Bronchial artery revascularization restores peribronchial tissue oxygenation after lung transplantation

With the interruption of the bronchial arteries after lung transplantation, nutritive support is dependent on collateral flow by the pulmonary arteries with desaturated venous blood. Consequently, oxygen deficiency of the peribronchial and dependent lung tissue may occur. Using a canine model for left lung transplantation, we investigated hypoxic peribronchial tissue after conventional lung transplantation and demonstrated restitution of tissue oxygenation after transplantation with bronchial artery revascularization (BAR) (BAR group: Po2 120.4 +/- 28.7 mm Hg; control group Po2 6.8 +/- 2.8; p < 0.001). BAR in lung transplantation protects peribronchial tissue of the transplanted graft from hypoxia in the early phase after reperfusion.

Inflammatory regulation of extracellular matrix remodeling in calcific aortic valve stenosis

BACKGROUND

Calcific aortic stenosis (AS), the most frequent heart valve disorder in developed countries, leads to the calcification and fibrous thickening of the valve. While several studies have addressed the process of valvular calcification, the molecular pathomechanisms of the extensive matrix remodeling remain unclear. Because inflammation is present in stenotic valves, we hypothesized that the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) might influence cell proliferation and regulate the expression and activation of matrix metalloproteinases (MMPs)--enzymes that are thought to be involved in calcific AS.

METHODS

Immunohistochemistry for leukocytes, TNFalpha, MMP-1, and the endogenous MMP inhibitor tissue inhibitor of metalloproteinase (TIMP)-1 was performed on human stenotic (n = 19) and control (n = 8) valves. Primary cultures of human aortic valve myofibroblasts were incubated with and without TNFalpha, and cell proliferation was assessed. The expression and activation of MMP-1 were detected by Western blotting and a specific MMP-1 activity assay.

RESULTS

Control valves showed scattered macrophages and low expression of TNFalpha, MMP-1, and TIMP-1. In stenotic valves, leukocyte infiltration and a strong, colocalized expression of TNFalpha and MMP-1 were present, while TIMP-1 remained unchanged. Double-label immunofluorescence localized TNFalpha mainly to macrophages. In cultured human aortic valve myofibroblasts, TNFalpha stimulated proliferation and induced a time-dependent increase in MMP-1 expression and activation, while TIMP-1 remained unchanged.

CONCLUSION

The results indicate that matrix remodeling in calcific AS involves the expression and activation of MMPs. Activated leukocytes, by the secretion of TNFalpha, may stimulate valvular myofibroblasts to proliferate and express MMPs, thus regulating actively the matrix remodeling in calcific AS.

Influence of receptor activator of nuclear factor kappa B on human aortic valve myofibroblasts

Calcific aortic valve stenosis, the main heart valve disease in the elderly, is based on progressive calcification and fibrous thickening of the valve. Several reports addressed the pathogenesis of tissue calcification in this disorder, but few data exist on the molecular mechanisms of the fibrosis and remodeling of the extracellular matrix. The cytokine "receptor activator of nuclear factor kappa B ligand" (RANKL), is expressed in stenotic aortic valves and involved in valvular calcification during calcific aortic valve stenosis. The present study aimed to assess the influence of RANKL on the molecular mechanisms of connective tissue remodeling. In an established cell culture model of primary human aortic valve myofibroblasts, stimulation with RANKL increased cell proliferation as compared to medium alone. Matrix metalloproteinase (MMP)-1 was detectable time-dependently in conditioned media from RANKL-stimulated cells, but absent in media from control cells. MMP-1 activity was increased by RANKL, as measured by collagenase activity assay. Zymography showed an increase in active MMP-2 in RANKL-stimulated cells. These results support the concept that MMPs are involved in the connective tissue remodeling during calcific aortic valve stenosis. RANKL might regulate this process by promoting cell proliferation and MMP expression and activation.

Increased aortic wall stress in aortic insufficiency: clinical data and computer model☆

OBJECTIVE

The study was aimed at determining which cardiac pathologies are associated with increased longitudinal stress in the aorta and therefore may be responsible for the intimal transverse tears seen in aortic dissections.

METHODS

Aortic root contrast injections were analyzed in 90 cardiac patients to measure the downward motion of the annulus during a cardiac cycle. A finite element model of the pressurized aortic root, arch and supra-aortic vessels was created to assess the influence of the aortic root motion on the aortic wall stress.

RESULTS

The axial displacement of the aortic root ranged from 0 to 14 mm. A multivariate analysis showed that aortic insufficiency (AI) grade, hypokinesis of the left ventricle (HKI), and myocardial hypertrophy (HTR) were 3 independent variables which correlated with the axial displacement of the aortic root (DISP), such that ARM (mm)=5.379 (P<0.0001) +1.186 x AI grade (P=0.0016) - 1.611 x HKI (P=0.0078) - 1.399 x HTR (P=0.0355) with R2=0.23. The major finding of the stress analysis was that in the ascending aorta, at approximately 2 cm above the sino-tubular junction, the longitudinal stress due to aortic root motion was 32% higher in patients with AI than in patients without AI, thereby increasing the risk of transverse intimal rupture.

CONCLUSIONS

Cardiac patients with AI are likely to experience enhanced longitudinal stress in the ascending aorta due to increased aortic root motion. Thus, these patients should be targeted and their aortic root movement monitored because it may be an important risk factor for aortic dissection.

Poly(ADP-ribose) polymerase inhibitor PJ-34 reduces mesenteric vascular injury induced by experimental cardiopulmonary bypass with cardiac arrest

The aim of this study was to investigate effects of poly(ADP-ribose) polymerase (PARP) inhibition on mesenteric vascular function and metabolism in an experimental model of cardiopulmonary bypass (CPB) with cardiac arrest. Twelve anesthetized dogs underwent 90-min hypothermic CPB. After 60 min of cardiac arrest, reperfusion was started for 40 min following application of either saline vehicle (control, n = 6) or a potent PARP inhibitor, PJ-34 (10 mg/kg iv bolus and 0.5 mg.kg(-1).min(-1) infusion for 20 min, n = 6). PJ-34 led to better recovery of cardiac output (2.2 +/- 0.1 vs. 1.8 +/- 0.2 l/min in control) and mesenteric blood flow (175 +/- 38 vs. 83 +/- 4 ml/min, P < 0.05 vs. control) after reperfusion. The impaired vasodilator response of the superior mesenteric artery to acetylcholine, assessed in the control group after CPB (-32.8 +/- 3.3 vs. -57.6 +/- 6.6% at baseline, P < 0.05), was improved by PJ-34 (-50.3 +/- 3.6 vs. -54.3 +/- 4.1% at baseline, P < 0.05 vs. control). Although plasma nitrate/nitrite concentrations were not significantly different between groups, mesenteric nitric oxide synthase activity was increased in the PJ-34 group (P < 0.05). Moreover, the treated group showed a marked attenuation of mesenteric venous plasma myeloperoxidase levels after CPB compared with the control group (75 +/- 1 vs. 135 +/- 9 ng/ml, P < 0.05). Pharmacological PARP inhibition protects against development of post-CPB mesenteric vascular dysfunction by improving hemodynamics, restoring nitric oxide production, and reducing neutrophil adhesion.

Mesenteric injury after cardiopulmonary bypass: Role of poly(adenosine 5′-diphosphate-ribose) polymerase*

OBJECTIVES

To investigate the effects of the ultrapotent poly(adenosine 5'-diphosphate-ribose) polymerase (PARP) inhibitor INO-1001 on cardiac and mesenteric function during reperfusion in an experimental model of cardiopulmonary bypass with cardioplegic arrest.

DESIGN

Prospective, randomized, and blinded experimental study.

SETTING

Research laboratory.

SUBJECTS

: Twelve anesthetized dogs underwent cardiopulmonary bypass with hypothermic cardioplegic cardiac arrest.

INTERVENTIONS

After 60 mins of hypothermic cardiac arrest, either PARP inhibitor INO-1001 (1 mg/kg, n = 6) or vehicle (control, n = 6) was administered during reperfusion.

MEASUREMENTS AND MAIN RESULTS

Left ventricular hemodynamic variables were measured by combined pressure-volume-conductance catheters. Coronary and mesenteric blood flow and vasodilatory responses to acetylcholine and sodium nitroprusside as well as mesenteric lactate and creatinine phosphokinase release were also determined. The administration of INO-1001 led to a significantly improved recovery of left ventricular systolic function (p < .05) after 60 mins of reperfusion. Coronary and mesenteric blood flow were also significantly higher in the INO-1001 group (p < .05). Although the vasodilatory response to sodium nitroprusside was similar in both groups before and after cardiopulmonary bypass and similar in response to acetylcholine before cardiopulmonary bypass, PARP-inhibited dogs had lower mesenteric vascular resistance after cardiopulmonary bypass (p < .05). Mesenteric lactate and creatinine phosphokinase release was significantly lower in the PARP inhibitor treated group (p < .05).

CONCLUSION

PARP inhibition with INO-1001 improves the recovery of myocardial function and prevents mesenteric vascular dysfunction and tissue injury after cardiopulmonary bypass with hypothermic cardiac arrest.

A new computer model of mitral valve hemodynamics during ventricular filling

OBJECTIVE

Quantitative description of left ventricular diastolic filling and mitral valve function remains difficult despite advances in echocardiography. The purpose of the present study was to develop a lumped parameter model of left ventricular filling and validate it in porcine trials under physiological conditions and after valve replacement.

METHODS

Six animals were instrumented with aortic flow meter, left atrial pressure catheter and combined left ventricular pressure-conductance catheter. The model simulates ventricular and arterial pressures and flows during diastolic filling. Input parameters include maximum mitral valve area, blood viscosity and density, atrial compliance, left ventricular active relaxation characteristics and initial pressure and flow values. The outputs of the model are atrial and ventricular pressure as well as transmitral flow as a function of time. The model primarily consists of a system of four first-order, non-linear ordinary differential equations which were solved with MATLAB software.

RESULTS

Left atrial and ventricular pressure data and model flow curves were nearly identical under baseline conditions, during rapid preload reduction by vena caval occlusion and after prosthetic valve replacement. Measured and model based calculation of early diastolic filling volume (E-wave), showed an excellent correlation under all three conditions (r = 0.998, P < 0.0001; r = 0.997, P < 0.0001; r = 0.974, P < 0.0001, respectively) with a mean difference less then two percent.

CONCLUSION

The new lumped parameter model of left ventricular filling allows for the first time a detailed simulation of pressure and flow curves in the left heart including transmitral hemodynamics.

A Case of Pulmonary Artery Sling Associated With Long-Segment Funnel Trachea and Bronchus Suis

An infant with pulmonary sling syndrome associated with an abnormal branching of the trachea, bronchus suis, complicated by long segment intrathoracic tracheal stenosis (ie, "funnel trachea") and concomitant tracheomalacia underwent reoperation at 5 months of age. We review the anatomy of this rare entity and describe the surgical technique to avoid the residual stenosis.

INO-1001 a novel poly(ADP-ribose) polymerase (PARP) inhibitor improves cardiac and pulmonary function after crystalloid cardioplegia and extracorporal circulation

Poly(ADP-ribose) polymerase (PARP) activation plays a key role in free radical-induced injury in the context of systemic inflammation and ischemia/reperfusion. In the present preclinical study, we investigated the effects of INO-1001, a novel PARP inhibitor, on cardiac and pulmonary function during reperfusion in an experimental model of cardioplegic arrest and extracorporal circulation. Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 min of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6), or INO-1001 (1 mg/kg), a potent PARP inhibitor (n = 6). Biventricular hemodynamic variables were measured by combined pressure-volume-conductance catheters. Coronary and pulmonary blood flow and vasodilative responses to acetylcholine and sodium nitroprusside as well as pulmonary gas exchange were also determined. The administration of INO-1001 led to a significantly better recovery of left and right ventricular systolic function (P < 0.05) after 60 min of reperfusion. Coronary blood flow was also significantly higher in the INO-1001 group (P < 0.05). Although the vasodilative response to sodium nitroprusside was similar in both groups, acetylcholine resulted in a significantly greater increase in coronary and pulmonary blood flow in the INO-1001 group (P < 0.05). Pulmonary function in terms of alveolar arterial oxygen difference was better preserved in the INO-1001-treated group (P < 0.05). Thus, PARP inhibition improves the recovery of myocardial and endothelial function after hypothermic cardiac arrest and reduces pulmonary injury associated with extracorporal circulation.

Ventricularization of the atrialized chamber: A concept of Ebstein's anomaly repair

BACKGROUND

We report results of a technique of Ebstein's anomaly repair by creating a predominantly monocuspid valve with simultaneous ventricularization of the atrialized right ventricular (aRV) chamber.

METHODS

Between March 1993 and April 2003, Ebstein's anomaly repair by valvuloplasty with combined ventricularization was performed in 23 patients aged 13.6 (4.1-52.6) years presenting with tricuspid valve regurgitation (TVR) (I degrees, n = 1; II degrees, n = 3; III degrees, n = 13; IV degrees, n = 6). Valvuloplasty consisted of creating a predominantly monocuspid valve at the level of the anatomical atrioventricular junction resulting in a ventricularization of the atrialized chamber. Postoperatively all survivors were examined regularly with an actual prospective evaluation.

RESULTS

One early death (4.4%) occurred and was caused by right heart failure. Follow-up was 4.6 (0.5-10.9) years. Important recurrent atrioventricular valve regurgitation caused by rupture of fixation sutures occurred in 3 patients (13%), necessitating reintervention at 3 (0.03-4) months (revalvuloplasty, n = 2; TV replacement, n = 1). One patient presenting with hypoplastic right ventricle with consecutive right heart failure underwent creation of a total cavopulmonary connection at 10 months. At present all patients are doing well. Actual echocardiographic examination revealed significant improvement of right atrioventricular valve regurgitation (p < 0.0001) and favorable restoration of RV geometry and function.

CONCLUSIONS

This technique of Ebstein's anomaly repair with ventricularization of the atrialized chamber provides excellent results regarding right atrioventricular valve function and leads to a favorable restoration of RV geometry and function.

Expression and activity of matrix metalloproteinase-2 in calcific aortic stenosis

Calcific aortic stenosis is the main heart valve disease in the elderly, leading to massive focal calcification and thickening of the valve cusps. Matrix metalloproteinases (MMPs) are thought to contribute to this process. Therefore, the study assessed the expression of the gelatinases MMP-2 and MMP-9 and the endogenous tissue inhibitor of metalloproteinase (TIMP)-2 as well as the gelatinolytic activity in normal and stenotic valves. Human tricuspid aortic valves with and without calcific aortic stenosis were studied by immunohistochemistry for MMP-2, MMP-9 and TIMP-2. The gelatinolytic activity in native valve sections was assessed by gelatin in situ zymography with or without addition of the MMP activator p-aminophenymercuric acetate (APMA). Staining intensities for MMP-2 and TIMP-2 were elevated in stenotic valves as compared to controls. Minor staining of MMP-9 was present exclusively in stenotic valves. The morphologic distribution of gelatinolytic activity was comparable to the staining pattern of MMP-2, and since MMP-9 immunostaining demonstrated only a low number of positive cells, the observed gelatinolytic activity is likely due to MMP-2. Gelatinolytic activity was low in normal valves but significantly increased by the MMP activator APMA. In contrast, stenotic valves showed a strong basal gelatinolytic activity that could not be significantly enhanced by APMA suggesting that MMP-2 is present as a latent pro-enzyme in normal valves and activated in stenotic valves. Thus, MMP-2 might be involved in the matrix remodeling during calcific aortic stenosis.