Vascular anomalies and tracheoesophageal compression: a single institution's 25-year experience.

BACKGROUND: Vascular rings are uncommon anomalies in which preferred strategies for diagnosis and treatment may vary among institutions. In this report, we offer a description of our approach and a review of our 25-year experience. METHODS: A retrospective review was conducted of all pediatric patients with symptomatic tracheoesophageal compression secondary to anomalies of the aortic arch and great vessels diagnosed from 1974 to 2000. RESULTS: Thirty-one patients (38%) of eighty-two patients (mean age, 1.7 years), were identified with double aortic arch, 22 patients (27%) with right arch left ligamentum, and 20 patients (24%) with innominate artery compression. Our diagnostic approach emphasized barium esophagram, along with echocardiography. This regimen was found to be reliable for all cases except those with innominate artery compression for which bronchoscopy was preferred, and except those with pulmonary artery sling for which computed tomography or magnetic resonance imaging, in addition to bronchoscopy, were preferred. Left thoracotomy was the most common operative approach (70 of 82; 85%). Ten patients (12%) had associated heart anomalies, and 6 (7%) patients underwent repair. Complications occurred in 9 (11%) patients and led to death in 3 (4%) patients. CONCLUSIONS: In our practice, barium swallow and echocardiography are sufficient in diagnosing and planning the operative strategy in the majority of cases, with notable exceptions. Definitive intraoperative delineation of arch anatomy minimizes the risk of misdiagnosis or inadequate treatment.

The enhancement of hemodynamic performance in Fontan circulation using pain free spontaneous ventilation.

OBJECTIVE: Positive pressure ventilation is known to have a deleterious effect on pulmonary blood flow in patients with Fontan physiology. We evaluated the hemodynamic effects of pain free, spontaneous, non-positive pressure ventilation in patients undergoing Fontan staging procedures or completion. Fontan procedures, with creation of low pressure passive pulmonary circulation. METHODS: Between May 1997 and May 1999 50 consecutive patients undergoing either bi-directional Glenn (BDG, n=23) or completion Fontan (n=27), were managed with early extubation. Anaesthetic management included continuous narcotics, caudal block, epidural block, or hyperbaric spinal. Post-operative management included low dose dopamine (3 mcg/kg per min), nitro-glycerine (0.3 mcg/kg per min) and nitroprusside (0.3 mcg/kg per min). Post-operative management was identical for all patients. Twelve patients were randomly selected to undergo continuous cardiac output and cardiac index (CI) determinations utilizing extra vascular Doppler probes placed on the ascending aorta, allowing for continuous aortic diameter and Doppler wave form velocity recordings. All patients were extubated either in the operating room or within one hour post-operatively. There were no deaths and no complications in the series. Mean length of stay (LOS) for BDG was 4.3+/-0.5 days. Mean LOS for Fontan patients was 11+/-4 days. RESULTS: Mean pulmonary artery pressure (MPAP) fell from 19+/-3.464 pre-extubation to 14+/-3.271 immediately post-extubation, 13.2+/-2.261 6 h post-extubation, and 11.7+/-2.146 12 h post-extubation. All decreases in MPAP post-extubation were significant (P=<0.05). CI pre-extubation was 3.25+/-1.09, immediately post-extubation 5.05+/-1.297, 12 h post-extubation 6.225+/-1.19. All increases in CI post-extubation were significant (P=<0.05). CONCLUSION: Resumption of pain free, spontaneous, non-positive pressure ventilation enhances hemodynamic performance in patients with Fontan circulation and clearly improves outcome.

Total anomalous pulmonary venous connection and a constellation of craniofacial, skeletal, and urogenital anomalies in a newborn and similar features in his 36-year-old father.

We report on a newborn male born to non-consanguineous parents with total anomalous pulmonary venous connection (TAPVC) and additional findings of malformed ears, hypertelorism, brachyphalangy in the hands, pterygium of the elbows, knees, and wrists, complex lower limb pre-axial polydactyly, tibial shortening, clubfeet, horseshoe kidney and a micropenis. He had a 46,XY karyotype. His 36-year-old father had similar craniofacial and limb anomalies suggesting an autosomal dominant syndrome with variable expression. Our patients may represent the 3rd and 4th examples of a newly-described syndrome by Baraitser et al. [(1997) Clin Dysmorphol 6:111-121] which is distinguished by malformed ears, complex pre-axial polydactyly and tibial aplasia in the lower limbs, severe brachyphalangy in the hands, and a micropenis.

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.

The management of pulmonary atresia, ventricular septal defect, and multiple aorta pulmonary collateral arteries by definitive single stage repair in early infancy.

OBJECTIVE: The management of infants and children with pulmonary atresia, ventricular septal defect, and multiple aorta pulmonary collateral arteries (PA/VSD/MAPCA) has proven to be challenging. Therapeutic approaches have included staged unifocalization, shunting, coiling of collateral vessels, and heart/lung transplantation. Results have been variable and frustrating. Hoping to take advantage of growth potential in pulmonary segments supplied by MAPCA, a more radical approach was adopted in March of 1997. This consists of single stage complete unifocalization with closure of the ventricular septal defect and establishment of right ventricular to pulmonary arterial continuity with a cryopreserved pulmonary allograft (Rastelli type correction) through a midline sternal incision. METHODS: During an 18-month period, eleven consecutive infants with PA/VSD/MAPCA underwent complete surgical correction. The ages ranged from 5 days to 5 months. Weights ranged from 2.2 to 5.6 kg. Through a standard median sternotomy incision, the pericardium and both pleural spaces were opened. Normothermic cardiopulmonary bypass was instituted. Section of all collaterals was accomplished without hypoxemia, and all collaterals were ligated at their origin from the aorta. They were then brought through posterior mediastinum to construct a pulmonary artery confluence. The ventricular septal defect was closed, and continuity was established between the right ventricle and the newly created pulmonary artery confluence with cryopreserved allografts. RESULTS: Ten of 11 patients survived operation, with postoperative courses that were uncomplicated. Length of stay ranged from 7-16 days, with a median length of stay of 11 days. One perioperative death occurred in a patient with preoperative co-morbidities of necrotizing enterocolitis, with no functioning gastrointestinal tract, intraventricular hemorrhage, and ventilator dependency since birth. At angiography, this patient has no demonstrable central pulmonary arteries and multiple diminutive aorta pulmonary collaterals. Autopsy revealed no demonstrable pulmonary arteries within the pulmonary parenchyma. All patients have been followed closely, and have grown normally. Two patients undergone repeat cardiac catheterization because of the echocardiographic demonstration of right ventricle pressures that had exceeded 50% of systemic. Both patients were treated with balloon angioplasty and one of these patients has had stenting of stenotic pulmonary arterial segments. No other patients have required additional hospitalization. Right ventricular pressures have remained less than fifty percent of systemic by echocardiographic assessment in all other patients. CONCLUSIONS: We feel that a single stage correction of pulmonary atresia, ventricular septal defect, and multiple aorta pulmonary collateral arteries can be accomplished in early infancy with acceptable morbidity and mortality. The initiation of normothermic cardio-pulmonary bypass greatly facilitates dissection of collaterals and prevents hypoxemia. Interventional cardiology with balloon angioplasty and stenting of abnormal pulmonary arterial segments is both an important essential adjunct in the management of these patients. We remain optimistic that a single stage approach to this complex lesion coupled with cardiac catheterization, balloon angioplasty, and stenting, will provide long-term results superior to staged approaches.

Methemoglobin levels during prolonged combined nitroglycerin and sodium nitroprusside infusions in infants after cardiac surgery.

Nitroglycerin (NTG) and sodium nitroprusside (SNP) are routinely used perioperatively in infants with congenital heart defects. In this study, NTG and SNP were infused in the operating room to increase venous capacitance, reduce systemic and pulmonary afterload, facilitate weaning off cardiopulmonary bypass, stabilize hemodynamics for transport to the intensive care unit (ICU), and reduce the fluid resuscitation needed upon arrival in the ICU. Because of the risk for accumulation of methemoglobin (MetHb) and cyanmethemoglobin (cyan-MetHb) during prolonged continuous infusion of NTG and SNP, it was decided to (1) quantify ICU use, (2) measure % MetHb at 12-hour intervals, and (3) look indirectly for the accumulation of cyan-MetHb by comparing simultaneous pulse oximetry (SpO2) (Nellcor N-100 [Nellcor, Haywood, CO]) and CO-oximetry (SaO2) (Corning 270 [Corning, Medfield, MA]). A total of 69 arterial samples were obtained from 16 infants (median age 4.4 months) following cardiac surgery with bypass. Median doses of NTG, 6.0 mg/kg (range 0.7 to 27.5), and SNP, 3.3 mg/kg (range 0.6 to 33.4), were infused over a median of 64.5 hours (range 12 to 183) (N = 16 patients). The median MetHb was 0.6% (range 0.0 to 1.5) after infusions of NTG, 1.8 micrograms/kg/min (range 0.5 to 4), and SNP, 1.3 micrograms/kg/min (range 0.3 to 8.4) (N = 69 measurements). Regression analysis of oximetry data yielded the equation: SpO2 = 1.04 SaO2 - 3.7%, r = 0.97. The mean difference between SpO2 and SaO2 data pairs was 0.0% (bias) with a SD (precision) of +/- 2.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal membrane oxygenation in the successful treatment of traumatic adult respiratory distress syndrome: case report and review.

We present the case of a 25-year-old, 28-week pregnant woman with two gunshot wounds to the chest. Extracorporeal membrane oxygenation (ECMO) was begun within 12 hours, despite poor results in prior studies and the need for anticoagulation postoperatively, since oxygenation was rapidly deteriorating despite aggressive treatment. The patient ultimately made a full recovery.

Limiting edema in neonatal cardiopulmonary bypass with narrow-range molecular weight hydroxyethyl starch.

The marked edema observed in neonatal cardiopulmonary bypass is thought to result from pathologic increases in capillary permeability. Pentafraction is a subfraction of hydroxyethyl starch that is thought to be of appropriate size and shape to be retained by leaking capillaries and seal endothelial gaps in capillary basement membranes. To test the hypothesis that pentafraction would reduce edema in neonatal cardiopulmonary bypass, we established a model of edema formation in neonatal bypass in which neonatal piglets underwent 2 hours of normothermic cardiopulmonary bypass with crystalloid prime and no myocardial ischemia. Before initiation of bypass, experimental animals (n = 11) received intravenous pentafraction, 3 gm/kg. Control animals (n = 10) received an equivalent volume of saline. Hemodynamic parameters, animal weight, fluid redistribution, and percent tissue water of individual organs were assessed during and after bypass. Pentafraction treatment resulted in significant differences in (1) lowered percent body weight gain from baseline (11% versus 48%), (2) lowered volume requirement to maintain venous reservoir during cardiopulmonary bypass (148 ml/kg versus 581 ml/kg), (3) less fluid loss from the peritoneum (11 ml/kg versus 115 ml/kg), and (4) lowered percent tissue water of kidney, pancreas, stomach, jejunum, colon, and skeletal muscle (p less than 0.05 by unpaired t test). Pentafraction had no effect on hemodynamic parameters during bypass nor in percent tissue water of heart, lung, liver, spleen, skin, or brain. In summary, pentafraction lessened weight gain and fluid requirements during cardiopulmonary bypass, favorably influencing the percent tissue water of certain organs. If pentafraction functions as proposed, it may have wide applicability not only in cardiopulmonary bypass (or extracorporeal membrane oxygenation) but also in other clinical scenarios with altered capillary permeability.

Evaluation of umbilical catheter and tube placement in premature infants.

Umbilical arterial and venous catheters, endotracheal tubes, and nasogastric tubes are routinely used in treating premature infants, and radiologists play a critical role in evaluating proper catheter and tube placement and recognizing potential complications. Ideally, an umbilical venous catheter should be positioned in the right atrium; an umbilical arterial catheter, between T-6 and T-10 (high position) or between L-3 and L-5 (low position); an endotracheal tube, 1.5 cm above the carina, with the infant's head in a neutral position; and a nasogastric tube, in the body of the stomach. Catheters and tubes can be malpositioned in a variety of vessels and the main stem bronchi, respectively. Complications include extraluminal placement of catheters (which can result in death), thrombi in the aorta and pulmonary artery, aortic aneurysm, subglottic stenosis, intubation granuloma, and perforation of the esophagus and stomach.

Combination of metolazone and furosemide in the treatment of edema in the first month of life.

A combination of metolazone (0.2 mg/kg/day) and furosemide (4 mg/kg/day) was used in the treatment of a 2-week-old neonate who developed severe edema after cardiac surgery. The edema, which was initially responsive to furosemide, became resistant to high doses of this diuretic even with the concomitant use of ethacrynic acid. The addition of metolazone to furosemide induced prompt diuresis and natriuresis. This combination of diuretics can be helpful in the treatment of refractory edema in young infants.

Myocardial adenine nucleotide metabolism in pediatric patients during hypothermic cardioplegic arrest and normothermic ischemia.

Quantitative assessment of high-energy phosphate levels, including degradation or utilization during ischemia, has not previously been performed in infants and children. Animal experiments suggest that high-energy phosphate metabolism varies with maturation. To help answer these questions, 24 patients aged 2 months to 8 years underwent myocardial biopsy immediately after the institution of cardiopulmonary bypass (16 to 20 degrees C). Additional samples were obtained at 16 and 45 minutes after aortic cross-clamping and administration of cardioplegia (St. Thomas's solution) (in vivo ischemia). Seven patients also underwent major myocardial resection. Resected specimens were placed in a 37 degrees C bath and divided into equal-sized samples that were removed at ten-minute intervals (in vitro ischemia). All samples were immersed in liquid nitrogen and analyzed for adenine nucleotide pool metabolites using high-performance liquid chromatography. Levels of adenosine triphosphate were high before cross-clamping but diminished during the period of protected ischemia. Adenosine triphosphate loss was much more pronounced in patients less than 18 months old (p less than 0.05) and was associated with accumulation of adenosine monophosphate and inosine, a finding not seen in patients more than 18 months old (p less than 0.05). The same trends documented during in vivo ischemia were noted during in vitro ischemia. Immaturity of 5'-nucleotidase results in accumulation of adenosine monophosphate during ischemia. It is known that 5'-nucleotidase is present in neonatal myocardial cell membranes and absent from the cytosol.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic thrombosis in neonates and infants.

Aortic thrombosis in the neonate occurs most frequently as a complication of umbilical artery catheterization. There is still controversy concerning the appropriate management of this problem. Complications associated with umbilical artery cannulation are numerous and include renal failure, which may necessitate peritoneal dialysis. Because of this possibility, we illustrate and advocate a retroperitoneal approach to the abdominal aorta for thromboembolectomy.

Giant cutaneous hemangioma associated with axillary arteriovenous fistula causing congestive heart failure in the newborn infant.

Although histopathologically benign, cutaneous hemangiomas may be pathophysiologically malignant if they are associated with significant arteriovenous malformation that is hemodynamically compromising. Rapid surgical intervention may be required to prevent clinical deterioration from congestive heart failure as in the case reported here. Angiography may directly influence the surgical approach to the lesion.

The effects of cardioplegic potassium concentration and myocardial temperature on electrical activity in the heart during elective cardioplegic arrest.

A major objective of cardioplegic arrest for protection of the heart during cardiac operations is total electromechanical quiescence. Recent studies from our laboratory in which we used multiple bipolar intracardiac and unipolar intramural electrodes have detected the presence of electrical activity in the lower atrial septum, the atrioventricular node-His bundle complex, and in ventricular myocardium during elective cardioplegic arrest that cannot be detected on the limb-lead electrocardiogram. Moreover, this low-amplitude electrical activity is not associated with visible mechanical activity of the heart and occurs at ventricular septal temperatures previously thought to be adequate for myocardial protection. The present study was designed to determine the effect of cardioplegic solution potassium concentration and myocardial temperature on the occurrence and duration of low-amplitude electrical activity during elective cardioplegic arrest. Fifty adult mongrel dogs were subjected to two consecutive 20 minute periods of cardioplegic arrest. The animals were divided into six groups, depending upon the cardioplegic solution potassium concentration they received and on whether or not topical cooling techniques were employed. The probability of occurrence of low-amplitude electrical activity during the arrest interval was significantly decreased by application of topical hypothermic techniques and reinfusion of hyperkalemic, as compared to normokalemic, cardioplegic solution. These effects of hyperkalemic cardioplegic solution and myocardial hypothermia acted synergistically, but independently, to decrease the likelihood of low-amplitude electrical activity occurring during the period of cardioplegic arrest. Nevertheless, low-amplitude electrical activity did occur in all groups after each cardioplegic solution administration and was not detected by routine monitoring techniques. This suggests that low-amplitude electrical activity may represent a fundamental type of metabolic activity that can be recorded from the heart during arrest and may be responsible for the temporary depression in ventricular function that frequently follows a period of elective cardioplegic arrest.

Cryosurgical modification of retrograde atrioventricular conduction. Implications for the surgical treatment of atrioventricular nodal reentry tachycardia.

Paroxysmal supraventricular tachycardia resulting from atrioventricular nodal reentry is a common arrhythmia that usually responds to medical therapy. When atrioventricular nodal reentry tachycardia is refractory to medical therapy, cryoablation or endocardial catheter ablation of the His bundle has been employed to protect the ventricles from the tachycardia. However, these techniques necessitate implantation of a permanent ventricular pacemaker. A cryosurgical procedure that ablates the anatomic-electrophysiologic substrate for atrioventricular nodal reentry tachycardia while preserving antegrade atrioventricular conduction has been described. The purpose of the present study was to determine the effects of this procedure on retrograde atrioventricular conduction and on the ventricular echo phenomenon in particular. Thirty adult mongrel dogs underwent either the cryosurgical procedure (n = 20) or a sham operation (n = 10). The animals were studied either immediately postoperatively (acute cryosurgery group and control group, n = 10 for each group) or 14 weeks postoperatively (chronic cryosurgery group, n = 10). Decremental ventricular pacing and programmed premature ventricular pacing protocols were used to determine the retrograde atrioventricular nodal conduction time, Wenckebach point, atrioventricular nodal refractory periods, and ventricular echo reflection time. No electrophysiologic alterations were noted in the sham-operated group. In the acute cryosurgery group, the retrograde Wenckebach point, atrioventricular nodal conduction time, functional refractory period of the atrioventricular node, effective refractory period of the atrioventricular node, and ventricular echo reflection time were all significantly prolonged. In the chronic cryosurgery group, no significant change in ventriculoatrial conduction was noted, but the ventricular echo phenomenon was eliminated in all but one animal. These data further document that this cryosurgical procedure is capable of ablating the anatomic-electrophysiologic substrate necessary for atrioventricular nodal reentry tachycardia while preserving atrioventricular conduction.

Alteration of antegrade atrioventricular conduction by cryoablation of peri-atrioventricular nodal tissue. Implications for the surgical treatment of atrioventricular nodal reentry tachycardia.

Paroxysmal supraventricular tachycardia due to atrioventricular nodal reentry is a common arrhythmia that usually responds to medical therapy. When atrioventricular nodal reentry tachycardia is refractory to medical therapy, surgical cryoablation or endocardial catheter ablation of the His bundle has been employed to protect the ventricles from the tachycardia. However, these techniques necessitate implantation of a permanent ventricular pacemaker. The purpose of the present study was to develop a cryosurgical procedure capable of ablating the anatomic-electrophysiological substrate of atrioventricular nodal reentry by modifying, rather than ablating, atrioventricular conduction. Thirty-three adult mongrel dogs underwent either the cryosurgical procedure (n = 23) or a sham operation (n = 10). All animals were restudied immediately postoperatively (acute cryosurgery group [n = 12) and sham group [n = 10]), and 11 animals (chronic cryosurgery group) subjected to cryosurgery were studied 14 weeks postoperatively. Decremental atrial pacing and programmed premature atrial stimulation protocols were utilized to determine atrioventricular nodal conduction time, atrioventricular nodal refractory period, and the Wenckebach point before and after operation in all animals. No electrophysiological alterations were noted in the sham-operated group. In the cryosurgery groups, atrioventricular nodal conduction time, functional refractory period of the atrioventricular node, and the Wenckebach point were all significantly prolonged in the immediate postoperative period, but only atrioventricular nodal conduction time remained prolonged 14 weeks postoperatively. The potential application of the new cryosurgical procedure for the treatment of atrioventricular nodal reentry tachycardia was demonstrated in three animals that exhibited dual atrioventricular nodal conduction preoperatively but had monophasic atrioventricular conduction curves postoperatively. The results in these animals documented that the cryosurgical procedure is capable of ablating the anatomic-electrophysiological substrate necessary for atrioventricular nodal reentry tachycardia.

Monitoring of the electrical status of the ventricle during cardioplegic arrest.

Present methods used to assess the status of myocardial preservation during cardioplegic arrest include monitoring the peripheral electrocardiogram (ECG) and ventricular myocardial temperature, and visual inspection of the heart to verify complete mechanical arrest. This study was designed to determine if these parameters are adequate to ensure complete electromechanical arrest after the application of standard cardioplegic techniques. The electrical status of the ventricle in adult mongrel dogs was monitored continuously during elective hyperkalemic hypothermic arrest for the presence of electrical activity in either the atrium or ventricle with 25 intramural electrodes, three epicardial reference electrodes, a His bundle catheter, and three peripheral ECGs. Occurrence of ventricular electrical activity was documented in the arrested heart (determined visually) when the peripheral ECG was quiescent; the activity persisted for a significant period of time before electromechanical activity could be detected by standard monitoring techniques. This electrical activity is believed to originate in the lower atrial septum and to conduct through the AV node to the ventricles at myocardial temperatures previously thought to be safe. Thus, continuous monitoring of intramural electrical activity would appear to be a more reliable technique than those currently used to determine the adequacy of myocardial preservation during elective cardioplegic arrest.

Late fractionated potentials and continuous electrical activity caused by electrode motion.

Late fractionated potentials, recorded during cardiac mapping to find the source of a ventricular arrhythmia, have been ascribed particular localizing value. Re-entry is assumed when these highly amplified and filtered recordings span diastole during tachycardia. The purpose of this study was to see if such potentials can occur artifactually. A saline soaked 7 X 2 X 3 cm sponge was sewn to the epicardium of the right ventricle in five non-infarcted, open-chest dogs. Two bipolar button electrodes, one with 1 mm and one with 1 cm interelectrode spacing, were attached to the outer surface of the sponge and a bipolar wire hook electrode was placed just under the outer surface of the sponge. Thus all three electrodes were 3 cm from the nearest myocardium yet still subjected to cardiac motion. The electrodes were recorded at gains of 4,000-40,000 and filtered to pass 50-300 hertz. One to three rapid deflections were recorded during the QRS from all electrodes. In seven of the the 15 electrode recordings, two or three additional deflections, 1100-200 microV in amplitude, occurred after the QRS. These late potentials were fractionated and recurred reproducibly from cycle to cycle. In two cases, these late fractionated potentials could be made to span diastole by rapid pacing to simulate tachycardia. Clamping the sponge to sliminate motion between the sponge and electrode caused this late activity to disappear. Thus, in highly amplified and filtered recordings, electrode motion can cause artifacts resembling late fractionated potentials and continuous electrode activity.