the year 2010 are presented in this report, based on a voluntary registry which is organized by the German Society for Thoracic and Cardiovascular Surgery. In 2010 a total of 95,734 cardiac surgical procedures (ICD and pacemaker procedures excluded) have been collected in this registry. More than 12.4% of the patients were older than 80 years compared to 11.8% in 2009. Hospital mortality in 42,804 isolated CABG procedures (14.2% off-pump procedures) was 2.8%. In 25,127 isolated valve procedures (including 3660 transcatheter-valve implantations) a mortality of 4.9% has been observed. This voluntary registry of the German Society for Thoracic and Cardiovascular Surgery will continue to be an important tool enabling quality control and illustrating the development of cardiac surgery in Germany.

Sirolimus (rapamycin) halts and reverses progression of allograft vascular disease in non-human primates.

Background. Current immunosuppressive protocols fail to prevent chronic rejection often manifested as graft vascular disease (GVD) in solid organ transplant recipients.Several new immunosuppressants including sirolimus, a dual function growth factor antagonist, have been discovered, but studies of drug efficacy have been hampered by the lack of a model of GVD in primates, as a prelude to clinical trials. As described earlier, we have developed a novel non-human primate model of GVD where progression of GVD is quantified by intravascular ultrasound (IVUS). Methods. Twelve cynomolgus monkeys underwent aortic transplantation from blood group compatible but mixed lymphocyte reaction-mismatched donors. To allow the development of GVD in the allograft, no treatment was administered for the first 6 weeks. Six monkeys were treated orally with sirolimus from day 45 after transplantation to day 105. Results. Progression of GVD measured as change in intimal area from day 42 to 105 was halted in sirolimus-treated monkeys compared to untreated monkeys (P <0.001, general linear model). On day 105, the intimal area±SEM was 3.7±1.0 and 6.4±0.5 mm2, respectively (P <0.05, t test). The magnitude of allograft intimal area on day 105 correlated inversely with sirolimus trough levels (R2=0.67, P <0.05). Regression of the intimal area was seen in four of six sirolimus-treated monkeys, which was significantly different from the untreated monkeys (P <0.05). Conclusions. Our results in the first non-human primate model of GVD showed that treatment with sirolimus not only halted the progression of preexisting GVD but also was associated with partial regression. Sirolimus trough blood levels were correlated with efficacy. Therefore, sirolimus has the potential to control clinical chronic allograft rejection.

Emergency coronary artery bypass graft surgery for acute coronary syndrome : Beating heart versus conventional cardioplegic cardiac arrest strategies

Background— Aim of this study was to compare the outcome of beating heart versus conventional coronary artery bypass graft (CABG) strategies in acute coronary syndromes for emergency indications. Methods and Results— 638 consecutive patients with acute coronary syndrome (ACS) receiving emergency CABG surgery via midline sternotomy from January 2000 to September 2005 were evaluated. Propensity score analysis was used to predict the probability of undergoing beating heart (BH) (n=240) versus cardioplegic cardiac arrest (CA) (n=398) strategies. Patients presented with stable hemodynamics (n=531) or in cardiogenic shock (CS) (n=107). Hospital and follow-up outcome was compared by propensity score adjusted multiregression analysis. BH included 116 on-pump and 124 off-pump (OPCAB) procedures. There was a propensity to operate CS patients on the beating heart (multivariate odds ratio [OR], 3.8; P=0.001). Under stable hemodynamics significant predictors for BH selection were logEuroSCORE >20% (OR, 2.05), creatinine >1.8 mg/dL (OR, 4.12), complicated percutaneous coronary intervention (OR, 1.88), ejection fraction <30% (OR, 2.64), whereas left main disease (OR, 0.68), circumflex artery (OR, 0.32), and 3-vessel disease (OR, 0.67) indicated preference for cardioplegic arrest. Time from skin incision to culprit lesion revascularization was significantly reduced in BH patients. BH surgery led to a significant benefit in terms of less drainage loss, less transfusion requirement, less inotropic support, shorter ventilation time, lower stroke rate, and shorter intensive care unit stay. In CS, BH was associated with lower incidence of stroke, inotropic support, acute renal failure, new atrial fibrillation and sternal wound healing complications. In CS patients, hospital mortality rate was reduced when using beating heart strategies (P=0.048). Overall survival, major adverse cerebral and cardiovascular event rate, and repeated revascularization was comparable during a 5-year follow-up. Conclusions— Beating heart strategies are associated with an improved hospital outcome and comparable long-term results for high-risk patients presenting acute coronary syndrome with or without CS.

Global surgical experience with the Acorn cardiac support device.

OBJECTIVE Surgical intervention is an option for treating the remodeled and dilated left ventricles of patients with heart failure. Providing end-diastolic support with an innovative mesh-like cardiac support device reduces mechanical stress, improves function, and reverses cardiac remodeling in animal models without safety issues. The objective of this study was to review the global clinical safety and feasibility experience of this device. METHODS The Acorn CorCap cardiac support device (Acorn Cardiovascular, Inc, St Paul, Minn) has been implanted worldwide in more than 130 patients with dilated cardiomyopathy with or without concomitant cardiac surgery. The device is positioned around the ventricles and given a custom fit. A series of 48 patients were implanted with the device in initial safety and feasibility studies, of whom 33 also received concomitant cardiac surgery. RESULTS At implantation, 11 patients were in New York Heart Association class II, 33 were in class III, and 4 were in class IV. The average CorCap implantation time was 27 minutes. The mean intraoperative reduction in left ventricular end-diastolic dimension was 4.6% +/- 1%. There were no device-related intraoperative complications. Eight early and 9 late deaths occurred during follow-up extending to 24 months. Actuarial survival was 73% at 12 months and 68% at 24 months. There were no device-related adverse events or evidence of constrictive disease, and coronary artery flow reserve was maintained. Ventricular chamber dimensions decreased, whereas ejection fraction and New York Heart Association class were improved in patients overall and in those patients implanted with the CorCap device without concomitant operations. CONCLUSIONS The CorCap device appears safe for patients with dilated cardiomyopathy. Randomized clinical trials are underway in Europe, Australia, and North America.

De novo desmin mutation N116S is associated with arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease, frequently accompanied by sudden cardiac death and terminal heart failure. Genotyping of ARVC patients might be used for palliative treatment of the affected family. We genotyped a cohort of 22 ARVC patients referred to molecular genetic screening in our heart center for mutations in the desmosomal candidate genes JUP, DSG2, DSC2, DSP and PKP2 known to be associated with ARVC. In 43% of the cohort, we found disease-associated sequence variants. In addition, we screened for desmin mutations and found a novel desmin-mutation p.N116S in a patient with ARVC and terminal heart failure, which is located in segment 1A of the desmin rod domain. The mutation leads to the aggresome formation in cardiac and skeletal muscle without signs of an overt clinical myopathy. Cardiac aggresomes appear to be prominent, especially in the right ventricle of the heart. Viscosimetry and atomic force microscopy of the desmin wild-type and N116S mutant isolated from recombinant Escherichia coli revealed severe impairment of the filament formation, which was supported by transfections in SW13 cells. Thus, the gene coding for desmin appears to be a novel ARVC gene, which should be included in molecular genetic screening of ARVC patients.

Mitral valve repair in patients with end stage cardiomyopathy: who benefits?

OBJECTIVE Patients with end stage cardiomyopathy frequently present with additional severe mitral regurgitation. We analyzed the outcome of mitral valve reconstruction in this high risk patient group. METHODS Sixty-six patients with significant mitral regurgitation and an ejection fraction (EF) below 30% (dilated cardiomyopathy=53, ischemic cardiomyopathy (ICM)=13) were retrospectively evaluated from 07/96 and 02/02. All received annuloplasty ring implantation and additional repair (n=4) if required. Mean follow-up was 28+/-18 months. RESULTS Mitral valve repair (MVR) was technically feasible in all patients. Intraoperative transesophageal echocardiography (TEE) revealed none (n=60) or only trivial (n=6) residual mitral regurgitation. Thirty day mortality was 6.1%. Actuarial survival after 1 and 5 years was 86+/-4 and 66+/-8%, respectively. During follow-up seven patients were transplanted due to lack of clinical improvement after 10+/-7 months (range 1-23). Echocardiography revealed a significant improvement in EF (25+/-10.5% pre-op, 34+/-15% post-op) and a slight decrease in left ventricular end-diastolic diameter (69+/-10 mm pre-op, 67+/-13 mm follow up). Patients were in NYHA functional -class 3 (median) preoperatively and in class 2 at long term-follow-up. Gender, left ventricular enddiastolic diameter, preoperative ejection fraction or type of surgical approach (sternotomy, right lateral minithoracotomy) had no significant influence on patient outcome. Patients with ICM or patients older than 60 years showed an increased risk for clinical events both early post-operatively and at long-term follow-up. CONCLUSION MVR can be performed with low perioperative morbidity and mortality even in patients with advanced heart failure, modifying selection criteria for potential candidates may further improve long term outcome.

Flow cytometric quantitation of calcium-dependent and -independent mitogen-stimulation of T cell functions in whole blood: inhibition by immunosuppressive drugs in vitro

We have optimized assays to measure mitogen-stimulated rat lymphocyte activation in whole blood and have used these assays to quantitate the potencies of immunosuppressive drugs with different mechanisms of action. To define the optimal conditions for measuring T cell functions in whole blood, the effects of different concentrations of mitogens that activate T cells through calcium-dependent and -independent pathways were measured over time. Proliferation was measured by tritium-labeled thymidine ([3H]-TdR) incorporation and by flow cytometric analysis of proliferating cell nuclear antigen (PCNA)/DNA content. Furthermore, we detected the increases in percent expression of cell-surface activation antigens (CD25, CD134, CD71, CD11a and CD54). Concanavalin A (Con A) stimulated maximum lymphocyte proliferation and expression of T cell surface activations by 72-96 h, which was 48 h later than stimulation by phorbol 12-myristate 13-acetate (PMA) plus anti-CD28 monoclonal antibody (mAb) or PMA plus ionomycin (IONO). Addition of sirolimus, tacrolimus, cyclosporine or the active metabolite of leflunomide, A77 1726, to mitogen-stimulated whole blood produced drug concentration-dependent inhibitions of lymphocyte proliferation and expression of cell surface activation antigen expression. From these data, we determined drug potencies (inhibitory concentration of 50%, IC(50)) and drug concentrations causing maximum inhibition of T cell functions (I(max)). We developed simple and reproducible assays to measure different lymphocyte functions in whole blood cultures. These assays were used to investigate the mechanisms of different immunosuppressive drugs. These methods can be exploited to measure T cell functions in blood collected from subjects treated with immunosuppressants in vivo.

Ca2+/Calmodulin-Dependent Protein Kinase II and Protein Kinase A Differentially Regulate Sarcoplasmic Reticulum Ca2+ Leak in Human Cardiac Pathology

Background —Sarcoplasmatic reticulum (SR) Ca2+-leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF). However, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy (Hy) to HF are still controversial. Methods and Results —We investigated healthy control myocardium (NF, n=5) as well as myocardium from patients with compensated Hy (n=25) and HF (n=32). In Hy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylate RyR2 at levels which are not different from NF. Accordingly, inhibitors of these kinases reduce the SR Ca2+-leak. In HF, however, the SR Ca2+-leak is nearly doubled compared to Hy leading to reduced systolic Ca2+-transients, a depletion of SR Ca2+-storage and elevated diastolic Ca2+-levels. This is accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation is not increased in HF and is independent of previous β-blocker treatment. In HF CaMKII inhibition but not inhibition of PKA yields a reduction of the SR Ca2+-leak. Moreover, PKA inhibition further reduces SR Ca2+-load and systolic Ca2+-transients. Conclusions —In human Hy CaMKII as well as PKA functionally regulate RyR2 and may induce SR Ca2+-leak. In the transition from Hy to HF the diastolic Ca2+-leak increases and disturbed Ca2+-cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2-phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.Background— Sarcoplasmic reticulum (SR) Ca2+ leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF); however, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy to HF are still controversial. Methods and Results— We investigated healthy control myocardium (n=5) and myocardium from patients with compensated hypertrophy (n=25) and HF (n=32). In hypertrophy, Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylated RyR2 at levels that were not different from healthy myocardium. Accordingly, inhibitors of these kinases reduced the SR Ca2+ leak. In HF, however, the SR Ca2+ leak was nearly doubled compared with hypertrophy, which led to reduced systolic Ca2+ transients, a depletion of SR Ca2+ storage and elevated diastolic Ca2+ levels. This was accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation was not increased in HF and was independent of previous &bgr;-blocker treatment. In HF, CaMKII inhibition but not inhibition of PKA yielded a reduction of the SR Ca2+ leak. Moreover, PKA inhibition further reduced SR Ca2+ load and systolic Ca2+ transients. Conclusions— In human hypertrophy, both CaMKII and PKA functionally regulate RyR2 and may induce SR Ca2+ leak. In the transition from hypertrophy to HF, the diastolic Ca2+ leak increases and disturbed Ca2+ cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2 phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.