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Biomedical subjects

R A Jonas

Publications and source records attributed to R A Jonas.

At least 19 recordsLinked to original sources
PubMed2001

General health status of children with D-transposition of the great arteries after the arterial switch operation.

BACKGROUND: To study the long-term impact on general health status of D-transposition of the great arteries (D-TGA) after the arterial switch operation (ASO) during infancy, we asked parents to complete the Child Health Questionnaire, Parent Form-50 when their children were 8 years old. METHODS AND RESULTS: Of 160 eligible patients, questionnaires were completed for 155 subjects (96%). Median age at surgery was 6 days (range 1 to 67 days), and median age at completion of the Child Health Questionnaire was 8.1 years (7.6 to 10.0 years). Subsequent to questionnaire completion, children underwent psychometric testing. Mean Physical Health Summary and Psychosocial Summary scores were 54.0+/-6.1 and 49.7+/-9.9, respectively, which were similar to those of normal subjects. Compared with the normative sample, parents of D-TGA patients reported more problems with attention, learning, and speech, as well as greater frequency of developmental delay (P<0.001 for each). Worse Psychosocial Summary scores were significantly associated with lower full-scale IQ (P=0.001) and lower achievement in reading (P=0.005) and math (P=0.007). Worse Physical Health Summary scores were associated with longer hospital stay after the ASO (P=0.02). General health status scores were not significantly related to presence of ventricular septal defect, age at surgery, perfusion variables during the ASO, sex, or history of cardiac reoperation. CONCLUSIONS: At age 8 years, children with D-TGA after ASO have an overall physical and psychosocial health status similar to that of the general population. Lower IQ and academic achievement are associated with worse psychosocial health status, whereas longer hospital course after initial surgery is associated with worse physical health status.

Brain Damage, Chronic↗
PubMed2001

Neurodevelopmental outcomes in children after the fontan operation.

BACKGROUND: Previous studies of patients after the Fontan operation have reported IQ scores lower than population norms. In the past decade, changes have occurred both in surgical methods used and in the patient population undergoing Fontan palliation. The present study examined the impact of these changes on neurodevelopmental outcomes after Fontan. METHODS AND RESULTS: Neuropsychological tests were administered to 27 five-year-old children after Fontan. Mean age at repair was 2 years 4 months. The present sample was compared with an earlier Fontan group (EFG) of 133 patients who underwent surgery in the 1970s and 1980s. Mean age at repair for the EFG was 7 years 3 months. Compared with EFG, the present study sample was younger at Fontan (P=0.0001) and more likely to have undergone a Norwood procedure (P=0.02), a pre-Fontan bidirectional cavopulmonary anastomosis (P<0.001), and Fontan fenestration (P=0.001). Although mean full-scale, verbal, and performance IQ scores were within 1 SD (15 points) of the population mean of 100 (93+/-16, 95+/-15, and 91+/-17, respectively), mean full-scale and performance IQ scores were significantly lower than this population mean (P=0.03 and P=0.01, respectively). CONCLUSIONS: Compared with a historical cohort of Fontan patients from this institution, a staged approach to Fontan earlier in life is not detrimental to neurodevelopmental outcome. Neurodevelopmental outcomes in children after Fontan are in the normal range, but performance remains lower than the general population.

Adolescent↗
PubMed2001

Are outcomes of surgical versus transcatheter balloon valvotomy equivalent in neonatal critical aortic stenosis?

BACKGROUND: For neonates with critical aortic valve stenosis who are selected for biventricular repair, valvotomy can be achieved surgically (SAV) or by transcatheter balloon dilation (BAV). METHODS AND RESULTS: Data regarding 110 neonates with critical aortic valve stenosis were evaluated in a study by the Congenital Heart Surgeons Society from 1994 to 1999. Reduced left ventricular function was present in 46% of neonates. The initial procedure was SAV in 28 patients and BAV in 82 patients. Mean percent reduction in systolic gradient was significantly greater with BAV (65+/-17%) than SAV (41+/-32%; P<0.001). Higher residual median gradients were present in the SAV versus BAV group (36 mm Hg [range, 10 to 85 mm Hg] versus 20 mm Hg [0 to 85 mm Hg], P<0.001). Important aortic regurgitation was more often present after BAV (18%) than SAV (3%; P=0.07). Time-related survival after valvotomy was 82% at 1 month and 72% at 5 years, with no significant difference for SAV versus BAV, even after adjustment for differences in patient and disease characteristics. Independent risk factors for mortality were mechanical ventilation before valvotomy, smaller aortic valve annulus (z score), smaller aortic diameter at the sinotubular junction (z score), and a smaller subaortic region. A second procedure was performed in 46 survivors. Estimates for freedom from reintervention were 91% at 1 month and 48% at 5 years after the initial valvotomy and did not differ significantly between groups. CONCLUSIONS: SAV and BAV for neonatal critical aortic stenosis have similar outcomes. There is a greater likelihood of important aortic regurgitation with BAV and of residual stenosis with SAV.

Acute Disease↗
PubMed2001

Effects of hematocrit on cerebral microcirculation and tissue oxygenation during deep hypothermic bypass.

BACKGROUND: One rationale for hemodilution during hypothermic cardiopulmonary bypass (CPB) has been improved microcirculation. However, the optimal degree of hemodilution remains unclear. We therefore studied cerebral microcirculation and tissue oxygenation in a new intravital microscopic model at 3 different hematocrit (Hct) values. METHODS AND RESULTS: Three groups of 5 piglets with a cranial window over the parietal cortex underwent cooling at Hct of 10%, 20%, or 30%, followed by 1-hour deep hypothermic circulatory arrest (DHCA) and rewarming on CPB. For assessment of functional capillary density (FCD), plasma was labeled with fluorescein-isothiocyanate-dextran. Rhodamine-stained leukocytes were observed in postcapillary venules with analysis for adhesion and rolling. NADH, a natural intracellular fluorophore that increases during ischemia, was measured densitometrically during bypass and DHCA. FCD did not significantly differ from baseline during cooling in any group. However, during early reperfusion (5 minutes) after DHCA, the FCD was significantly higher in the Hct 30% group than in the Hct 10% group. Leukocyte adherence decreased in all groups during CPB and was only moderately increased at the end of the experiment. However, severe hemodilution (Hct 10%) was associated with a significantly greater number of rolling leukocytes relative to Hct 30%. CONCLUSIONS: Higher Hct does not impair cerebral microcirculation and reduces white cell/endothelial activation after deep hypothermic bypass and circulatory arrest. Severe hemodilution (Hct 10%) results in evidence of inadequate cerebral tissue oxygenation during the cooling phase of CPB. This study suggests that Hct of 30% is preferable relative to lower Hct values during hypothermic CPB, particularly if DHCA is used.

Animals↗
PubMed2001

Surgical outcome of double-outlet right ventricle with subpulmonary VSD.

BACKGROUND: Optimal management of double-outlet right ventricle with subpulmonary ventricular septal defect remains controversial. We reviewed our 7-year experience with patients who had this anatomic configuration. METHODS: Between January 1992 and January 1999, 20 patients underwent an arterial switch operation (ASO group), and 12 underwent a bidirectional Glenn procedure followed by a modified Fontan in 10 (Glenn/Fontan). Mean follow-up was 23 +/- 18 months. RESULTS: An initial palliative operation was done in 19 patients (9 in the ASO group, 10 in the Glenn/Fontan group). There were no deaths in the Glenn/Fontan group. Four patients in the ASO group died within 33 days postoperatively. Two of them had a single coronary artery, 1 had a straddling mitral valve, 1 had a hypoplastic aortic arch, and 1 had multiple ventricular septal defects. Three patients had reoperation for subaortic stenosis (n = 2) or pulmonary stenosis (n = 1) after the ASO. Four patients (3 in the ASO group, 1 in the Glenn/Fontan) required a pacemaker for postoperative complete atrioventricular block. Actuarial survival at 5 years for the entire group was 87% (70% confidence interval, 81% to 93%). CONCLUSIONS: The ASO remains our preferred treatment for infants with double-outlet right ventricle and subpulmonary ventricular septal defect. However, associated anatomic defects are important risk factors.

Child, Preschool↗
PubMed2001

Surgery for coarctation of the aorta in infants weighing less than 2 kg.

BACKGROUND: Low- and very low-birth weight infants are now candidates for reparative cardiac surgery. Outcomes after coarctation repair have not been characterized in this patient population. METHODS: We performed a retrospective review of 18 consecutive neonates less than 2 kg who underwent repair of aortic coarctation between August 1990 and December 1999. RESULTS: Median weight was 1,330 g, and median gestational age was 31 weeks. A ventricular septal defect was present in 5 patients, and Shone's complex in 4. Sixteen patients had resection and end-to-end anastomosis, and 2 had resection and subclavian flap. Median clamp time was 15.5 minutes. One patient died during hospitalization. Two patients died late postoperatively (5-year estimated survival 80%). Mean follow-up was 28.5 months. Eight patients (44%) had a residual or recurrent coarctation, 5 underwent balloon dilation, and 3 underwent reoperation. Freedom from reintervention for recoarctation was 60% at 5 years. Shone's complex or a hypoplastic arch was an independent risk factor for decreased survival (p < 0.001). Very low birth weight was a multivariate predictor for increased risk of recoarctation (p = 0.01). CONCLUSIONS: Coarctation repair in less than 2-kg premature non-Shone's infants can be performed with a low mortality. The rate of recoarctation is higher in the very low-birth weight infants, but can be managed with low risk.

Analysis of Variance↗
PubMed2001

Congenital supravalvar aortic stenosis: a simple lesion?

The underlying cause of congenital supravalvular aortic stenosis (SVAS) has recently been identified as a loss-of function mutation of the elastin gene on chromosome 7q11.23, resulting in an obstructive arteriopathy of varying severity, which is most prominent at the aortic sinutubular junction. The generalized nature of the disease explains the frequent association with stenoses of systemic and pulmonary arteries. Furthermore, localization of the supravalvular stenosis at the level of the commissures of the aortic valve has important implications for both aortic valve function and coronary circulation. This review summarizes the recent advances with regard to the pathogenesis of SVAS and describes the multitude of clinically relevant pathologic features other that the mere 'supra-aortic' narrowing that have important implications for surgical therapy.

Aorta↗
PubMed2001

The risk of having additional obstructive lesions in neonatal coarctation of the aorta.

Infants with coarctation of the aorta may have obstructions at other sites within the left heart which are not always apparent on the initial echocardiogram. The magnitude of the risk of having the additional obstructions is not well described, with few reliable quantitative criterions for identifying patients at the highest risk. We determined the frequency of additional, late appearing, stenotic lesions within the left heart, and the predictive morphologic features on the initial cross-sectional echocardiogram. We identified all patients with coarctation of the aorta diagnosed by 3 months of age, excluding those with complex cardiac disease or definite additional stenotic lesions at presentation, leaving 101 patients for study. At follow-up, 31 stenotic lesions were diagnosed in 23 patients, 15 of whom had at least 1 intervention. Mitral stenosis was diagnosed in 11 patients, aortic stenosis in 10, subaortic stenosis in 8, and supravalvar aortic stenosis in 2. The probability for freedom from obstructive lesions was 81% at 1 year, 74% at 3 years, and 70% at 5 years. Echocardiographic predictors of mitral stenosis included smaller mitral valvar annuluses, presence of a mean transmitral gradient between 2.5 and 5.0 mmHg, and elongation of the area of intervalvar fibrous continuity. Predictors of aortic stenosis were smaller mitral valvar annuluses, an initial aortic valvar gradient between 15 and 20 mmHg, and obliteration of the commissure between the right and non-coronary leaflets of the aortic valve. Predictors of subaortic stenosis were smaller mitral valvar annuluses and elongation of the area of intervalvar fibrous continuity. Patients with Z-scores for the diameter of the mitral valve of less than -1 were at the highest risk for manifesting obstructive lesions at any level. Associated stenoses in the left heart are common in the setting of aortic coarctation. When Doppler data is equivocal, features of the cross-sectional echocardiogram can identify the sub-group of infants at increased risk.

Aortic Coarctation↗
PubMed2001

Optimal surgical approach for repair of aortopulmonary window.

BACKGROUND: This is a review of the experience over 26 year in a single institution with surgical repair of aortopulmonary window. METHODS: Between July 1973 and March 1999, 38 patients underwent surgery for aortopulmonary window at a median age of 5 weeks, and with a median weight of 3.9 kg. Median follow-up was 6.6 years, with a range from 0.8 to 26 years. Additional defects were present in 25 (65%) patients, including interruption of the aortic arch in 7, tetralogy of Fallot in 7, ventricular septal defect in 5, functionally univentricular anatomy in 3, aortic coarctation in 2, and anomalous origin of a coronary artery in 1. We approached via an aortotomy in 45%, an incision through the defect in 31%, and using a pulmonary arteriotomy in 24% of patients. Closure was achieved using a single patch in 30 patients (79%). RESULTS: There were 3 (7.9%) in-hospital deaths. Actuarial patient survival was 88% at 10 years. Three patients required reinterventions for stenoses of the great arteries. Freedom from any reintervention was 70% at 10 years. By multivariate analysis, the approach through a pulmonary arteriotomy was shown to result in a higher need for reintervention (p = 0.01). CONCLUSIONS: Repair of aortopulmonary window can be done with excellent results. A pulmonary arteriotomy should be avoided.

Aortopulmonary Septal Defect↗
PubMed2001

Higher hematocrit improves liver blood flow and metabolism during cardiopulmonary bypass in piglets.

OBJECTIVES: Hemodilution has been applied conventionally during cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) to counteract the increase in viscosity and deleterious rheological effects caused by hypothermia. However, liver dysfunction after low-flow bypass and DHCA is common, and little is known about the effects of hematocrit (Hct). The purpose of the present study is to evaluate the impact of two hemodilution priming protocols used clinically on liver perfusion and metabolism. MATERIALS AND METHODS: Ten piglets were randomized into 2 groups. One group (n = 5) had a crystalloid prime resulting in an Hct of about 15 % (low hematocrit; group L), the other (n = 5) a total-blood prime (Hct = 25 %; high hematocrit; group H). All animals underwent 70 min cooling at full flow (150 ml/kg/min), 30 min of low flow (50 ml/kg/min) at 15 degrees C followed by 45 min of DHCA and 75 min of rewarming at full flow. Liver blood flow (LBF) was assessed at the beginning of CPB at 34 degrees C, at the end of cooling at 15 degrees C, at the end of low flow, 5 min after the start of warming, and at the end of rewarming at 34 degrees C by injections of radioactive microspheres. Liver function was evaluated at the same time using the MEGX test, which measures the metabolism of lidocaine. RESULTS: LBF was insignificantly reduced during cooling, decreased during low flow (p = 0.001), and increased again after DHCA with the highest flow at the end of rewarming. LBF tended to be lower at all times in group L (p = 0.096). The liver lidocaine metabolic rate did not significantly decrease during cooling and low flow, but was increased at the end of rewarming (p = 0.01); the metabolism was higher in group H (p = 0.025). Multiregression analysis revealed liver blood flow (p = 0.003) and hematocrit (p < 0.001) as independent determinants of the liver lidocaine metabolism; arterial blood pressure and temperature did not have significant influence in this model. CONCLUSION: Hemodilution results in a tendency towards reduced liver blood flow during CPB; much worse is the resulting impaired liver metabolism, independent of reduced blood flow and pressure. Avoidance of low hematocrit during CPB may be a useful adjunct to preserve liver function in patients undergoing cardiac surgery with long duration CPB and DHCA.

Animals↗
PubMed2001

Developmental and neurologic effects of alpha-stat versus pH-stat strategies for deep hypothermic cardiopulmonary bypass in infants.

OBJECTIVES: In a randomized single-center trial, we compared developmental and neurologic outcomes at 1 and 2 to 4 years of age in children who underwent reparative cardiac operations at less than 9 months of age after use of the alpha-stat versus pH-stat strategy during deep hypothermic cardiopulmonary bypass. METHODS: Among 168 children eligible for follow-up, 1-year developmental evaluations were carried out on 111, neurologic evaluations on 110, and electroencephalographic evaluations on 102. Parents of 122 children completed questionnaires on behavior and development when children were 2 to 4 years of age. RESULTS: The Psychomotor Development Index scores of the alpha-stat and pH-stat groups did not differ significantly (P =.97). For Mental Development Index scores, the treatment group effect differed according to diagnosis (P =.007). In the D -transposition of the great arteries (n = 59) and tetralogy of Fallot (n = 36) subgroups, the pH-stat group had slightly higher Mental Development Index scores than the alpha-stat group, although these differences were not statistically significant. In the ventricular septal defect subgroup (n = 16), the alpha-stat group had significantly higher scores. Psychomotor Development Index and Mental Development Index scores were significantly higher in the group with D -transposition of the great arteries than in the other 2 groups (P =.03 and P =.01, respectively). Across all diagnoses, Mental Development Index scores were significantly higher than Psychomotor Development Index scores (P <.001). Treatment group assignment was not significantly associated with abnormalities on neurologic examination (P =.70) or electroencephalographic examination (P =.77) at 1 year or with parents' ratings of children's development (P =.99) or behavior (P =.27) at age 2 to 4 years. CONCLUSIONS: Use of alpha-stat versus pH-stat acid-base management strategy during reparative infant cardiac operations with deep hypothermic cardiopulmonary bypass was not consistently related to either improved or impaired early neurodevelopmental outcomes.

Body Temperature↗
PubMed2001

Critical aortic stenosis in the neonate: a multi-institutional study of management, outcomes, and risk factors. Congenital Heart Surgeons Society.

OBJECTIVES: We sought to determine factors that would predict whether a biventricular repair or Norwood procedure pathway would give the best survival in neonates with critical aortic stenosis. METHODS: Survival and risk factors were determined with parametric time-dependent event analysis for patients undergoing either the Norwood procedure or biventricular repair, and predicted optimal pathway and survival benefit were derived from multivariable linear regression. RESULTS: From 1994 to 2000, 320 neonates with critical left ventricular outflow obstruction were entered into a prospective multi-institutional study. Patients who died without intervention (n = 19) and those with primary cardiac transplantation (n = 6) were excluded. An initial intended biventricular repair pathway was indicated in 116 patients, with survival of 70% at 5 years. An initial Norwood procedure was performed in 179 patients, with survival of 60% at 5 years. Using predictions from separate multivariable hazard models for survival with each of the 2 pathways, we determined predicted optimal pathway and survival benefit for each patient. Significant independent factors associated with greater survival benefit for the Norwood procedure versus biventricular repair included younger age at entry, lower z-score of the aortic valve and left ventricular length, higher grade of endocardial fibroelastosis, absence of important tricuspid regurgitation, and larger ascending aorta. Predicted survival benefit favored the Norwood procedure in 50% of patients who had biventricular repair, and it favored biventricular repair in 20% of patients who had the Norwood procedure. CONCLUSIONS: Morphologic and functional factors can be used to predict optimal pathway and survival benefit in neonates with critical left ventricular outflow obstruction.

Aortic Valve Stenosis↗
PubMed2001

Long-term results of the lateral tunnel Fontan operation.

OBJECTIVES: Completion of a total cavopulmonary anastomosis with an intra-atrial lateral tunnel is known to yield good early and midterm results. In this study, we sought to determine the long-term outcome (10 years) after a lateral tunnel Fontan procedure. METHODS: Between October 1987 and December 1991, 220 patients (aged 11 months to 32 years) with a wide range of underlying diagnoses underwent a fenestrated or nonfenestrated lateral tunnel Fontan procedure at our institution. Current follow-up information was available for 196 patients (94%, mean follow-up = 10.2 +/- 0.6 years). Risk factor analysis included patient-related and procedure-related variables, with death, failure, and bradyarrhythmia or tachyarrhythmia as outcome parameters. RESULTS: There were 12 early deaths (<30 days or hospital death), 7 late deaths, 4 successful takedown operations, and 4 heart transplantations. Kaplan-Meier estimated survival was 93% at 5 years and 91% at 10 years, and freedom from failure was 90% at 5 years and 87% at 10 years. Freedom from new supraventricular tachyarrhythmia was 96% at 5 years and 91% at 10 years; freedom from new bradyarrhythmia was 88% at 5 years and 79% at 10 years. Three patients had evidence of protein-losing enteropathy. Multivariable risk factors for development of supraventricular tachyarrhythmia included heterotaxy syndrome, atrioventricular valve abnormalities, and preoperative bradyarrhythmia. Risk factors for bradyarrhythmia included systemic venous anomalies. The sole risk factor for late failure was a previous coarctation repair. CONCLUSION: The lateral tunnel Fontan procedure results in excellent long-term outcome even when used in patients with diverse anatomic diagnoses. The incidence of atrial tachyarrhythmia is low and mainly depends on the underlying cardiac morphology and preoperative arrhythmia. The good long-term outcome after an intracardiac lateral tunnel Fontan procedure should serve as a basis for comparison with other surgical alternatives.

Adolescent↗
PubMed2001

Valve-sparing operation for balloon-induced aortic regurgitation in congenital aortic stenosis.

OBJECTIVE: Aortic regurgitation after balloon dilation of congenital aortic stenosis may be treated with valve repair as an alternative to replacement. METHODS: Charts and echocardiograms of all patients undergoing aortic valve operations after balloon dilation of congenital aortic stenosis at our institution between January 1988 and December 1999 were reviewed. RESULTS: Twenty-one patients underwent valvuloplasty for predominant aortic regurgitation 9 months to 15 years (mean, 6.1 years) after balloon dilation. The mean +/- SD age at the time of the operation was 11 +/- 7 years. Aortic regurgitation was caused by a combination of commissural avulsion (10), cusp dehiscence with retraction (9), cusp tear (5), central incompetence (2), perforated cusp (1), or cusp adhesion to the aortic wall (1). Repair techniques included commissural reconstruction with a pericardial patch (8), pericardial patch cusp augmentation (6), primary suture repair (6), raphae release and debridement (4), commissurotomy (4), commissural resuspension with sutures (3), and cusp release (1). There were no deaths. At a mean follow-up of 30.1 months (range, 9 months-8 years), all patients were asymptomatic, and the grade of aortic regurgitation had been significantly reduced (P <.001). Left ventricular end-diastolic dimension z scores and proximal regurgitant jet/aortic anulus diameter ratios were significantly reduced (P <.001) and remained so over time. Freedom from reoperation for late failure was 100%, and overall freedom from reintervention was 80% at 3 years. CONCLUSION: Aortic valve repair for balloon-induced aortic regurgitation is reproducible and durable at medium-term follow-up.

Adolescent↗
PubMed2001

Long-term results after early primary repair of tetralogy of Fallot.

OBJECTIVE: Early primary repair of tetralogy of Fallot has been routinely performed at Children's Hospital, Boston, since 1972. We evaluated the long-term outcome of this treatment strategy including the influence of a transannular patch. METHODS: Fifty-seven patients less than 24 months of age (median 8 months) underwent primary repair of tetralogy of Fallot between January 1972 and December 1977. Thirty-one patients had a transannular patch. Survival and freedom from reintervention were determined by the Kaplan-Meier method with 95% confidence intervals. RESULTS: There were 8 early deaths, and 1 patient died 24 years after initial repair. Recent follow-up was obtained for 45 of the 49 long-term survivors (92%). Median follow-up was 23.5 years. Ten patients underwent reintervention, 8 of whom underwent relief of right ventricular outflow tract obstruction. Right ventricular outflow tract obstruction occurred in 6 patients without a transannular patch and 2 with a transannular patch (33% vs 6%, P =.04). One pulmonary valve replacement was performed at another institution 20 years after the repair. Forty-one long-term survivors were in New York Heart Association class I and 4 were in class II. Actuarial survival was 86% at 20 years (95% confidence intervals = 80%-92%). Freedom from reintervention was 93% at 5 years (95% confidence intervals = 87%-99%) and 79% at 20 years (95% confidence intervals = 70%-86%). No significant differences were found between patients with and without a transannular patch (survival, P =.34; freedom from reintervention, P =.09, log-rank tests). CONCLUSIONS: Long-term survival is excellent and the freedom from reintervention is satisfactory after early primary repair of tetralogy of Fallot in the 1970s. Use of a transannular patch does not reduce late survival and is associated with a lower incidence of right ventricular outflow tract obstruction.

Exercise Tolerance↗
PubMed2001

Prediction of safe duration of hypothermic circulatory arrest by near-infrared spectroscopy.

OBJECTIVE: Hypothermic circulatory arrest is widely used for adults with aortic arch disease as well as for children with congenital heart disease. At present, no method exists for monitoring safe duration of circulatory arrest. Near-infrared spectroscopy is a new technique for noninvasive monitoring of cerebral oxygenation and energy state. In the current study, the relationship between near-infrared spectroscopy data and neurologic outcome was evaluated in a survival piglet model with hypothermic circulatory arrest. METHODS: Thirty-six piglets (9.36 +/- 0.16 kg) underwent circulatory arrest under varying conditions with continuous monitoring by near-infrared spectroscopy (temperature 15 degrees C or 25 degrees C, hematocrit value 20% or 30%, circulatory arrest time 60, 80, or 100 minutes). Each setting included 3 animals. Neurologic recovery was evaluated daily by neurologic deficit score and overall performance category. Brain was fixed in situ on postoperative day 4 and examined by histologic score. RESULTS: Oxygenated hemoglobin signal declined to a plateau (nadir) during circulatory arrest. Time to nadir was significantly shorter with lower hematocrit value (P <.001) and higher temperature (P <.01). Duration from reaching nadir until reperfusion ("oxygenated hemoglobin signal nadir time") was significantly related to histologic score (r (s) = 0.826), neurologic deficit score (r (s) = 0.717 on postoperative day 1; 0.716 on postoperative day 4), and overall performance category (r (s) = 0.642 on postoperative day 1; 0.702 on postoperative day 4) (P <.001). All animals in which oxygenated hemoglobin signal nadir time was less than 25 minutes were free of behavioral or histologic evidence of brain injury. CONCLUSION: Oxygenated hemoglobin signal nadir time determined by near-infrared spectroscopy monitoring is a useful predictor of safe duration of circulatory arrest. Safe duration of hypothermic circulatory arrest is strongly influenced by perfusate hematocrit value and temperature during circulatory arrest.

Analysis of Variance↗