From January 1978 to December 1988, 109 phrenic nerve paralyses (PNP) occurred in a total of 9149 cardiac operations performed in a population of patients younger than 15 years old (1.2%) whose age varied from 1 day to 15 years old and mean weight was 11.3 +/- 8.7 kg. PNP was diagnosed in 43 patients after closed procedures (1.2% of 3509 procedures) and in 66 patients after open heart operations (1.2% of 5640 operations). PNP was right sided in 49 cases and left sided in 60 cases. Open heart operations that predisposed to PNP were those which needed harvesting of autologous pericardium (P less than 0.0001) and wide exposure of the great vessels. The modified right Blalock-Taussig shunt was the main cause of PNP in closed procedures (P less than 0.02). Small children tolerated PNP less well. They needed longer ventilatory support (P less than 0.0005) and developed more respiratory complications. Seventeen children underwent plication of the affected hemidiaphragm and could be subsequently extubated. It is concluded that for prevention of PNP, a high level of attention should be exercised in neonates and small children, particularly when pericardium is harvested or when exposure needs extensive dissection of the great vessels and thymus resection, or at reoperation. We also prefer to avoid the use of iced slush lavage. PNP, when symptomatic, is best managed by continuous positive airway pressure (CPAP) ventilation. Diaphragmatic plication is recommended when after 2-3 weeks there is no recovery of diaphragmatic function or when there are troublesome respiratory complications.
In 45 young dogs an enlargement angioplasty of the left pulmonary artery was performed using patches made from one of three autologous materials (jugular vein, unmodified pericardium, and glycerolized pericardium) or from two heterologous materials (lyophilized human dura mater and modified bovine carotid artery). Catheterization and angiographic studies performed 5 to 6 months after the operation showed that all patched vessels had remained patent, except in three dogs which had received heterologous implants. The animals were killed 5-24 months after operation (mean weight increase: 84%), and the implants were studied by optical microscopy and morphometry, scanning and transmission electron microscopy, and indirect immunofluorescence with antidog Factor VIII rabbit antiserum. The two heterologous tissues exhibited limited biocompatibility, as estimated from 10 criteria obtained at histologic studies. Conversely, all three autologous biomaterials were characterized by infiltration of noninflammatory cells, near-complete endothelialization, and neosynthesis of structural proteins; infectious foci were very rare or absent. These results suggest that autologous tissues, although deendothelialized at the time of implantation, constitute the most suitable material for patch angioplasty, as far as endothelial triggering, cellularity and resistance to infection are concerned.
The study of collagen fibers by X-ray diffraction, utilizing semiquantitative indices for appraisal of "structuration" and "orientation" was applied to 30 aortic valve grafts. These grafts, of pig origin, were studied in the fresh state, after tanning with aldehydes, and after having been implanted in patients for at least 18 months. It was shown that the collagen fibers are preferentially orientated parallel to the transverse axis of the valve cusps, and that this arrangement, enhanced by tanning, had a tendency to disappear in the post-implantation samples. The structuration index which concerns the fibril network was also augmented by tanning, and was found a little high or slightly diminished in post-implantation cusps. Evidence for a new compound, probably fibrin, was found in the diffraction patterns of implanted cusps, but crystallized calcium was noticeably absent.
Seventy-six patients, with a mean age of 11.6 years, presenting with congenital subvalvar aortic stenosis were operated upon between 1965 and 1979. Seventy had moderate subvalvular stenosis. Eighty-eight percent had myotomy combined with resection of the obstruction. Five patients (6.6%) died postoperatively. Of 48 survivors followed up between 6 months to 13 years postoperatively (mean 4.2 years), 4 underwent reoperation and 2 of them died. Survival at 5 years and 10 years was 96% and survival without reoperation at 5 years and 10 years was 91%. When last seen, 90% of the patients were asymptomatic, left ventricular hypertrophy on ECG had disappeared in 63%. No patient had atrioventricular block. Two thirds of the patients had no systolic thrill and of 13 patients recatheterized (3.2 years follow-up) 9 had a peak systolic gradient below 50 mmHg. If, postoperatively 60% of the patients had aortic insufficiency versus 31% preoperatively for the whole period, this percentage fell to 33% after 1976. As subaortic stenosis is a progressive disease and late surgical results are correlated to preoperative peak systolic gradient, early surgery is recommended. Close postoperative follow-up is needed since recurrence of aortic stenosis is possible (and acquired aortic insufficiency may persist).
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