Anomalous origin of the right coronary artery from the main pulmonary artery: diagnosis and management

Anomalous origin of the right coronary artery (ARCA) from the main pulmonary artery (MPA) is a rare congenital anomaly, with only 18 reported cases in the pediatric age group. More than half of these had associated cardiac anomalies that masked the presence of ARCA. Conversely, in many patients with ARCA as an isolated anomaly, the diagnosis has been missed during lifetime. The only patient with an isolated ARCA who was diagnosed in infancy presented with congestive heart failure. Asymptomatic infants with ARCA from the MPA have not been previously reported. Three additional cases, two infants and a child with ARCA from the MPA, are reported in this paper. The diagnostic dilemmas and the prognosis are discussed and management is recommended.

Pleural drainage after repair of tetralogy of Fallot

Prolonged pleural effusion after congenital heart surgery results in extended hospitalization. Pleural drainage was evaluated in 39 consecutive patients undergoing repair of tetralogy of Fallot, to identify risk factors for persistent pleural effusion. Duration and amount of drainage was examined by the Kaplan-Meier method and risk factors were evaluated by univariable and multivariable analyses. Median time of pleural drainage was 6.1 days, range 3 to 42 days. Duration of pleural drainage correlated with length of hospital stay (p < 0.0001). Postrepair right atrial pressure (p = 0.018) and preoperative hemoglobin (p = 0.035) were risk factors for persistent drainage. The presence of a previous right thoracotomy reduced drainage duration (p = 0.034). Prolonged mechanical ventilation increased the average daily volume of effusion (p < 0.0001). In conclusion, prolonged pleural effusion is an important morbidity factor after repair of tetralogy of Fallot. Bilateral chest tube insertion is indicated in patients with high preoperative hemoglobin and elevated postrepair right atrial pressure. Right thoracotomy is the preferred surgical approach when a preliminary palliative shunt is required.

Comparative effects of bicarbonate, tris-(hydroxymethyl)aminomethane and dichloroacetate in newborn swine with normoxic lactic acidosis

A total of 20 newborn piglets age 11.5 +/- 0.3 days and weighing 3.7 +/- 0.1 kg were studied under pentobarbital anesthesia. After stabilization following surgical procedures, baseline values for blood gases, base excess (BE), heart rate (HR), aortic pressure (AoP), left-ventricular contractility (LV dP/dtmax), carotid artery flow (CarF) and renal artery flow (RenF) were measured and normal lactic acid 0.2 ml/kg was infused over 1 h and the same parameters repeated. Then sodium bicarbonate (BC, n = 8), Tris-(hydroxymethyl)aminomethane (THAM, n = 6) or dichloroacetate (DCA, n = 6) were infused over 1 h. The doses of BC and THAM were calculated from the standard formula: Mmol = Base deficit x kg x 0.3. DCA was given at a dose of 300 mg/kg. Following lactic acid infusion, pH was 7.00 +/- 0.4 and BE was -20.6 +/- 1.2. Acidosis was associated with a significant (p < 0.05) increase in AoP (+18.6 +/- 7.4%) and decreases in HR (-13.9 +/- 2.7%) and RenF (-43.8 +/- 10.4%). Values of dP/dtmax and CarF were higher during acidosis in all but 3 animals. Following infusion of alkalizing agents pH and BE values were highest with BC and lowest with DCA and the differences were statistically significant (p < or = 0.05). In general, all three alkalizing agents reversed, in part or completely, the changes in cardiovascular parameters associated with acidosis so that following alkali infusion the changes were not statistically significant when compared to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of acute hypoxemia on responses to dopamine and dobutamine in neonatal swine

The effects of acute hypoxemia on cardiovascular responses to dopamine (DA) and dobutamine (DB) were studied in 2-4 day (n = 21) and 13-17 day (n = 27) old swine under sodium pentobarbital anesthesia. Sequential 10-min infusions of 2, 5 and 15 mu/kg/min of DA or DB or normal saline were administered under conditions of normoxemia and repeated during hypoxemia. Data are presented as mean percent of baseline value +/- SE. During normoxemia, DA increased aortic pressure, cardiac output, heart rate, LV dP/dt max and renal resistance and decreased mesenteric resistance in both ages, while DB increased heart rate, LV dP/dt max and cardiac output in both age groups and decreased total arterial resistance and renal resistance in the youngest. Increases in LV dP/dt max were larger with DA as compared to DB (p less than 0.05) with the highest dose in younger (152 +/- 5% vs. 124 +/- 4%) and older (201 +/- 29% vs. 157 +/- 9%) animals. Hypoxemia reduced heart rate responses to DA and DB in older piglets, contractility responses to DB in older animals, aortic pressure responses to DA in all animals and renal resistance responses to DA in older animals. Hypoxemia had little or no effect on cardiac output and total arterial, mesenteric and carotid resistance responses to DA and DB. Thus, in the newborn: 1) DA is a stronger inotropic agent during normoxemia and hypoxemia while the chronotropic effects of the two drugs did not differ. 2) Changes in cardiac output with both drugs did not differ significantly during normoxemia and were not affected by hypoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative effects of bicarbonate and dichloroacetate in newborn swine with hypoxic lactic acidosis

Sodium bicarbonate (BC) and dichloroacetate (DCA) were studied in 7- to 14-day-old (n = 25) anesthetized swine with hypoxic acidosis. BC (base deficit X kg X 0.3, n = 10), DCA (300 mg/kg, n = 7) or saline (n = 8) was infused for 1 h. Blood lactic acid, dP/dtmax, heart rate and cardiac output increased and base excess and total arterial and carotid resistances (R) decreased with acidosis; aortic pressure, renal and mesenteric R did not change. BC induced higher pH, base excess and lactic acid. Heart rate in all and dP/dtmax with BC and DCA were restored; renal and mesenteric R and aortic pressure decreased in all. Cardiovascular responses to DCA and BC did not differ except for renal R.

CONCLUSION

BC is a more effective alkalizer than DCA, which induced a greater renal vasodilation; both restored contractility.

Young long distance runners. Physiological and psychological characteristics

This study presents the physiological and psychological characteristics and the running histories of 16 subjects who began long distance running at age 4-12 years. Running duration was 3-15 years (mean 8.4 +/- 3.6 yrs). Seven children completed 41 marathons, seven 30-mile races, and eight 60-mile races. The other nine competed at shorter distances. All trained at 30-105 miles/week. Two stress fractures, one back sprain and one knee injury occurred. Athletes who reported injuries from recollection may have underreported some injuries. At age 15.4 +/- 4.2 years bone age was 15.3 +/- 2.6 years and height was at 51 +/- 26.0 percentile. Athletes had larger left ventricular diastolic diameter, higher max O2 uptake, and delayed onset of anaerobic metabolism compared to controls. Psychological profile: IQ = 121 +/- 11, scholastic grade point average (GPA) (n = 13) was less than or equal to 3.0 in four, 3.6-3.9 in four, and 4.0 in five. Cattell 16 personality factor (PF): Seven scored above the 85th percentile on boldness, warmth, conformity, sensitivity, dominance, and high drive with tension. Eight scored above the 93rd percentile for self discipline and emotional stability. Human Figure Drawing showed a distorted body image in seven. Two developed anorexia nervosa, and another girl committed suicide. Thus, high physical fitness and no growth retardation were observed. These runners, however, shared distinct positive and negative personality characteristics. The relatively high incidence of severe psychological disorders possibly suggests a need for psychological screening for young children entering a strenuous training program and for close monitoring for development of psychological problems during the program.

Age-related digoxin-verapamil interactions in the adult rat

We have previously described a method for inducing atrial ectopic tachycardia (AET) in the anesthetized adult rat using digoxin, 30 mg/kg s.c. In this study, we used this model to study digoxin-verapamil interactions in young and older male rats and have found age-related differences in their responses to digoxin alone and to digoxin-verapamil interactions as well. Overall, 90% of the animals of both groups combined that developed AET, developed a ventricular proarrhythmic response to verapamil. Thus, this model might broaden the pre-clinical evaluation of anti-arrhythmic agents and predict which drugs are most likely to have a proarrhythmic effect.

Dilated cardiomyopathy complicating a case of epidermolysis bullosa dystrophica

A child with epidermolysis bullosa dystrophica, recessive type (EBDR) developed significant anemia at 9 years of age and was treated with long-term transfusion therapy. At age 17 he had symptoms of congestive heart failure secondary to dilated cardiomyopathy. Treatment with digoxin and vasodilators for the past year has failed to improve his cardiomyopathy significantly. Chronic iron overload and secondary hemosiderosis may have contributed to his problems, and we propose that chelation therapy be used in any child receiving long-term transfusion therapy.

Acute rheumatic fever in Wisconsin

Medical records of patients discharged from Children's Hospital of Wisconsin from January 1980 to May 1988 who fulfilled the revised Jones criteria for acute rheumatic fever were reviewed. A total of 13 patients were hospitalized with a first attack of acute rheumatic fever during this period. Migratory polyarthritis was present in 92% of the patients and carditis in 62%. Mitral regurgitation was present in all cases of carditis. Only six patients (46%) had a history of a preceding streptococcal infection, half of whom were treated with antibiotics. While there is no evidence to support a new outbreak of acute rheumatic fever in Wisconsin, our data demonstrate that the disease is still prevalent within the eastern region of the state. Patients with Group A streptococcal pharyngitis must be identified and treated to prevent this disease from increasing in incidence.

Cardiac glycoside toxicity in small laboratory animals

Cardiac glycosides are frequently administered to laboratory animals for research purposes. The effects achieved depend not only upon the particular glycoside and dose administered, but also upon an entire array of variables from the species of animal to the temperature of the animal housing facility. We review a number of these factors and their influence upon the effects achieved by the administration of cardiac glycosides to laboratory animals.

Bilateral origin of the left anterior descending coronary artery in a young man

Abnormalities of coronary artery origin from the aorta have been implicated in sudden death in sports among young athletes. We describe an 18-year-old patient who presented with nonspecific chest pain, developed ventricular couplets during recovery from a stress test, and whose coronary angiograms revealed bilateral left anterior descending coronary arteries, an abnormality that has not been previously reported.

A model of atrial ectopic tachycardia in the rat

A model of atrial ectopic tachycardia (AET) in the adult rat is described. Pentobarbital-anesthetized adult male rats given digoxin 30 mg/kg s.c. develop AET 50 min after administration. Heart rate and rhythm were determined by electrocardiography using limb leads, I, II and III. This model of AET is simple, sustained and economical. As a supplement to models of ventricular arrhythmias, this model might broaden the pre-clinical evaluation of antiarrhythmic agents.

Reevaluation of digoxin-encainide interactions using an animal model

The effects of intravenous encainide on digoxin-induced atrial ectopic tachycardia (AET) were investigated in the rat using 3-channel simultaneous limb-lead electrocardiography. Pentobarbital-anesthetized (35 mg/kg, intraperitoneal) adult male rats were given digoxin subcutaneously, 30 mg/kg. After onset of AET, rats received either saline (0.5 ml/kg) or encainide; 0.25, 0.5, 1.0, or 2.0 mg/kg intravenously in repeated doses at 15-min intervals. At all doses, encainide converted digoxin-induced AET to ventricular arrhythmias, prolonged recovery time, and increased mortality in comparison to saline-treated animals. An additional group of anesthetized rats was not given digoxin. These animals received encainide (2.0 mg/kg, intravenously) in repeated doses at 15-min interval and developed dose-related increase in the P-R interval only. Blood samples were obtained by cardiac puncture from 12 additional anesthetized, digoxin-treated rats 5 min after the fourth intravenous dose of saline (0.5 ml/kg, n = 6) or encainide (1.0 mg/kg, n = 6). Serum was prepared and analyzed by affinity column-mediated immunoassay. Digoxin levels were the same in both groups. These results suggest that encainide may exacerbate digoxin-induced arrhythmias (proarrhythmic effect) in this species. In view of our findings of digoxin-encainide interactions in the rat, we recommend caution if these drugs are coadministered in humans.

Lyme disease presenting as heart block

Lyme disease is now recognized as an infectious process capable of involving multiple organs including the cardiovascular system. We recently treated a boy whose complaints on admission related only to symptomatic heart block that was severe enough to require transvenous pacing. This boy was subsequently determined to have had Lyme Disease after his medical testing was reevaluated for possible tick exposure. In rare instances symptomatic heart block may be the sole presenting complaint of Lyme Disease in children.

Chest pain, dyspnea on exertion, and exercise induced asthma in children and adolescents

The contribution of maximal exercise tests to the evaluation of 180 patients with chest pain associated with exercise (n = 147) or dyspnea on exertion (DOE, n = 33) was examined. The ages ranged from 5 to 22 (mean 13.2) years, and 68 patients were females. All patients had a normal cardiovascular examination, electrocardiogram, chest x-ray, and 2D-echocardiogram. Maximal exercise tests were performed on a treadmill or bicycle ergometer, and flow volume loops were performed before and after exercise (n = 65). Exercise tests did not reveal any cardiovascular abnormalities, but 14 patients with chest pain (9.5%) and seven patients with DOE (21.2%) developed exercise-induced asthma. Postexercise decrease in peak expiratory flow rate was 26.2 +/- 3.7 percent in patients with chest pain and 39.4 +/- 8.9 percent in those with DOE. Only five patients had a personal history and four others had a family history of asthma. Seven patients had a personal or family history of allergies.

IMPLICATIONS

exercise-induced asthma should be considered in pediatric patients with symptoms of chest pain or dyspnea on exertion; when exercise tests are performed, flow volume loops should be included before and after exercise; maximal exercise tests are unlikely to unmask any cardiovascular abnormalities in such patients.

Age-related responses to stimulation of cardiopulmonary receptors in swine

Cardiovascular responses to stimulation of cardiopulmonary receptors were evaluated in standard breed developing swine (1-2 days, 1-2 wk, and 2 mo of age) and sexually mature miniswine anesthetized with 0.25-0.50% halothane in O2. Cryptenamine, a mixture of veratrum viride alkaloids (VVA), was administered as right atrial or left ventricular bolus injections in doses of 5-20 micrograms/kg. In developing swine, mean aortic pressure (AoP) decreased after 10-20 micrograms/kg VVA in 1- to 2-wk olds and after 5-20 micrograms/kg VVA in 2-mo olds. Bradycardia was always elicited. Renal (Ren) and femoral (Fem) vasodilation occurred in the 1- to 2-wk-old and 2-mo-old groups after 5-20 micrograms/kg VVA. Mesenteric (Mes) vasodilation was elicited with 10-20 micrograms/kg VVA in the 1- to 2-wk-old group and with 5-20 micrograms/kg VVA in 2-mo olds. In the 1- to 2-day-old group, VVA did not significantly alter Ren, Fem, and Mes vascular resistance. In mature miniswine, 20 micrograms/kg VVA elicited decreases in AoP and heart rate that were similar in magnitude to responses obtained with only 5 micrograms/kg VVA in dogs. Cardiovascular responses to VVA were abolished after bilateral vagotomy but were not altered after denervation of the carotid sinuses. The results indicate postnatal maturation of the Bezold-Jarisch reflex in swine.

Altered exercise performance and abnormal sympathetic responses to exercise in patients with anorexia nervosa

We evaluated the cardiovascular and sympathetic responses to exercise in patients with anorexia nervosa to determine whether their bradycardia results from a high level of physical fitness. Twenty adolescent patients with anorexia nervosa underwent maximal exercise tests, and the results were compared with those in 15 age-matched adolescent girls. In the patients with anorexia, maximal values were heart rate 174 +/- 2.8 bpm, systolic blood pressure 127 +/- 3.4 mm Hg, oxygen consumption 31 +/- 1.1 ml/kg/min, and plasma norepinephrine concentration 1581 +/- 238 pg/ml (n = 16). In the controls, corresponding values were significantly higher (P less than 0.025): heart rate 193 +/- 2.1 bpm, systolic blood pressure 163 +/- 4.4 mm Hg, oxygen consumption 39.3 +/- 1.6 ml/kg/min, and plasma norepinephrine 2695 +/- 413 (n = 10). Anaerobic threshold occurred at the same percent of maximal work in patients and controls. Results of exercise ECGs in all controls were normal, but five patients with anorexia nervosa developed significant ST segment depression. Thus, in patients with anorexia nervosa there is abnormal working capacity and cardiovascular responses to exercise and abnormal sympathetic responses to the stimulus of exercise, and a myocardial abnormality manifested as ST segment depression during exercise in some.

Maturation-related differences in regional circulatory effects of dopamine infusion in swine

The cardiovascular effects of dopamine (DPA) infusions were evaluated in developing swine, less than or equal to 1 day, 2 weeks, and 2 months of age, anesthetized with halothane in 50% N2O and O2. DPA was given by intravenous infusion in randomized doses of 2, 5, 10 and 20 micrograms/kg/min for 10 min. Depressor responses and bradycardia were observed during 2 micrograms/kg/min in 2-week-olds and during 2, 5 and 10 micrograms/kg/min in 2-month-olds. During infusion of 20 micrograms/kg/min, DPA pressor responses were observed in animals less than or equal to 2 weeks of age; in addition, tachycardia occurred in 1-day-old swine. Renal resistance decreased during infusion of 2 micrograms/kg/min in all swine. It increased during 10 and 20 micrograms/kg/min in the 1-day and 2-week groups, but not in the 2-month group. Mesenteric resistance decreased during infusion of 2, 5 and 10 micrograms/kg/min in less than or equal to 2-week-olds and at all doses in 2-month-olds. Following combined alpha- and beta-adrenergic receptor blockade, infusion of 20 micrograms/kg/min DPA inhibited renal vasoconstriction in most animals and elicited mesenteric vasodilation in all. The results indicate that dopaminergic responses undergo a postnatal maturation which has a different time course for different regional circulations.

Pulmonary sequestration causing congestive heart failure in infancy: a report of two cases and review of the literature

Congestive heart failure as a presenting symptom in infants with pulmonary sequestration is rare, and the cases of only 3 such patients have been reported. The clinical features, hemodynamics, and management of two additional patients are described. Both were seen in severe congestive heart failure in the absence of any associated cardiac anomalies. The physical findings, plain roentgenograms, electrocardiograms, and echocardiograms may provide some diagnostic clues, but cardiac catheterization is the essential diagnostic investigation. In 1 patient, pneumonectomy was performed because of extensive changes throughout the affected lung. In the other, ligation of the anomalous systemic artery to the sequestered lobe was the only surgical procedure. Both patients are doing well 15 months and 18 months after operation. Success with the latter surgical approach has not been reported previously.

Adrenal contribution to coronary regulation in the newborn

Evidence for adrenergic regulation of the coronary vessels was sought in 27 newborn lambs. Sympathetic activity was altered by temporarily lowering cephalic perfusion pressure (CPP) from 90 to 20 mmHg while aortic pressure was held constant. Heart rate (HR) and left ventricular dP/dt max increased markedly, while end-diastolic pressure and stroke volume fell. These changes were accompanied by an increase in coronary blood flow (CBF), myocardial O2 consumption (MVO2), and reduced coronary resistance (CF) (P less than 0.005). After beta blockade, which prevented an augmentation of metabolic demand, the same maneuver resulted in coronary vasoconstriction, reflected by reduced CBF and increased CR (P less than 0.02). This response was eliminated by alpha blockade with phentolamine (2 mg/kg). In 13 lambs subjected to bilateral adrenalectomy or sham operation, lowering CPP elicited similar positive chronotropic and inotropic changes, increases of MVO2 and CBF, and reduced CR. Following beta blockade, lowering CPP in the sham group caused coronary constriction. However, no changes in CBF or CR were elicited in the adrenalectomized lambs. These observations indicate that integrity of the adrenal glands is required for adrenergic control of the coronary vessels in the newborn. Chronotropic and inotropic regulation is mediated by direct neural action and is not dependent on adrenal function.

Cor triatriatum: masked by complex congenital cardiac anomalies

The radiographic, angiographic, hemodynamic, and surgical features of 2 cases of cor triatriatum complicated by other cardiac anomalies are presented. In the first case, the patient had tetralogy of Fallot, the scimitar syndrome, and left ventricular obstruction. In the second case the patient had truncus arteriosus. The first case was revealed only after augmentation of pulmonary flow by an aorta-pulmonary artery anastomosis. In the second case, the diagnosis was retrospectively suggested by certain angiographic and hemodynamic clues. The prospective diagnosis was made only after a modified Rastelli procedure for truncus arteriosus. The difficulties encountered in making the diagnosis in both cases are discussed. It is stressed that a high index of suspicion, thorough accumulation and examination of hemodynamic data, and excellent angiograms and plain film radiography are all necessary to an early diagnosis of cor triatriatum when the latter is complicated by other congenital heart anomalies.

Effects of acutely increasing systemic vascular resistance on oxygen tension in tetralogy of Fallot

Effects of phenylephrine hydrochloride on the degree of hypoxia were studied in six cyanotic patients with tetralogy of Fallot. Baseline aortic and right atrial oxygen saturations, blood gas tensions, pH, and indicator-dilution curves were obtained under stable conditions. Phenylephrine was infused while systemic arterial pressure was monitored continuously. Aortic and right atrial blood samples were measured at each 10 mm Hg systolic pressure increment and decrement and analyzed for pH, PO2, PCO2, and oxygen saturation. A 40 mm Hg peak systolic aortic pressure rise was the arbitrary end point for phenylephrine infusion and the indicator-dilution curve repeated. Aortic oxygen tensions rose in all from 4 to 28 mm Hg (mean, 14 mm Hg). The net right-to-left shunt decreased from 10% to 40% (mean, 25%) with phenylephrine infusion as compared to the shunt under basal conditions. The presumed mechanism related to the increase in systemic vascular resistance relative to right ventricular outflow obstruction with resultant augmentation of pulmonary blood flow. It is concluded that acutely raising systemic vascular resistance in patients with tetralogy of Fallot using phenylephrine infusion has a beneficial effect on systemic arterial oxygen level and might be the medical treatment of choice for protracted hypoxic spells.

Prosthetic valve replacement in children

Reported clinical experience with prosthetic valve replacement in children have suggested a high operative mortality. We placed 25 valves in 24 children with one operative death. There has been one late death related to pacemaker malfunction, but the remainder of the patients have generally done extremely well. The children have not undergone elective anticoagulation, and the long-term embolism rate has not exceeded the incidence of systemic embolization in adults who have been controlled on warfarin sodium (Coumadin) therapy. The objective of prosthetic valve replacement is myocardial preservation. We believe that valve replacement with currently available prostheses should be undertaken in any child with valvular malfunction who is not well controlled with good medical management.