In vitro biological and mechanical evaluation of various scaffold materials for myocardial tissue engineering

A cardiac patch is a construct devised in regenerative medicine to replace necrotic heart tissue after myocardial infarctions. The cardiac patch consists of a scaffold seeded with stem cells. To identify the best scaffold for cardiac patch construction we compared polyurethane, Collagen Cell Carriers, ePTFE, and ePTFE SSP1-RGD regarding their receptiveness to seeding with mesenchymal stem cells isolated from umbilical cord tissue. Seeding was tested at an array of cell seeding densities. The bioartificial patches were cultured for up to 35 days and evaluated by scanning electron microscopy, microscopy of histological stains, fluorescence microscopy, and mitochondrial assays. Polyurethane was the only biomaterial which resulted in an organized multilayer (seeding density: 0.750 × 10(6) cells/cm(2)). Cultured over 35 days at this seeding density the mitochondrial activity of the cells on polyurethane patches continually increased. There was no decrease in the E Modulus of polyurethane once seeded with cells. Seeding of CCC could only be realized at a low seeding density and both ePTFE and ePTFE SSP1-RGD were found to be unreceptive to seeding. Of the tested scaffolds polyurethane thus crystallized as the most appropriate for seeding with mesenchymal stem cells in the framework of myocardial tissue engineering.

An unusual form of supracardiac total anomalous pulmonary venous return via a right-sided vertical vein in a heterotaxy syndrome case

Heterotaxy syndromes comprise a great variety of possible cardiac defects. Anomalies of the pulmonary venous system are well recognized in heterotaxy syndromes but constitute a frequently underdiagnosed subgroup. The case report describes a girl with a rare form of supracardiac total anomalous pulmonary venous return via a right-sided vertical vein to the right innominate vein in heterotaxy syndrome with dextrocardia, unbalanced atrioventricular septal defect with severe left ventricular hypoplasia, and transposition of the great arteries with pulmonary stenosis. Careful evaluation and imaging before surgical repair is crucial for such complex cardiac anomalies.

Hypertension after heart and heart/lung transplantation in childhood--study on the evolution of short-term blood pressure regulation

Arterial hypertension complicates the follow-up of heart- and heart/lung-transplanted children. We investigated the evolution of BRS as short-time BP regulation mechanism and BP after heart and heart/lung transplantation. Twenty patients (15 males; mean age 15.1 ± 4.3 yr) were studied twice at intervals of 2.96 ± 0.87 yr. BRS was calculated using non-invasive beat-to-beat BP measurement system. HRV was calculated (LF, sympathetic influence; HF, parasympathetic influence). BRS increased in 10 patients (3.67 ± 1.43 ms/mmHg vs. 7.59 ± 3.40 mmHg, p = 0.005) (group 1). Six of 10 patients received antihypertensive medication. BRS decreased or remained unchanged in 10 patients (8.93 ± 7.9 ms/mmHg vs. 5.32 ± 6.6 ms/mmHg, p = 0.008) (group 2) with 9/10 patients necessitating antihypertensive medication. Group 1 showed LF/HF increase (LF/HF 1.03 ± 0.9 vs. 4.36 ± 2.32, p = 0.03); group 2 showed LF/HF decrease (LF/HF 3.7 ± 2.1 vs. 1.84 ± 1.1, p = 0.023). Evolution of BRS after heart and heart/lung transplantation in childhood seems to influence the necessity of antihypertensive medication. With time, increasing short-time BP regulation involving sympathetic reinnervation may improve BP.

Hand-carried ultrasound devices in pediatric cardiology: clinical experience with three different devices in 110 patients

BACKGROUND

The aims of this study were to determine the usefulness of hand-carried ultrasound devices in pediatric cardiology and to compare the performance of three different hand-carried ultrasound devices in a pediatric cardiology outpatient clinic and intensive care unit.

METHODS

One hundred ten patients (49 male; mean age, 6.4 ± 5.2 years; range 0.1-38 years) with congenital heart defects or innocent heart murmurs were examined using Siemens Acuson P10, Siemens Acuson P50, and Philips CX 50 systems. The quality of images and the accuracy of B-mode measurements were compared with those obtained using a standard echocardiographic system (Philips iE33).

RESULTS

Fifty-nine patients were examined with the Siemens Acuson P10, 29 with the Siemens Acuson P50, and 22 with the Philips CX 50 system. There were no significant differences in B-mode measurements. The Acuson P10 system, however, showed significantly lower image quality, with 64.54% of all studies considered of excellent quality compared with 92.83% with the Acuson P50 and 95.52% with the CX 50 (P < .05) and a mean quality score (1 = fair, 5 = excellent) of 3.5 versus 4.57 with the Acuson P50 and 4.86 with the CX 50 (P < .05). This was attributed to the limited capacity for accurate diagnosis in children with body weights < 10 kg and complex heart defects.

CONCLUSION

Hand-carried ultrasound devices represent a valuable alternative to standard echocardiographic systems in pediatric cardiology. In particular, systems including all echocardiographic modalities offer unlimited versatility in outpatient and intensive care.

[MRI for therapy planning in patients with atrial septum defects]

PURPOSE

The aim of this study was to determine the value of a combined magnetic resonance imaging (MRI) protocol including steady-state free precession (SSFP) imaging, phase-contrast measurements and contrast-enhanced MR angiography (CE-MRA) for presurgical or preinterventional diagnostic imaging in patients with suspected atrial septum defects.

MATERIAL AND METHODS

Out of 65 MRI studies of patients with suspected atrial septum defects, 56 patients were included in the study. The atrial septum defects were identified on cine images. Velocity encoded flow measurements were used to determine shunt volumes, which were compared with invasive oxymetry in 24 patients. Contrast-enhanced MRI was used to assess the thoracic vessels in order to detect vascular anomalies. The findings were compared with the intraoperative results.

RESULTS

A total of 24 patients with high shunt volumes were treated either surgically (16 patients) or interventionally (8 patients) and 32 patients with low shunt volumes did not require surgical or interventional treatment. The vascular anomaly, which in all cases was anomalous pulmonary venous return, was confirmed by the intraoperative findings. The type and location of atrial septal defects which required treatment, were confirmed intraoperatively or during the intervention. The results of shunt quantification by MRI showed a good correlation with the results of invasive oximetry (r=0.91, p <0.0001).

CONCLUSION

A combined MRI protocol including cine SSFP images, velocity-encoded flow measurements and CE-MRA is an accurate method for preoperative and preinterventional evaluation of atrial septum defects.

Right ventricle-to-pulmonary artery shunt related complications after Norwood procedure

OBJECTIVE

The right ventricle-to-pulmonary artery (RV-PA) shunt in the Norwood procedure (NP) for children with hypoplastic left-heart syndrome (HLHS) provides stable early hemodynamics and improves survival in many centers. However, lower pulmonary-to-systemic flow ratio causes early cyanosis and may require earlier second-stage procedure. The aim of the study was to present shunt-related results after NP with RV-PA shunt and our technique of RV-PA shunt construction.

METHODS

Between June 2001 and August 2010, 236 children with HLHS and variants underwent NP with RV-PA shunt, and were operated on by the same surgeon. The medical records were retrospectively reviewed.

RESULTS

To date, 180 children at a mean age of 7.0 ± 1.6 months with a mean weight of 6.4 ± 0.9 kg underwent second-stage procedure. The mean systemic oxygen saturation before stage 2 operation was 74.8 ± 6.6% and mean arterial partial oxygen pressure was 32.8 ± 6.7 mm Hg. These two parameters were significantly lower than after NP (p = 0.029, p < 0.001, respectively). Between stage 1 and 2 operation, three children (1.3%) died due to the shunt obstruction. Four children (1.7%) underwent re-operations due to shunt problems (one of them died), and the other four (1.7%), stent implantation in RV-PA shunt. Two infants (1.1%) developed aneurysm of the right ventricle infundibulum, which was resected during stage 2 without complications. One child required early (before fifth month of age) second-stage procedure due to the shunt obstruction. The patients with right-sided to the neo-aorta course of the RV-PA shunt had significantly more frequent delayed sternal closure after NP than children with left-sided shunt (35.5% vs 14.1%; p = 0.008).

CONCLUSIONS

The RV-PA shunt can be a safe and efficient technique in providing optimal pulmonary blood flow in the children with HLHS after Norwood procedure, performed with minimal rate of complications. In our experience, the use of RV-PA shunt in NP does not require earlier second-stage procedure.

Right Ventricle-to-Pulmonary Artery Shunt in Norwood Procedure: Early Results

The aim of this study was to evaluate experience and predictors of early mortality in patients with hypoplastic left heart syndrome (HLHS)–type defects undergoing Norwood procedure (NP) with right ventricle-to-pulmonary artery (RV-PA) shunt. Between 2001 and 2009, a consecutive series of 229 children with HLHS-type single ventricle underwent NP with application of RV-PA shunt. Demographic, echocardiographic, and clinical perioperative data were retrospectively analyzed. The mean duration of follow-up of survivors was 4.5 ± 2.1 years (60 days to 8.1 years). Follow-up was complete for 92.1% of patients. Major early postoperative complications included sepsis/generalized infection in 40 (17.5%), pericardial effusion in 9 (3.9%), and wound infection in 8 (3.5%). The early (30-day) survival was 87.8% (n = 201). In the late postoperative period, 12 (5.9%) died. Early nonsurvivors were more frequently older than 14 days ( P = .045) at initial surgery, had lower operative weight ( P = .024), had more frequent associated cardiac ( P < .001) and/or extracardiac anomalies ( P < .001), and were more likely to have a restrictive interatrial communication before operation ( P = .024). Use of the right RV-PA shunt has helped to mitigate some previously described predictors of early death after NP. Longer follow-up will be required to determine whether the RV-PA shunt modification confers an important survival benefit.

Preclinical evaluation of a new self-expanding device for closure of muscular ventricular septal defects in a pig model

OBJECTIVES

Aim of our study was the preclinical evaluation of a new self expanding device for interventional closure of muscular ventricular septal defects (mVSDs) in an acute pig model.

BACKGROUND

Devices currently in use for closure of mVSDs still have their limitations. The deployment of the disks is dependent from the expansion of the stent, which can be associated with problems for sufficient closure of the mVSDs. This was the reason for developing a modified device with only one disk

MATERIALS AND METHODS

The device was constructed in a single wire technique with a unique configured retention disk. mVSDs were created in six pigs with a specially designed punch instrument, and subsequently closed with our new device during the same session using a jugular or femoral vein approach. Potential residual shunting volumes were estimated by echocardiography and hemodynamic measurements. After closure, animals were sacrificed, and hearts were harvested for macropathologic evaluation. In two animals, MRI was performed for additional noninvasive evaluation.

RESULTS

Devices were successfully implanted in all animals with good alignment of the disk to the left ventricular septum, even if the stent was oversized. Echocardiography, hemodynamics, angiography and macropathology revealed complete closure of all mVSDs. MRI and echocardiography showed a good visibility of the device.

CONCLUSIONS

Our preclinical study shows successful closure of iatrogenic created mVSDs without residual shunting. The device is characterized by a more controlled deployment, an independent deployment of disk and waist, and a good alignment of the left ventricular disk to the muscular septum.