Long-term experience with the omniscience cardiac valve.

BACKGROUND AND AIMS OF THE STUDY: This study reports mortality and morbidity rates observed with the Omniscience valve prosthesis. Complication rates were calculated from a prospective, long-term follow up study of patients with the Omniscience valve prosthesis in the aortic, mitral, or both aortic and mitral positions. METHODS: The Omniscience heart valve was implanted into 200 consecutive patients (42.5% aortic valve replacement (AVR); 51.5% mitral valve replacement (MVR); 6% AVR/MVR), with an average age of 57 +/- 12 years, at the author's institution. Patients were checked regularly at a clinic which specialized in prosthetic valve follow up. Only one patient was lost to follow up during this 13-year period (99.5% completeness of follow up). RESULTS: The total follow up was 1475 patient-years (pt-yr); mean follow up 8.0 +/- 2.9 years. Survival probability at 12 years, including freedom from both early and late mortalities, was 67.1 +/- 6.7% for AVR and 62.8 +/- 6.0% for MVR patients. There were no structural valve failures. Twelve-year freedom from thromboembolism was 85.5 +/- 5.0% and 85.2 +/- 6.5% for AVR and MVR, respectively. For thromboembolism + anticoagulation-related hemorrhage, the 12-year freedom rates were 79.4 +/- 5.3% for AVR and 77.3 +/- 6.7% for MVR patients. CONCLUSIONS: The Omniscience valve demonstrated a low risk of late complications, comparable with that of other modern mechanical valves. Omniscience valve patients also exhibited excellent hematology values and good functional improvement during this long-term prospective follow up. It is concluded that the Omniscience valve has satisfactory long-term clinical performance in both the aortic and mitral positions.

Are intraaortic balloons suitable for reuse? A survey study of 112 used intraaortic balloons.

To assess the safety of reusing single-use intraaortic balloon devices (IABs), 112 used devices were investigated in terms of physical integrity, gas leakage inspection, mechanical performance, surface chemistry and morphology, and physical stability. These IABs were all used clinically only once, and the duration of the IABs in vivo ranged from 6 to 312 h. Macroscopic examination of the balloons and the outer catheters revealed no obvious change in either shape or color. No discernible abrasions or cracks were observed on the balloons. However, 61% of the balloons were creased, and 40% of the central lumens and 21% of the sheaths showed visible bending flaws. Moreover, 65% of the balloons and 38% of the central lumens were contaminated by visible residual organic debris. The physical integrity of each device was verified in a specially designed leakage-fatigue tester for 72 h. Ninety-seven percent of the devices passed the leakage inspection. Stress-strain testing, differential scanning calorimetry, attenuated total reflection-Fourier transform infrared, and scanning electron microscopy analyses clearly indicated that there were no significant differences in the mechanical properties, bulk material morphology, surface chemistry, and external surface morphology between the used balloons and virgin controls. Although some surface modifications occurred on the internal side of the balloons, the external surfaces of most balloons suffered no trauma. Most of the used IABs examined in this study maintained physical and mechanical properties similar to those of the virgin devices. The chemistry of the balloon material was stable after short-term in vivo use. However, it does not seem possible to establish a rigorous protocol of cleaning, sterilization, and inspection to guarantee a safer reuse of these devices. The presence of residual organic debris that cannot be eliminated results in an imperative preclusion not to reuse the IABs.

North American experience with the Perma-Flow prosthetic coronary graft.

BACKGROUND: The Perma-Flow prosthetic coronary graft is a 5-mm polytetrafluoroethylene tube into which is incorporated a Venturi flow restrictor. An aorto-superior vena caval fistula is created and coronary anastomoses are constructed proximal to the resistor in side-to-side fashion, where arterial pressure is maintained. From November 1992 through December 1995, eight investigational centers in North America have implanted this graft in 40 patients with inadequate autologous alternatives. METHODS: Patients were selected for inclusion in this study if coronary artery bypass grafting was required and adequate autologous conduit to complete revascularization was not available. Operative data were completed by the implantating surgeon and referred to a central center, the Minneapolis Heart Institute, for correlation. Follow-up was conducted by data coordinators at each institution, and follow-up data were obtained directly from these coordinators for inclusion in the study. RESULTS: Patient age ranged from 53 to 82 years, and 15 patients were undergoing reoperations (38%). On each Perma-Flow graft one to four coronary side-to-side anastomoses were constructed. In addition, left internal mammary artery (n = 26), greater saphenous vein (8), right internal mammary artery (4), and gastroepiploic artery (4) were used to complete revascularization. Aortic (2) or mitral valve replacement (1) was also carried out. There were seven operative deaths (18%) and two late deaths (4 and 6 months). After 1 to 37 months (mean, 13 +/- 9 months) of follow-up, 29 of 31 surviving patients are asymptomatic. Echocardiographic heart size has not increased from the postoperative value, indicating limited volume load has not affected heart size. Protocol catheterization (n = 32) in 28 patients 1 week to 1 year postoperatively revealed 7 of 73 studied coronary anastomoses (9.5%) and two distal extensions and resistors were occluded (7%). In 1 patient during sternal debridement at 1 year, no flow was found in the graft. CONCLUSIONS: The Perma-Flow graft is a useful adjunct to complete revascularization in patients with deficient autologous conduit.

A novel microporous polyurethane vascular graft: in vivo evaluation of the UTA prosthesis implanted as infra-renal aortic substitute in dogs.

A novel microporous polyurethane blood conduit developed at the University of Texas at Arlington was implanted as an infra-renal substitute in dogs. The prosthesis was fabricated by precipitating a solution of the polymer with dry nitrogen onto a rotating mandrel. The grafts were sterilized either by gamma radiation (series I) or ethylene oxide (series II); they were implanted for the following prescheduled periods: 4, 24, 48 hours, and 1 week (short-term) and 2, 4 weeks, 3 and 6 months (medium-term). The thrombohematological characteristics of each animal were evaluated prior to implantation and confirmed that the index of blood coagulability was normal. In the short-term group, five out of eight grafts were patent and three were partially occluded; four grafts in the medium-term group were patent; one was partially occluded; and three were thrombosed at retrieval. One week after implantation, the prostheses were surrounded by an external capsule, which was present mainly at the two anastomoses. The external capsule covered the entire graft at 3 months. No kinking of the grafts was observed and the presence of a mild yellow stain related to bilirubin uptake was detected at 2 weeks, 1, 3, and 6 months. Histological studies have revealed the formation of a thin internal capsule at both anastomoses, 2 weeks postimplantation, which was not anchored to the graft wall. In the medium-term group, the thrombosed grafts failed to develop an internal capsule, whereas the patent graft exhibited a thick internal capsule made of neocollagenous tissue over the entire graft. This new microporous polyurethane prosthesis did not perform satisfactorily as an infra-renal substitute in dogs and its in vivo stability requires further assessment. Thus, the concept of a polyurethane with closed pores does not achieve what was anticipated.

Spontaneous hemothorax in a patient with hereditary multiple exostoses.

A case of spontaneous hemothorax in a 7-year-old child secondary to erosion of the diaphragm by an exostosis coming from the left sixth rib is reported. This rare case of hemothorax with hereditary multiple exostoses is made even rarer by the concomitant perforation of the diaphragm.

In vivo evaluation of four chemically processed biological grafts implanted as infrarenal arterial substitutes in dogs.

Four chemically processed grafts implanted as arterial substitutes in dogs were evaluated as blood conduits in terms of patency rates, healing characteristics and biostability. Omniflow, Biopolymeric, Dardik-Biograft of the second generation and BIMA grafts were implanted as infrarenal aortic substitutes for 4, 24 and 48 h (short-term), 1, 2 and 4 wk (medium-term), 3 and 6 month (long-term), each type of graft being implanted for a complete series. The explanted grafts were evaluated macroscopically and processed for light and scanning electron microscopy. One Omniflow graft was occluded at 6 months and two Dardik-Biografts were thrombosed, one at 24 h and one at 1 month. All explanted grafts in the Biopolymeric series and in the BIMA were patent at the animals' death. Histological studies revealed frequent subintimal fibrosis in the Biopolymeric and Omniflow grafts. A peripheral inflammatory reaction was present in most grafts explanted. Scanning electron microscopy showed an aggravation of flow surface irregularities, after implantation of Omniflow, Biopolymeric and Dardik-Biograft, compared to virgin prostheses. These grafts presented an internal capsulae on the graft flow surface along the anastomoses. The capsulae slightly extended towards the centre of the graft after long-term implantation, (6 month) and corresponded to the pannus. Endothelial-like cells covered this pannus. The BIMA graft performed the most satisfactorily and retained its blood compatibility best, that is, the luminal surface was smooth with only minor thrombotic deposits and a thin pannus along the anastomotic lines.

Comparison of processed bovine internal mammary arteries and autologous veins as arterial femoral substitutes in dogs: blood compatibility and pathological characteristics.

This study was undertaken to compare the chemically processed internal mammary artery (BIMA) and the autologous femoral vein as arterial grafts. The BIMA prosthesis was implanted as a left femoral artery bypass and the femoral vein as a right femoral artery bypass graft in 27 dogs. In groups of three dogs the grafts were implanted for predetermined durations: 4, 24 and 48 hours (short term), 1, 2 and 4 weeks (medium term) and 3, 6 and 9 months (long term). All autologous veins were patent when the dogs were killed. The patency rates of the BIMA grafts were 100% in the short-term group, 67% in the medium-term group and 29% in the long-term group. The deposition of labelled fibrinogen and platelets on flow surfaces, the structural preservation of the wall of the BIMA prosthesis and accumulation of thrombi during the period of implantation were studied.

Hydrophilic polyurethane versus autologous femoral vein as substitutes in the femoral arteries of dogs: quantification of platelets and fibrin deposits.

Hydrophilic, microporous polyurethane vascular prostheses displayed good mechanical characteristics and the behaviour in vitro was excellent. The in-vivo results were, however, disappointing. To obtain a better understanding of the phenomena involved in the acute and early thrombosis, we implanted the polyurethane graft in the canine left femoral artery and an autologous femoral vein in the right for 4 and 24 h. At 4 h, one polyurethane graft was totally occluded and the other two were close to complete occlusion; at 24 h, none was patent. On the other hand, all autologous veins were patent. The thrombotic matrix incorporating both platelets and fibrinogen, quantified by labelling, was anchored along the anastomotic lines. This study confirms that polyurethane occlusion is initiated by hyperplastic reaction, but does not explain why.

A five year study of the incidence of valve-related complications with the Omniscience cardiac prosthesis.

A total of 228 Omniscience cardiac valve prostheses were implanted in 210 patients at two hospitals in Canada from November, 1979 to August, 1984. The 184 operative survivors were followed for a mean duration of 28.5 months (maximum 62.7 months) and for a total of 438 patient-years. Actuarial analysis for AVR, MVR, and all patients showed survival probabilities at five years of 97.2%, 98.9%, and 97.0% respectively. The five-year actuarial probabilities of remaining free of any thrombotic complications were 96.9% for AVR, 96.4% for MVR, and 95.7% overall. When considering only serious thrombotic complications (thromboembolism with deficit or valve thrombosis), the event-free rates are 100% for AVR, 98.9% for MVR, and 98.6% for the overall patient group at five years. These rates for survival and freedom from thrombotic complication demonstrate the clinical safety and effectiveness of the Omniscience prosthesis. In addition, there were no cases of structural failure or intrinsic mechanical malfunction of the prosthesis.

[Partial sternectomy for metastatic tumor with reconstruction using a methylmethacrylate plate]. / Sternectomie partielle pour tumeur métastatique avec reconstruction par plaque de méthylméthacrylate.

A case of partial sternectomy for metastatic thyroid carcinoma is reported. En bloc excision was followed by reconstruction using a molded plate of methylmethacrylate. Sternal tumours are rare and operations for cure of metastases are justified only if the general condition of the patient permits and in the patient with a single metastasis whose primary cancer operation was a radical one. Extensive en bloc excision is based on preoperative investigation in which computerized axial tomography has an important place in delineating the extent of the tumour and providing accurate knowledge of the margins of the section. Reconstruction with methyl-methacrylate allows a rigid setting with a material that can be molded, is radiolucent, inert and well tolerated. In the upper sternum it contributes to the stability of the shoulder girdle and protects the underlying mediastinal structures in a cosmetically acceptable way.

[Right atrial rupture caused by closed chest injury]. / Rupture atriale droite par traumatisme fermé du thorax.

A case of right atrial laceration secondary to closed chest trauma is reported. Thirteen cases treated surgically with success have previously been reported. Rupture of a cardiac chamber represents 64 p. 100 of cardiac events after closed chest trauma; the right atrium is involved in 61 p. 100 of atrial lesions, either at the auricle or at the veno-atrial junction. The diagnosis is often difficult due to the gravity of associated lesions but it should be suspected systematically. In the absence of a pericardial laceration tamponade may develop; when associated wih pericardial rupture, a recurrent hemothorax may be observed. The emergency surgery should be performed through a median sternotomy or an anterior thoracotomy. Although repair may be possible on the beating heart, cardiopulmonary bypass is extremely useful for repair and exploration of the coronary vessels in the atrioventricular groove. The prognosis depends on the rapidity of patient transport and the speed of diagnosis.

[A new simplified method for implanting temporary epicardial electrodes]. / Nouvelle méthode simplifiée d'implantation d'électrodes épicardiques temporaires.

The authors present a new simplified method for implanting temporary epicardial electrodes, which can be carried out extemporaneously during operation from a standard electrode. The modified electrode showed an improvement over the standard electrode in the myocardial thresholds with respect to milliamperage as well as voltage at both atrial and ventricular levels (p less than 0.05 for atrial and P less than 0.005 for ventricular). On the 7th day after placement the modified electrode appears to be more reliable than the standard electrode and demonstrates less degeneration of its threshold and current characteristics (P less than 0.05).