Biomedical subjects
Publications and source records attributed to Edgar G Chedrawy.
We report a case of a 20-year-old man with a functional single left ventricle who underwent a successful Fontan operation into a single left pulmonary artery, the right pulmonary artery being atretic. The literature of a single-lung Fontan procedure is also reviewed.
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In the absence of a ventricular pump, the status of the pulmonary circulation is crucial to the success of the Fontan operation. In an updated version (1999) of the optimal criteria for the Fontan operation, several of these criteria address the pulmonary circulation: pulmonary artery pressure, pulmonary vascular resistance, pulmonary artery size, and absence of significant pulmonary artery branch stenosis. This chapter reviews the role of the pulmonary circulation in a successful Fontan operation, with a particular emphasis on surgical techniques to repair severe distal or hilar pulmonary artery stenosis or atresia. The special situation of the patient with a single pulmonary artery is also addressed. Severe hilar pulmonary artery stenosis or atresia can be repaired by the technique of intrapulmonary pulmonary artery reconstruction with pericardial patch or tube and allow the successful completion of the Fontan operation. In the selected patient with a single pulmonary artery and optimal hemodynamics, the Fontan operation is possible with good outcome. However, further experience is needed in a larger number of patients to assess the long-term outcome of these treatment strategies.
BACKGROUND: Myoblasts and stem cells implanted into myocardium can differentiate into myocytes and may functionally improve impaired ventricles. For implanted cells to actually contribute to the synchronous contractions of the heart, however, they must be anatomically integrated with the existing native myocardial fibers. METHODS: Isogenic Lewis rats were used as donors and recipients to simulate clinical autotransplantation. Either skeletal myoblasts or marrow stromal stem cells were isolated from donors, culture expanded, and labeled with 4',6-diamidino-2-phenylindole (4',6-diamidino-2-phenylindole). Labeled cells were then injected into the myocardium of recipients. At intervals specimens were obtained, sectioned, and stained with hematoxylin and eosin and immunohistochemically against connexin-43 to demonstrate gap junctions (intercalated discs). RESULTS: At 1 week the labeled cells were still undifferentiated, but early expression of connexin-43 could be detected at contact points between the implanted cells and the native myocytes. By 4 to 6 weeks, labeled, fully differentiated myocytes could be seen to interconnect among themselves and with native cardiomyocytes by means of intercalated discs. In sections parallel to the myofibers, full integration of new labeled myocytes with the native myofiber cells could be observed. Furthermore, the labeled myofibers were in parallel with the native, unlabeled fibers. We postulate that such supracellular structural integration was enhanced by fiber stretching during cardiac contractions, sending signals for cellular reorientation and incorporation, in which the cytoskeletal system may play an important role. CONCLUSION: We conclude that implanted precursor cells can be integrated into native myocardial structure so as to contribute to myocardial function. Direct cell-to-cell contact seems to be an important signaling mechanism, which has implications for cellular implantation strategies.
Cellular cardiomyoplasty (cell therapy for myocardial regeneration) targets the basic pathophysiology of heart failure, the irreversible loss of functional cardiomyocytes, and represents a novel means of augmenting cardiomyocyte number and contractile function of the failing heart. We discuss briefly the concept of myocardial regeneration and explore various cell types that may act as potential sources for myocardial tissue engineering.