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In a retrospective study of 32 consecutive patients undergoing a total cavopulmonary connection (TCPC), we tried to determine if the trend for decreasing age at Fontan completion and reducing the intervals between the staged procedures during the past decade was associated with a change in morbidity and outcome. In 8 patients the Fontan circulation was completed in one stage and in 24 patients an intermediate step by hemi-Fontan or bidirectional cavopulmonary anastomosis was performed before Fonlan completion. Mean age at TCPC and mean interval since the previous palliation have decreased significantly during the past decade. Although major complications were significantly reduced over time the occurrence and duration of postoperative pleural effusions were not. Decreasing age as well as intervals in staged Fontan palliation have beneficial influence on major complications and outcome, without significantly affecting the duration of pleural effusions at Fontan completion. [ABSTRACT FROM AUTHOR]

OBJECTIVES--To compare the efficacy of a purely transvenous cardioverter-defibrillator (ICD) system with that of a system with a supplementary subcutaneous patch. To evaluate clinical follow up of these lead arrangements that do not require thoracotomy. DESIGN--A simplified defibrillation protocol to test two different lead arrangements during implantation, with routine clinical follow up after implantation. SETTING--Tertiary referral centre for treatment of arrhythmia. PATIENTS--22 consecutive patients selected for implantation of an ICD because of life-threatening ventricular arrhythmias (ventricular fibrillation or sustained ventricular tachycardia) of whom 20 entered the test protocol. INTERVENTION--Implantation of an ICD with transvenously inserted intracardiac leads and a subcutaneous patch and assessment of effective defibrillation followed by testing of the purely transvenous approach. MAIN OUTCOME MEASURES--Reproducible conversion of ventricular fibrillation to sinus rhythm at a certain energy level, providing a safety margin of at least 10 J for both lead arrangements. Confirmation of efficacy during clinical follow up (mean 6 months). RESULTS--A transvenous lead system combined with a subcutaneous axillary patch was implanted in 20/22 patients and it provided adequate and acceptable energy levels. In 10/20 tested patients a purely transvenous lead configuration provided an acceptable safety margin as well. Nine patients had clinical recurrences: all these arrhythmias were successfully converted. CONCLUSION--A transvenous lead system was sufficient in 50% of the patients at the time of implantation. Data on long-term clinical follow up of this arrangement are not available. The approach without thoracotomy with a subcutaneous patch is feasible and effective in most patients selected for ICD treatment. [ABSTRACT FROM PUBLISHER]

The aim of this study was to evaluate and compare the calcification potential of kangaroo and porcine aortic valves after fixation in 0.6% or 2.0% concentrations of glutaraldehyde in the rat subcutaneous model. Two groups of Sprague Dawley rats were implanted with aortic valve leaflets after fixation in 0.6% or 2% glutaraldehyde. Collagen solubility was determined as a measure of the extent of fixation. From each group, animals were sacrificed after 24 h and weekly for up to 10 weeks after implantation. Calcium was determined by Inductively Coupled Plasma-Mass Spectrophotometry. The localisation of calcium deposits was assessed by light and electron microscopy. Data were analysed using linear regression and a backward stepwise analysis of variance, to determine predictors for calcification in the experimental model.

A readily available scaffold of consistent quality for cell seeding is necessary in tissue valve engineering. This study examines the biochemical and mechanical effects of cryopreservation on porcine aortic valve matrices. Porcine aortic valve matrices were prepared according to a modified enzymatic decellularisation protocol. Matrices were examined before and after cryopreservation for up to six months. Collagen content was determined by a hydroxyproline assay after reaction with ehloramine-T. Proteoglycan content was estimated by quantifying uronic acids chemically and by capillary electrophoresis. The mechanical properties of the aortic wall and valvular leaflet tissue were determined by tensile measurements using a computerised texture analyser. The histology and ultrastructure of all tissue before and after cryopreservation were examined by light and electron microscopy.

This article focuses on a comparative study of kangaroo and porcine aortic valves, that found that kangaroo aortic valves are more similar to human aortic valves. The precise mechanism of calcification of bioprosthetic valves is still controversial. Kangaroo aortic valves have been reported to calcify less than porcine aortic valves in the sheep circulatory model. The ultrastructure and arrangement of the structural layers of the kangaroo and porcine aortic valves indicate similar micromechanics. Kangaroo and porcine valves differ however, in the relative proportions of their structural layers.

Locating the site of increased resistance within the vascular tree in pulmonary arterial hypertension could assist in both patient diagnosis and tailoring treatment. Wave intensity analysis (WIA) is a wave analysis method that may be capable of localizing the major site of reflection within a vascular system. We investigated the contribution of WIA to the analysis of the pulmonary circulation in a rabbit model with animals subjected to variable occlusive pulmonary disease. Animals were embolized with different sized microspheres for 6 wk ( n = 10) or underwent pulmonary artery (PA) ligation for 6 wk ( n = 3). These animals were compared with a control group ( n = 6) and acutely embolized animals ( n = 4). WIA was performed and compared with impedance-based methods to analyze wave reflections. The control group showed a relatively high extent of reflected waves (15.7 ± 10.6%); reflections had a net effect of pressure reduction during systole, suggesting an open-end reflector. The pattern of wave reflection was not different in the group with partial PA ligation (12.4 ± 4.1%). In the chronically embolized group, wave reflection was not observed (3.6 ± 1.5%). In the acute embolization group, wave reflection was more prominent (37.3 ± 12.6%), with the appearance of a novel wave increasing pressure, suggesting the appearance of a closed-end reflector. Wave reflections of an open-end type are present in the normal rabbit pulmonary circulation. However, the pattern and nature of reflections vary according to the extent of pulmonary vascular occlusion. NEW & NOTEWORTHY The study proposes an original framework of a complementary analysis of wave reflections in the time domain and in the frequency domain. The methodology was used in the pulmonary circulation with different forms of chronic obstructions. The results suggest that the pulmonary vascular tree generates a reflection pattern that could actually assist the heart during ejection, and chronic obstruction significantly modifies the pattern.

Background: With more than 15,000 implanted patients worldwide and a survival rate of 80% at 1-year and 59% at 5-years, left ventricular assist device (LVAD) implantation has become an interesting strategy in the management of heart failure patients who are resistant to other kinds of treatment. There are limited data in the literature on the change over time of exercise capacity in LVAD patients, as well as limited knowledge about the beneficial effects that rehabilitation might have on these patients. Therefore, the aim of our study was to evaluate the evolution of exercise capacity on a cohort of patients implanted with the same device (HeartWare © ) and to analyse the potential impact of rehabilitation., Methods: Sixty-two patients implanted with a LVAD between June 2011 and June 2015 were screened. Exercise capacity was evaluated by cardiopulmonary exercise testing at 6 weeks, 6 and 12 months after implantation., Results: We have observed significant differences in the exercise capacity and evolution between the trained and non-trained patients. Some of the trained patients nearly normalised their exercise capacity at the end of the rehabilitation programme., Conclusions: Exercise capacity of patient implanted with a HeartWare © LVAD increased in the early period after implantation. Rehabilitation allowed implanted patients to have a significantly better evolution compared to non-rehabilitated patients.

Background: Aortic regurgitation (AR) is a valvular disease that can lead to systolic heart failure. Treatment options besides cardiac surgery are limited and consequently severe AR is associated with higher mortality and morbidity when not operated. In this investigation, we examined the effects of a novel cardiac myosin activator, Omecamtiv-mecarbil (OM), in rats with chronic severe AR., Methods: AR was created by retrograde puncture of the aortic valve leaflets in 20 adults Wistar rats. 12 animals survived the acute AR phase and were randomized 2 months thereafter into OM (n = 7) or placebo groups (n = 5). Two rats underwent a sham operation and served as controls. Equal volumes of OM or placebo (NaCl 0.9%) were perfused in the femoral vein by continuous infusion (1.2 mg/kg/hour) during 30 min. Doppler-echocardiography was performed before and at the end of the infusion periods., Results: OM increased indices of global cardiac function (cardiac output, stroke volume), and increased systolic performance (fractional shortening, ejection fraction, left ventricular end systolic diameter) (all p < 0.05). These effects concurred with decreases in indices of LV preload (left atrial size, left ventricular end diastolic diameter) as well in the aortic pre-ejection period / left ventricular ejection time ratio (all p < 0.05). The severity score of the regurgitant AR jet did not change. Placebo infusion did not affect these parameters., Conclusion: The cardiac myosin activator OM exerts favorable hemodynamic effects in rats with experimental chronic AR.

Arterial compliance (C) is related to the elasticity, size, and geometrical distribution of arteries. Compliance is a determinant of the load that impedes ventricular ejection. Measuring compliance is difficult, particularly in the pulmonary circulation in which resistive and compliant vessels overlap. Comparing different methods for quantification of compliance to a method that involves a continuous flow might help to identify the optimal method. Pulmonary arterial compliance was computed in six pigs based on the stroke volume to pulse pressure ratio, diastolic decay exponential fitting, area method, and the pulse pressure method (PPM). Compliance measurements were compared to those obtained under continuous flow conditions through a right ventricular bypass (Heartware Inc., Miami Lakes, FL, USA). Compliance was computed for various flows using diastolic decay exponential fitting after an abrupt interruption of the pump. Under the continuous flow conditions, resistance (R) was a decreasing function of the flow, and the fitting to P = e -t/RC yielded a pulmonary time constant (RC) of 2.06 s ( ± 0.48). Compliance was an increasing function of flow. Steady flow inter-method comparisons of compliance under pulsatile flow conditions showed large discrepancies and values (7.23 ± 4.47 mL/mmHg) which were lower than those obtained under continuous flow conditions (10.19 ± 1 0.31 mL/mmHg). Best agreement with steady flow measurements is obtained with the diastolic decay method. Resistance and compliance are both flow-dependent and are inversely related in the pulmonary circulation. The dynamic nature of the pulsatile flow may induce a non-uniformly distributed compliance, with an influence on the methods of measurement.

Objectives: Concerns have been raised about the durability of the first-generation Mitroflow aortic bioprosthesis (model 12 A-LX) due to the lack of anticalcification treatment. This study reflects a 10-year experience with this prosthesis for aortic valve replacement., Methods: From June 2003 to May 2012, the Mitroflow prosthesis was used for aortic valve replacement in 510 patients, of whom only 467 with complete clinical follow-up were included for analysis. Study end-points were survival and incidence of structural valve degeneration (SVD). Analysis of SVD was based on cumulative incidence function and competing-risk Cox regression., Results: The mean patient age was 76.4 ± 6.1 years. Valve sizes from 23 to 25 were used in 70.4%, whereas sizes from 19 to 21 were used in only 19.2%, thereby avoiding patient-prosthesis mismatch in 89.1%. Within a median follow-up time of 6.6 years (interquartile range 4.4), a cumulative 2375 patient-years, the survival rate was 86.2%, 67.3% and 33.3% at 1, 5 and 10 years, respectively. The cumulative incidence of SVD, with death as a competing risk, was 0%, 0.7% and 6.2% at 1, 5 and 10 years, respectively. Only age <75 years tended to affect the late hazard of SVD (hazard ratio 0.50, 95% confidence interval 0.23-1.08, P  = 0.08), regardless of valve-specific issues., Conclusions: The data do not support the concerns about early accelerated structural degeneration of the first-generation Mitroflow bioprosthesis used for aortic valve replacement in patients older than 75 years. We postulate that limiting the number of small prostheses using a proper implantation technique has enhanced the reduction in risk of significant patient-prosthesis mismatch as the main determinant of early SVD., (© The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

To date an optimal decellularization protocol of heart valve leaflets (HVL) and pericardia (PER) with an adequate preservation of the extracellular matrix (ECM) is still lacking. This study compares a 4 day Triton X-100-based protocol with faster SDC-based protocols for the decellularization of cardiac tissues. Decellularized and non-treated HVL and PER were processed for histological, biochemical and mechanical analysis to determine the effect of these agents on the structure, ECM components, and biomechanical properties. Tissues treated with SDC-based protocols still showed nuclear material, whereas tissues treated with Triton X-100 1% + ENZ ± TRYP were completely cell free. For both decellularized tissues, an almost complete washout of glycosaminoglycans, a reduction of soluble collagen and an alteration of the surface ultrastructure was observed. Interestingly, only the elastic fibers of pericardial tissue were affected and this tissue had a decreased maximum load. This study showed that both detergents had a similar impact on the ECM. However, Triton X-100 1% +DNase/RNase (ENZ) ± Trypsin (TRYP) is the only protocol that generated completely cell free bioscaffolds. Also, our study clearly demonstrated that the decellularization agents have more impact on pericardial tissues than on heart valve leaflets. Thus, for the purpose of tissue engineering of heart valves, it is advisable to use valvular rather than pericardial matrices.

Background: In the pulmonary circulation, there is a linear relationship between systolic pulmonary arterial pressure (SPAP) and mean pulmonary arterial pressure (MPAP). The aim of this study was to determine the passive or active nature of this mechanism by exploring the relationship in patients with and without autonomic rhythm control of the heart and pulmonary circulation., Methods: Pulmonary arterial pressure recordings from non-transplanted patients and patients with heart transplants or double lung transplants were retrospectively reviewed. The relationships between systolic, diastolic, and mean pulmonary arterial pressures were explored., Results: A linear relationship was observed between the SPAP and MPAP, whether patients were paced (MPAP = 0.56 SPAP + 3.86 mmHg, r (2)  = 0.889), treated with inotropes (MPAP = 0.55 SPAP + 5.52 mmHg, r (2)  = 0.947) or pulmonary vasodilators (MPAP = 0.58 SPAP + 2.41 mmHg, r (2)  = 0.927), were exercising (MPAP = 0.61 SPAP + 1.18 mmHg, r (2)  = 0.967), had a heart transplant (MPAP = 0.66 SPAP +0.87 mmHg, r (2)  = 0.849), a double lung transplant (MPAP = 0.7 SPAP +0.48 mmHg, r (2)  = 0.915), or no intervention (MPAP = 0.59 SPAP +1.75 mmHg, r (2)  = 0.937)., Conclusion: We demonstrate that the linear relationship between SPAP and MPAP remains in several situations. Therefore, we conclude that the underlying mechanism is a passive consequence of the elastic properties of the cardiopulmonary unit.

Background and Aim of the Study: Currently, no effective crosslinking reagents are available to treat xenogenic decellularized heart valve matrices. The study aim was to evaluate the crosslinking effect of quercetin, catechin, caffeic acid and tannic acid on porcine aortic valve matrices., Methods: Cytotoxicity of the different crosslinkers was evaluated. The mechanical properties of crosslinked porcine matrices and control matrices (non-fixed) were examined by tensile strength testing, as was the cytocompatibility of the fixed matrices. Crosslinked and control matrices were implanted subcutaneously in Wistar rats (n = 9) and, after two weeks, their calcium contents were determined using inductively coupled plasma-mass spectrometry. The antibody reaction against porcine tissue in rat serum was also determined., Results: Cytotoxicity studies showed that crosslinkers, even at high concentrations, did not inhibit cell viability. All crosslinkers except tannic acid improved the mechanical strength of acellular porcine matrices. Moreover, the tensile strength of quercetin-fixed matrices was comparable with that of glutaraldehyde (GTA)-fixed leaflets. Light microscopic evaluation showed that crosslinked matrices caused only a mild lymphocytic inflammatory reaction. Furthermore, quercetin-fixed leaflets exhibited a well-preserved matrix without infiltration of CD3+ cells. After two weeks, calcium levels were 206.33 µg/mg for controls (non-fixed), and 151.33 µg/mg, 181 µg/mg and 163.66 µg/mg for quercetin-, catechin-, and caffeic acid-fixed matrices, respectively. At two weeks after implantation the quercetin-crosslinked matrices also elicited the lowest levels of IgG antibodies., Conclusion: The study results identified quercetin as the most suitable crosslinker for heart valve tissue engineering, and a possible alternative to GTA. Further studies are essential to determine whether quercetin crosslinking will allow autologous cell repopulation in order to create a viable heart valve.