Chung-Chi Wang

Correctness of multi-detector-row computed tomography for diagnosing mechanical prosthetic heart valve disorders using operative findings as a gold standard

The purpose was to compare the findings of multi-detector computed tomography (MDCT) in prosthetic valve disorders using the operative findings as a gold standard. In a 3-year period, we prospectively enrolled 25 patients with 31 prosthetic heart valves. MDCT and transthoracic echocardiography (TTE) were done to evaluate pannus formation, prosthetic valve dysfunction, suture loosening (paravalvular leak) and pseudoaneurysm formation. Patients indicated for surgery received an operation within 1 week. The MDCT findings were compared with the operative findings. One patient with a Björk-Shiley valve could not be evaluated by MDCT due to a severe beam-hardening artifact; thus, the exclusion rate for MDCT was 3.2% (1/31). Prosthetic valve disorders were suspected in 12 patients by either MDCT or TTE. Six patients received an operation that included three redo aortic valve replacements, two redo mitral replacements and one Amplatzer ductal occluder occlusion of a mitral paravalvular leak. The concordance of MDCT for diagnosing and localizing prosthetic valve disorders and the surgical findings was 100%. Except for images impaired by severe beam-hardening artifacts, MDCT provides excellent delineation of prosthetic valve disorders.

Neonatal cardiac multidetector row CT: why and how we do it

Neonatal congenital heart disease is a most difficult area of diagnostic radiology because of the small patient body size and fast resting heart rate. Recently, the spatial and temporal resolution of multidetector-row CT (MDCT) has evolved so that neonatal congenital heart disease can be precisely diagnosed. We describe the role of MDCT in neonatal congenital heart disease and offer tips for the scanning procedure to familiarize radiologists with this developing field.

Spherically Symmetric Mesenchymal Stromal Cell Bodies Inherent with Endogenous Extracellular Matrices for Cellular Cardiomyoplasty

Cell transplantation via direct intramyocardial injection is a promising therapy for patients with myocardial infarction; however, retention of the transplanted cells at the injection sites remains a central issue following injection of dissociated cells. Using a thermoresponsive hydrogel system with a multiwell structure, we successfully developed an efficient technique to generate spherically symmetric bodies of mesenchymal stromal cells (MSCs) inherent with endogenous extracellular matrices (ECMs) for direct intramyocardial injection. After injection through a needle and upon transferring to another growth surface, the time required to attach, migrate, and proliferate was significantly shorter for the MSC bodies than the dissociated MSCs. Employing a syngeneic rat model with experimental myocardial infarction, an intramyocardial injection was conducted with a needle directly into the peri‐infarct areas. There were four treatment groups (n = 10): sham, phosphate‐buffered saline, dissociated MSCs, and MSC bodies. The results obtained in the echocardiography and catheterization measurements demonstrated that the MSC body group had a superior heart function to the dissociated MSC group. Histologically, it was found that MSC bodies could provide an adequate physical size to entrap into the interstices of muscular tissues and offer a favorable ECM environment to retain the transplanted cells intramuscularly. Additionally, transplantation of MSC bodies stimulated a significant increase in vascular density, thus improving the cardiac function. These results indicated that the spherically symmetric bodies of MSCs developed in the study may serve as a cell‐delivery vehicle and improve the efficacy of therapeutic cell transplantation. STEM CELLS 2009;27:724–732

Visualization of neonatal coronary arteries on multidetector row CT: ECG-gated versus non-ECG-gated technique

BackgroundMultidetector CT (MDCT) seems to be a promising tool for detection of neonatal coronary arteries, but whether the ECG-gated or non-ECG-gated technique should be used has not been established.ObjectiveTo compare the detection rate and image quality of neonatal coronary arteries on MDCT using ECG-gated and non-ECG-gated techniques.Materials and methodsTwelve neonates with complex congenital heart disease were included. The CT scan was acquired using an ECG-gated technique, and the most quiescent phase of the RR interval was selected to represent the ECG-gated images. The raw data were then reconstructed without the ECG signal to obtain non-ECG-gated images. The detection rate and image quality of nine coronary artery segments in the two sets of images were then compared. A two-tailed paired t test was used with P values <0.05 considered as statistically significant.ResultsIn all coronary segments the ECG-gated technique had a better detection rate and produced images of better quality. The difference between the two techniques ranged from 25% in the left main coronary artery to 100% in the distal right coronary artery.ConclusionFor neonates referred for MDCT, if evaluation of coronary artery anatomy is important for the clinical management or surgical planning, the ECG-gated technique should be used because it can reliably detect the coronary arteries.

Porous tissue grafts sandwiched with multilayered mesenchymal stromal cell sheets induce tissue regeneration for cardiac repair.

AIMS To provide the basis for uniform cardiac tissue regeneration, a spatially uniform distribution of adhered cells within a scaffold is a prerequisite. To achieve this goal, a bioengineered tissue graft consisting of a porous tissue scaffold sandwiched with multilayered sheets of mesenchymal stromal cells was developed. METHODS AND RESULTS This tissue graft (sandwiched patch) was used to replace the infarcted wall in a syngeneic Lewis rat model with an experimentally chronic myocardial infarction (MI). There were four treatment groups (n >/= 10): sham, MI, empty patch, and sandwiched patch. After a 7 day culture of the sandwiched patch, a tissue graft with relatively uniform cell concentrations was obtained. The cells were viable and tightly adhered to the tissue scaffold, as the endogenous extracellular matrix inherent with multilayered cell sheets can act as an adhesive agent for cell attachment and retention. At retrieval, the area of the empty patch was relatively enlarged, suggesting reduced structural support, while that of the sandwiched patch remained about the same (P = 0.56). In the immunofluorescent staining, host cells together with neo-microvessels were clearly observed in the empty patch; however, there were still a large number of unfilled pores within the patch. In the sandwiched patch, besides host cells, originally seeded cells were populated within the entire patch. No apparent evidence of apoptotic cell death was found in both studied patches. Thus, the sandwiched-patch-treated hearts demonstrated a better heart function to the empty-patch-treated hearts (P < 0.05). CONCLUSION The results demonstrated that this novel bioengineered tissue graft can serve as a useful cardiac patch to restore the dilated left ventricle and stabilize heart functions after MI.

Three-dimensional cell aggregates composed of HUVECs and cbMSCs for therapeutic neovascularization in a mouse model of hindlimb ischemia

The proximity of cells in three-dimensional (3D) organization maximizes the cell-cell communication and signaling that are critical for cell function. In this study, 3D cell aggregates composed of human umbilical vein endothelial cells (HUVECs) and cord-blood mesenchymal stem cells (cbMSCs) were used for therapeutic neovascularization to rescue tissues from critical limb ischemia. Within the cell aggregates, homogeneously mixed HUVECs and cbMSCs had direct cell-cell contact with expressions of endogenous extracellular matrices and adhesion molecules. Although dissociated HUVECs/cbMSCs initially formed tubular structures on Matrigel, the grown tubular network substantially regressed over time. Conversely, 3D HUVEC/cbMSC aggregates seeded on Matrigel exhibited an extensive tubular network that continued to expand without regression. Immunostaining experiments show that, by differentiating into smooth muscle cell (SMC) lineages, the cbMSCs stabilize the HUVEC-derived tubular network. The real-time PCR analysis results suggest that, through myocardin, TGF-β signaling regulates the differentiation of cbMSCs into SMCs. Transplantation of 3D HUVEC/cbMSC aggregates recovered blood perfusion in a mouse model of hindlimb ischemia more effectively compared to their dissociated counterparts. The experimental results confirm that the transplanted 3D HUVEC/cbMSC aggregates enhanced functional vessel formation within the ischemic limb and protected it from degeneration. The 3D HUVEC/cbMSC aggregates can therefore facilitate the cell-based therapeutic strategies for modulating postnatal neovascularization.

MDCT evaluation after closure of atrial septal defect with an Amplatzer septal occluder.

OBJECTIVE The essay describes the protocol for and interpretation of MDCT scans in the evaluation of patients after insertion of an Amplatzer septal occluder. CONCLUSION In anatomic regions that cannot be confidently evaluated with transthoracic echocardiography, MDCT is useful for evaluating Amplatzer septal occluders for protrusion, migration, and residual shunt. Radiologists should be familiar with the imaging protocol and interpretation.

Gradual Pulmonary Artery Enhancement: New Sign of Septal Defects on CT

OBJECTIVE Hemodynamic information observed on serial images obtained with bolus tracking might help in diagnosing septal defects on CT. Our purpose was to qualitatively and quantitatively examine a new sign called gradual pulmonary artery enhancement. CONCLUSION Gradual pulmonary artery enhancement is a newly recognized CT sign that may be helpful in evaluating septal defects.

Hybrid therapy for interrupted aortic arch with aortopulmonary window in a low birth weight infant

Interrupted aortic arch (IAA) is rarely associated with aortopulmonary window. Single‐stage total correction is the preferred therapeutic option. When total correction is unfeasible, staged repair could be the therapeutic choice. Here, we presented a low birth weight infant who underwent bilateral pulmonary arteries banding and stenting ductus arteriosus by hybrid procedure. Hybrid procedure avoids long‐term central line insertion and guarantees ductal flow. It also avoids the side effects from prostaglandin infusion.

Percutaneous Coronary Intervention under Extracorporeal Membrane Oxygenation Support for High-Risk Acute Myocardial Infarction with Cardiogenic Shock

Acute myocardial infarction (AMI) complicated by cardiogenic shock is an uncommon, but fatal condition. It should be treated by early revascularization, including medication, percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG). Extracorporeal membrane oxygenation (ECMO) has been shown to lower the mortality rate associated with emergency PCI or CABG procedures in patients with unstable hemodynamics. We present a patient with coronary artery disease (CAD) consisting of triple vessel disease (TVD), a significant left main (LM) artery lesion, AMI and cardiogenic shock, who underwent PCI under ECMO support. There were no short-term or middle-term complications related to the PCI procedure; however, ECMO implantation led to a superficial wound infection. The patient was alive and well at six-month follow-up. We also review the literature regarding PCI under ECMO support for AMI complicated with cardiogenic shock patients.