[Aortic valve replacement with a pulmonary autograft (the Ross operation) in adult and pediatric patients. A preliminary study]. / Reemplazamiento valvular aórtico con autoinjerto pulmonar (operación de Ross), en pacientes adultos y pediátricos. Estudio preliminar.

INTRODUCTION AND OBJECTIVES: Aortic valve replacement with the patients own pulmonary autograft (the Ross procedure) is by now, the best surgical method for the replacement of the diseased aortic valve in certain groups of patients, this is particularly true for young adults and children or neonates with complex left ventricular outflow tract obstructions. The procedure was described by Donald Ross in 1967, and many years have passed. So in view of the accumulated experience the indications have extended to a wide group of patients which include children, neonates and young adults with formal contraindications for anticoagulation. In this publication we present our experience and our preliminary results in a group of fifteen patients which include adult and pediatric. MATERIAL AND METHODS: In six patients the etiology of lesion was congenital and in the remainder nine the valve had an acquired lesion. Two patients had an open heart procedure before this operation both of them to relieve an obstruction to the left ventricular outflow tract. In this group of patients the Ross procedure was carried out inserting the pulmonary autograft in the aortic position as a total root which was always reconstructed with cryopreserved pulmonary homograft, the mean homograft diameter was 26.1 +/- 4 mm (19-35). RESULTS: In all patients a transesophageal echocardiogram was performed in the operating room and postoperative, 1 or 2 months later. Only in one patient a mild aortic regurgitation was detected, no significant transaortic or transpulmonary gradients were detected postoperative. One patient was reoperated for bleeding in the postoperative course, there was no hospital mortality in our group and all the patients had an uneventful postoperative period. In the short term follow-up (41-155 days). All the patients are free of anticoagulant therapy, all them are in New York Heart Association Functional Class I. CONCLUSIONS: The patients presented in this publication which include adult and pediatric, are the first group of patients operated in our country with some excellent preliminary results. We hope that this procedure will become popular and that other surgical groups will adopt it as another surgical tool to replace a diseased aortic valve.

Anatomic and physiologic bases for the Ross procedure.

Now that the Ross procedure (RP) has been established as the best method of aortic valve replacement (AVR) in several cohorts of patients, it is appropriate to analyze the evolution, as well as the anatomic and physiologic bases for it. Reviewing the evolution of this operation, one may understand the time lapse between its inception and the universal performance of this procedure. Experimental work began as early as 1927 by Hochrein. He was followed by the Stanford group, Lower in 1960 and 1961, and Pillsbury and Shumway in 1966. Successful clinical application by Donald Ross in 14 patients, two in the mitral and 12 in the aortic positions, was accomplished in 1967. Several important developments followed, including Marcel Geens' study of the blood supply to the ventricular septum in 1971 together with the improvement in surgical results following the initial experience of Gonzalez-Lavin and Ross. Further developments included assessment of the tensile strength of the pulmonary valve (PV) by Gorczynski (1982), ability to grow by Murata (1984), a finding of low Ca++ content of the PV by Livi in 1987 and of excellent hydraulic function by Wareesena in 1994. Finally there was universal acceptance by Elkins, Duran, and others, culminating with the Ross Registry and the establishment of the Ross Colloquium by Oury et al. A review of the anatomical features of the PV are compared with those of the aortic valve (AV), including gross anatomy and relationship to the sinotubular junction, scan microscopy and anisotropic properties of both AV and PV. The blood supply to the ventricular septum will be outlined by reviewing Marcel Geens work. The hemodynamics as reported by several investigators are reviewed. The clinical evidence of growth by Elkins et al. is outlined. Based on this increasing knowledge, indications and contraindications for AVR by the RP are discussed.

Simplified method of evaluating dysfunction in St. Jude medical prosthetic heart valves.

The St. Jude medical valve is one of the most common heart valve prostheses used. More than 450,000 have been implanted. Patients with these prosthetic valves need full anticoagulation and close follow-up for life. Without adequate oral anticoagulation, thrombotic complications may develop. A simple method of evaluating the full range of motion of the valve leaflets can be attained by fluoroscopy. Fluoroscopy is easily available, non-invasive, and diagnostic. This article demonstrates early recognition of valve dysfunction due to thrombosis with fluoroscopy leading to prompt treatment.

Charles P. Bailey and Dwight E. Harken--the dawn of the modern era of mitral valve surgery.

The modern era of mitral valve surgery began in the 1940s. I acknowledge the important contributions of two of our country's outstanding pioneers, Charles P. Bailey and Dwight E. Harken. Their trials and tribulations should encourage future generations of cardiac surgeons to proceed with further developments in this field.

The substitution of arginine for glycine 85 of the alpha 1(I) procollagen chain results in mild osteogenesis imperfecta. The mutation provides direct evidence for three discrete domains of cooperative melting of intact type I collagen.

We report a case of mild osteogenesis imperfecta in a 56-year-old male undergoing aortic valve replacement surgery. The primary defect in this patient was the substitution of arginine for glycine 85 in one of the two chains of alpha 1(I) procollagen. The thermal stability of the type I collagen synthesized by the patient's cultured skin fibroblasts was examined by enzymatic digestion. Digestion of the mutant type I collagen with trypsin and chymotrypsin at increasing temperatures sequentially generated three discrete collagenous fragments, approximately 90, 170, and 230 amino acids shorter than normal type I collagen. This incremental thermal denaturation is indicative of cooperative melting blocks within the type I collagen. This is the first demonstration of such cooperative blocks of melting in intact, essentially normal post-translationally modified type I collagen. This direct evidence for cooperative melting domains of uncut type I collagen suggests that discrete blocks of amino acids function as core sites stabilizing the collagen helix. The location of mutations of the alpha chains of type I collagen relative to these discrete blocks of amino acids may influence the severity of the disease phenotype.

Thromboxane A2 receptor blockade improves contractile function following cardiopulmonary bypass in dogs and pigs.

Thromboxane A2/prostaglandin endoperoxide (TP) receptor antagonists have been reported to decrease the extent of myocardial damage after coronary ligation. The purpose of this study was to determine if the TP antagonist SQ 30,741 can protect myocardial tissue during cardiac arrest and cardiopulmonary bypass (CPB) in dogs and pigs. In the first part of the study, anesthetized dogs were subjected to normothermic CPB (37.5 degrees C) at a flow rate of 2 liters/m2/min. Dogs were treated with either 5 mg/kg + 5 mg/kg/hr SQ 30,741 or vehicle starting before CPB. The aorta was cross-clamped for 25 min and then released to allow reperfusion. In another study, pigs had hypothermic (28 degrees C) CPB but with arrest for 1 hr. Myocardial recovery was assessed by segment shortening as determined by sonomicrometry. Canine hearts treated with SQ 30,741 had a significantly improved reperfusion contractile function such that at 60 min postreperfusion, segmental shortening returned to 96% of pre-bypass levels vs 70% in vehicle-treated controls (P less than 0.05). In pigs, 70% of vehicle-treated pigs could not be weaned off CPB and died. All six pigs treated with SQ 30,741 survived. SQ 30,741 prevented platelet loss in dogs, but did not in pigs. Thus, SQ 30,741 significantly improved reperfusion function in hearts subjected to CPB.

The pericardial valve in the aortic position ten years later.

To assess the behavior of the pericardial valve at 10 years after implantation, the cases of 240 patients who had undergone aortic valve replacement with the standard Ionescu-Shiley (Shiley, Inc., Irvine, Calif.) bovine pericardial valve between February 1977 and December 1983 were reassessed. Follow-up of the 224 hospital survivors was 99.6% complete. Fifty-seven valve-related events occurred. Fourteen were thrombotic events (1.2%/patient-year), 28 were intrinsic tissue failures (2.4%/patient-year), 13 were cases of prosthetic valve endocarditis (1.1%/patient-year), and 2 were paravalvular leaks (0.17%/patient-year). The linearized rate for death, reoperation, or both resulting from valve-related events was 3.6%/patient-year. Time-related hazard function for the instantaneous risk of death and/or reoperation resulting from valve-related events demonstrated an exponential increase after 80 months. These data, in conjunction with our previous reports on the histologic changes in pericardial collagen and the incidence of calcification (26/28), should be considered regarding new and future generations of pericardial bioprostheses. Although this device provides good hemodynamics and carries a low incidence of thromboembolism, it has a limited durability. New generations of pericardial valves may have improved structural features, but the behavior of glutaraldehyde-fixed, formaldehyde-stored bovine pericardium as currently selected and prepared is unlikely to change.

Hospital death on a cardiac surgical service: negative influence of changing practice patterns.

From January 1982 through December 1985, 3,772 patients underwent a cardiac surgical procedure for coronary or acquired heart disease. Operative mortality increased from 4% in 1982 to 7% in 1985 (p less than 0.001 by chi 2 analysis). There was an increase over time of patients older than 70 years (p less than 0.001). Female patients increased from 31% in 1982 to 35% in 1985 (p less than 0.001). The percentage of patients having isolated coronary artery bypass grafting decreased from 69% in 1983 to 60% in 1985 (p less than 0.001), and hospital mortality after this procedure increased (p = 0.058). Patients requiring more complex procedures including multiple-valve operations or combined valve replacement or repair plus bypass grafting increased from 1982 through 1985 (p = 0.005). Reoperations for multiple-valve procedures or combined valve repair or replacement plus coronary artery bypass grafting also increased (p = 0.02), particularly for patients more than 70 years of age (p less than 0.001). Changing practice patterns have had a negative impact on surgical results. This evolution in cardiac surgical practice has important implications related to peer review and quality-assurance screening, diagnosis-related group reimbursement, and reporting of surgical outcomes to governmental agencies.

Mechanical testing of cryopreserved aortic allografts. Comparison with xenografts and fresh tissue.

Reports indicate that cryopreserved aortic valve allografts have a better long-term survivability than other bioprostheses, such as the porcine xenograft. Unlike xenografts, allograft valves do not require treatment with glutaraldehyde and may therefore retain much of their original mechanical function. The effects of cryopreservation on the mechanical integrity of collagen fibers and mucopolysaccharides, however, are still largely unknown. We therefore compared the mechanical behavior of cryopreserved allograft leaflet material to that of fresh tissue and xenografts by measuring their bending stiffness (nine strips of tissue) and their uniaxial tensile stress/strain and stress/relaxation behavior (six strips of each tissue type). The bending tests showed no significant difference between the pliability of cryopreserved allografts and fresh pig aortic valve tissue, but the xenograft material was significantly stiffer than both (p less than 0.001). The mean circumferential tensile elastic moduli of the allografts, fresh tissue, and xenografts at a stress of 300 kPa were 9.1 +/- 5.4 MPa, 13.0 +/- 1.7 MPa, and 12.5 +/- 3.0 MPa, respectively, and were not significantly different from each other. We also found that the transition from a low to a high modulus on the stress/strain curves, a measure of extensibility, occurs at 23%, 22%, and 12% strain for the three materials. There was no significant difference between the allograft and the fresh tissues, but the xenograft material was less extensible than the other two (p less than 0.001). The xenograft tissue also had significantly lower rates of stress relaxation than the other two materials (p less than 0.005). Thus no detectable differences were found between the mechanical behavior of the cryopreserved allograft aortic leaflets and fresh tissue, whereas the xenograft material was less extensible and less capable of relaxing than both the allograft and fresh tissue. The ability of allografts valves to respond to tensile and flexural stresses in a manner similar to that of the natural aortic valve may therefore contribute to their good in vivo survivability.