Adverse results of a decellularized tissue-engineered pulmonary valve in humans assessed with magnetic resonance imaging

OBJECTIVES

Matrix P® and Matrix P plus® tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology.

METHODS

Between June 2006 and August 2008, 17 Matrix P® and 10 Matrix P plus® TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required.

RESULTS

Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V(max) = 3.7 ± (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 ± 3%) and stenosis with moderate-to-severe insufficiency (V(max) = 3.5 ± 0.8 m/s, RGF = 38 ± 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case.

CONCLUSIONS

The high frequency of Matrix P® and Matrix P plus® graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.

Anatomical and functional assessment of the intra-atrial lateral tunnel in the Fontan circulation

OBJECTIVES

In patients after completion of the total cavopulmonary connection (TCPC) with an intra-atrial lateral tunnel, deviations of the tunnel from an ideal straight tubular shape were observed. However, little is known about frequency and adverse effects of such shape deviations. We sought to analyse tunnel anatomy, dimensions and blood flow using cardiac magnetic resonance imaging (CMR).

METHODS

Fifty-four patients with hypoplastic left heart syndrome (HLHS; mean age 6.0 ± 2.4 years) underwent CMR with gradient-echo cine sequences, 2D- and 3D-phase-contrast imaging. We analysed anatomy, diameters, cross-sectional areas, volumes and blood flow of the tunnel.

RESULTS

Twenty-five patients had a tubular tunnel. In 29 patients, bulging and/or narrowing of the tunnel were present. Cross-sectional areas and volumes of the tunnel were not significantly different between the two groups. There were also no differences for the mean blood flow and the mean and maximal flow velocity (P = 0.05-0.6). In all the patients, the normalized tunnel volume was related to age (r = 0.44; P = 0.002) and body surface area (BSA; r = 0.42; P = 0.005). The mean tunnel blood flow correlated with age (r = 0.73; P = 0.001) and BSA (r = 0.83; P < 0.0001).

CONCLUSIONS

A considerable percentage of patients with an intra-atrial lateral tunnel develop mild deviations of the tunnel from ideal tubular shape. The correlation between tunnel volume and mean blood flow with age and BSA suggests that the capacity of the tunnel adjusts to body growth, independent of tunnel shapes that deviate from a fluid-dynamically favourable shape. Follow-up CMRs are needed to detect long-term effects of irregular tunnel shapes on flow dynamics.

Determination of volume-time curves for the right ventricle and its outflow tract for functional analyses

PURPOSE

The determination of right ventricular volumes and function is of increasing interest for the postoperative care of patients with congenital heart defects. The presentation of volumetry data in terms of volume-time curves allows a comprehensive functional assessment. By using manual contour tracing, the generation of volume-time curves is exceedingly time-consuming.

METHODS

This study describes a fast and precise method for determining volume-time curves for the right ventricle and for the right ventricular outflow tract. The method applies contour detection and includes a feature for identifying the right ventricular outflow tract volume. The segregation of the outflow tract is performed by four-dimensional curved smooth boundary surfaces defined by prespecified anatomical landmarks.

RESULTS

The comparison with manual contour tracing demonstrates that the method is accurate and improves the precision of the measurement. Compared to manual contour tracing the bias is <0.1% ± 4.1% (right ventricle) and -2.6% ± 20.0% (right ventricular outflow tract). The standard deviations of inter- and intraobserver variabilities for determining the volume of the right ventricular outflow tract are reduced to less than half the values of manual contour tracing. The time consumption per patient is reduced from 341 ± 80 min (right ventricle) and 56 ± 11 min (right ventricular outflow tract) using manual contour tracing to 46 ± 9 min for a combined analysis of right ventricle and right ventricular outflow tract.

CONCLUSION

The analysis of volume-time curves for the right ventricle and its outflow tract discloses new evaluation methods in clinical routine and science.

Normal values of aortic dimensions, distensibility, and pulse wave velocity in children and young adults: a cross-sectional study

BACKGROUND

Aortic enlargement and impaired bioelasticity are of interest in several cardiac and non-cardiac diseases as they can lead to cardiovascular complications. Cardiovascular magnetic resonance (CMR) is increasingly accepted as a noninvasive tool in cardiovascular evaluation. Assessment of aortic anatomy and bioelasticity, namely aortic distensibility and pulse wave velocity (PWV), by CMR is accurate and reproducible and could help to identify anatomical and bioelastic abnormalities of the aorta. However, normal CMR values for healthy children and young adults are lacking.

METHODS

Seventy-one heart-healthy subjects (age 16.4 ± 7.6 years, range 2.3-28.3 years) were examined using a 3.0 Tesla CMR scanner. Aortic cross-sectional areas and aortic distensibility were measured at four positions of the ascending and descending thoracic aorta. PWV was assessed from aortic blood flow velocity measurements in a aortic segment between the ascending aorta and the proximal descending aorta. The Lambda-Mu-Sigma (LMS) method was used to obtain percentile curves for aortic cross-sectional areas, aortic distensibility and PWV according to age.

RESULTS

Aortic areas, PWV and aortic distensibility (aortic cross-sectional areas: r = 0.8 to 0.9, p < 0.001; PWV: r = 0.25 to 0.32, p = 0.047 to 0.009; aortic distensibility r = -0.43 to -0.62, p < 0.001) correlated with height, weight, body surface area, and age. There were no significant sex differences.

CONCLUSIONS

This study provides percentile curves for cross-sectional areas, distensibility and pulse wave velocity of the thoracic aorta in children and young adolescents between their 3rd and 29th year of life. These data may serve as a reference for the detection of pathological changes of the aorta in cardiovascular disease.

Fifteen-year single-center experience with the Norwood operation for complex lesions with single-ventricle physiology compared with hypoplastic left heart syndrome

OBJECTIVE

The Norwood procedure, the first surgical step of staged palliation for hypoplastic left heart syndrome, is also applied for other complex single-ventricle lesions with systemic outflow tract obstruction or aortic arch hypoplasia. We reviewed our 15-year institutional experience with the Norwood procedure for patients with and without hypoplastic left heart syndrome.

METHODS

A total of 41 patients without hypoplastic left heart syndrome and 212 patients with hypoplastic left heart syndrome who underwent a Norwood procedure between January 1996 and December 2010 were enrolled. Full medical records were reviewed to assess the determinants of outcome.

RESULTS

Early failure (death or cardiac transplantation) was 7% in patients without hypoplastic left heart syndrome and 13% in patients with hypoplastic left heart syndrome (P = .29). Frequency of postoperative complications, duration of postoperative ventilation, and length of vasoactive drug treatment were not different between groups. Transplant-free survival until the second operative step trended to be higher for patients without hypoplastic left heart syndrome (92% vs 80%, P = .067). Recurrent aortic arch obstruction was more common in patients without hypoplastic left heart syndrome (15/39 vs 32/171, P = .008), but there were 4 patients with stenosis of the proximal aortic arch. In subsequent procedures, 31 patients without hypoplastic left heart syndrome underwent superior cavopulmonary anastomosis and 5 biventricular repair. Overall transplant-free survival was not different between groups (P = .119) but trended to be higher in patients with a systemic or substantial left ventricle remnant contributing to cardiac output (P = .082).

CONCLUSIONS

Early and long-term survivals and postoperative complications were similar between patients with and without hypoplastic left heart syndrome undergoing a Norwood operation. Recurrent aortic arch obstruction was common in both groups but more prevalent in patients without hypoplastic left heart syndrome.

Improved MRI of the neonatal heart: feasibility study using a knee coil

As a first step towards the development of a neonatal cardiac MRI (CMRI) coil, we investigated the utilization, handling and image quality of a knee coil for CMRI in infants at 3 Tesla. Scout imaging and cine imaging with optimized pulse sequence parameters were performed in two neonates and the resulting images were evaluated for diagnostic purposes. All images were of high diagnostic quality. Complete examinations took less than five minutes. The excellent signal-to-noise ratio provided by this coil allowed all cine studies to be acquired with only three averages. In conclusion, a knee coil can be successfully applied in neonates for CMRI, but the coil design could be improved further to facilitate routine clinical use.

Maladaptive aortic properties in children after palliation of hypoplastic left heart syndrome assessed by cardiovascular magnetic resonance imaging

BACKGROUND

The status of the reconstructed aorta in hypoplastic left heart syndrome is considered an important determinant of long-term prognosis. Therefore, we assessed the anatomy, elastic properties, and viability of the aorta and right ventricular function in patients with hypoplastic left heart syndrome by cardiovascular magnetic resonance imaging.

METHODS AND RESULTS

Cardiovascular magnetic resonance imaging was performed in 40 patients with hypoplastic left heart syndrome (age, 6.0±2.2 years) and 13 control subjects (age, 6.6±2.2 years). Aortic dimensions and distensibility were calculated at different locations of the aorta using gradient-echo cine imaging at 3.0 T. Additionally, pulse-wave velocity, right ventricular ejection fraction, and aortic late gadolinium enhancement for viability assessment were measured. Compared with control subjects, patients with hypoplastic left heart syndrome had increased axial diameters of the aortic root (36.0±5.5 versus 24.1±2.7 mm/m(2); P<0.01), ascending aorta (32.0±5.0 versus 21.3±1.5 mm/m(2); P<0.01), and transverse aortic arch (22.7±5.2 versus 18.7±2.5 mm/m(2); P<0.01). Wall distensibility was reduced in the ascending aorta (4.1±2.4 versus 13.5±7.2 10(-3) mm Hg(-1); P<0.01) and transverse aortic arch (5.4±3.6 versus 10.3±3.5 10(-3) mm Hg(-1); P<0.01). Pulse-wave velocity trended higher in patients (P=0.06). Reduced distensibility in the ascending aorta correlated with the amount of late gadolinium enhancement in a volume that included the aortic root and the ascending aorta (r=-0.72, P<0.01), and both parameters correlated with decreased right ventricular ejection fraction.

CONCLUSIONS

Adverse aortic properties post palliation of hypoplastic left heart syndrome manifest themselves by aortic dilatation, decreased distensibility, and increased volume of nonviable aortic wall tissue. The negative association between aortic late gadolinium enhancement and right ventricular ejection fraction suggests unfavorable aortic-ventricular coupling. The potential impact of these findings on long-term right ventricular function should be evaluated in future studies.

Restrictive enlargement of the pulmonary annulus at surgical repair of tetralogy of Fallot: 10-year experience with a uniform surgical strategy

OBJECTIVES

Retrospective data suggest that a wide pulmonary annulus after Fallot repair aggravates pulmonary regurgitation. Therefore, since 1997, in our institution transannular patch enlargement was only intended for patients with a native pulmonary annulus z-score less than -4. If transannular patching was needed, enlargement was aimed to diameters within the range of a z-score of -2. We sought to determine whether this strategy of restrictive enlargement of the pulmonary annulus was adequate to reduce transannular patch rate and to limit pulmonary annulus width without increased right ventricular pressure load.

METHODS

Two-hundred-and-sixteen Fallot patients were retrospectively analysed. Ninety-eight patients underwent repair between 1997 and 2006 adhering to our uniform strategy (Group 1). One hundred and eighteen patients were operated between 1977 and 1996 without a uniform strategy (Group 2). Transannular patch rate, native and postoperative pulmonary annulus z-score, postoperative right ventricular outflow tract velocity on echocardiography and early reoperation rate for right ventricular outflow tract obstruction were analysed in both groups.

RESULTS

Compared to Group 2, patients in Group 1 were younger at repair, transannular patch rate was significantly reduced (32 vs 68%, p<0.0001) and postoperative pulmonary annulus diameters were smaller (z-score -2.1+/-1.5 vs 0.0+/-3.1, p<0.0001). However, no difference in right ventricular outflow tract velocity (2.4+/-0.8 vs 2.2+/-0.8m/s; p=NS) or the incidence of early reoperation for right ventricular outflow tract obstruction was found between the groups (3/98 vs 1/118; p=NS).

CONCLUSION

Restrictive enlargement of the pulmonary annulus at Fallot repair lowers transannular patch rate, limits the postoperative width of the pulmonary annulus but does not result in increased right ventricular pressure load or reoperation rate for residual right ventricular outflow tract obstruction. A limitation of postoperative pulmonary regurgitation can be expected when the extent of pulmonary annulus enlargement at repair is limited.

[Acquired von Willebrand syndrome in two children with congenital heart defects and abnormal haemodynamics]

Acquired von Willebrand syndrome is a rare bleeding disorder associated with other primary diseases such as cardiovascular disorders which can cause severe haemorrhage during surgery or interventional procedures. It should be suspected if there is no history of bleeding and abnormal von Willebrand factor (VWF) values in patients with predisposing disorders. We present two children with congenital heart defects and no personal or family history of bleeding. In these patients we preoperative diagnosed acquired von Willebrand syndrome with coagulation tests including analysis of the VWF multimeric pattern.