Hidroxiapatia sintética pura, hidroxiapatia sintética associada ao colágeno e hidroxiapatia sintética associada ao lipossoma como substitutos ósseos em defeitos provocados na tíbia de cäes: aspectos da osteointegraçäo à microscopia de luz transmitida / Pure synthetic hydroxyapatite, collagen associated synthetic hydroxyapatite and liposome associated synthetic hydroxyapatite as a bone substitute for defects in bone healing of dogs: transmited light microscopy osteointegration aspects

Utilizaram-se 40 cäes clinicamente sadios com o objetivo de avaliar histologicamente o efeito da hidroxipatita sintética pura (HAP-91), da HAP-91 associada ao colágeno (COL.HAP-91) e da HAP-91 associada ao lipossoma (INT.HAP-91) como substitutos ósseos em defeitos provocados na tíbia dos animais. Após protocolo anestésico, o procedimento cirúrgico constou de incisäo na face medial e no terço proximal da tíbia esquerda, com retirada de um fragmento ósseo com cerca de 10 x 6mm de tamanho. Os animais foram separados em quatro grupos de 10 cada. No grupo 1 a falha óssea foi preenchida com HAP-91, no grupo 2 com COL.HAP-91 e no grupo 3 com INT.HAP-91. O grupo quatro näo recebeu tratamento. Dois animais de cada grupo foram sacrificados nos dias 8, 30, 60, 120 e 180 de pós-operatório para coleta de material para histopatologia. Aos oito dias observou-se neoformaçäo óssea no grupo-controle e ao redor do implante nos grupos tratados com HAP-91 e INT.HAP-91. Aos 30 dias, notou-se preenchimento do defeito nos mesmos grupos, fato näo observado no grupo COL.HAP-91. Conclui-se que a cicatrizaçäo óssea ocorreu nos grupos controle e tratados com HAP-91 e INT.HAP-91, mais precoce neste último grupo. Nos animais tratados com COL.HAP-91 näo houve cicatrizaçäo completa

New devices for chronic ventricular support.

Congestive heart failure affects 5 million people in the United States with 500,000 new cases diagnosed each year. Medical and surgical therapy have helped many patients but when these options fail, heart transplantation remains the only other treatment available to help improve their condition. Heart transplantation suffers from the lack of a sufficient number of suitable donor organs, the complications of chronic immunosuppression, and many patients die while on the waiting list. A number of pulsatile and nonpulsatile cardiac assist devices are being developed to provide chronic support for patients with heart failure and to be an alternative to heart transplantation. It is estimated that as many as 60,000 patients with heart failure could be helped by mechanical devices used for chronic support. For these devices to be effective they must provide sufficient cardiac output to allow patients to perform their daily activities, have a low risk of thromboemboli, be fully implantable thereby reducing the risk of infection, and have a low incidence of device malfunction requiring part or all of the device to be replaced. In this article, we will review several new devices which have been developed over the past 5 years or so and will be in human clinical trials in the United States soon, either as a bridge or as an alternative to heart transplantation.

Pseudoabscess of the aortic root caused by ectopic seating of an aortic prosthesis.

An approach to some of the technical problems involved in aortic valve replacement includes positioning of some or all of the prosthetic ring in a position ectopic to the true aortic annulus. Such placement can create the apparent appearance of an echolucent region adjacent to the prosthetic ring that shows flow on color Doppler interrogation to suggest the presence of an abscess cavity. This case demonstrates how such a pseudoabscess can be created and the clinical and echocardiographic clues that were used to make the correct diagnosis.

Mitral, tricuspid, and aortic valve repair or reconstruction.

The term repair is most properly applied to disease affecting the mitral and tricuspid valves or their annuli. The rationale, description, and analyses of the most recent evolution in these repair techniques are reviewed. The aortic valve cannot easily be repaired in the true sense of the word. The more proper term is sparing of the aortic valve in diseases that primarily affect the aortic root and annulus or reconstruction of the valve using pericardium in disease that primarily affects the valve. The evolution and current rationale for these techniques are also reviewed, and opinions regarding their future potential are rendered.

Prognostic value of noninvasive testing one year after orthotopic cardiac transplantation.

OBJECTIVES: We sought to evaluate the prognostic value of routine noninvasive testing--stress thallium-201 imaging, rest two-dimensional echocardiography and rest equilibrium radionuclide angiography--1 year after cardiac transplantation. BACKGROUND: Coronary artery vasculopathy is the most important cause of late death after orthotopic cardiac transplantation. Several clinical variables have been identified as risk factors for development of coronary vasculopathy. Traditional noninvasive diagnostic testing has been shown to be relatively insensitive for identifying patients with angiographic vasculopathy. METHODS: Results of prospectively acquired noninvasive testing in 47 consecutive transplant recipients alive 1 year after transplantation were related to subsequent survival. Other clinical variables previously shown to be associated with the development of coronary artery vasculopathy were also included in the analysis. RESULTS: The 5-year survival rate after cardiac transplantation was 81%. By univariate analysis, echocardiography (chi-square 9.21) and stress thallium-201 myocardial perfusion imaging (chi-square 16.76) were predictive for survival, whereas rest equilibrium radionuclide angiography was not. Clinical contributors to survival were donor age (chi-square 4.56), number of human leukocyte antigen mismatches (chi-square 3.06) and cold ischemic time (chi-square 3.23). By multivariate analysis, stress myocardial imaging remained the only significant predictor of survival (risk ratio 0.27; 95% confidence interval 0.06 to 0.89). CONCLUSIONS: Normal thallium-201 stress myocardial perfusion imaging 1 year after cardiac transplantation is an important predictor of 5-year survival.

Optimal timing of coronary artery bypass graft surgery after acute myocardial infarction.

BACKGROUND: To assess optimal timing for coronary artery bypass graft surgery (CABG) after an acute myocardial infarction (AMI), all patients undergoing CABG without associated procedures at our institution from January 1, 1991, to July 30, 1992, were reviewed. Patients were divided into three groups based on time from infarct to revascularization. The control group consisted of patients operated on for angina refractory to medical management. Relative risks (incident infarction group divided by incident control group) were established for need of vasopressors, new balloon to separate from bypass, perioperative myocardial infarction, and hospital mortality. METHODS AND RESULTS: One hundred sixteen patients underwent CABG within 6 weeks of infarction. In the experimental group, 58 patients underwent CABG for non-Q-wave infarction, and 58 patients underwent CABG for Q-wave infarction. In the control group, 255 patients underwent surgery for angina without infarction. Patients were analyzed by group relative to the time between infarction and CABG. Patients were analyzed between infarction and CABG and assigned to one of three groups. Group 1 patients were revascularized within 48 hours; group 2, between 3 and 5 days; and group 3, after 5 days. Significance was determined by Fisher's exact or Mantel-Haenszel chi 2 test where appropriate. Multivariate analysis was performed on statistics that were significant. All patients within all groups after Q-wave or non-Q-wave myocardial infarction had a significantly higher risk of needing an intra-aortic balloon pump and vasopressors to be weaned from bypass and a greater incidence of perioperative MI compared with control patients. Surgical mortality is highest immediately after Q-wave infarctions. CONCLUSIONS: Patients with non-Q-wave infarction may undergo CABG relatively safely at any time. Acceptable timing for CABG after Q-wave infarction is after 48 hours.

Optimal timing and indications for cholecystectomy in cardiac transplant patients.

Cardiac transplant is performed with increasing frequency as the treatment for end-stage cardiac disease. Although cholelithiasis is more frequent in both pretransplant and posttransplant patients, no standard management approach exists. Because many such patients are cared for outside the transplant center, it is important that general surgeons develop an appropriate strategy to manage this entity. We present our experience with 11 patients from our institution who underwent cholecystectomy before or after cardiac transplantation. In addition, we have reviewed the 76 reported cases of cholecystectomy performed in precardiac or postcardiac transplant patients from centers throughout the world. Any procedure in this patient group requires critical consideration in regard to the timing and type of procedure. Pretransplant patients are well recognized cardiac risks, and posttransplant immunosuppressed patients are at considerable risk for septic complications. Six patients underwent cholecystectomy prior to heart transplant. Five were performed laparoscopically, one as an open procedure. We also report five laparoscopic cholecystectomies in patients after cardiac transplant. One patient in the pretransplant group died 7 days after surgery from an uncontrollable arrhythmia. There were no hemodynamic or septic complications in either group. Current summated experience (87 cases) indicates that the mortality rate for urgent cholecystectomy in the posttransplant group is at least 36%. Because the first presentation of gallstones in this population is often acute cholecystitis, asymptomatic calculi cannot be considered benign. Elective cholecystectomy, laparoscopic or open, is tolerated well both before and after transplant. Given these facts, it seems reasonable to recommend pretransplant screening and posttransplant surveillance for gallstones.(ABSTRACT TRUNCATED AT 250 WORDS)

New frontiers in heart transplantation. Clinical applications of basic research and new surgical approaches.

The growing understanding of alloimmune responses may help elucidate the mechanisms a novel immunomodulatory strategies, affording insights into new single or combination regimens. These insights are currently elusive because of the number of immuno-suppressive agents and techniques, the array of possible organ transplants, and the variety of experimental in vitro and in vivo models in diverse species. These possibilities add a bewildering level of complexity to the usual therapeutic problems of selecting drug doses, vehicles, routes, and schedules of administration. Although the results of in vitro assays have been used as indices of alloreactivity, they show only inconsistent correlations with clinical events. Only stringently controlled in vivo studies in rodents, large animals models, and humans will determine which agents or procedures represent real improvements over conventional therapy. The results of preclinical transplantation models and initial clinical trials suggest that immunosuppression for transplant patients is likely to evolve into various combination regimens. It appears now that there will be a choice between cyclosporine and FK506 as baseline immunosuppression because clinical experience has shown that these two drugs cause excessive nephrotoxicity when used in combination. Ideally the combination of additional new agents will enable the doses of cyclosporine and FK506 to be lowered to levels that are nonnephrotoxic and at the same time minimize or completely eliminate the need for corticosteroids and anti-T cell antibody therapy. The diverse mechanisms of immunosuppressive action of the new drugs under investigation certainly offer the hope for creative and effective strategies for the control of many forms of graft rejection in the near future.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved ultrastructural lung preservation with prostaglandin E1 as donor pretreatment in a primate model of heart-lung transplantation.

Donor pretreatment with prostaglandin E1 as a pulmonary vasodilator has developed as a simple, effective means to provide excellent preservation in heart-lung transplantation. This study was undertaken to investigate the degree of ultrastructural preservation of the lung with prostaglandin E1 and other pulmonary vasodilators in a primate heart-lung transplantation model. Heart-lung transplantation was performed in 14 African green monkeys. Donor cardiac preservation was achieved with cold crystalloid cardioplegic solution (10 ml/kg). Lung preservation was achieved with cold, modified Euro-Collins solution delivered into the main pulmonary artery (60 ml/kg total). Vasodilator agents were administered intravenously 15 minutes before aortic crossclamping. The heart-lung grafts were stored at 4 degrees C for 6 hours. Three groups of animals were studied: five donors with prostaglandin E1 (0.1 to 4.0 micrograms/kg per minute), five donors with prostacyclin (0.1 to 0.35 micrograms/kg per minute), and four donors with nitroprusside (0.8 to 5.0 micrograms/kg per minute). After transplantation, arterial blood gas measurements and lung biopsies were performed at 1- and 3-hour intervals. Five formalin blocks per specimen were sectioned for hematoxylin and eosin staining. Cellular preservation and endothelial cell swelling were evaluated with electron microscopy. The specimens were graded for alveolar hemorrhage, endothelial cell swelling, and cellular preservation (grade 0, minimal, to grade 3, severe) and a mean score was obtained for each preservative agent. Prostaglandin E1-treated specimens demonstrated the least amount of endothelial swelling (mean score of 1.0) compared with prostacyclin- and nitroprusside-treated specimens (mean scores of 1.4 and 2.7, respectively). All nitroprusside-treated specimens demonstrated moderate to severe endothelial cell swelling. Interstitial and alveolar hemorrhage was noted in poorly preserved specimens, but there were no significant differences between groups. We conclude that prostaglandin E1 provides improved cellular preservation by decreasing the extent of endothelial cell swelling as observed on electron microscopy.

Pulmonary artery balloon counterpulsation: safe after peripheral placement.

Pulmonary artery balloon counterpulsation is a promising experimental technique for treatment of right ventricular failure. However, clinical application has been limited in that the only device presently available (the large-volume intraaortic balloon) must be placed within a synthetic graft. Because a balloon with a smaller volume (which could be placed through a peripheral vein and be contained entirely within the pulmonary artery) would make the technique feasible on a wider scale, we tested an 8-mL pulmonary artery balloon placed through the femoral vein in 12 dogs. Two groups of animals were compared. One group had the pulmonary artery balloon in place but not counterpulsating; the other had the pulmonary artery balloon in place and counterpulsating. Each group was studied for 12 hours. A variety of hemodynamic parameters were measured. Effective diastolic augmentation and systolic unloading were noted in all 6 dogs that underwent counterpulsation (5.0 +/- 1.1 mm Hg of diastolic augmentation and 9.5 +/- 1.6 mm Hg of systolic unloading). Pulmonary function, as measured by arterial blood gas sampling and pulmonary vascular resistance, was not impaired. Examination of the heart and lungs showed no detrimental pathologic effects of pulmonary artery balloon counterpulsation. Placement of the balloon through a peripheral vein with a guidewire was easy and uncomplicated. We conclude that pulmonary artery balloon counterpulsation is safe over an extended period of 12 hours in the canine model and that diastolic augmentation and systolic unloading can be produced.

Method of single-lung transplantation in the absence of a left atrial cuff.

A method used clinically for anastomosing the pulmonary veins to the left atrium, in the absence of a left atrial cuff, during single-lung transplantation by reconstructing the atrium with pericardium is described. Postoperative ventilation/perfusion scans show normal pulmonary blood flow.

Mechanical circulatory support decreases neurologic complications in the treatment of traumatic injuries of the thoracic aorta.

The surgical treatment of traumatic injuries of the thoracic aorta is controversial because a number of technical approaches have been recommended. Despite the technique employed, spinal cord ischemia continues to be a persistent problem. Nineteen patients with confirmed aortic injuries secondary to blunt trauma were treated at the Yale-New Haven (Conn) Medical Center from 1984 to 1991. The patients were analyzed in two groups: group 1 (n = 10) underwent repair using mechanical circulatory support and group 2 (n = 9) underwent repair without mechanical circulatory support. Sixteen patients survived. Three patients died of complications of multiple trauma. The groups were comparable with respect to aortic cross-clamp time, preoperative systolic blood pressure, and Injury Severity Score. Three patients in the nonmechanical support group developed neurologic complications (P less than .05). No patient in the mechanical support group had a neurologic complication. We believe that mechanical circulatory support reduces the incidence of neurologic complications following traumatic injuries of the thoracic aorta and should be used whenever clinically feasible.

Heart-lung transplantation: initial experience in New England.

Between May 1988 and June 1989, five combined heart-lung transplants were performed. There were two males, age 16 and 19 years, and three females age 33, 34, and 19 years. Three patients had primary pulmonary hypertension, one had cystic fibrosis, and the fifth had doxorubicin-induced cardiomyopathy with associated pulmonary hypertension. All patients were severely restricted in functional capacity and were oxygen-dependent. Four grafts were distantly procured (ischemic times 1:15, 2:35, 2:45, 3:45); one was procured on-site (ischemic time 0:58). Four of five grafts functioned well (PO2 on FIO2 30% postoperatively: 102, 120, 180, and 129 torr). One graft (distantly procured with an ischemic time of 1:15) showed total failure of oxygenation secondary to fluid overload during donor surgery; the recipient could not be weaned from cardiopulmonary bypass. All patients were extubated 24 to 30 hours postoperatively. Rejection episodes have been infrequent and all have been successfully treated with pulse steroids. Four of the five patients are alive and well with normal cardiopulmonary function and normal functional capacity 15, 12, 8, and 6 months after surgery. Heart-lung transplantation is an effective therapy for properly selected patients with end-stage cardiopulmonary disease resulting from a variety of primary disorders.

Management of postoperative bleeding after tonsillectomy.

Tonsillectomy is a safe operative procedure today, but hemorrhage remains a continuing problem. Excessive bleeding requires prompt attention by the surgeon and immediate treatment. Should local measures to control bleeding fail, external carotid artery ligation may be a life-saving procedure.

Effects of reperfusion after acute coronary occlusion on the beating, working heart compared to the arrested heart treated locally and globally with cardioplegia.

To determine whether acutely ischemic myocardium could be more effectively salvaged by reperfusion on cardiopulmonary bypass (CPB) in the cardioplegia-treated heart than with reperfusion in the beating, working heart, 52 greyhound dogs underwent 3 hours of left anterior descending (LAD) occlusion and were randomly assigned to one of four groups. In Group I (19 dogs) the LAD occlusion was released at 3 hours and reperfusion continued in the beating, working heart for an additional 3 hours. Group II (six dogs), Group III (14 dogs), and Group IV (13 dogs) were placed on CPB and underwent 45 minutes of hypothermic ischemic arrest protected by aortic root potassium cardioplegia. In Group II, only aortic root potassium cardioplegia was given; in Group III, the ischemic area was perfused with potassium cardioplegic solution via a graft from the internal mammary artery (IMA) to the LAD. In Group IV, blood cardioplegic solution via the IMA-LAD graft was used. After the cross-clamp and local occlusion were removed, CPB was discontinued after an additional 45 minutes and reperfusion was continued off CPB for an additional 1 1/2 hours (total 6 hours). The ischemic area at risk was determined by injecting monastryl blue dye via the left atrium while the LAD was briefly reoccluded. After the animal had been sacrificed and the left ventricle had been sectioned, the area of myocardial necrosis was determined by nonstaining with triphenyltetrazolium chloride (TTC). For each group, the ratios of area of necrosis/area at risk (AN/AR) were calculated and postreperfusion arrhythmias were documented. Postreperfusion arrhythmias were noted in 11 of 12 animals in the beating, working heart group and only two of 24 in the combined CPB groups. The mean AN/AR was 66% +/- 2% in the beating, working heart (Group I), 59% +/- 6% after infusion of potassium cardioplegic solution into the aortic root (Group II), 57% +/- 6% with blood cardioplegia (Group IV), and 38% +/- 6.5% after global and local application of the potassium cardioplegic solution into the ischemic area (Group III). This study suggests that the reperfused ischemic myocardium will sustain less necrosis and less postreperfusion arrhythmias when the heart is protected by global and local cold potassium cardioplegia on CPB.