Molecular characterization of signalling complexes involved in G-protein coupled receptor-induced cardiac hypertrophy

In response to pathological stresses, the heart undergoes a remodelling process associated with cardiac hypertrophy. Since sustained hypertrophy can progress to heart failure, there is an intense investigation about the intracellular signalling pathways that control cardiomyocyte growth. Accumulating evidence has demonstrated that most stimuli known to initiate pathological changes associated with the development of cardiac hypertrophy activate G protein-coupled receptors (GPCRs) including the αl-adrenergic- (αl-AR), Angiotensin II- (AT-R) and endothelin-1- (ET-R) receptors. In this context, we have previously identified a cardiac scaffolding protein, called AKAP-Lbc (Α-kinase anchoring protein), with an intrinsic Rho specific guanine nucleotide exchange factor activity, that plays a key role in integrating and transducing hypertrophic signals initiated by these GPCRs (Appert-Collin, Cotecchia et al. 2007). Activated RhoA controls the transcriptional activation of genes involved in cardiomyocyte hypertrophy through signalling pathways that remain to be characterized. Here, we identified the nuclear factor-Kappa Β (NF-κΒ) activating kinase ΙΚΚβ as a novel AKAP-Lbc interacting protein. This raises the hypothesis that AKAP-Lbc might promote cardiomyocyte growth by maintaining a signalling complex that promotes the activation of the pro-hypertrophic transcription factor NF-κΒ. In fact, the activation of NF- κΒ-dependent transcription has been detected in numerous disease contexts, including hypertrophy, ischemia/reperfusion injury, myocardial infarction, allograft rejection, myocarditis, apoptosis, and more (Hall, Hasday et al. 2006). While it is known by more than a decade that NF-κΒ is a critical mediator of cardiac hypertrophy, it is currently poorly understood how pro-hypertrophic signals controlling NF-κΒ transcriptional activity are integrated and coordinated within cardiomyocytes. In this study, we show that AKAP-Lbc and ΙΚΚβ form a transduction complex in cardiomyocytes that couples activation of αl-ARs to NF-κB-mediated transcriptional reprogramming events associated with cardiomyocyte hypertrophy. In particular, we can show that activation of ΙΚΚβ within the AKAP-Lbc complex promotes NF-κB-dependent production of interleukine-6 (IL-6), which, in turn, enhances foetal gene expression. These findings indicate that the AKAP-Lbc/ΙΚΚβ complex is critical for selectively directing catecholamine signals to the induction of cardiomyocyte hypertrophy.

Urological surgery and antiplatelet drugs after cardiac and cerebrovascular accidents.

PURPOSE: The perioperative treatment of patients on dual antiplatelet therapy after myocardial infarction, cerebrovascular event or coronary stent implantation represents an increasingly frequent issue for urologists and anesthesiologists. We assess the current scientific evidence and propose strategies concerning treatment of these patients. MATERIALS AND METHODS: A MEDLINE and PubMed search was conducted for articles related to antiplatelet therapy after myocardial infarction, coronary stents and cerebrovascular events, as well as the use of aspirin and/or clopidogrel in the context of surgery. RESULTS: Early discontinuation of antiplatelet therapy for secondary prevention is associated with a high risk of coronary thrombosis, which is further increased by the hypercoagulable state induced by surgery. Aspirin has recently been recommended as a lifelong therapy. Clopidogrel is mandatory for 6 weeks after myocardial infarction and bare metal stents, and for 12 months after drug-eluting stents. Surgery must be postponed beyond these waiting periods or performed with patients receiving dual antiplatelet therapy because withdrawal therapy increases 5 to 10 times the risk of postoperative myocardial infarction, stent thrombosis or death. The shorter the waiting period between revascularization and surgery the greater the risk of adverse cardiac events. The risk of surgical hemorrhage is increased approximately 20% by aspirin and 50% by clopidogrel. CONCLUSIONS: The risk of coronary thrombosis when antiplatelet agents are withdrawn before surgery is generally higher than the risk of surgical hemorrhage when antiplatelet agents are maintained. However, this issue has not yet been sufficiently evaluated in urological patients and in many instances during urological surgery the risk of bleeding can be dangerous. A thorough dialogue among surgeon, cardiologist and anesthesiologist is essential to determine all risk factors and define the best possible strategy for each patient.

Role of innate immunity in cardiac inflammation after myocardial infarction.

Over the past two decades, inflammation has emerged as a key pathophysiological process during myocardial infarction. It develops consecutively to the activation of innate immune defense mechanisms, in response to the release of endogenous molecules by necrotic cells and the extracellular matrix. These danger signals are sensed by cellular receptors normally involved in antimicrobial defenses, including toll-like receptors and a subset of NOD-like receptors, which promote intracellular signaling dependent on nuclear factor kappaB and on the formation of the inflammasome. These mechanisms stimulate the expression of multiple inflammatory mediators and growth factors, sequentially inducing the recruitment of inflammatory cells, the clearance of injured tissue, angiogenesis, and the proliferation of fibroblasts, eventually resulting in scar formation and infarct healing. Dysregulation of these responses may result in continued cardiomyocyte loss, fibrosis beyond the limits of the infarcted area, reactive hypertrophy and chamber dilatation, a process termed adverse cardiac remodeling, leading to functional compromise and heart failure. This review presents the current state of knowledge on the process of immune activation within the infarcted myocardium and its consequences.

Increased blood glucose variability during therapeutic hypothermia and neurological recovery after cardiac arrest

INTRODUCTION. Recent studies suggest that increased blood glucose variability (BGV) is associated with ICU mortality1. Hypothermia is known to induce insulin resistance, thus potentially increasing BGV. No studies however have examined the effect of therapeutic hypothermia (TH) on insulin requirements and BGV. OBJECTIVES. To examine the effect of TH on BGV and its relationship to outcome in patients with coma after cardiac arrest (CA). METHODS. We prospectively studied 132 consecutive comatose CA patients treated with TH (target core temp 33_C for 24 h, using surface cooling). All patients were treated with intravenous insulin (blood glucose target 6-8 mM), according to a written algorithm, with nurse-driven adjustment of insulin dose. For each patient, standard deviation of repeated blood glucose samples was used to calculate BGV. Two time-points, comparable in duration, were studied: TH (stable maintenance phase, i.e. 6-24 h, core temp ± 33_C) vs. Normothermia (NT, i.e. after rewarming, stable normothermic phase, core temp ± 37_C). Mortality and neurological recovery (Glasgow-Pittsburgh Cerebral Performance Categories, CPC, dichotomized as good = CPC 1-2 vs. poor = CPC 3-5) were assessed at hospital discharge. Statistical analysis was performed with ANOVA for repeated measures. RESULTS. Compared to NT, TH was associated with increased intravenous insulin dose (0.8 ± 1.1 vs. 1.6 ± 2 U/h, P\0.0001), higher mean (6.9 ± 1.3 vs. 7.7 ± 1.8 mM, P\0.0001) and maximum (9.1 ± 3.7 vs. 10.9 ± 3.6 mM, P\0.0001) blood glucose, and increased BGV (1.3 ± 1.2 vs. 1.7 ± 1.1 mM, P = 0.004). Increased BGV was strongly associated with mortality (2.5 ± 1.5 mM in non-survivors vs. 1.6 ± 1 mM in survivors, P\0.001) and worse outcome (2.3 ± 1.4 mM in patients with poor vs. 1.5 ± 0.8 mM in those with good neurological recovery, P\0.0001). CONCLUSIONS. Therapeutic hypothermia is associated with increased insulin requirements and higher blood glucose variability,which in turn correlateswithworse prognosis in patientswith post- CA coma. Strategies aimed to maintain stable glycemic profile and avoid blood glucose variability might contribute to optimize the management of TH and may translate into better outcome.

L'autopsie moléculaire de la mort subite cardiaque: de la salle d'autopsie au cabinet du praticien [Molecular autopsy of sudden cardiac death: from postmortem to clinical approach]

Sudden cardiac death is one of the most prevalent cause of death in developed countries. Its aetiology varies according to the age. Some cardiac diseases may explain sudden death with minimal or no anatomic findings. However, many cardiac diseases, as for example channelopathies and hypertrophic cardiomyopathy have a genetic basis. Therefore genetic analyses (molecular autopsy) are becoming a useful tool in forensic medicine to identify the cause of sudden cardiac death and to improve the early diagnosis of asymptomatic carriers among relatives.

Endothelial dependant coronary vasoreactivity measured by 82Rb cardiac PET in obstructive sleep apnea patients before and after CPAP treatment

Introduction: Obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular diseases. Endothelial dysfunction is believed to be one of the pathophysiological mechanism underlying this association. Our aim was to compare endothelial dependent coronary vasoreactivity in obstructive sleep apnea (OSA) patients and controls by quantifying myocardial blood flow (MBF) response to cold pressure testing (CPT) with 82Rb cardiac PET/CT. Methods: Twenty-four OSA patients (2W/22M, mean age 58 yo, mean BMI 28.6 kg/m2) with an apnea-hypopnea index (AHI) >30/h and 9 healthy volunteers (AHI <10/h) underwent a full night sleep recording (PSG) and a dynamic 82 Rb cardiac PET/CT scan at rest, during CPT and adenosine stress. In OSA patients the same measurements (PSG and PET/CT) were respeated 6 weeks after initiating continuous positive airway pressure (autoCPAP) treatment. To reflect differences in baseline cardiac work, values were normalized according to ratepressure product (RPP). Results: At baseline, untreated OSA patients had a mean AHI of 48.8/h and showed a lower MBF response to CPT than controls (1.1 ± 0.2 mL/min/g vs. 1.3 ± 0.4 mL/min/g, P = 0.048). When treated with CPAP, CPT-MBF was not different between controls and well-treated OSA patients (1.2 ± 0.3 mL/min/g vs 1.3 ± 0.4 mL/min/g, P = 0.68), but it was significantly lower for insufficiently treated patients (n = 10) with a residual AHI >10/h (0.9 ± 0.2 mL/min/g vs 1.3 ± 0.4 mL/min/g, P = 0.03). There was also a trend toward a difference in CPT-MBF between insufficiently and well-treated OSA patients (1.2 ± 0.3 mL/min/g vs 0.9 ± 0.2 mL/min/g, P = 0.15). Conclusion: Untreated OSA patients have an impaired coronary endothelial function as measured by MBF response to CPT compared to control subjects. This difference disappears after 6 weeks of autoCPAP therapy but only in OSA patients showing a good response to CPAP (AHI <10/h). Further studies are needed to determine by which mechanism OSA and CPAP treatment influence coronary vasoreactivity.

From diabetes to heart disease : studies on dyslipidemia-induced B-cell dysfunction, immunomodulation in heart transplantation, and cardiac stem cell therapy

Diabetes is a growing epidemic with devastating human, social and economic impact. It is associated with significant changes in plasma concentrations of lipoproteins. We tested the hypothesis that lipoproteins modulate the function and survival of insulin-secreting cells. We first detected the presence of several receptors that participate in the binding and processing of plasma lipoproteins and confirmed the internalization of fluorescent LDL and HDL particles in insulin-secreting β-cells. Purified human VLDL and LDL particles reduced insulin mRNA levels and β-cell proliferation, and induced a dose-dependent increase in the rate of apoptosis. In mice lacking the LDL receptor, islets showed a dramatic decrease in LDL uptake and were partially resistant to apoptosis caused by LDL. VLDL-induced apoptosis of β-cells involved caspase-3 cleavage and reduction in levels of the c-Jun N-terminal (JNK) Interacting Protein-1 (IB1/JIP-1). In contrast, the pro-apoptotic signaling of lipoproteins was antagonized by HDL particles or by a small peptide inhibitor of JNK. The protective effects of HDL were mediated, in part, by inhibition of caspase-3 cleavage and activation of the protein kinase Akt/PKB. Heart disease is a major cause of morbidity and mortality among patients with diabetes. When heart failure is refractory to medical therapy and cannot be improved by electrical resynchronization, percutaneous angioplasty or coronary graft bypass surgery, heart transplantation remains a "last resort" therapy. Nevertheless, it is limited by the side effects of immunosuppressive drugs and chronic rejection. Localized expression of immunomodulatory genes in the donor organ can create a state of immune privilege within the graft, and was performed in rodent hearts by infecting cells with an adenovirus encoding indoleamine 2,3-dioxygenase (IDO), the rate-limiting enzyme in the catabolism of tryptophane. Other strategies are based on genetic manipulation of dendritic cells (DCs) with immunosuppressive genes and in vitro exposure of DCs to agents that prevent their maturation by inflammatory cytokines. Finally, we used 5-bromo-2'-deoxyuridine, which is incorporated into DNA and diluted with cell division, to identify long-term label retaining cells in the adult rodent heart. The majority of these cells were positive for the stem cell antigen-1 (Sca-1) and negative for the endothelial precursor marker CD31. They formed cardiospheres in vitro and showed differentiation potential into mesenchymal cell lineages. When cultured in cardiomyogenic differentiation medium, they expressed cardiac-specific genes. Taken together, these data provide evidence of slow-cycling stem cells in the rodent heart. Chronic shortage of donor organs opens the way to cardiac stem cell therapy in humans, although the long way from animal experimentation to routine therapy in patients may still take several years. - Du diabète de type 2 à la maladie coronarienne : trois études sur les dysfonctions de la cellule sécrétrice d'insuline induites par les dyslipidémies, l'immunomodulation dans la transplantation cardiaque, et la thérapie par des cellules souches myocardiques. Le diabète de type 2 a pris les dimensions d'une épidémie, avec des conséquences sociales et économiques dont nous n'avons pas encore pris toute la mesure. La maladie s'accompagne souvent d'une dyslipidémie caractérisée par une hypertriglycéridémie, des taux abaissés de cholestérol HDL, et des concentrations de cholestérol LDL à la limite supérieure de ce qui est considéré comme acceptable. L'hypothèse à la base de cette étude est qu'une modification des taux plasmatiques de lipoprotéines pourrait avoir une influence directe sur la cellule β sécrétrice d'insuline en modifiant sa fonction, sa durée de vie et son taux de régénération. Dans un premier temps, nous avons mis en évidence, sur la cellule β, la présence de plusieurs récepteurs impliqués dans la captation des lipoprotéines. Nous avons confirmé la fonctionnalité de ces récepteurs en suivant l'internalisation de LDL et de HDL marqués. En présence de VLDL ou de LDL humains, nous avons observé une diminution de la transcription du gène de l'insuline, une prolifération cellulaire réduite, et une augmentation de l'apoptose, toutes fonctions de la dose et du temps d'exposition. L'apoptose induite par les VLDL passe par une activation de la caspase-3 et une réduction du taux de la protéine IB1/JIP-1 (Islet Brain1/JNK Interacting Protein 1), dont une mutation est associée à une forme monogénique de diabète de type 2. Par opposition, les HDL, ainsi que des peptides inhibiteurs de JNK, sont capables de contrer la cascade pro-apoptotique déclenchée, respectivement, par les LDL et les VLDL. Ces effets protecteurs comprennent l'inhibition du clivage de la caspase-3 et l'activation de la protéine kinase Akt/PKB. En conclusion, les lipoprotéines sont des éléments clés de la survie de la cellule β, et pourraient contribuer au dysfonctionnement observé dans le pancréas endocrine au cours du développement du diabète. La maladie cardiaque, et plus particulièrement la maladie coronarienne, est une cause majeure de morbidité et de mortalité chez les patients atteints de diabète. Plusieurs stratégies sont utilisées quotidiennement pour pallier les atteintes cardiaques: traitements médicamenteux, électromécaniques par resynchronisation électrique, ou communément appelés « interventionnels » lorsqu'ils font appel à l'angioplastie percutanée. La revascularisation du myocarde par des pontages coronariens donne également de très bons résultats dans certaines situations. Il existe toutefois des cas où plus aucune de ces approches n'est suffisante. La transplantation cardiaque est alors la thérapie de choix pour un nombre restreint de patients. La thérapie génique, en permettant l'expression locale de gènes immunomodulateurs dans l'organe greffé, permet de diminuer les réactions de rejet inhérentes à toute transplantation (à l'exception de celles réalisées entre deux jumeaux homozygotes). Nous avons appliqué chez des rongeurs cette stratégie en infectant le coeur greffé avec un adénovirus codant pour l'enzyme indoleamine 2,3-dioxygénase (IDO), une enzyme clé dans le catabolisme du tryptophane. Nous avons procédé de manière identique in vitro en surexprimant IDO dans les cellules dendritiques, dont le rôle est de présenter les antigènes aux lymphocytes Τ du receveur. Des expériences similaires ont été réalisées en traitant les cellules dendritiques avec des substances capables de prévenir, en partie du moins, leur maturation par des agents pro-inflammatoires. Finalement, nous avons exploré une stratégie utilisée couramment en hématologie, mais qui n'en est encore qu'à ses débuts au niveau cardiaque : la thérapie par des cellules souches. En traitant des rongeurs avec un marqueur qui s'incorpore dans l'ADN nucléaire, le 5-bromo- 2'-deoxyuridine, nous avons identifié une population cellulaire se divisant rarement, positive en grande partie pour l'antigène embryonnaire Sca-1 et négative pour le marqueur endothélial CD31. En culture, ces cellules forment des cardiosphères et sont capables de se différencier dans les principaux types tissulaires mésenchymateux. Dans un milieu de differentiation adéquat, ces cellules expriment des gènes cardiomyocytaires. En résumé, ces données confirment la présence chez le rongeur d'une population résidente de précurseurs myocardiques. En addenda, on trouvera deux publications relatives à la cellule β productrice d'insuline. Le premier article démontre le rôle essentiel joué par la complexine dans l'insulino-sécrétion, tandis que le second souligne l'importance de la protéine IB1/JIP-1 dans la protection contre l'apoptose de la cellule β induite par certaines cytokines.

Controlled contrast transcranial Doppler and arterial blood gas analysis to quantify shunt through patent foramen ovale.

BACKGROUND AND PURPOSE: A right-to-left shunt can be identified by contrast transcranial Doppler ultrasonography (c-TCD) at rest and/or after a Valsalva maneuver (VM) or by arterial blood gas (ABG) measurement. We assessed the influence of controlled strain pressures and durations during VM on the right-to-left passage of microbubbles, on which depends the shunt classification by c-TCD, and correlated it with the right-to-left shunt evaluation by ABG measurements in stroke patients with patent foramen ovale (PFO). METHODS: We evaluated 40 stroke patients with transesophageal echocardiography-documented PFO. The microbubbles were recorded with TCD at rest and after 4 different VM conditions with controlled duration and target strain pressures (duration in seconds and pressure in cm H2O, respectively): V5-20, V10-20, V5-40, and V10-40. The ABG analysis was performed after pure oxygen breathing in 34 patients, and the shunt was calculated as percentage of cardiac output. RESULTS: Among all VM conditions, V5-40 and V10-40 yielded the greatest median number of microbubbles (84 and 95, respectively; P&lt;0.01). A significantly larger number of microbubbles were detected in V5-40 than in V5-20 (P&lt;0.001) and in V10-40 than in V10-20 (P&lt;0.01). ABG was not sensitive enough to detect a shunt in 31 patients. CONCLUSIONS: The increase of VM expiratory pressure magnifies the number of microbubbles irrespective of the strain duration. Because the right-to-left shunt classification in PFO is based on the number of microbubbles, a controlled VM pressure is advised for a reproducible shunt assessment. The ABG measurement is not sensitive enough for shunt assessment in stroke patients with PFO.

Hypertension differentially affects the expression of the gap junction protein connexin43 in cardiac myocytes and aortic smooth muscle cells.

Electrical and mechanical coupling of myocytes in heart and of smooth muscle cells in the aortic wall is thought to be mediated by intercellular channels aggregated at gap junctions. Connexin43 (Cx43) is one of the predominant membrane proteins forming junctional channels in the cardiovascular system. This study was undertaken to assess its expression during experimental hypertension. Rats were made hypertensive by clipping one renal artery (two-kidney, one-clip renal hypertension) or by administering deoxycorticosterone and salt (DOCA-salt hypertension). After four weeks, rats from both models showed a similar increase in intra-arterial mean blood pressure, as well as in the thickness of both aorta and heart walls. Northern blot analysis showed that, compared to controls, hypertensive rats expressed twice more Cx43 in aorta, but not in heart. These results suggest that localized mechanical forces induced by hypertension are major tissue-specific regulators of Cx43 expression.

Experience and intermediate-term results using the Contegra heterograft for right ventricular outflow reconstruction in adults.

OBJECTIVES: The Contegra bioprosthesis (valved heterologous bovine jugular vein) is used for reconstruction of the right ventricular outflow tract (RVOT) in congenital heart malformations and pulmonary valve replacement in different settings. Compared to pulmonary homografts, the Contegra conduit is readily available 'on the shelf'. So far, its use was mainly described in children. The aim of this study is to evaluate the feasibility and the outcome of Contegra graft implantation in the adult. METHODS: Between November 1999 and December 2007, a total of 32 Contegra grafts were implanted in 31 patients (24 men and 7 women), with a mean age of 35.7+/-10.5 years (range 18-54 years). All operations have been completed through median sternotomy with cardiopulmonary bypass. Indications included: Ross procedure for aortic valve disease (n=22); re-operation of corrected Fallot-tetralogy (n=5); isolated pulmonary valve disease (n=2); re-operation of double outlet right ventricle (DORV) (n=1); pulmonary stenosis in congenital dilated cardiomyopathy (DCM) (n=1). Conduit sizes included 22 mm (n=31), 20 mm (n=1). RESULTS: There was no hospital mortality and no valved conduit related early morbidity. In the median follow-up of 38 months (range 1-99 months) of 28 patients there was one late death, not conduit related (total mortality 3.6%). Re-operation for symptomatic graft stenosis was realised in two patients, 7 and 16 months after primo-implantation, corresponding to graft related late morbidity of 7.1%. CONCLUSIONS: In this small review of 32 operations using the Contegra graft for RVOT reconstruction in adult cardiac surgery for different indications, we observed good postoperative mid-term results concerning conduit function. Mean transpulmonary pressure gradients remain low (13.3+/-6.6 mmHg postoperative, 14.5+/-7.9 mmHg at follow-up). The use of the Contegra graft seems to be a good alternative to the homograft with low operative mortality and morbidity. Long-term outcome data are not available and further investigations must be performed to evaluate results.

Incremental Prognostic Value of Myocardial Blood Flow Quantification with Rb-82 Cardiac PET in Patients With Known or Suspected CAD

Rb-82cardiac PET has been used to non-invasively assess myocardial blood flow (MBF)and myocardial flow reserve (MFR). The impact of MBF and MFR for predictingmajor adverse cardiovascular events (MACE) has not been investigated in aprospective study, which was our aim. MATERIAL AND METHODS: In total, 280patients (65±10y, 36% women) with known or suspected CAD were prospectivelyenrolled. They all underwent both a rest and adenosine stress Rb-82 cardiacPET/CT. Dynamic acquisitions were processed with the FlowQuant 2.1.3 softwareand analyzed semi-quantitatively (SSS, SDS) and quantitatively (MBF, MFR) andreported using the 17-segment AHA model. Patients were stratified based on SDS,stress MBF and MFR and allocated into tertiles. For each group, annualizedevent rates were computed by dividing the number of annualized MACE (cardiacdeath, myocardial infarction, revascularisation or hospitalisation forcardiac-related event) by the sum of individual follow-up periods in years.Outcome were analysed for each group using Kaplan-Meier event-free survivalcurves and compared using the log-rank test. Multivariate analysis wasperformed in a stepwise fashion using Cox proportional hazards regressionmodels (p<0.05 for model inclusion). RESULTS: In a median follow-up of 256days (range 168-440d), 44 MACE were observed. Ischemia (SDS≥2) was observed in95 patients who had higher annualized MACE rate as compared to those without(55% vs. 9.8%, p<0.0001). The group with the lowest MFR tertile (MFR<1.76)had higher MACE rate than the two highest tertiles (51% vs. 9% and 14%,p<0.0001). Similarly, the group with the lowest stress MBF tertile(MBF<1.78mL/min/g) had the highest annualized MACE rate (41% vs. 26% and 6%,p=0.0002). On multivariate analysis, the addition of MFR or stress MBF to SDSsignificantly increased the global χ2 (from 56 to 60, p=0.04; and from56 to 63, p=0.01). The best prognostic power was obtained in a model combiningSDS (p<0.001) and stress MBF (p=0.01). Interestingly, the integration ofstress MBF enhanced risk stratification even in absence of ischemia.CONCLUSIONS: Quantification of MBF or MFR in Rb-82 cardiac PET/CT providesindependent and incremental prognostic information over semi-quantitativeassessment with SDS and is of value for risk stratification.

Towards no-scar cardiac surgery - minimally invasive access through umbilicus for aortic valve replacement.

There is an ever-growing trend towards less-invasive procedures in all fields of medicine. We designed an animal study to prove the concept that trans-apical aortic valve replacement from an incision within the umbilicus through a single channel for instruments is feasible, which would be a major leap towards no-scar cardiac surgery. In three adult pigs, after creating a single 3-cm incision at a place where the human umbilicus would be, we introduced a 30F sheath through a tunnel created by an endoscopic vein-harvesting device up to the cardiac apex, through it and up to the left ventricle simulating the approach for trans-apical aortic valve replacement. We used a standard Amplatz nitinol occluder to seal the defect in ventricle wall later. The animals were followed up for 1h. Blood loss was minimal, and no tamponade occurred in any of the animals. In addition, we performed a test with water column static pressure to evaluate the impact of preclotting on the sealing properties of the occluders: 1 min flow-through was 2860+/-176 ml for the standard occluders and 348+/-56 ml for preclotted occluders (p<0.001).

Alloimmunity and nonimmunologic risk factors in cardiac allograft vasculopathy.

Graft vasculopathy is an accelerated form of coronary artery disease that occurs in transplanted hearts. Despite major advances in immunosuppression, the prevalence of the disease has remained substantially unchanged during the last two decades. According to the 'response to injury' paradigm, graft vasculopathy is the result of a continuous inflammatory response to tissue injury initiated by both alloantigen-dependent and independent stress responses. Experimental evidence suggests that these responses may become self-sustaining, as allograft re-transplantation into the donor strain at a later stage fails to prevent disease progression. Histological evidence of endothelitis and arteritis, in association with intima fibrosis and atherosclerosis, reflects the central role of alloimmunity and inflammation in the development of arterial lesions. Experimental results in gene-targeted mouse models indicate that cellular and humoral immune responses are both involved in the pathogenesis of graft vasculopathy. Circulating antibodies against donor endothelium are found in a significant number of patients, but their pathogenic role is still controversial. Alloantigen-independent factors include donor-transmitted coronary artery disease, surgical trauma, ischaemia-reperfusion injury, viral infections, hyperlipidaemia, hypertension, and glucose intolerance. Recent therapeutic advances include the use of novel immunosuppressive agents such as sirolimus (rapamycin), HMG-CoA reductase inhibitors, calcium channel blockers, and angiotensin converting enzyme inhibitors. Optimal treatment of cardiovascular risk factors remains of paramount importance.