Electrophysiologic changes during acute rejection of heterotopically transplanted rat hearts.

Noninvasive monitoring of heart allograft rejection was performed by electrophysiologic techniques using an implanted electrode located on the epicardial surface of the heterotopic transplanted heart of rats. R wave and slew rate determinations were performed daily in 30 syngeneic and 66 allogeneic transplants. These determinations were later compared with histopathologic studies of the transplanted hearts. R wave and slew rate values of allogeneic or rejecting hearts were found to decrease significantly compared with syngeneic or nonrejecting hearts on the days studied. This noninvasive electrophysiologic method may be a promising method for monitoring heart allograft rejection.

Warm ischemic time tolerance after ventilated non-heart-beating lung donation in piglets.

OBJECTIVE: The availability of lungs for transplantation could be ameliorated with the use of organs retrieved from ventilated non-heart-beating donors (VNHBD). The aim of this work is to determine the limit to tolerable in situ warm ischemia time (WIT) for lung grafts after circulation is stopped. METHODS: Twenty piglets underwent left lung allotransplantation. Animals were randomly allocated based on the donor's status before lung harvesting into the following study groups: Sham (n = 5), Heart-beating donors-non-warm ischemia; I-30 (n = 5), I-60 (n = 5) and I-90 (n = 5), VNHBD-WIT of 30, 60 and 90 min, respectively. Right pulmonary artery and bronchus were permanently occluded one hour after transplantation. Assessment of pulmonary function was monitored hourly by hemodynamic, oxygenation and pulmonary mechanic measurements during a period of 6 h after reperfusion. Lung grafts were weighed pre- and post-transplantation. RESULTS: Cold ischemic time was similar for all groups, and averaged 80.1+/-2.7 min. Final mean lung weight was significantly greater in VNHBD (92.5+/-3.1 g vs. Sham values 75.6+/-2.4 g, P < 0.01). After right lung exclusion, hemodynamic changes consisted of a sustained increase in pulmonary vascular resistance and a reduction in cardiac output. Lung mechanics also modified, with a rise in airway resistance and a fall in compliance. CONCLUSIONS: Post-transplantation lung graft function from VNHBD with up to 90 min of WIT, is equivalent to those achieved by grafts harvested after heart-beating donation. This method may be a promising strategy of increasing the pulmonary donor pool.

Does a critical hemodynamic situation develop from right ventriculotomy and free wall infarct or from small changes in dysfunctional right ventricle afterload?

An experimental model for right ventricle free wall infarct associated with double ventriculotomy and tricuspid insufficiency was created to evaluate whether right ventricle failure can cause profound refractory heart failure or whether modifications in right ventricular afterload are more influential in this regard. In our model, the left ventricle, interventricular septum and right atrial wall were maintained intact and pulmonary banding made it possible to modify right ventricular afterload during the experiment. The results of our study showed that pure right ventricular failure does affect the hemodynamic state negatively, but it is not itself, a cause of death in dogs. A slight increase in the dysfunctional right ventricular afterload produced a profound deterioration in the hemodynamic state that required pulmonary artery debanding within no more than 10 minutes.

Reduced-size lung transplantation from adult to neonatal swine.

BACKGROUND: Lung donor shortage is a critical factor limiting the expansion of pediatric lung transplantation programs. This report details the surgical technical feasibility of a training model of lobar lung transplantation as well as the perioperative monitoring to evaluate the appropriate pulmonary graft function. METHODS: Ten hybrid Large-White pigs underwent left lower lobe lung allotransplantation; Donors weighed 15 to 20 kg and recipients 5 to 7 kg. The first five animals were used to learn the surgical anatomy and to establish the surgical technique and instrumentation's model (Group A). One hour after transplantation the right lung was excluded. Lung function and hemodynamic data were collected sequentially in the following five animals (Group B). RESULTS: The left inferior pulmonary lobe was found to be the most suitable allograft for transplantation. Usually, bronchial size discrepancy allowed telescoping of the airway anastomosis. Left atrial clamping was well tolerated during the pulmonary vein anastomoses. Preoperative antiaggregation and postoperatively heparinization achieved with ACT values over 200 seconds, prevented left atrial thrombosis. After right lung exclusion, hemodynamic changes consisted of a sustained increase in pulmonary vascular resistance and a reduction in cardiac output. Lung mechanics were also modified, with a gradual rise in airway resistance and a fall in compliance. CONCLUSIONS: The neonatal pig tolerates left lobar pulmonary transplantation satisfactorily. Although it is a useful and promising surgical learning model, questions remain regarding the applicability of this experience to clinical pediatric lung transplantation.

[Physiological mode of pacing in pediatrics]. / Estimulación fisiológica en pediatría.

The concept of physiologic pacing is often primarily to involve the preservation of atrioventricular synchrony. Nevertheless, specially in children there are other mechanisms different than atrial filling to improve cardiac output such as heart rate increase with exercise. Taking as physiologic pacing those modes of pacing improving hemodynamic condition of the patient we must add to the DDD, the DDDR and SSIR modes of pacing. In this report our experience with 70 consecutive children paced in physiological mode of pacing is described: 51 in SSIR mode, DDD in 16, and DDDR in 3 cases. In five out of the 16 cases with DDD mode it was found an unidirectional crosstalk and in two atrial sensing failure (failure rate with DDD of 47.75% at 48 months of follow-up). In 26 children with rate responsive pacing by means of activity sensing a treadmill exercise test according to Bruce protocol was performed found a significant increase in both, heart rate and maximal work capacity, associated to an improvement in the clinical status and no evidence of arrhythmias in any case. In conclusion, rate responsive pacing by means of activity sensing in children is an adequate, reliable and effective physiological mode of pacing.

[Surgery of congenital cardiopathies without catheterization: initial experience with 141 consecutive cases]. / Cirugía de las cardiopatías congénitas sin cateterismo: experiencia inicial con 141 casos consecutivos.

Our initial experience with surgical treatment of congenital heart disease in 141 consecutive cases without the need of hemodynamic study is described. Ages ranged between 1 day and 15 years; 39 cases under 1 months of age (23 in the first week of life), 38 between 1 and 12 months, and 64 above 1 year of age. Diagnosis were: ductus 32 cases, atrial septal defect 24, Fallot's tetralogy 14, aortic coarctation 13, complete AV canal defect 7, D-transposition of the great arteries 5, ventricular septal defect 6, pulmonary atresia with intact ventricular septum 5, aortic stenosis 3, tricuspid atresia 4, pseudotruncus 2, univentricular heart 2, atrial myxomas, 2, Fallot's like 3, other type of congenital heart defect 19 cases. There was an adequate correlation between eco-2D images and anatomic-surgical findings. In conclusion, we think that a great percentage of cases affected of congenital heart disease should be considered for surgery without the need of a hemodynamic and angiocardiographic study.

[The 2-chambered right ventricle with an anomalous muscle bundle]. / Ventrículo derecho bicameral por banda anómala.

The clinical picture, course, electrocardiogram and chest X-Ray of 30 patients with the angiocardiographic diagnosis of double-chambered right ventricle, along with the echocardiogram in 18 and surgical results in 26 are analyzed. A ventricular septal defect was associated in most of the patients, that had spontaneous closure in some of them. The clinical picture and serial catheterization in some cases suggested progressive obstruction of the right ventricular outflow tract. In this, as in most of the reported series, the history, physical examination, ECG and roentgenogram were inconclusive for diagnosis of this entity. Two-dimensional echocardiography was the most reliable non invasive method to assess this malformation, even superior to catheterization in some aspects. The angiocardiographic findings are quite distinctive, allowing differentiation of other types of subpulmonary stenosis. In order to achieve a good surgical result is essential a precise diagnosis of this malformation and of the associated anomalies. The long-term prognosis was good as in most of the reported series.

[The treatment of the tracheobronchial stenosis by extracorporeal circulation]. / Tratamiento de las estenosis traqueo-bronquiales mediante circulación extracorpórea.

Six children with tracheobronchial stenosis secondary to cardiovascular ring were operated with extracorporeal surgery. Three of them with pulmonary sling had a tracheobroncoplasty with costal cartilage, one with xiphoides appendix and another with pericardio. One girl 2 years old was operated resecting three tracheal rings and anastomosis end to end. The child that was operated with pericardio died with infection and sepsis three months after the operation. The other five are well five, four and two years after plasty.