PubMed Health⌕ Search

Biomedical subjects

R A Jonas

Publications and source records attributed to R A Jonas.

At least 127 records · Page 7Linked to original sources
PubMed1994

Effects of MK-801 and NBQX on acute recovery of piglet cerebral metabolism after hypothermic circulatory arrest.

Brain protection during open heart surgery in the neonate and infant remains inadequate. Effects of the excitatory neurotransmitter antagonists MK-801 and NBQX on recovery of brain cellular energy state and metabolic rates were evaluated in 34 4-week-old piglets (10 MK-801, 10 NBQX, 14 controls) undergoing cardiopulmonary bypass and hypothermic circulatory arrest at 15 degrees C nasopharyngeal temperature for 1 h, as is used clinically for repair of congenital heart defects. MK-801 (dizocilpine) (0.75 mg/kg) or NBQX [2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline] (25 mg/kg) was given intravenously before cardiopulmonary bypass. Equivalent doses were placed in the cardiopulmonary bypass prime plus continuous infusions after reperfusion (0.15 mg kg-1h-1 and 5 mg kg-1h-1). Changes in high-energy phosphate concentrations and pH were analyzed by magnetic resonance spectroscopy in 17 animals until 225 min after reperfusion. Cerebral blood flow determined by radioactive microspheres as well as cerebral oxygen and glucose consumption were studied in 17 other animals. Cerebral blood flow and oxygen consumption were depressed relative to control by both MK-801 and NBQX at baseline. Recovery of phosphocreatine (p = 0.010), ATP (p = 0.030), and intracellular pH (p = 0.004) was accelerated by MK-801 and retarded by NBQX over the 45 min of rewarming reperfusion and the first hour of normothermic reperfusion. The final recovery of ATP at 3 h and 45 min reperfusion was significantly reduced by NBQX (46 +/- 26% baseline, mean +/- SD) versus control (81 +/- 19%) and MK-801 (75 +/- 8%) (p = 0.030). Cerebral oxygen consumption recovered to 105 +/- 30% baseline in group MK-801 and 94 +/- 31% in control but only to 61 +/- 22% in group NBQX (p = 0.070). Cerebral blood flow stayed significantly lower in group NBQX relative to control. Thus, MK-801 accelerates recovery of cerebral high-energy phosphates and metabolic rate after cardiopulmonary bypass and hypothermic circulatory arrest in the immature animal. At the dosage used NBQX exerts an adverse effect.

Animals↗
PubMed1994

Radical aortic root enlargement in the infant and child.

Complex multilevel left ventricular outflow tract obstruction includes some of the more challenging problems in congenital cardiac reconstructive surgery. Preoperative studies must carefully delineate the level of obstruction that may be entirely below the aortic annulus (i.e., subaortic stenosis), at the level of the aortic annulus (i.e., aortic annular hypoplasia), may be related to valve leaflet obstruction due to rigid or fused valve leaflets (i.e., aortic valve stenosis), or may be at the level of the tips of the commissures of the aortic valve (i.e., supravalvar aortic stenosis). Frequently, variable contributions are present from all these potential levels of obstruction. An important underlying goal in planning surgical therapy should be preservation of the child's own aortic valve, whenever possible. Operative procedures should preserve growth potential and minimize the need for repeat surgical procedures. A number of surgical options that incorporate these goals will be described.

Aortic Valve↗
PubMed1994

Rapid two-stage arterial switch operation. Evaluation of left ventricular systolic mechanics late after an acute pressure overload stimulus in infancy.

BACKGROUND: Banding of the pulmonary artery to induce left ventricular (LV) hypertrophy followed by arterial switch operation (ASO) within 2 weeks has been performed when a primary ASO was considered high risk because of inadequate LV hypertrophy. METHODS AND RESULTS: Potential adverse myocardial effects of the two-stage procedure were examined by comparing outcome in 18 patients after a rapid two-stage ASO with 33 patients after a primary ASO. Regional wall motion was assessed. Echocardiographic and noninvasive pressure data were combined to obtain LV dimension, wall thickness, mass, fractional shortening, rate-corrected mean velocity of shortening, and end-systolic wall stress. Afterload-adjusted velocity of shortening was obtained as a load-independent index of contractility. In the two-stage ASO group, the magnitude and rate of hypertrophy after pulmonary artery banding were measured serially. No wall motion abnormalities were seen in either group. Systolic dysfunction due to higher afterload and lower contractility was observed in the two-stage ASO group. Contractility below the limits of normal was seen in 25% of two-stage ASO compared with 3% of primary ASO; however, symptomatic or progressive LV dysfunction was not observed. There was a significant inverse relation between the peak rate of hypertrophy immediately after banding and contractility at late exam. Lower ejection fraction before and early after pulmonary artery banding correlated with depressed contractility on late examination. CONCLUSIONS: Myocardial contractility is lower after the two-stage ASO than after a primary repair. Severe or progressive dysfunction was not seen. A very high peak rate of hypertrophy and severe LV dysfunction after banding predict a greater reduction in late contractility.

Acute Disease↗
PubMed1994

Rapid two-stage arterial switch operation. Acquisition of left ventricular mass after pulmonary artery banding in infants with transposition of the great arteries.

BACKGROUND: Banding of the pulmonary artery (PAB) in preparation for arterial switch operation (ASO) in patients with transposition of the great arteries (TGA) represents a unique model of acute left ventricular pressure overload in humans. METHODS AND RESULTS: To establish the rate, magnitude, and determinants of left ventricular hypertrophy and the acute effect on ventricular function, serial bidimensional echocardiographic evaluations were performed on 26 patients with TGA after PAB. Mass, volume, and ejection fraction of the left ventricle were measured. Cardiac catheterization data before PAB and again before ASO were reviewed. The mean interval between the PAB and ASO was 9 +/- 4 days. The left ventricular to right ventricular pressure ratio before PAB was 0.5 and increased to 1.0 before ASO. The mean percentage increase in left ventricular mass from PAB to ASO was 96%, 95% of which was achieved in the first 7 days. The average rate of left ventricular hypertrophy for the entire period was 0.06 g/h and was 0.19 g/h during the interval from PAB to attainment of maximum left ventricular mass. The most rapid rate of hypertrophy was seen by day 2, with an exponential fall in the growth rate thereafter approaching zero by day 7. Ejection fraction was significantly reduced at 12 hours after PAB, but mean values returned to pre-PAB levels by 3.5 days after banding. The absolute rate of left ventricular hypertrophy correlated directly with body surface area but not to other hemodynamic variables. CONCLUSIONS: Doubling of left ventricular mass can be achieved in 1 week after PAB. Function falls acutely due to afterload excess and/or depressed contractility but recovers rapidly as compensatory hypertrophy occurs.

Echocardiography↗
PubMed1994

Innominate artery compression of the trachea in infants.

Innominate artery compression of the trachea in infants can cause severe biphasic stridor, cyanosis, and respiratory arrest. These episodes are sometimes referred to as "dying spells." In the past, aortopexy has been used for the treatment of this problem, but since many have questioned its success, its use has not been popularized or generally accepted. Over the past 4 years, 12 children have been successfully treated for innominate artery compression of the trachea with aortopexy. These children all initially presented with significant respiratory and/or feeding difficulties. Preoperative and postoperative videos were obtained to document the degree of tracheal compression and/or lumen size before and after surgery. Since treatment, all patients have been without further feeding problems or cyanosis. When performed in selected patients, aortopexy is successful in relieving tracheal obstruction from innominate artery compression. This article discusses proper patient selection, operative technique, and follow-up care. The management of compression in patients with less severe symptoms will also be addressed.

Airway Obstruction↗
PubMed1994

Anatomic subtype and survival after reconstructive operation for hypoplastic left heart syndrome.

We conducted a retrospective study of 78 patients who underwent palliative reconstructive operation for hypoplastic left heart syndrome representing an entire consecutive experience between 1983 and 1991 to identify predictors of mortality that might enable more appropriate triage of patients to either reconstruction or transplantation. Twenty-nine patients had aortic atresia, mitral atresia; 18 had aortic stenosis, mitral stenosis; 20 had aortic atresia and mitral stenosis; and 11 had miscellaneous forms of hypoplastic left heart syndrome. There were 29 hospital deaths (37%). A worst preoperative pH (p = 0.01) and immediate preoperative pH (p = 0.03) less than the median were predictors of hospital mortality. The anatomic subgroup aortic atresia, mitral stenosis (p = 0.06) had a possible increased hospital mortality. One patient was lost to follow-up. The Kaplan-Meier survival estimate among hospital survivors was 34% at 3 years and 25% at 5 years. The anatomic subgroup aortic atresia, mitral atresia (p = 0.02) had a worse late outcome (11% 3-year survival) whereas the subgroup aortic stenosis, mitral stenosis (p = 0.04; 76% 3-year survival) had a better late outcome. There were no other significant predictors of late survival other than immediate prerepair pH (p = 0.05). Interpretation of this experience is complicated by the large number of different surgical techniques used for both first-stage neonatal reconstruction and the Fontan procedure plus introduction of the bidirectional Glenn shunt as an intermediate step midway through the experience. Nevertheless in this time frame and with the variety of techniques used, this experience demonstrates that patients with aortic atresia, mitral atresia, particularly those who have been very acidotic in the neonatal period, are least likely to do well with the reconstructive approach to hypoplastic left heart syndrome and are the most appropriate subgroup to be directed to transplantation. Patients with aortic stenosis, mitral stenosis have an excellent late outcome with the reconstructive approach.

Boston↗
PubMed1994

Surgical alternatives to the Fontan procedure incorporating a hypoplastic right ventricle.

BACKGROUND: Frequently the definitive operation for patients with a right ventricle (RV) that is too small to support full cardiac output is a modified Fontan operation. However, other surgical options exist that incorporate a small RV in the atriopulmonary pathway when biventricular repair is not feasible because of RV or tricuspid valve hypoplasia. The risks and benefits of these options have not been well defined. METHODS AND RESULTS: Between 1988 and 1993, 8 patients (6 with pulmonary atresia and intact ventricular septum and 2 with tricuspid valve stenosis and RV hypoplasia) underwent a cavopulmonary connection, which allowed right atrial blood to flow either to the pulmonary artery via the RV or directly via the cavopulmonary anastomosis. Age at surgery ranged from 1.5 to 9 years. The proximal right pulmonary artery was ligated in 5 patients, and the atrial septal defect was closed during the same procedure in 7 of the 8 patients. The echocardiographic right ventricular-left ventricular volume ratio ranged from 9% to 25%, and tricuspid valve z-scores ranged from 0 to -4. There were no deaths at a median follow-up of 24 months (range, 7 to 61 months). Mild exertional limitation was evident in only one patient. Postoperative echocardiograms demonstrated pulsatile systolic flow across the RV outflow tract in 5 patients and low-velocity diastolic-systolic flow in a sixth patient with extreme tricuspid valve hypoplasia. At postoperative cardiac catheterization (6 patients) right atrial mean pressures ranged from 7 to 13 mm Hg and mixed venous saturations from 62% to 70%. CONCLUSIONS: Right atrial decompression via a superior vena cava-to-pulmonary artery anastomosis allows incorporation of a small RV into the pulmonary circulation and closure of the atrial septum, with excellent results to date.

Cardiac Catheterization↗
PubMed1994

Unique features and prognosis of primum ASD presenting in the first year of life.

BACKGROUND: Primum atrial septal defect (ASD) is a defect that is usually associated with few symptoms and can be electively repaired with good results. A review of our experience with primum ASD identified a subset of patients characterized by presentation with congestive heart failure (CHF) in the first months of life and a requirement for early operation. Echocardiograms, catheterizations, operative reports, and clinical data were reviewed and compared with that on all other patients with primum ASD. Patients with transitional or complete atrioventricular (AV) canal defects were excluded. METHODS AND RESULTS: From January 1984 to December 1992, significant CHF was present in the first year of life in 11 patients (10.5%) with primum ASD who were managed surgically among 105 total patients undergoing repair of primum ASD. This early CHF group had a higher incidence of hypoplastic left-sided cardiac structures (9 of 11 patients) compared with other primum ASD patients (5 of 94, P < .001), including patients with coarctation (CoA) (n = 9), abnormal mitral valve (n = 7), left ventricular hypoplasia (n = 5), and subaortic stenosis (subAS) (n = 7). Other differentiators from patients without early CHF included incidence of Downs syndrome (0% versus 19%), elevated pulmonary artery pressures (72% versus 33% systemic, P < .001), earlier mean age at operation (8 months versus 5.4 years), greater incidence of reoperation after initial ASD closure (5 of 8 patients, 12 operations [5 subAS, 3 mitral valve, 3 CoA, 1 pacemaker] versus 4 of 93 patients, P < .001), and higher mortality (36% versus 1%, P < .001). CONCLUSIONS: Left-sided obstructive lesions must be sought in children with primum ASD presenting with CHF in the first year of life. The presence of these lesions alters prognosis and surgical management and mandates close follow-up, with particular attention to late appearance or progression of subaortic stenosis or deterioration of mitral valve function.

Child, Preschool↗
PubMed1994

Outcomes in seriously ill neonates with coarctation of the aorta. A multiinstitutional study.

Among 326 severely symptomatic neonates with coarctation with or without ventricular septal defect, four died before an initial procedure was performed. Among the 322 undergoing an initial procedure, survival for at least 24 months was 84%; the hazard function for death was lower initially but more prolonged in patients without than in those with ventricular septal defect. Important mitral valve anomalies coexisted in 5% of patients, left ventricular hypoplasia in 5% (more commonly in patients without ventricular septal defect), narrowing of the left ventricular outflow tract in 9% (more common in patients without ventricular septal defect), and narrowing of the proximal arch in 1%; one or more of these anomalies was present in most patients without ventricular septal defect who died. Five percent of the 322 patients had more than one of these coexisting anomalies, and 8% had just one. The most commonly used technique of repair of the coarctation was resection and end-to-end anastomosis, but no technique was a risk factor for death by multivariable analysis. Extension of the area of resection so that the end-to-end anastomosis was proximal to the left subclavian artery but distal to the left common carotid artery did not increase risk; extensions beyond this, and in the case of patch graft repair, extensions proximal to the left subclavian artery, did increase risk. Patch graft repair was associated with the highest prevalence (21%) of reintervention to the coarctation repair. Among patients with coexisting moderate-sized or large ventricular septal defects, repair of the coarctation, pulmonary trunk banding, and subsequent repair of the defect were associated with the highest 2-year survival, 97% in those with single ventricular septal defect. The risk-adjusted outcomes in two institutions were less good than in all others.

Aortic Coarctation↗
PubMed1994

Effects of cerebroplegic solutions during hypothermic circulatory arrest and short-term recovery.

UNLABELLED: Previous studies have suggested that a simple crystalloid "cerebroplegic" solution may prolong the safe duration of hypothermic circulatory arrest. We tested the hypothesis that pharmacologic modification of the cerebroplegic solution would further enhance cerebral protection. Forty-six 4-week-old miniature piglets underwent core cooling to 15 degrees C nasopharyngeal temperature and 2 hours of hypothermic circulatory arrest. Twelve animals had a 50 ml/kg dose of saline infused into the carotid artery system at the onset of hypothermic circulatory arrest and repeat doses of 10 ml/kg every 30 minutes during arrest. Eleven animals received the same initial and repeat doses of University of Wisconsin organ preservation solution and 10 received University of Wisconsin solution with 7.5 mg/L of MK-801, an excitatory neurotransmitter antagonist. In 13 control animals blood was partially drained from the piglet before 2 hours of circulatory arrest at 15 degrees C and no cerebroplegic solution was infused. All solutions were delivered at 4 degrees C. Brain temperature (n = 24) at the onset of hypothermic circulatory arrest was 15.0 degrees +/- 0.1 degrees C (mean +/- standard error). Brain temperature after cerebroplegic infusion dropped to 13.0 degrees +/- 0.3 degrees C and stayed lower than brain temperature in the control group throughout the hypothermic circulatory arrest period. Recovery of cerebral adenosine triphosphate and intracellular pH determined by phosphorus 31 magnetic resonance spectroscopy (n = 22) was significantly improved by saline infusion and was further improved with University of Wisconsin solution and University of Wisconsin solution plus MK-801 (p < 0.001). Recovery of cerebral blood flow measured by microspheres (n = 24) also was augmented by University of Wisconsin solution (p < 0.001) but not in the presence of MK-801. The vascular resistance response to acetylcholine and nitroglycerin suggested that MK-801 has a direct vasoconstrictive effect. Recovery of cerebral oxygen consumption (n = 24) was increased by University of Wisconsin solution and University of Wisconsin solution with MK-801 (p = 0.002). Brain water content (n = 46) was significantly lower in all cerebroplegia-treated groups than in controls (p < 0.001). CONCLUSION: Cerebroplegia improves short-term recovery after 2 hours of circulatory arrest in hypothermic piglets. Pharmacologic modification with University of Wisconsin solution further improves the recovery of cerebral blood flow and metabolism. MK-801 does not augment the protective effects of University of Wisconsin solution and reduces the recovery of cerebral blood flow by a direct vascular action. Modified cerebroplegia may provide a novel approach to improved cerebral protection when prolonged hypothermic circulatory arrest is necessary.

Adenosine↗
PubMed1994

Outcomes in patients with interrupted aortic arch and ventricular septal defect. A multiinstitutional study. Congenital Heart Surgeons Society.

Among 183 neonates with interrupted aortic arch and ventricular septal defect entering a multiinstitutional study between 1987 and 1992, nine died before repair was accomplished. Among the remaining 174, survival at 1 month and 1, 3, and 4 years after repair was 73%, 65%, 63%, and 63%, respectively. The risk factors for death were low birth weight, younger age at repair, interrupted arch type B, outlet and trabecular ventricular septal defects, smaller size of the ventricular septal defect, and subaortic narrowing. Echocardiographically measured dimensions (expressed as Z-values) at all levels of the left heart-aorta complex were small. Two among thirty institutions were risk factors, and two others possibly were. Procedural risk factors for death after repair were (1) repair without concomitant procedures in patients with other important levels of obstruction in the left heart-aorta complex, (2) a Damus-Kaye-Stansel anastomosis, and (3) subaortic myotomy/myectomy in the face of subaortic narrowing. One-stage repair plus ascending aorta/arch augmentation had the highest predicted time-related survival in the 20% of patients with interrupted aortic arch and one or more coexisting levels of obstruction in the left heart-aorta complex, as did initial repair without or with aorta/arch augmentation in the 80% without these.

Aorta, Thoracic↗
PubMed1994

Result of biventricular repair for double-outlet right ventricle.

The choice of optimal repair for many patients with double-outlet right ventricle continues to challenge the heart surgeon. We present the results of a 10-year surgical experience with the biventricular repair for double-outlet right ventricle with situs solitus and atrioventricular concordance. Preoperative anatomic findings within this population of 73 patients are detailed. These morphologic features are correlated with type of anatomic repair and clinical outcome. Patients were classified by ventricular septal defect location. Normal coronary anatomy was found in the majority of patients with subaortic and doubly-committed ventricular septal defects. Patients with subpulmonary and noncommitted ventricular septal defects had a wide variety of coronary anatomy. Patients with subpulmonary and noncommitted ventricular septal defects also had a considerably higher prevalence of aortic arch obstruction. A tricuspid-to-pulmonary annular distance equal to or greater than the diameter of the aortic annulus was found to indicate the possibility of achieving a conventional ventricular septal defect-to-aorta intraventricular tunnel repair. Tricuspid-to-pulmonary annular distance sufficient for intraventricular tunnel repair predominates in those patients with a right posterior or right side-by-side aorta. Five types of repair were used during the study period: intraventricular tunnel repair, arterial switch with ventricular septal defect-to-pulmonary artery baffle, Rastelli-type extracardiac conduit repair, Damus-Kaye-Stansel repair, and atrial inversion with ventricular septal defect-to-pulmonary artery baffle. Overall actuarial survival estimate at 8 years is 81%. The presence of multiple ventricular septal defects and patient weight lower than the median were nearly significant risk factors for early mortality (p < 0.06). Nineteen patients (26%) required 24 reoperations. Patients with subaortic ventricular septal defects were significantly reoperation free (p < 0.05). Patients with noncommitted ventricular septal defects were at significantly higher risk for reoperation during the study period (p < 0.05). The prevalence of late right or left ventricular outflow obstruction in the nonsubaortic groups is concerning. The median age at repair in this series was 0.76 years, and there was a nonsignificant trend (p = 0.13) for early mortality in patients younger than 1 year of age. These patients tended to have other serious cardiac anomalies associated with double-outlet right ventricle that necessitated early operation. On the basis of these data, we favor early repair for double-outlet right ventricle if possible.

Abnormalities, Multiple↗
PubMed1993

A comparison of the perioperative neurologic effects of hypothermic circulatory arrest versus low-flow cardiopulmonary bypass in infant heart surgery.

BACKGROUND: Hypothermic circulatory arrest is a widely used support technique during heart surgery in infants, but its effects on neurologic outcome have been controversial. An alternative method, low-flow cardiopulmonary bypass, maintains continuous cerebral circulation but may increase exposure to known pump-related sources of brain injury, such as embolism or inadequate cerebral perfusion. METHODS: We compared the incidence of perioperative brain injury after deep hypothermia and support consisting predominantly of total circulatory arrest with the incidence after deep hypothermia and support consisting predominantly of low-flow cardiopulmonary bypass in a randomized, single-center trial. The criteria for eligibility included a diagnosis of transposition of the great arteries with an intact ventricular septum or a ventricular septal defect and a planned arterial-switch operation before the age of three months. RESULTS: Of 171 patients with D-transposition of the great arteries, 129 (66 of whom were assigned to circulatory arrest and 63 to low-flow bypass) had an intact ventricular septum, and 42 (21 assigned to circulatory arrest and 21 to low-flow bypass) had a ventricular septal defect. After adjustment for diagnosis, assignment to circulatory arrest as compared with low-flow bypass was associated with a higher risk of clinical seizures (odds ratio, 11.4; 95 percent confidence interval, 1.4 to 93.0), a tendency to a higher risk of ictal activity on continuous electroencephalographic (EEG) monitoring during the first 48 hours after surgery (odds ratio, 2.5; 95 percent confidence interval, 1.0 to 6.4), a longer recovery time to the first reappearance of EEG activity (only in the group with an intact ventricular septum, P < 0.001), and greater release of the brain isoenzyme of creatine kinase in the first 6 hours after surgery (P = 0.046). Analyses comparing durations of circulatory arrest produced results similar to those of analyses comparing treatments. CONCLUSIONS: In heart surgery in infants, a strategy consisting predominantly of circulatory arrest is associated with greater central nervous system perturbation in the early postoperative period than a strategy consisting predominantly of low-flow cardiopulmonary bypass. Assessment of the effect of these findings on later outcomes awaits follow-up of this cohort.

Brain Ischemia↗
PubMed1993

Effects of pH on brain energetics after hypothermic circulatory arrest.

The pH management that provides optimal organ protection during hypothermic circulatory arrest is uncertain. Recent retrospective clinical data suggest that the pH-stat strategy (maintenance of pH at 7.40 corrected to core temperature) may improve brain protection during hypothermic cardiopulmonary bypass with a period of circulatory arrest in infants. The impact of alpha-stat (group A) and pH-stat (group P) strategies on recovery of cerebral high-energy phosphates and intracellular pH measured by magnetic resonance spectroscopy (A, n = 7; P, n = 5), organ blood flow measured by microspheres, cerebral metabolic rate measured by oxygen and glucose extraction (A, n = 7; P, n = 6), and cerebral edema was studied in 25 4-week-old piglets undergoing core cooling and 1 hour of circulatory arrest at 15 degrees C. Group P had greater cerebral blood flow during core cooling (54.3% +/- 4.7% versus 34.2% +/- 1.5% of normothermic baseline, respectively; p = 0.001). The intracellular pH during core cooling showed an alkaline shift in both groups but became more alkaline in group A than in group P at the end of cooling (7.08 to 7.63 versus 7.09 to 7.41, respectively; p = 0.013). Recovery of cerebral adenosine triphosphate (p = 0.046) and intracellular pH (p = 0.014) in the initial 30 minutes of reperfusion was faster in group P. The cerebral intracellular pH became more acidotic during early reperfusion in group A, whereas it showed continuous recovery in group P. Brain water content postoperatively was less in group P (0.8075) than in group A (0.8124) (p = 0.05). These results suggest that compared with alpha-stat, the pH-stat strategy provides better early brain recovery after deep hypothermic cardiopulmonary bypass with circulatory arrest in the immature animal. Possible mechanisms include improved brain cooling by increased blood flow to subcortical areas, improved oxygen delivery, and reduction of reperfusion injury, as well as an alkaline shift in intracellular pH with hypothermia in spite of a stable blood pH.

Acidosis↗