PubMed Health⌕ Search

Biomedical subjects

R Di Donato

Publications and source records attributed to R Di Donato.

At least 19 recordsLinked to original sources
PubMed2003

Numerical simulation of a realistic total cavo-pulmonary connection: effect of unbalanced pulmonary resistances on hydrodynamic performance.

Total cavo pulmonary connection (TCPC) is one of the surgical techniques adopted to compensate the failure of the right heart in pediatric patients. The main goal of this procedure is the realization of a configuration for the caval veins and for the pulmonary arteries that can guarantee as low as possible pressure losses and appropriate lung perfusion. Starting from this point of view, a realistic TCPC with extracardiac conduit (TECPC) is investigated by means of Computational Fluid Dynamics (CFD) to evaluate the pressure loss under different pressure conditions, simulating different vessel resistances, on the pulmonary arteries. A total flow of 3 L/min, with a distribution between the inferior vena cava (IVC) and the superior vena cava (SVC) equal to 6/4, was investigated; three different boundary conditions for the pressure were imposed, resulting in three simulations in steady-state conditions, to the right pulmonary artery (RPA) and to the left pulmonary artery (LPA), simulating a balanced (deltaP(LPA-RPA) = 0 mmHg) and two unbalanced pulmonary resistances to blood flow (a pressure difference deltaP(LPA-RPA) = +/- 2 mmHg, respectively). The geometry for the TECPC was realized according to MRI derived physiological values for the vessels and for the configuration adopted for the anastomosis (the extra-cardiac conduit was inclined 22 degrees towards the left pulmonary artery with respect to the IVC axis). The computed power losses agree with previous in vitro Particle Image Velocimetry investigations. The results show that a higher resistance on the LPA causes the greater pressure loss for the TECPC under study, while the minimum pressure loss can be achieved balancing the pulmonary resistances, subsequently obtaining a balanced flow repartition towards the lungs.

Child↗
PubMed2001

Aortopulmonary window coexisting with tetralogy of Fallot.

Aortopulmonary window is a rare cardiac malformation presenting either in the isolated form, or in association with other cardiac anomalies. The isolated form usually presents an increased pulmonary blood flow as the main clinical feature, but if associated with other cardiac anomalies the clinical findings change according to the additional defect. Only 19 cases of aortopulmonary window associated with tetralogy of Fallot have been reported. Five of them have associated pulmonary atresia. We report two neonatal cases of aortopulmonary window and tetralogy of Fallot, one of them presenting an associated pulmonary atresia.

Aortopulmonary Septal Defect↗
PubMed2001

Pulmonary atresia with ventricular septal defect: prevalence of deletion 22q11 in the different anatomic patterns.

BACKGROUND: Pulmonary atresia with ventricular septal defect (PA-VSD) is one of the most common cardiac defects associated with DiGeorge syndrome. The pattern of the pulmonary circulation determines the complexity of this type of heart disease. The aim of this study was to establish the prevalence of DiGeorge syndrome with deletion 22q11 in patients with simple and complex PA-VSD. METHODS: Since 1993 we have studied 128 consecutive patients affected by PA-VSD. In 90 of our patients the PA-VSD was considered "simple" (group I), because it was not associated with any other cardiac defects. In the other 38 children the PA-VSD was considered "complex" (group II) owing to the presence of heterotaxia, tricuspid atresia, a double-inlet left ventricle, transposition of the great arteries and congenitally corrected transposition of the great arteries. RESULTS: In group I, 38 patients (42%) had genetic syndromes or major extracardiac anomalies; deletion 22q11 was detected in 31% of cases. Major aortopulmonary collateral arteries were present in 50% of group I patients and in 57% of those with deletion 22q11. In group II, 10 patients (26%) had genetic syndromes or major extracardiac anomalies but none had deletion 22q11 (p < 0.005); in no case was the presence of major aortopulmonary collateral arteries observed (p < 0.005). CONCLUSIONS: PA-VSD is an anatomically and morphogenetically heterogeneous disease: in the setting of DiGeorge syndrome or velocardiofacial syndrome, PA-VSD is associated with a peculiar cardiac pattern and is due to deletion 22, whereas in case of nonsyndromic PA-VSD or when this disease is associated with different syndromes or with other types of cardiac defects, it is due to other morphogenetic mechanisms.

Child Welfare↗
PubMed2001

A mathematical model of the fetal cardiovascular system based on genetic algorithms as identification technique.

The development of fetal cardiac surgery, considered the ultimate goal in the treatment of congenital cardiac malformations, needs to be supported by detailed knowledge of the blood circulation in the fetal cardiovascular system. The hemodynamic behavior in distal territories is usually inferred from vessel resistance indices, which give limited physiological information. This study presents a mathematical model of the human fetal global cardiovascular system, developed to clarify the relationships and differences existing between upper and lower body circulation. We modelled the heart with two time-varying capacitances, each representing the respective ventricle's pressure-volume relationship. The fetal vascular system was represented using two six-element Windkessel models, for the upper and lower body respectively. We obtained the identification of the set of circuital and elastance function parameters of the model using Genetic Algorithms (GAs), which follow the laws of evolutionary theory. We compared the results of our numerical study on the model identified with data collected from measurements and literature, to validate the proposed global cardiovascular system model of the human fetus. This model is intended as an instrument to investigate the differences in blood distribution between the different vascular districts in the upper and lower fetal body and the role of the aortic isthmus, the small tract of vessel connecting upper and lower fetal vascular beds; it may also represent a useful tool in the assessment of dynamic balance during mechanical assistance of circulation.

Algorithms↗
PubMed2000

Heterotaxy with left atrial isomerism in a patient with deletion 18p.

We report on a female infant with partial deletion of the short arm of chromosome 18 (del 18p) and heterotaxy with left atrial isomerism. Congenital heart defect (CHD) is found in 10% of the literature reports. Interestingly, situs abnormalities have been diagnosed in four patients with del 18p, including ours. This finding could imply that a locus or loci involved in the development of normal body situs lies within this chromosomal region. Del 18p must be consid- ered when evaluating a patient with phenotypic anomalies and CHD in lateralization defects.

Chromosome Deletion↗
PubMed2000

Elevated plasma homocysteine concentrations after pediatric heart transplantations.

Graft coronary artery vasculopathy is the main cause of late morbidity and mortality in cardiac allograft recipients. A high plasma homocysteine (hcy) concentration is now generally accepted as a risk factor for coronary arteriosclerosis, but little information exists for the pediatric age group. We therefore explored the potential role of hcy and antioxidants in 31 pediatric allograft recipients. We found hcy concentrations to be significantly higher in recipients than in control. Hcy continued to rise within the first 2 postoperative years. Vitamin A and E concentrations were significantly lower in transplant patients. Hyperhomocysteinemia was significantly more common in patients with complications than in those without. Our findings suggest that pediatric allograft recipients experience oxidant stress, as highlighted by the high plasma levels of Hcy and the low concentrations of vitamins A and E. Nutritional supplementation may be indicated to lower plasma hcy and to reduce oxidant stress.

Adolescent↗
PubMed1999

Deletion 22q11 in patients with interrupted aortic arch.

In our series of 27 children with various types of interruption of the aortic arch (IAA), deletion 22q11 is prevalent in patients with simple IAA type B, and is absent in patients with IAA type A and in those with associated additional major cardiac defects. Anomalies of the infundibular septum should be considered a characteristic aspect of children with IAA and deletion 22q11.

Abnormalities, Multiple↗
PubMed1992

Early identification of patients at risk for sinus node dysfunction after Mustard operation.

We studied 60 patients who had survived the Mustard procedure for transposition of the great arteries, performed between the ages of 2 days and 24 months (mean 4.51 +/- 3.79). All patients were given a postoperative 24-hour dynamic electrocardiogram at 15 days, 1 year and 3 years and then every 2 years. Those who were found to have sinus node dysfunction during follow-up, were given a dynamic electrocardiogram every 3-6 months. The average follow-up period was 38.7 +/- 19.8 months, median 36. Sinus node dysfunction was detected during follow-up in 20 patients (33.3% of the total), 8 of whom had had a pacemaker inserted. Risk factors for late development of sinus node dysfunction were found to include prolonged cross-clamping of the aorta during surgery (P = 0.003), especially over 50 minutes (relative risk 3.5:1), and the presence of even transient sinus node dysfunction after surgery (P = 0.006). These observations suggest, first, that sinus node dysfunction may develop after the Mustard operation as a combined effect of extensive atrial surgery and a long period of myocardial ischemia and, second, that the presence of the disease immediately after the operation sometimes indicates that it will recur or persist during follow-up.

Arrhythmias, Cardiac↗
PubMed1992

Ductus arteriosus in pulmonary atresia with and without ventricular septal defect. Anatomic and functional differences.

The pulmonary circulation is dependent on the ductus arteriosus in all patients with pulmonary atresia and intact ventricular septum and in some with pulmonary atresia and ventricular septal defect (tetralogy of Fallot type). To assess the time of ductal closure in these two patient categories, we compared the ages at first operation in 58 patients with pulmonary atresia and intact ventricular septum and 32 with pulmonary atresia and septal defect. The age distribution differed significantly between the groups. Whereas 90% of the children with intact ventricular septum required surgery in the first week of life, 50% of those with ventricular septal defect underwent surgery after the first month and 25% after the third month. The previously described and now confirmed anatomic differences of ductus arteriosus or different levels of endogenous prostaglandins may explain persistent patency of the ductus in pulmonary atresia with ventricular septal defect. The phenomenon may have important clinical implications regarding the timing and choice of surgical procedure.

Abnormalities, Multiple↗
PubMed1992

[Anomalous insertion of the mitral valve. A rare form of subaortic obstruction in children].

Among different anatomical causes of subaortic obstruction, anomalous attachment of the mitral valve on ventricular septum is one of the rarest. We report our experience with 4 such cases of subaortic obstruction. Their age at first observation ranged between 1 and 6 months. All patients had viscero-atrial situs solitus, levocardia and normal atrio-ventricular and ventriculo-arterial connections. None had associated cardiac septal defects. Cases with atrio-ventricular canal were excluded. All patients showed a systolic ejection murmur and electrocardiographic features of left ventricular hypertrophy; 3 presented congestive heart failure in the first 3 months of life. Diagnosis was made by 2D-echocardiography and cardiac catheterization in 3 patients and intraoperatively in 1. Only in the last 2 patients, correct diagnosis was made at the initial 2D-echocardiographic examination. Due to left ventricular hypertrophy, in the first 2 patients hypertrophic obstructive cardiomyopathy was originally suspected. One patient died intraoperatively during attempted transaortic resection of subaortic obstruction. Other 2 patients underwent left ventricle-aortic conduit implantation. Of these 2 patients, 1 died 3 months later for sepsis and the other was reoperated upon 3 years later for mitral valve replacement and conduit take-down, with good clinical result. The fourth patient is waiting for surgical intervention. Subaortic obstruction due to anomalous attachment of the mitral valve on ventricular septum may present with early congestive heart failure; the best diagnostic tool is 2D-echocardiography. Left ventricle-aortic conduit may represent a surgical alternative to transaortic resection.

Aortic Stenosis, Subvalvular↗
PubMed1990

Percutaneous balloon valvuloplasty of pulmonary valve stenosis, dysplasia, and residual stenosis after surgical valvotomy for pulmonary atresia with intact ventricular septum: long-term results.

Eight-six children (aged 20 days to 14 years, 20 under age 1 year) underwent 94 percutaneous balloon valvuloplasty for pulmonary valve stenosis. The patients were divided into three groups: typical pulmonary valve stenosis (71), pulmonary valve dysplasia (9), and residual stenosis after surgical valvotomy for pulmonary atresia with intact ventricular septum (PAIS) (6). Each of the three groups was divided into two subgroups. In the early cases, balloon catheters with diameter 10-20% exceeding pulmonary valve annulus were used and the drop of the gradient was 39.5%. In the later cases, balloon diameters 30-40% greater than the valve anulus or double balloons were used and a drop of 66.7% in the RV-PA pressure gradient was achieved. The dilation in patients with dysplastic valve and residual stenosis after surgical valvotomy for PAIS was less effective. Doppler echocardiography was the technique used to evaluate residual gradient. Six months to 4 years follow-up demonstrated a persistent decrease of the valve gradient.

Adolescent↗