RESUMEN
A 29-year-old gravid female presented at 22 weeks gestation with an acute Type I aortic dissection and coarctation of the aorta. She underwent emergent repair of her aortic dissection using cardiopulmonary bypass and hypothermia. At 25 weeks gestation, she underwent repair of her coarctation of the aorta. The patient had a cesarean delivery of a viable, normal male infant at 39 weeks gestation.
Asunto(s)
Aneurisma de la Aorta Torácica/cirugía , Coartación Aórtica/cirugía , Disección Aórtica/cirugía , Complicaciones Cardiovasculares del Embarazo/cirugía , Adulto , Cesárea , Femenino , Humanos , Recién Nacido , Masculino , Embarazo , Reoperación , ToracotomíaRESUMEN
The Norwood stage I procedure is often used for the initial treatment of infants with hypoplastic left heart syndrome. This procedure creates a systemic arterial to pulmonary artery shunt to establish pulmonary blood flow. We describe a method to facilitate placement of this shunt by attaching a polytetrafluoroethylene shunt to a pulmonary artery homograft patch before performing the median sternotomy. This technique facilitates the performance of the proximal shunt anastomosis and expedites the procedure.
Asunto(s)
Procedimientos Quirúrgicos Cardíacos/métodos , Síndrome del Corazón Izquierdo Hipoplásico/cirugía , Anastomosis Quirúrgica/métodos , Implantación de Prótesis Vascular/métodos , Humanos , Politetrafluoroetileno , Arteria Pulmonar/cirugíaRESUMEN
BACKGROUND: Recent reports have demonstrated successful early outcomes using mitral valve homografts in adults. We report our early results after homograft mitral valve replacement in 4 children with previous atrioventricular septal defects, previous placement of a prosthetic valve, and rheumatic valvular disease. METHODS: Between May 1996 and June 1997, 4 children (ages 5, 11, 13, and 15 years) underwent mitral valve replacement with cryopreserved mitral valve homografts at our institution. Preoperative echocardiography confirmed moderately severe to severe mitral regurgitation, stenosis, or both in all 4 patients. RESULTS: Successful homograft valve replacement was achieved in all 4 patients. Based on symptoms, physical examinations, and echocardiographic follow-up, all four homograft mitral valves are functioning well with normal hemodynamics. None of these patients are receiving warfarin. Follow-up has been limited to 10 months. CONCLUSIONS: In children requiring mitral valve replacement, the use of mitral valve homografts offers advantages over prosthetic valves, such as the avoidance of complications associated with thrombosis and anticoagulation. Homograft mitral valve replacement is technically feasible in children with congenital and rheumatic heart disease and previous prosthetic valves.
Asunto(s)
Insuficiencia de la Válvula Mitral/cirugía , Válvula Mitral/trasplante , Adolescente , Niño , Preescolar , Femenino , Humanos , Trasplante Homólogo , Resultado del TratamientoRESUMEN
The effect of chronic hypoxia on neonatal myocardial metabolism remains undefined. With a new neonatal piglet model, we determined changes in myocardial metabolism during global ischemia after chronic hypoxia. Five-day-old piglets (N = 30) were randomly assigned to two groups and exposed to an atmosphere of 8% oxygen or to room air for 28 days before they were killed. Left ventricular myocardium was then analyzed at control and at 15-minute intervals during 60 minutes of global normothermic ischemia to determine high-energy phosphate levels, glycogen stores, and lactate accumulation. Time to peak ischemic myocardial contracture was measured with intramyocardial needle-tipped Millar catheters as a marker of the onset of irreversible ischemic injury. Results showed an initially greater level of myocardial adenosine triphosphate in the hypoxic group (27 +/- 1.2 vs 19 +/- 1.8 micromol/gm dry wt, p = 0.001) and a delay in adenosine triphosphate depletion during 60 minutes of global ischemia compared with the control group. Initial energy charge ratios (1/2 adenosine diphosphate + adenosine triphosphate/adenosine monophosphate + adenosine diphosphate + adenosine triphosphate) were also greater in the hypoxic group (0.96 +/- 0.01 vs 0.81 +/- 0.04, p = 0.01) and remained so throughout global ischemia. Initial glycogen stores were greater in the hypoxic group (273 +/- 13.3 vs 215 +/- 14.7 micromol/gm dry weight, p = 0.02) when compared with the control group. Lactate levels in the hypoxic group were initially higher (19.1 +/- 6.4 vs 8.9 +/- 3.1 micromol/gm dry weight, p = 0.001) compared with control levels and remained elevated throughout 60 minutes of ischemia. Time to peak ischemic contracture was prolonged in the hypoxic group (69.5 +/- 1.8 vs 48.9 +/- 1.4 minutes, p = 0.001) compared with the controls group. These data show that chronic hypoxia results in significant myocardial metabolic adaptive changes, which in turn result in an improved tolerance to severe normothermic ischemia. These beneficial effects are associated with elevated baseline glycogen storage levels and an accelerated rate of anaerobic glycolysis during ischemia.
Asunto(s)
Hipoxia/metabolismo , Miocardio/metabolismo , Función Ventricular Izquierda , Animales , Animales Recién Nacidos , Enfermedad Crónica , Modelos Animales de Enfermedad , Glucógeno/análisis , Contracción Miocárdica , Miocardio/química , PorcinosRESUMEN
Biomaterials exposed to blood often fail due to thrombosis. Gas nuclei (air) in the material are thrombogenic and a potential cause of failure. The effects of gas nuclei on patency and blood flow were studied in 4 mm diameter arterial grafts (Gore ePTFE; Johnson and Johnson Vitagraft ePTFE; Bard ACG EXS) in the femoropopliteal position of dogs. Control and denucleated (air-free) grafts were implanted bilaterally. Grafts were denucleated by immersion in degassed saline and exposure to 4 torr vacuum and 3,000-20,000 psig pressure. Graft patency was determined at harvest in 46 dogs. Blood flow was measured with acoustic flow probes in eight dogs. Denucleated graft patency was 60% after 2 days of implant while control patency was 22% (P < .05). Measured blood flow was higher in denucleated grafts than in control grafts (P < .02) in 4 of 5 dogs which had significantly different flows. Patency and flow decreased to zero for both control and denucleated grafts over periods of up to 80 days. Air in the control grafts may have been absorbed within several days, leading to late similarity with the denucleated grafts. Thus, removing the air from 4 mm ePTFE grafts decreased acute thrombosis and increased the patency.
Asunto(s)
Materiales Biocompatibles , Prótesis Vascular , Arteria Femoral/cirugía , Grado de Desobstrucción Vascular , Animales , Perros , Arteria Femoral/fisiología , Tereftalatos Polietilenos , Politetrafluoroetileno , Flujo Sanguíneo Regional , Factores de TiempoRESUMEN
The Argon Beam Coagulator uses radiofrequency energy to excite argon gas that may be used for ventricular ablation. The effects of power level and number of applications of the Argon Beam Coagulator were compared wtih cryothermia. Ten mongrel dogs underwent cardiac extirpation. The endocardial surfaces of 5 hearts were used for the creation of lesions using the Argon Beam Coagulator at five power levels with either one or two applications. Five hearts were used for endocardial and epicardial lesions using cryothermia (15-mm-diameter probe at -70 degrees C) for 1, 2, 3, or 4 minutes. The Argon Beam Coagulator lesions showed an increase in depth with increasing power levels (2.25 +/- 1.05 mm at 50 W to 6.64 +/- 0.75 mm at 150 W) and number of applications (maximum depth of 6.64 +/- 0.75 mm with one application, 11.2 +/- 1.1 mm with two applications). Cryothermia lesions were similar in depth regardless of duration or site of application (range, 6.1 to 10.2 mm). Both techniques resulted in homogeneous and well-demarcated lesions. These data show that the Argon Beam Coagulator results in discrete endocardial lesions, which may be created quickly and reproducibly. This may be a useful alternative for the operative ablation of endocardial scar in the treatment of ventricular tachycardia.
Asunto(s)
Criocirugía/instrumentación , Endocardio/cirugía , Ventrículos Cardíacos/cirugía , Coagulación con Láser/instrumentación , Animales , Perros , Endocardio/patología , Ventrículos Cardíacos/patología , Miocardio/patología , NecrosisRESUMEN
U74006F is a new 21-amino steroid (lazaroid) that prevents lipid peroxidation without glucocorticoid or mineralocorticoid side effects. Reperfusion injury has been reduced by the addition of various free radical scavengers and antiperoxidants to the reperfusate. To assess the effect of U74006F on reperfusion of donor hearts subjected to prolonged hypothermic ischemia, 21 isolated canine hearts were divided into three groups: control (group 1), drug (2 mg/kg) injected into the oxygenated blood perfusate immediately before 4 hours of preservation (group 2), and drug (2 mg/kg) injected 1 hour before heart isolation and again 15 minutes before reperfusion (group 3). After control left ventricular function studies (with an intraventricular balloon) and biopsy for high-energy phosphates and dry/wet ratios, the hearts were arrested with cold cardioplegia and cooled for 4 hours then reperfused for 3 hours. Left ventricular work was calculated by systolic and diastolic pressure curves, which showed a better return of function in group 3 hearts (1625, 2150, and 3493 mm Hg/ml in groups 1, 2, and 3, respectively, at 180 minutes of reperfusion; p = 0.02). This was likely the result of improved diastolic compliance in group 3. Dry/wet ratios showed increased tissue edema in all hearts at the end of reperfusion. Although high-energy phosphate concentrations were not different between groups, adenosine was best preserved in group 3 (p = 0.03), suggesting reduced washout of this precursor. In conclusion, administration of U74006F before preservation and reperfusion may be useful for donor heart protection.
Asunto(s)
Trasplante de Corazón/fisiología , Corazón/efectos de los fármacos , Peróxidos Lipídicos/antagonistas & inhibidores , Daño por Reperfusión Miocárdica/prevención & control , Pregnatrienos/farmacología , Nucleótidos de Adenina/metabolismo , Animales , Soluciones Cardiopléjicas , Perros , Miocardio/metabolismo , Preservación de Órganos/métodos , Factores de Tiempo , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
Currently available ventricular assist devices are technically difficult to implant, require continuous anticoagulation, and are associated with hemorrhagic and thromboembolic complications. Direct mechanical ventricular actuation is a biventricular assist device that can be applied in 3 to 5 minutes through a left anterior thoracotomy and has no direct blood contact or need for anticoagulation. The present study was designed to determine the effects of direct mechanical ventricular actuation in total biventricular circulatory support. Cardiogenic shock refractory to standard therapy developed in 2 patients awaiting cardiac transplantation. Direct mechanical ventricular actuation was applied and provided immediate hemodynamic stabilization in both. All inotropic agents and intraaortic balloon support were then discontinued. Fifty-six hours of circulatory support bridged the first patient to successful cardiac transplantation without complication. The patient is alive and well more than 1 year later without incident of infection or rejection. The second patient suffered cardiac arrest and required closed chest cardiopulmonary resuscitation before device application. After 45 hours of support, it was determined that irreversible neurologic injury had occurred and direct mechanical ventricular actuation was discontinued. Neither patient's native heart exhibited any histologic evidence of device-related trauma. Direct mechanical ventricular actuation has undergone limited clinical investigation since its original description 25 years ago, but in these initial trials, the device has proved effective. The concept of mechanically actuating the ventricles appears to be a valuable, yet under-utilized method of total circulatory support.
Asunto(s)
Trasplante de Corazón , Corazón Auxiliar , Choque Cardiogénico/terapia , Presión Sanguínea , Gasto Cardíaco , Femenino , Insuficiencia Cardíaca/complicaciones , Insuficiencia Cardíaca/terapia , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/complicaciones , Infarto del Miocardio/terapia , Miocardio/patologíaRESUMEN
This study assessed myocardial ischemia after resuscitation from cardiac arrest using direct mechanical ventricular actuation (DMVA) or cardiopulmonary bypass (CPB). Myocardial ischemic tolerance was better after DMVA resuscitation. Resuscitation using DMVA, when compared with CPB, may improve outcome when subsequent coronary artery bypass grafting (CABG) is required.
Asunto(s)
Puente Cardiopulmonar/instrumentación , Reanimación Cardiopulmonar , Paro Cardíaco/fisiopatología , Corazón Auxiliar , Hemodinámica/fisiología , Daño por Reperfusión Miocárdica/fisiopatología , Animales , Perros , Ventrículos Cardíacos/fisiopatologíaRESUMEN
Direct mechanical ventricular actuation (DMVA) is a unique non-blood-contacting biventricular assist device that provides circulatory support during ventricular fibrillation without demonstrating adverse effects on the myocardium. The purpose of this study was to assess the preservation of myocardial energy stores and myocardial responses to ischemia after circulatory support during ventricular fibrillation with direct mechanical ventricular actuation versus cardiopulmonary bypass. Twenty adult mongrel dogs were randomized to receive circulatory support with either cardiopulmonary bypass or direct mechanical ventricular actuation. After 4 hours of ventricular fibrillation, hearts were defibrillated and left ventricular transmural biopsies were obtained. Hearts were then excised and subjected to 90 minutes of normothermic total ischemia. Serial biopsies were obtained at 15-minute intervals to determine regional depletion of high energy phosphates. The time-to-peak ischemic contracture was recorded by using needle-tipped Millar catheters placed in the left ventricular endocardium, epicardium, septum, and right ventricle. Time-to-peak ischemic contracture of the endocardium (62.6 +/- 1.4 vs. 58.8 +/- 1.0 minutes, p less than 0.05) and septum (61.1 +/- 6.9 vs. 46.9 +/- 6.2 minutes, p less than 0.004) were significantly prolonged after direct mechanical ventricular actuation versus cardiopulmonary bypass, respectively. Similar trends were noted in the epicardium and right ventricular regions; however, these differences were not statistically significant. Left ventricular adenosine triphosphate (ATP) levels were better preserved after direct mechanical ventricular actuation (22 +/- 1.5 mumols/g dry wt) compared with cardiopulmonary bypass (17 +/- 1.9 mumols/g dry wt). The depletion of left ventricular endocardium ATP during normothermic ischemia was significantly delayed after direct mechanical ventricular actuation compared with cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Puente Cardiopulmonar , Corazón Auxiliar , Fibrilación Ventricular/terapia , Adenosina Trifosfato/metabolismo , Animales , Circulación Asistida/métodos , Circulación Coronaria/fisiología , Perros , Metabolismo Energético , Contracción Miocárdica/fisiología , Miocardio/metabolismo , Fibrilación Ventricular/fisiopatologíaRESUMEN
The ideal method for the preservation of donor hearts for transplantation is unclear. To assess the optimal temperature for donor myocardium preservation, the recovery of isolated canine hearts (n = 20) exposed to 4 hours of either standard ice-chest hypothermia (0-4 degrees C) or constant moderate hypothermia (12 degrees C) were compared. Functional and metabolic data were acquired before hypothermia and every 30 minutes during 3 hours of reperfusion with oxygenated blood. Mean end-systolic pressure-volume slopes were 2.11 +/- 0.06 and 2.09 +/- 0.06 mm Hg/ml for ice-chest hypothermia and constant moderate hypothermia, respectively (p = NS), which were unchanged from control. All y intercepts during reperfusion were decreased compared with control (p = 0.002) without any differences between groups. End-diastolic pressures were greater than control throughout the reperfusion period for both groups (p = 0.02), but there was a difference in change of end-diastolic pressures with time between groups (p = 0.04). Dry/wet ratios were similar after preservation and reperfusion in both groups. ATP recovered to control levels during reperfusion for both groups although energy charge ratios were greater for hearts exposed to constant moderate hypothermia (p = 0.007). These data indicate that intracellular energy stores are well maintained by preservation using either technique. Changes in function appear to be related to altered compliance irrespective of preservation temperature. These data suggest that a wide range of temperatures may be acceptable for donor heart preservation.
Asunto(s)
Frío , Corazón , Preservación de Órganos/métodos , Animales , Perros , Hipotermia Inducida/métodos , Reperfusión Miocárdica , Miocardio/metabolismo , Factores de Tiempo , Función Ventricular Izquierda/fisiologíaRESUMEN
The disadvantages of blood/interface interactions and difficult installation are common to current circulatory support devices. Direct mechanical ventricular actuation (DMVA) is a method of biventricular cardiac massage that avoids contact of blood with various surfaces. The purpose of this study was to compare hemodynamic responses and organ perfusion between DMVA and cardiopulmonary bypass (CPB). Twenty adult mixed-breed dogs randomized for DMVA or CPB were anesthetized with alpha-chloralose. During 4 hours of ventricular fibrillation, animals received either DMVA or CPB with aortic arch perfusion (90 to 120 ml/kg/min), bicaval venous return, and full left ventricle venting. Hemodynamics and organ perfusion were assessed by multivariant analysis of variance with repeated measures. Blood flow was similar to normal sinus rhythm (control) with either method; however, average CPB flows (control, 110%) were increased significantly over DMVA flows (control, 75%) (p = 0.016). The resulting mean arterial pressures were significantly greater during DMVA (control, 66%) compared to CPB (control, 49%) (p = 0.0011). Radiolabeled microspheres were the measure of organ perfusion during sinus rhythm and at 2 and 4 hours of circulatory support. Myocardial blood flow was equal to control in all regions during DMVA; CPB resulted in increased flows to the left ventricular epicardium, septum, and right ventricle. DMVA generated significantly greater flows to the renal cortex. All other organs demonstrated similar perfusion with either method. However, CPB displayed declining cerebral flows at 4 hours compared to DMVA (42% vs 55% control, respectively). Overall, DMVA provided hemodynamic stability equal to that of CPB. Rapid application and avoidance of blood/surface contact make DMVA a favorable method of temporary circulatory support.
Asunto(s)
Circulación Asistida/métodos , Puente Cardiopulmonar , Hemodinámica , Animales , Análisis Químico de la Sangre , Fenómenos Fisiológicos Sanguíneos , Temperatura Corporal , Perros , Flujo Sanguíneo RegionalRESUMEN
From 1979 to 1989, 18 patients were seen in the Electrophysiology Service, Duke University Medical Center, with automatic atrial tachycardia. There were 8 male and 10 female patients with a mean age of 28.1 +/- 2.9 years. Electrophysiological mapping localized automatic foci to right atrial sites (14 patients) and left atrial sites (4 patients). Depending on origin of the focus, patients were further diagnosed as having either chronic ectopic atrial tachycardia or inappropriate sinus tachycardia. Of the 15 patients with chronic ectopic atrial tachycardia, 6 responded to medical treatment; in 9, the tachycardia was not adequately controlled. Six of them were referred for surgical intervention. All 3 patients with inappropriate sinus tachycardia underwent operative therapy. In the surgical group of patients with chronic ectopic atrial tachycardia, all 6 had a tachycardia-induced cardiomyopathy with ejection fractions ranging from 14% to 27% (mean ejection fraction, 21% +/- 2.7%). Surgical techniques used (alone or in combination) included an isolation procedure in 1 patient, cryoablation in 4 patients, and excision of atrial appendages or portions of atrial free walls in 7. Normal sinus rhythm developed in all surgical patients except 1 patient who had intractable congestive heart failure preoperatively and died of this condition and stroke. The overall success rates for medical and surgical therapy were 33.3% and 88.9%, respectively (p less than 0.01). Long-term follow-up was possible for 7 (87.5%) of 8 patients 3 to 7 years after operation. All patients with chronic ectopic atrial tachycardia were cured, but only 1 of 3 patients with inappropriate sinus tachycardia was in sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Taquicardia Atrial Ectópica/cirugía , Taquicardia Sinusal/cirugía , Taquicardia Supraventricular/cirugía , Adolescente , Adulto , Enfermedad Crónica , Criocirugía , Electrocardiografía , Femenino , Estudios de Seguimiento , Atrios Cardíacos/patología , Atrios Cardíacos/cirugía , Humanos , Masculino , Persona de Mediana Edad , Nodo Sinoatrial/cirugía , Taquicardia Atrial Ectópica/diagnóstico , Taquicardia Atrial Ectópica/tratamiento farmacológico , Taquicardia Atrial Ectópica/patología , Taquicardia Sinusal/diagnóstico , Taquicardia Sinusal/tratamiento farmacológico , Taquicardia Sinusal/patologíaRESUMEN
Direct mechanical ventricular actuation (DMVA) is a non-blood-contacting method for biventricular support. To compare effects of DMVA and cardiopulmonary bypass (CPB), 13 swine were supported by DMVA or CPB during 4 hours of ventricular fibrillation. Hearts were then rapidly excised and sectioned into right ventricular (RV) and left ventricular (LV) free wall slabs and subjected to total normothermic ischemia. Time to peak ischemic contracture (TIC) of LV endocardium (endo), LV epicardium (epi) and RV were determined using Millar needle transducers. Mean TIC was compared between DMVA (n = 6), CPB (n = 7), and control (n = 18). Significant decreases in LV endo TIC were found after DMVA (53.3 +/- 3.3 min) and CPB (56.2 +/- 2.4 min) compared with control (62.5 +/- 1.0), p less than 0.05. Myocardial blood flow was measured using microspheres during normal sinus rhythm and after 2 and 4 hr of circulatory support. Nonsignificant decreases in endo flow occurred during CPB and DMVA compared with control. LV endo adenosine triphosphate (ATP) levels (mumol/g dry weight) were significantly decreased after DMVA (9.0 +/- 2.5) and CPB (4.0 +/- 2.7) compared with control (17.8 +/- 0.6), p less than 0.05. Although CPB maintained mean arterial pressure by increased pump flows (mean, 129 ml/kg/min) and LV intracavitary pressures were kept below 5 mmHg with LV venting, resulting endo flows and ATP levels were decreased. DMVA generated decreased cardiac outputs (mean, 67 ml/kg/min) under these vasodilated states, yet maintained endo flow and ATP levels as well as CPB. These experimental data show that different mechanisms of myocardial perfusion and metabolism result from CPB and DMVA.