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Biomedical subjects

A R Castaneda

Publications and source records attributed to A R Castaneda.

At least 91 records · Page 5Linked to original sources
PubMed1986

Cardiac output estimates in the pediatric intensive care unit using a continuous-wave Doppler computer: validation and limitations of the technique.

We compared the cardiac index obtained by means of a continuous-wave Doppler computer with simultaneous thermodilution measurements in 25 children in the pediatric intensive care unit (40 observations). The aortic diameter was measured at various levels to determine which provided the best measure of cardiac index. The Doppler measurements were performed independently by a physician trained in Doppler cardiography and by a nurse with no experience in echocardiography. Both the nurse and physician obtained high-quality flow velocity recordings in all patients in a mean time of 5 minutes or less. Cardiac index and total systemic vascular resistance measured by means of Doppler and thermodilution techniques were highly correlated (r = 0.86 and r = 0.93, respectively). The highest correlation was obtained when Doppler cardiac index was computed by means of the internal diameter measured at the aortic anulus. There was no significant difference between the nurse's and physician's measurements. We conclude that cardiac index can be accurately determined in the pediatric intensive care unit by means of continuous-wave Doppler computer, even when operated by personnel not trained in Doppler cardiography.

Cardiac Output↗
PubMed1986

Transthoracic intracardiac monitoring lines in pediatric surgical patients: a ten-year experience.

A study of 6,690 transthoracic intracardiac monitoring (TIM) catheters in 5,666 pediatric patients undergoing cardiac surgical procedures during a 10-year period demonstrates the safety of this monitoring method. The utility of TIM catheters in patients undergoing a modified Fontan procedure, those undergoing repair of tetralogy of Fallot, and those with elevated or labile pulmonary resistance is stressed. Right atrial (RA) and left atrial (LA) catheters are particularly safe; they have a low incidence of bleeding complications (RA = 0%, LA = 0.13%) and retention complications (RA = 0.15%, LA = 0.63%). Pulmonary artery (PA) catheters that are introduced through the right ventricular infundibulum have higher complication rates (1.07%); unpredictable hemodynamic compromise occurs in approximately 0.5% of such patients. PA catheters placed through the wall of the atrium have a lower complication rate-approximately equal to that for RA and LA catheters. The benefits of TIM catheters far outweight the associated risks if care is exercised in placing and removing them, and if complications are rapidly recognized and aggressively managed. The continued use of TIM catheters in pediatric cardiac surgical patients is therefore strongly recommended.

Cardiac Catheterization↗
PubMed1986

Complete atrioventricular canal and tetralogy of Fallot: surgical considerations.

A review of 13 autopsy specimens and of 13 patients who were operated on for complete atrioventricular (AV) canal and tetralogy of Fallot between 1975 and 1985 revealed a number of anatomical details that are important in the successful repair of this combined lesion. A bridging anterior leaflet was present in 25 hearts. A septum primum was present and attached to leaflet tissue in 13. In all 26, a ventricular septal communication was present beneath the bridging anterior leaflet and extended anteriorly, but in 14 there was no ventricular septal defect underneath the posterior leaflet. Additional pathological features included the following: leaflet tissue deficiency (4 hearts), single left papillary muscle (3), accessory valve orifice (4), and left ventricular (4) or right ventricular (RV) (1) dominance. All 26 had infundibular stenosis, and 10 had hypoplastic pulmonary annuli. One had pulmonary atresia, and 6 had branch pulmonary artery stenosis. Surgical technique was modified to include incision of the septum primum in 7. Because of rightward displacement of the anterior ventricular septum and also to minimize the risk of causing subaortic stenosis, the bridging anterior leaflet was divided more toward the tricuspid orifice so as to parallel the crest of the ventricular septum. Transannular RV outflow patches were used in 10 patients, and a right ventricle-pulmonary artery conduit was placed in 1 patient. Three required repair of branch pulmonary artery stenosis. There were no hospital deaths. Three patients died late of residual AV valve regurgitation and branch pulmonary artery stenosis (2) and sepsis (1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Biological sealants and knitted Dacron: porosity and histological comparisons of vascular graft materials with and without collagen and fibrin glue pretreatments.

Woven Dacron used in extracardiac conduits tends to form a poorly adherent, obstructing layer of pseudointima. Knitted high-porosity conduits allow fibrous and vascular ingrowth and more secure anchoring of the pseudointima. However, at the time of insertion, the porosity rate must be sufficiently low to prevent excessive bleeding in the heparinized patient. Pretreatments with biological sealants are available to temporarily reduce the porosity of knitted Dacron at the time of implantation with subsequent resorption of the sealant. We compared in vitro water porosity rates of knitted Dacron pretreated with conventional techniques, fibrin glue, and collagen impregnation. Only the collagen-impregnated and fibrin glue-treated grafts decreased the porosity of knitted Dacron to an acceptable level. To assess the biocompatibility and resorption of biomaterials used in sealing conduits, pretreated Dacron was implanted subcutaneously in weaning rats. Foreign-body response of untreated Dacron was unchanged by conventional techniques. Fibrin glue also resulted in good capillary ingrowth as well as occasional punctate multifocal deposits of calcium phosphate. The collagen-impregnated grafts differed in the intensity of the inflammatory response and tissue adhesion, possibly related to the degree of collagen cross-linking. This may have important implications regarding structure of the pseudointima in vascular grafts sealed with these materials.

Biocompatible Materials↗
PubMed1986

Valve replacement in children less than 5 years of age.

Between 1966 and 1984, there were 63 children less than 5 years of age who underwent 70 valve replacements (49 mitral [5 repeat], 6 aortic, 11 tricuspid [systemic ventricle; 2 repeat]), 2 tricuspid [pulmonary ventricle] and 1 multiple [mitral-aortic]) at Children's Hospital. Tissue valves were used in 20%. Since 1980, only Björk-Shiley and St. Jude valves have been used. The most common indication for valve replacement was mitral regurgitation after repair of atrioventricular (AV) canal (34%). Mortality dropped considerably over time: 76% before 1979, 33% from 1979 to 1982 and 22% since 1982. More than two-thirds of fatalities were operative deaths, usually within 3 days of surgery. Actuarial survival curves for those operated on since 1980 predict 1 and 5 year survival of 73 and 51%, respectively. For the 46 operative survivors 1 and 5 year valve survival was 97 and 70%, respectively. Postoperative hemodynamics were significantly improved on elective postoperative catheterizations. All but one patient with non-tissue valves received anticoagulant therapy. Postoperative complications included thromboembolism (1.6/100 patients-years) and hemorrhage (0.8/100 patient-years). The frequency of intravascular hemolysis and endocarditis was 1.6%, comparable with adult experience. Complete heart block requiring a pacemaker developed in nine patients (14.1%), in all after AV valve replacement. Valve replacement in young children generally results in considerable hemodynamic improvement. The mortality rate remains above that observed in adults but has declined considerably for those operated on after 1980.

Actuarial Analysis↗
PubMed1986

First-stage palliation of hypoplastic left heart syndrome. The importance of coarctation and shunt size.

After Norwood's initial report of successful first-stage palliation of hypoplastic left heart syndrome in neonates, an improved understanding of both the pathologic anatomy and physiology of this common condition has led to improving surgical results. Twenty-five neonates have been treated by modifications of the Norwood procedure, and the early mortality between January, 1984, and July, 1985, has been 24% (six deaths). Two premature neonates weighing less than 2 kg died, as did two neonates who could not be resuscitated with prostaglandin E1 and had cardiac arrests immediately preoperatively. There have been four late deaths. The frequent occurrence (80%) of a juxtaductal coarctation or coarctation shelf necessitates alteration of surgical technique. Failure to do so will be reflected in an early persistent postoperative metabolic acidosis with an arterial oxygen tension greater than 35 to 40 mm Hg in the operating room or greater than 40 to 45 mm Hg in the intensive care unit. A similar acid-base derangement will be seen if the systemic-to-pulmonary shunt is excessively large. Careful ventilatory and pharmacologic management of the ratio of pulmonary to systemic vascular resistance is an essential part of the perioperative management of these neonates with two parallel competing circulations. Late postoperative catheterization findings have emphasized the importance of a wide atrial septectomy, because restrictive atrial septal defects have developed in a number of children, despite partial surgical atrial septectomy. Central pulmonary artery reconstruction must be carefully performed to avoid distorted hypoplastic pulmonary arteries that would be unsuitable for a second-stage modified Fontan procedure.

Acid-Base Imbalance↗
PubMed1986

Surgery for coarctation of the aorta in the neonate.

Between 1972 and 1984, 100 consecutive neonates (less than or equal to 30 days old) underwent repair of coarctation of the aorta. Mean (+/- SD) age at operation was 12.0 +/- 8.0 days; mean weight was 3.1 +/- 0.5 kg. Simple coarctation was present in 29 patients (group I), 32 patients had additional ventricular septal defects (group II) and 39 patients had additional complex heart disease (group III). An associated patent ductus arteriosus was present in a total of 81 patients. Subclavian flap angioplasty (SFA) was performed in 70 patients, resection and end-to-end anastomosis (E-E) in 24 patients, and miscellaneous procedures in six patients. All SFA procedures were performed after 1977, and 87.5% of E-Es were done before 1977. The early mortality was 33.3% for patients undergoing E-E and 11.4% for those undergoing SFA. Freedom from reintervention for recoarctation after 5 years was 92.9% for patients who underwent E-E and 75.2% for those who underwent SFA. Actuarial survival at 4 years was 85.5% for group I, 79.9% for group II, and 42.9% for group III. Follow-up was 97.7% for a mean (+/- SD) of 41.9 +/- 37.1 months. It is likely that some of the differences between patients undergoing SFA and E-E with respect to early mortality and freedom from reintervention are due to the different time frames during which the procedures were done. However, neonatal ductal tissue after SFA may contract and fibrose causing recoarctation, while disadvantages related to the circumferential suture line after E-E may have been overemphasized in the past. A prospective randomized trial of these two techniques is warranted.

Aortic Coarctation↗
PubMed1986

Extending the limits for modified Fontan procedures.

During the early development of atriopulmonary anastomotic operations (Fontan-Kreutzer), a number of physiologic and anatomical limits were proposed by the Fontan group as selection criteria. Among 167 consecutive patients undergoing modified Fontan procedures from 1973 through 1985, 109 (65%) patients exceeded one or more of the original selection criteria in areas of age, anomalies of systemic or pulmonary venous connection, pulmonary artery distortion, and pulmonary artery pressure. Twenty-six patients had a mean pulmonary artery pressure greater than 15 mm Hg, with 16 operative survivors (62%). Nineteen patients had anomalies of systemic and/or pulmonary venous connection, and 16 survived (84%). There were 44 patients under the age of 4 years, and 26 survived (59%). Twenty-five patients were older than 15 years, and 23 (92%) survived the Fontan procedure. Pulmonary artery distortion, relating to prior palliative operations, was found in 34 patients. Seventeen of these 34 survived a modified Fontan procedure (50%). Twenty-six patients had a pulmonary arteriolar resistance more than 2 Wood units times square meter, and 14 survived (54%), whereas 81 of 93 with a pulmonary arteriolar resistance of less than 2 U X m2 survived (87%). Multivariate analysis showed that pulmonary arteriolar resistance and pulmonary artery distortion had a significant, negative impact on survival, but age and anomalies of systemic and/or pulmonary venous connection did not. Pulmonary artery pressure was not an independent predictor of outcome. The results show that the original criteria may be exceeded in the areas of age and anomalies of pulmonary or systemic venous connection. Pulmonary artery pressure alone should not contraindicate a Fontan procedure if pulmonary arteriolar resistance is low. Pulmonary artery distortion from a prior palliative operation and elevated pulmonary arteriolar resistance increase the risk of a Fontan procedure.

Adolescent↗
PubMed1985

Extravascular lung water in children immediately after operative closure of either isolated atrial septal defect or ventricular septal defect.

Extravascular lung water (EVLW) was measured in 16 patients with congenital heart disease by the cold green dye, double indicator dilution technique. Five patients with optimally corrected tetralogy of Fallot served as controls, and EVLW in this group was 4.7 +/- 0.5 ml/kg (111 +/- 13 ml/m2) (mean +/- standard deviation). In 5 asymptomatic patients with atrial septal defect (ASD), normal pulmonary artery (PA) pressure and increased pulmonary blood flow, EVLW was 5.7 +/- 2.8 ml/kg (132 +/- 63 ml/m2), which was not significantly different from the value of control patients. However, in 6 patients with ventricular septal defect, PA hypertension, normal left atrial pressure and an equivalent left-to-right shunt to ASD patients, EVLW was 15.9 +/- 3.8 ml/kg (270 +/- 60 ml/m2). This was significantly different from values in both control and ASD patients (p less than 0.01). It is concluded that in the face of normal pulmonary vascular resistance, PA pressure is transmitted to the microvasculature, causing hydrostatic pulmonary edema. Other factors that may be implicated in the pathogenesis of pulmonary edema, such as increased pulmonary blood flow and relative lymphatic insufficiency in infants, cannot be excluded.

Child↗
PubMed1985

Subxiphoid two-dimensional echocardiographic identification of tricuspid valve abnormalities in transposition of the great arteries with ventricular septal defect.

Tricuspid valve morphology was examined using subxiphoid 2-dimensional echocardiography (2-D echo) in 39 infants aged 2 years or younger who had transposition of the great arteries (TGA) and ventricular septal defect (VSD) (group I). Age-matched control groups were 21 patients with simple TGA (group II), 30 patients with VSD and normally related great arteries (group III), and 15 normal patients (group IV). Valve abnormalities, consisting of chordal attachments to the infundibular septum or ventricular septal crest, straddling, overriding or some combination of these, were identified in 25 of 39 patients (64%) in group I, no patients in groups II or IV and 6 of 30 patients (20%) in group III. Intraatrial baffle repair was performed in 27 patients in group I (median age at surgery 3.5 months) and 19 patients in group II (median age 4 months). Preoperative right ventricular angiography, performed in all patients with TGA, demonstrated tricuspid regurgitation (TR) with biventricular dysfunction in 1 patient in group I. After surgery, TR was present in 9 of 17 group I patients and none of the 8 group II patients who underwent catheterization. All patients in whom TR was not present preoperatively had abnormal chordal attachments; 3 required valve replacement. These results demonstrate that tricuspid valve abnormalities are common in patients with TGA and VSD and may be identified preoperatively using 2-D echo. Patients with abnormal chordal attachments are at increased risk for TR after intraatrial baffle repair and should be considered for arterial switch repair.

Cardiac Catheterization↗
PubMed1985

Accuracy of prospective two-dimensional echocardiographic evaluation of left ventricular outflow tract in complete transposition of the great arteries.

Thirty-two consecutive infants with transposition of the great arteries (TGA) and ventricular septal defect underwent subxiphoid 2-dimensional echocardiography (2-D echo). Two independent observers prospectively evaluated each echocardiogram for the presence or absence of left ventricular (LV) outflow tract obstruction, whether outflow obstruction was dynamic or fixed, or both, and the precise anatomic type of fixed obstruction. Compared with the LV-to-pulmonary artery gradient determined at cardiac catheterization, 2-D echo yielded low false-negative (7 to 13%) and false-positive (0 to 6%) rates for diagnosing the presence or absence of LV outflow tract obstruction. Moreover, the false-negative cases were only minor errors, because the measured LV-pulmonary artery gradients proved to be less than 25 mm Hg. Compared with the long-axial oblique LV angiogram, 2-D echo yielded no false-negative results in detection of outflow tract obstruction, which was at least partly fixed. Compared with autopsy/surgical observation, 2-D echo made no significant errors in delineating the exact anatomic type of fixed obstruction. The diagnostic accuracy of 2-D echo in detecting and characterizing LV outflow tract obstruction limits the need for "routine" cardiac catheterization before repair in infants with TGA and intact ventricular septum. Furthermore, because certain types of fixed LV outflow tract obstruction are difficult for the surgeon to visualize and alleviate, precise knowledge of the anatomic type of fixed obstruction influences the choice among Rastelli, intraatrial baffle and arterial switch procedures in patients with TGA and ventricular septal defect.

Cardiac Catheterization↗
PubMed1985

Assessment of hemodynamic status in the intensive care unit immediately after closure of ventricular septal defect.

Hemodynamic values measured 12 to 24 hours postoperatively in the intensive care unit (ICU) were compared with those measured at a later cardiac catheterization in 68 patients after closure of ventricular septal defect (VSD). A pulmonary arterial (PA) saturation of more than 80% or a pulmonary to systemic blood flow ratio (Qp:Qs) greater than 1.5 in the ICU were sensitive indicators for identifying patients at risk of having a hemodynamically significant residual left-to-right shunt (Qp:Qs greater than 1.5) at catheterization. Measurement of PA pressure in the ICU was a useful predictor of PA pressure at catheterization. In the absence of factors known to alter PA pressure, measurement of PA pressure in the ICU overestimates what it will be at a subsequent cardiac catheterization. Early assessment of hemodynamics after closure of VSD is useful in identifying patients at risk of having hemodynamically significant residual VSD and those who may have persistent PA hypertension.

Adolescent↗
PubMed1985

Single ventricle (single- or double-inlet) complicated by subaortic stenosis: surgical options in infancy.

Intracardiac obstruction to the systemic circulation can develop in patients with many forms of congenital heart disease. When transposition of the great arteries accompanies tricuspid atresia, narrowing of the ventricular septal defect (VSD) leads to subaortic stenosis. In a similar fashion, a restrictive bulboventricular foramen compromises systemic arterial outflow in patients who have single left ventricle with subaortic outflow chamber. The same effect can be seen in VSD closure in mitral atresia with normally related great vessels. Although some forms of single ventricle can be treated by ventricular septation, the modified Fontan procedure can be more generally applied to this entity. Pulmonary vascular resistance must be low, however, which excludes the application of the Fontan principle in infants. While pulmonary artery banding may protect the lungs from the development of excessive pulmonary vascular resistance, it may also accelerate the development of subaortic obstruction. We have successfully applied the Norwood operation, as described for hypoplastic left heart syndrome, to palliate subaortic stenosis due to restrictive VSD in 3 infants with single ventricle or atrioventricular valve atresia. Consideration should be given to a primary Norwood procedure in infants with single ventricle in whom subaortic stenosis is likely to develop. Patients who do receive pulmonary artery bands should be followed closely for the development of subaortic stenosis and should undergo an early, physiologically corrective operation if it occurs.

Aortic Stenosis, Subvalvular↗
PubMed1985

Pulmonary valvotomy under normothermic caval inflow occlusion.

Pulmonary valve stenosis may require urgent surgical relief in infancy or elective valvotomy in childhood. A retrospective study has been made of 94 children who underwent pulmonary valvotomy for pulmonary valve stenosis between 1972 and 1983 using the technique of normothermic caval inflow occlusion. There were no early deaths nor late deaths. The group included 13 neonates less than 1 week old and 14 other infants under 1 year of age. The mean follow-up is 45 months. No child has had a second valvotomy for recurrent valvar stenosis. Two children have required re-operation for placement of a transannular right ventricular outflow patch for hypoplastic pulmonary annulus. Neonates who present early with critical pulmonary valve stenosis may remain moderately to severely cyanosed for several days after a satisfactory valvotomy but this is almost invariably followed by a progressive increase in oxygen saturation to an acceptable level. One neonate, who had a Blalock-Taussig shunt at 2 weeks of age for persistent postvalvotomy cyanosis, had the shunt ligated at 2 years. Pulmonary valvotomy under normothermic caval inflow occlusion is a safe, cost-effective technique which provides excellent early and late haemodynamic results. This operation sets a standard against which the newly introduced technique of percutaneous balloon pulmonary valvotomy should be assessed.

Adolescent↗
PubMed1985

Long-term follow-up of patients with synthetic right heart conduits.

Between 1971 and 1983, 201 patients received synthetic right heart conduits, predominantly porcine-valved Dacron conduits, at The Children's Hospital, Boston. There were 45 hospital deaths (22%). Follow-up has been achieved in 148 of 156 survivors (95%). Thirty-four conduits have been replaced, all because of conduit obstruction. The actuarial freedom from conduit replacement was 81% at 5 years, 61% at 7 years, and 0% at 10 years for valved conduits. There was no significant difference to 5 years in reoperation rate between patients with Carpentier-Edwards and those with Hancock conduits. Patients older than 18 years at the time of conduit insertion were 92% free of conduit replacement at 5 years. Those with nonvalved conduits were 100% reoperation free at 4 years. The actuarial survival of patients with valved conduits was 91% at 5 years and 83% at 10 years. The poor performance of porcine-valved tightly woven Dacron conduits warrants a change to use of an alternative conduit, particularly in smaller children. Possible alternatives include antibiotic-sterilized homografts and valved or nonvalved high-porosity knitted Dacron conduits appropriately pretreated with collagen impregnation or fibrin glue.

Actuarial Analysis↗