Biomedical subjects
Publications and source records attributed to T R Karl.
During the past year there have been many important scientific and clinical publications addressing important aspects of pediatric cardiac surgery. Herein we review some of the more significant contributions, with our own commentary added. Space limitations prevent a more comprehensive review.
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BACKGROUND: Pulmonary valve and left ventricular outflow tract abnormalities (LVOT) may not be absolute contraindications to arterial switch operation (ASO). METHODS: In this study we analyze long-term outcome for 26 such transposition patients (6.3% of our ASO cohort). Median age and weight were 69 days (7 to 3,631 days) and 4.5 kg (2.6 to 34 kg). Pulmonary valve abnormalities included bicuspid valve (n = 4) and dysplastic valve (n = 5). The LVOT abnormalities (n = 17) included accessory atrioventricular valve/endocardial cushion tissue, fibromuscular ring, anomalous muscle bands, and septal malalignment. Patients with dynamic LVOT obstruction were excluded. The median preoperative left ventricular to pulmonary artery peak systolic pressure gradient was 30 mm (0 to 93 mm), or 50 mm (16 to 93 mm) if patients with isolated valve abnormalities are excluded. The ASO was performed according to our standard technique with or without LVOT resection or pulmonary valvotomy as required. RESULTS: There were two perioperative deaths (7.7%; 95% confidence interval, 0.9% to 25%), and no late deaths during 1,934 patient-months of follow-up time. Actuarial freedom from reoperation for neoaortic valve or LVOT problems is 87% (+/- 7) at 130 months, representing two reoperations. One was performed for neoaortic insufficiency plus LVOT obstruction, and the other for isolated LVOT obstruction. One patient currently has significant neoaortic insufficiency, and median gradient at last follow-up is 0 mm Hg (range, 0 to 35 mm Hg). CONCLUSIONS: The ASO can be performed in selected patients with transposition of the great arteries and with LVOT abnormalities with early and late survival and functional status similar to that of matched patients with normal pulmonary valves and LVOT (p > 0.05), but with a greater hazard for reoperation (p < 0.05). Selection for ASO should be based on anatomic criteria rather than left ventricular to pulmonary artery gradient alone, to avoid assigning these patients with transposition of the great arteries to treatment strategies less satisfactory than ASO.
Coronary sinus orifice atresia is rare. We describe two cases, one with an atrioventricular septal defect and another with supracardiac totally anomalous pulmonary venous drainage. The association with the latter has not been described previously. The importance of diagnosing the defect is emphasized and surgical treatment is discussed.
OBJECTIVES: The study's object was to analyze the outcomes of transatrial-transpulmonary repair in children with tetralogy of Fallot and anomalous coronary artery crossing the right ventricular outflow tract. METHODS: The transatrial-transpulmonary approach was used in 611 consecutive repairs, 36 (5.9%) of which were associated with a surgically relevant coronary artery anomaly. The median age and weight of the patients at repair were 23 months (2.8-170 months) and 9.9 kg (5.2-41 kg), respectively. Anomalies included left anterior descending coronary artery from right coronary artery or single right coronary artery (n = 22), right coronary artery from left coronary artery or left anterior descending coronary artery (n = 8), and large right coronary artery conal branch (n = 6). Diagnosis was established before the operation in 25 of 36 cases by angiography (n = 24) or echocardiography (n = 1). The approach was successful in 34 cases, in 25 of which placement of a limited transannular patch was necessary. Two patients had a right ventricle-pulmonary artery conduit as a result of proximity of the coronary branch to the pulmonary arterial anulus and inability to adequately relieve the right ventricular outflow tract obstruction. RESULTS: There have been no early or late deaths. Mean right ventricle-pulmonary artery gradient at last follow-up was 19 mm Hg (95% confidence interval 14.5-24 mm Hg), compared with 15 mm Hg (95% confidence interval 12.5-17.5 mm Hg) for patients with normal coronary arteries (P = .3). Actuarial freedom from reoperation at 120 months was 96.5% (95% confidence interval 79.8%-99.5%) and was also similar between patients with and without coronary artery abnormalities (P = .92). CONCLUSIONS: Surgically important coronary anomalies in tetralogy of Fallot can be dealt with through the transatrial-transpulmonary approach in most cases without major alterations in technique. Outcomes are similar to those of other patients with tetralogy of Fallot. The presence of anomalous coronary arteries does not impart incremental risk after this surgical strategy.
OBJECTIVE: The clinical application of centrifugal ventricular assist devices (VAD) has generally been limited to adults and large paediatric patients. In our experience neonates and small paediatric patients requiring ventricular support post-cardiopulmonary bypass are well supported by VAD. In this study we analyse our experience. METHODS: We have examined the records of our VAD patients who weighed less than 6 kg. Thirty-four patients, ranging in age from 2 to 258 days (median 60 days) and weight from 1.9 to 5.98 kg (median 3.7 kg), underwent 35 VAD procedures. One patient was supported on VAD twice. RESULTS: All patients had congenital heart lesions and were placed on VAD either because they could not be weaned from cardiopulmonary bypass after repair or palliation of the lesion (71.5%), or for support in the post-operative period due to refractory low cardiac output (28.5%). Twenty-two of the 35 VAD procedures (0.63, 95% CI: 0.45-0.78) resulted in successful weaning and decannulation, this was similar to the weaning probability for patients greater than 6 kg (P = 0.07). There were 10 late deaths in this group, with a 1-year KM survival of 0.31 (95% CI: 0.17-0.47). Most late deaths were related to irreversible cardiac disease processes as were the elective discontinuance of VAD outcomes. Neither weight, age, VAD duration, CPB duration, X clamp duration, univentricular anatomy or TGA anatomy predicted successful discharge from hospital (P > 0.05)--Weight P = 0.576; Age P = 0.532; VAD duration P = 0.181; CBP duration P = 0.549; X clamp duration P = 0.984; Univentricular anatomy P = 0.481; TGA anatomy P = 0.099. CONCLUSION: We believe centrifugal ventricular assist is a realistic option in very small patients who require post-cardiopulmonary bypass support. It is relatively easy to establish and manage, the results, although showing no factors predictive of successful discharge, are encouraging.
Two infants with anomolous origin of the left circumflex coronary artery from the pulmonary artery had to be operated on at ages 40 days and 30 days because of severe myocardial dysfunction. This illustrates that the clinical course of anomalous origin of the circumflex artery from the pulmonary artery may not always be as favorable as reported in the literature.
BACKGROUND: The objective of this study was to review anatomic features and surgical strategies in children with double-outlet right ventricle (DORV) and to assess risk factors for early mortality. METHODS AND RESULTS: Records were reviewed of all children with DORV undergoing surgery between 1978 and 1993. Noncomplex patients (group 1) had atrioventricular (AV) concordance, a single ventricular septal defect (VSD), balanced ventricles, no straddling AV valves, and no major pulmonary artery anomaly. Group 2 (complex) comprised all remaining patients. Independent risk factors analyzed included location of the main VSD, presence of additional VSDs, coarctation, ventricular outflow obstruction, ventricular hypoplasia, age at operation, operation before 1985, previous palliation, and type of definitive operation. Of 193 patients, 117 were in group 1 and 76 in group 2. In 148 patients, biventricular repair was undertaken, including 111 of 117 group 1 patients and 37 of 76 group 2 patients. Early mortality was higher among group 2 patients undergoing biventricular repair than among group 1 patients (8 of 37 versus 4 of 111, P<.005) and higher than group 2 patients undergoing a Fontan procedure (none of 29, P<.01). Aortic arch obstruction, operation before 1985, and multiple VSDs were significant risk factors for mortality. Age <1 month (P<.05) and multiple VSDs (P<.005) were independent risk factors after definitive repair. Up-to-date follow-up is available on 144 surviving patients, with 127 (88%) in New York Heart Association class I and the remaining 17 in class II. Overall 10-year survival probability was 81%, whereas probability of survival, free from reoperation (after definitive surgery), was 65% at 10 years. CONCLUSIONS: Biventricular repair can be achieved in most patients with DORV with low risk. In complex DORV, a Fontan procedure is associated with a lower surgical mortality.
BACKGROUND: Congenitally corrected transposition of the great arteries is a complex cardiac lesion, usually associated with ventricular septal defect, left ventricular outflow tract obstruction, and tricuspid valve abnormalities. A subset of patients without left ventricular outflow tract obstruction have undergone Senning plus arterial switch operation in an attempt to place the left ventricle in the systemic circuit and the right ventricle in the pulmonary circuit. METHODS: Fourteen patients have had the operation performed since July 1989. Age and weight medians were 12 months (range, 0.5 to 120 months) and 8.2 kg (range, 3.2 to 34 kg). All but 1 patient had a left ventricular to right ventricular pressure ratio greater than 0.7, due to a large ventricular septal defect (with or without a previous pulmonary artery band), severe congestive heart failure caused by right ventricular dysfunction and tricuspid insufficiency, or a pulmonary artery band for left ventricular retraining. At least 10 patients had strong contraindications to "classic" repair, including right ventricular hypoplasia (n = 2), moderate to severe right ventricular dysfunction (n = 5), or moderate to severe tricuspid insufficiency (n = 9). RESULTS: There was one hospital death, occurring in a neonate (7%; 95% confidence interval = 0% to 34%). Actuarial survival beyond 10 months is 81% (95% confidence interval = 42% to 95%), currently with 389 patient-months of total follow-up time. The median grade of tricuspid insufficiency fell from 3/4 preoperatively to 1/4 postoperatively (p = 0.003). Right ventricular function is normal in 11/12 current survivors, all but 1 of whom are in New York Heart Association class I or II. CONCLUSIONS: Senning plus arterial switch operation is a good option for selected patients with congenitally corrected transposition of the great arteries with a similar or lower early risk (as compared with classic repairs). Some of the long-term problems associated with congenitally corrected transposition of the great arteries may be avoided with this strategy.
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OBJECTIVES: The purpose of this study was to determine the physiologic variables that predict major adverse events in children in the intensive care unit after cardiac operations. METHODS: A cohort observational study was conducted. At the time of admission to the intensive care unit and 4, 8, 12, and 24 hours later the following variables were recorded: mean arterial pressure, heart rate, cardiac index, oxygen delivery, mixed venous oxygen saturation, base deficit, blood lactate, gastric intramucosal pH, carbon dioxide difference (the difference between arterial carbon dioxide tension and gastric intraluminal carbon dioxide tension), and toe-core temperature gradient. Major adverse events were prospectively identified as cardiac arrest, need for emergency chest opening, development of multiple organ failure, and death. RESULTS: Ninety children were included in the study; 12 had major adverse events and there were 4 deaths. Blood lactate level, mean arterial pressure, and duration of cardiopulmonary bypass were the only significant, independent predictors of major adverse events when measured at the time of admission to the intensive care unit. The odds ratio (95% confidence intervals) for major adverse events if a lactate level was greater than 4.5 mmol/L was 5.1 (1.2 to 21.1), for admission hypotension 2.3 (0.5 to 9.8), and for a cardiopulmonary bypass time greater than 150 minutes 13.7 (3.3 to 57.2). Four hours after admission lactate and carbon dioxide difference, and 8 hours after admission lactate and base deficit, were independently significant predictors. The odds ratios for major adverse events if the blood lactate level was greater than 4 mmol/L at 4 and 8 hours were 8.3 (1.8 to 38.4) and 9.3 (1.9 to 44.3), respectively. At no time in the first 24 hours were cardiac output, oxygen delivery, mixed venous oxygen saturation, toe-core temperature gradient, or heart rate significant predictors of major adverse events. CONCLUSIONS: In the context of our current treatment strategies, the duration of cardiopulmonary bypass and blood lactate level, measured in the early postoperative period, were the best predictors of impending major adverse events.
OBJECTIVE: To assess the impact of the bidirectional cavopulmonary shunt, total cavopulmonary connection, and baffle fenestration on outcome of the Fontan operation in our unit. METHOD: We reviewed 123 bidirectional cavopulmonary shunts and 264 Fontan operations performed from 1980 to 1995. Analysis of pulmonary artery size (right and left main and lower lobe branches) before and after bidirectional cavopulmonary shunt was performed. Outcome of the Fontan operation was analysed in various time periods to assess the effect of prior bidirectional cavopulmonary shunt, use of the lateral tunnel, and fenestration. RESULTS: Operative risk for the bidirectional cavopulmonary shunt was 4% (CI = 2-10%) with a survival of 89% (CI = 83-95%) at 36 months. Probability of conversion to Fontan operation at 36 months was 49% (CI = 38-61%). Pulmonary artery size (Nakata and lower lobe indices) fell after bidirectional cavopulmonary shunt (P = 0.0006). Fontan risk dropped from 8.5% (1980-1987) to 1.8% (1988-1995) (P = 0.02), coinciding with the use of the bidirectional cavopulmonary shunt. There was no further risk reduction after introduction of the lateral tunnel and baffle fenestration, although these comparisons are limited by relatively small numbers. Duration of hospital stay related to pleural effusions was lowest for patients with a fenestrated lateral tunnel operation (P < 0.05). CONCLUSION: The bidirectional cavopulmonary shunt is a suboptimal stimulus for pulmonary artery enlargement, but may reduce the risk of Fontan operation in selected children. Fenestrated lateral tunnel operations have reduced the duration of postoperative pleural effusions.
OBJECTIVE: Evaluation of a consistent policy of elective repair of truncus arteriosus at 2-3 months of age for the patients who are independent of hospital ward care, and long-term outcome. METHODS: Retrospective study of 82 patients with truncus arteriosus who underwent total repair at the Victorian Paediatric Cardiac Surgical Unit between 1979 and December 1995. The timing was based on a consistent policy of elective repair at 2-3 months of age for patients who were independent of hospital ward care. Earlier repair was performed when the patients were in uncontrolled congestive heart failure. RESULTS: Follow-up was complete for all patients with a mean of 76 months (1-183). There were 11 hospital deaths (13.4% CL 9-18.5), and five late deaths, actuarial survival at 80 months was 81% (CL 70-88%) with 39 patients uncensored at that point. For the purpose of this presentation, patients have been grouped according to their age at repair; 1, neonates n = 17 (hospital mortality = 5); 2, infants 1-6 months of age n = 48 (hospital mortality = 4); 3, patients beyond 6 months n = 17 (hospital mortality = 2). This series includes 10 patients with interrupted aortic arch with no mortality, and 10 patients with discontinuous pulmonary artery (hospital mortality = 2). Thirty-seven patients have had 54 conduits replaced to date. Using multiple regression, body weight < 3 kg was the only significant independent risk factor for hospital mortality. CONCLUSIONS: Our management policy tended to gather patients with risk factors described elsewhere into presentation group 1 and low risk truncus patients into presentation group 2. Deferral of surgery to 2-3 months of age is possible and lowers the surgical risk.
The combination of atrioventricular septal defect (AVSD) and tetralogy of Fallot (TOF) constitutes one of the more difficult entities presented to the cardiac surgeon, from both an anatomic and physiological point of view. TOF is encountered in 2.7% to 10% of cases of AVSD, and AVSD complicates 1% to 6.5% of cases of TOF. At least 75% of children with TOF and AVSD have Down's syndrome. The gold standard for rapid noninvasive diagnosis of AVSD with TOF is two-dimensional echocardiography. We prefer to perform elective surgery at 18 to 36 months of age. Our technique is a combination of our patch repair for AVSD and our transatrial transpulmonary repair of TOF. We have performed repair of AVSD with TOF (or double-outlet right ventricle) in 26 patients, of mean age and weight, 34.6 months (2 to 44 months) and 11.8 kg (3 to 37 kg), respectively. There was one hospital death (3.9%, CL = 0% to 20%). Over a follow-up time of 1,650 patient months, there have been two late deaths. Actuarial survival is similar to that for isolated TOF, although freedom from reoperation is significantly worse. Currently, repair of AVSD and TOF is considered a palliative rather than curative operation, but on balance one that has favorably altered the early and midterm outlook for many children.
The arterial switch operation is appropriate treatment for most forms of transposition of the great arteries. In this review we analyze indications, techniques, and outcome for various subsets of patients with transposition of the great arteries, including those with an intact septum beyond 21 days of age, intramural coronary arteries, aortic arch obstruction, the Taussig-Bing anomaly, discordant (corrected) transposition, transposition of the great arteries with left ventricular outflow tract obstruction, and univentricular hearts with transposition of the great arteries and subaortic stenosis.
An 11-month-old child underwent unifocalization of the major aortopulmonary collateral arteries, but did not tolerate occlusion of both vessels simultaneously. Using a Y-shaped homograft tube, we translocated the vessels sequentially and avoided severe hypoxemia.
Early intervention is necessary in neonates with critical aortic stenosis. The advent of alternate therapy, particularly balloon aortic valvuloplasty, requires a reappraisal of the traditional surgical approach, including the efficacy of initial transvalvar gradient reduction and freedom from recurrence of obstruction in the longer term. This report describes a series of 33 consecutive infants who underwent surgical aortic valvotomy in the first month of life. The hospital mortality was 18 percent with a 5-year probability of survival of 66 percent (90 percent CI, 50 percent to 79 percent). Fourteen reinterventions, nine reoperations and five balloon dilatations, were required at a median age of 0.8 years (range 9 days to 6 years). Three patients died after reintervention (one early and two late). The median follow-up time was 5.8 years (range 0.2 to 14 years). At last follow-up Doppler investigation the average Doppler mean and peak gradients were 34 mm Hg and 18 mm Hg, respectively. Open valvotomy in neonatal aortic valve stenosis allows the use of an appropriate surgical approach with low initial mortality and satisfactory 5-year freedom from reintervention.
OBJECTIVE: Aortic arch obstruction is a commonly associated problem in the Taussig-Bing anomaly. Between 1983 and 1995, 28 consecutive patients with Taussig-Bing anomaly underwent arterial switch operation with baffling of the left ventricle to neoaorta. Group A: 11/28 had associated aortic arch obstruction. Group B: 17/28 had isolated Taussig-Bing anomaly. We assessed whether the coexistence of subpulmonary ventricular septal defect and aortic arch obstruction pose an incremental risk factor. PATIENTS AND RESULTS: Group A: Mean age and weight were 1.4+/-1.3 months and 3.5+/-0.4 kg. The aortic arch obstruction included: hypoplasia (5/11), interruption (4/11) and discrete coarctation (2/11). Seven patients had a one-stage correction, and four had initial arch repair followed by arterial switch operation. There were no hospital deaths (CL 0-28%). Over a follow-up of 638 patient-months (mean 64+/-39), there have been no late deaths, and all patients are in New York Heart Association class 1. There have been three cases of recurrent aortic arch obstruction (two requiring reoperation, and one requiring balloon dilation). One patient has been reoperated upon for right ventricular outflow tract obstruction. The actuarial survival and freedom from reoperation rates at 6 years were 100% (CL = 66-100%) and 72.9% (CL=38-92%) respectively. Group B: Mean age and weight were 5.9+/-8.4 months and 5+/-2.1 kg. All patients had a one-stage operation. There were two early deaths (11.8%, CL = 1-36%) and one late death over a follow-up of 678 patient-months (mean 52+/-31). All survivors are in New York Heart Association class 1 and there have been no reoperations. The actuarial survival and freedom from reoperation rates at 6 years were 81% (CL = 56-93%) and 100% (CL = 76-100%) respectively. CONCLUSIONS: 1. Aortic arch obstruction has not adversely affected early or late survival (P>.05) or late functional class. 2. Patients with Taussig-Bing anomaly and aortic arch obstruction may have a higher reoperation rate than those with normal arch anatomy. 3. Taussing-Bing anomaly, with or without aortic arch obstruction, can be repaired with arterial switch operation during the neonatal period with good outcome.