Traditionally patients with pulmonary atresia, ventricular septal defect, diminutive or absent central pulmonary arteries, and multiple aortopulmonary collaterals have been managed by staged procedures necessitating multiple operations. We have taken a different approach to this lesion. Between August 1992 and March 1994, ten patients aged 1.43 months to 37.34 years (median 2.08 years) at the severe end of the morphologic spectrum of this lesion underwent a one-stage complete unifocalization and repair from a midline sternotomy approach. The median Nakata index of true pulmonary arteries was 50.0 (range 0 to 103.13) and they provided vascular supply to up to nine lung segments (median 5 segments). The number of collaterals per patient ranged from two to five with a median of four. The collaterals provided vascular supply to a median of 15 lung segments per patient (range 11 to 20). Complete unifocalization was achieved in all patients with emphasis on native tissue-to-tissue connections via anastomosis of collaterals to other collaterals and to the native pulmonary arteries. In only one patient (37.34 years old) was it necessary to use a non-native conduit for peripheral pulmonary artery reconstruction. The ventricular septal defect was left open in one patient (5 years old) because of diffuse distal hypoplasia and stenosis of the pulmonary arteries and the collaterals. The postrepair peak systolic right ventricular/left ventricular pressure ratio ranged from 0.31 to 0.58 (median 0.47). There were no early deaths. Complications were bleeding necessitating reexploration in one patient, phrenic nerve palsy in three patients, and severe bronchospasm in three patients. Follow-up (median 8 months, range 2 to 19 months) was complete in all patients. One patient was reoperated on for pseudoaneurysm of the central homograft conduit and then again for stenosis of the left lower lobe collateral. After this last operation at 13 months after the initial repair she died of a preventable cardiac arrest caused by pneumothorax. The patient with open ventricular septal defect underwent balloon dilation of the unifocalized pulmonary arteries, with a current pulmonary/systemic flow ratio of 1.4 to 1.8:1, and is awaiting ventricular septal defect closure. One other patient underwent balloon dilation of the reconstructed right pulmonary artery, with a good result. All survivors (9/10) are clinically doing well. This approach establishes normal cardiovascular physiology early in life, eliminates the need for multiple systemic-pulmonary artery shunts and use of prosthetic material, and minimizes the number of operations required.(ABSTRACT TRUNCATED AT 400 WORDS)

In utero placement of aortopulmonary shunts reproduces the aberrant hemodynamic state of children with cogenital heart disease with left-to-right shunts; postnatal pulmonary hypertension, increased pulmonary blood flow, and vascular remodeling. In addition, the lambs have a unique paradoxical increase in pulmonary vascular volume that attenuates an increase in pulmonary vascular resistance. This experimental preparation provides a useful and consistent model for the study of the pathogenesis of pulmonary hypertension.

Annuloplasty is the cornerstone of surgical mitral valve repair. A percutaneous transvenous catheter-based approach for mitral valve repair was tested by placing a novel annuloplasty device in the coronary sinus of sheep with acute ischemic mitral regurgitation. Mitral regurgitation was reduced from 3-4+ to 0-1+ in all animals (P < 0.03). The annuloplasty functioned by reducing septal-lateral mitral annular diameter (30 +/- 2.1 mm preinsertion vs. 24 +/- 1.7 mm postinsertion; P < 0.03). These preliminary experiments demonstrate that percutaneous mitral annuloplasty is feasible. Further study is necessary to demonstrate long-term safety and efficacy of this novel approach.

To investigate early endothelial function associated with increased pulmonary blood flow, vascular shunts were placed between the ascending aorta and main pulmonary artery in 18 late-gestation fetal sheep. Four weeks after delivery, the lambs were instrumented to measure vascular pressures and blood flows, and blood was collected to measure plasma concentrations of guanosine 3',5'-cyclic monophosphate [cGMP, the second messenger to nitric oxide (NO)-mediated vasodilation] and L-arginine (the precursor for NO synthesis). The responses to the endothelium-dependent vasodilators acetylcholine (ACh, 1.0 microgram/kg) and ATP (0.1 mg.kg-1.min-1), the endothelium-independent vasodilators M & B-22948 (a cGMP-specific phosphodiesterase inhibitor, 2.5 mg/kg) and inhaled NO (40 ppm), and N omega-nitro-L-arginine (an inhibitor of NO synthase, 5 mg/kg) were then compared with responses in 12 age-matched controls. Vasodilator responses in control lambs were determined during pulmonary hypertension induced by U-46619 (a thromboxane A2 mimic). Shunted lambs displayed a selective impairment of endothelium-dependent pulmonary vasodilation, an augmented pulmonary vasoconstricting response to NO synthase inhibition, increased plasma cGMP concentrations, and decreased L-arginine concentrations. Taken together, these data suggest that lambs with pulmonary hypertension and increased pulmonary blood flow have early aberrations in endothelial function, as manifested by increased basal NO activity, that cannot be further increased by agonist-induced endothelium-dependent vasodilators.