Pediatric myocardial infarction after racemic epinephrine administration.

Myocardial infarction is a previously unreported complication of treatment with racemic epinephrine that is used commonly in the emergency department for severe respiratory distress in bronchiolitis or croup syndrome. We describe a pediatric patient who presented with the croup syndrome and severe respiratory distress that required multiple doses of nebulized racemic epinephrine in the emergency department. The patient developed ventricular tachycardia and mild chest discomfort during one treatment, which resolved spontaneously on discontinuation of the nebulization. Persistently abnormal electrocardiograms and elevated creatine phosphokinase MB isoenzyme (CPK-MB) levels suggested a myocardial infarction had occurred. Subsequent echocardiography, cardiac catheterization, and angiography revealed an anatomically normal heart with normal coronary circulation; however, a stress nuclear study showed a small myocardial infarct. The significance of this previously unreported complication of racemic epinephrine is discussed, along with recommendations for proper use in the emergency department.

Effects of dipyridamole and inhaled nitric oxide in pediatric patients with pulmonary hypertension.

Inhaled nitric oxide (iNO) causes selective pulmonary vasodilation by increasing pulmonary vascular levels of cyclic guanosine monophosphate (cGMP). Dipyridamole, a drug with several putative vasodilator mechanisms, is an inhibitor of cGMP-specific phosphodiesterases (PDE5); it therefore has the potential to increase pulmonary vascular cGMP levels, lower pulmonary vascular resistance, augment iNO-induced pulmonary vasodilation, and attenuate excessive pulmonary vasoreactivity. To test dipyridamole in the pulmonary circulation, we studied pediatric patients undergoing cardiac catheterization who had severe resting pulmonary hypertension (Group 1; n = 11) or exaggerated acute hypoxia-induced pulmonary vasoconstriction (Group 2; n = 4). In Group 1, we compared the effects of iNO (20 ppm), dipyridamole (0.6 mg/kg), and combined treatments (iNO + dipyridamole) on pulmonary and systemic hemodynamics. In Group 2 we measured the pulmonary and systemic effects of dipyridamole while the patients were breathing room air and hypoxic gas mixtures (FIO2 = 0.16). One patient in Group 1 had a hypotensive response to dipyridamole and was exluded from study. In the remaining 12 studies done on 10 patients, iNO caused a selective decrease in mean pulmonary artery pressure (Ppa) and indexed pulmonary vascular resistance (PVRI) without affecting mean aortic pressure (Pao) or indexed systemic vascular resistance (SVRI). Dipyridamole decreased PVRI to similar values as did iNO, but this effect was primarily due to an increase in cardiac index (CI), and was not associated with any change in Ppa, and was associated with a decrease in Pao and SVRI. In comparison with individual treatments, combined therapy (iNO + dipyridamole) did not augment pulmonary vasodilation in the group as a whole; however, in 50% of patients, combined therapy decreased PVRI by 20% more than did iNO or dipyridamole alone. In Group 2, Ppa and the pulmonary-to-systemic resistance ratio (Rp/Rs) increased to suprasystemic levels during acute hypoxia. Pretreatment with dipyridamole blunted the increase in Ppa and Rp/Rs during repeat hypoxia, keeping Ppa at a subsystemic level and Rp/Rs < 1. We conclude that: (1) dipyridamole nonselectively reduces PVRI, primarily through an increase in CI; (2) in combination with iNO, dipyridamole augments the decrease in PVRI in some patients; and (3) dipyridamole blunts the severity of acute hypoxic pulmonary vasoconstriction in children with exaggerated hypoxic pressor responses.

The use of papaverine in arterial sheaths to prevent loss of femoral artery pulse in pediatric cardiac catheterization.

This study evaluated the efficacy of intraarterial papaverine infusion after pediatric cardiac catheterization in reducing the incidence of lost pulse. This study was conducted at a teaching pediatric hospital and was designed as a randomized, prospective, double-blind, placebo-controlled study. Patients were children 5 years old or less undergoing antegrade and retrograde heart catheterization. The intervention used was an intraarterial infusion of placebo or 1.5 mg/kg papaverine after catheterization. Bilateral femoral artery ultrasound study was performed pre- and postcatheterization, including two-dimensional, color, spectral, and pulsatility index analysis. Outcome measures included clinical loss of pulse, ultrasound findings, plus other clinical factors. Fifty-six patients participated in the study (28 per group). Six patients clinically lost the pulse in the catheterized arteries [four in the papaverine and two in the placebo groups (p > 0.64)]. Clinical loss of pulse correlated with diminished pulsatility index (p < 0.035). The use of papaverine did not prevent decreased pulse or pulsatility index (p > 0.79). Increased arterial time was the only clinical factor associated with lost pulse (p < 0.0004). Pulsatility index <3.34 correlated with loss of pulse in the catheterized artery. The results indicated that intraarterial papaverine infusion after femoral artery catheterization does not prevent loss of pulse in the catheterized artery, and decreased pulsatility index correlates with diminished pulse and represents a good noninvasive method of evaluating femoral artery patency and flow.

Chronic posttraumatic thoracic aortic aneurysm presenting with dysphagia.

Chronic posttraumatic thoracic aortic aneurysms are rare. The natural history of these aneurysms is symptomatic enlargement. Herein is reported a chronic posttraumatic thoracic aortic aneurysm that became symptomatic by producing extrinsic compression of the esophagus. Despite the chronic nature of these aneurysms they should be repaired when found.

Second natural history study of congenital heart defects. Aortic stenosis: echocardiography.

BACKGROUND: Recent advances in the field of echocardiography have made it possible to obtain a complete morphological and hemodynamic assessment of patients with aortic stenosis. Therefore, comprehensive two-dimensional and Doppler examinations were performed on patients with aortic stenosis returning for the Second Natural History Study of Congenital Heart Defects (NHS-2). METHODS AND RESULTS: Two hundred thirty-two patients with aortic stenosis underwent comprehensive two-dimensional and Doppler examinations. Of these, 96 were in the medically treated group, 49 had undergone aortic valve replacement, and 87 had had aortic valvotomy. The valve replacement group had a significantly smaller left ventricular diastolic cavity than did the medically treated group; both had smaller dimensions than the valvotomy group. There was no significant difference in left ventricular wall thickness or fractional shortening among the three groups. The valvotomy group had a significantly higher mean aortic valve gradient than did either the medically treated group or the valve replacement group. The degree of aortic regurgitation was more severe in the valvotomy group than in the other two groups. For all patients, there was a direct relation between the aortic valve gradient and the mean wall thickness and an inverse relation between the aortic valve mean gradient and fractional shortening. The only echocardiographic parameter that correlated with the presence or absence of symptomatology was the fractional shortening. CONCLUSIONS: These observations provide an objective measurement for assessing the status of the aortic valve and left ventricular response in patients with aortic stenosis returning for NHS-2. Limitations of echocardiography in this study are discussed.

Second natural history study of congenital heart defects. Pulmonary stenosis: echocardiography.

BACKGROUND: Two-dimensional and Doppler echocardiography can provide information about valve morphology, right ventricular size and function, and hemodynamics in patients with pulmonary stenosis. Therefore, two-dimensional and Doppler echocardiographic examinations were performed on patients with pulmonary stenosis returning for the Second Natural History Study of Congenital Heart Defects. METHODS AND RESULTS: Three hundred twenty-five patients with pulmonary stenosis underwent two-dimensional and Doppler echocardiographic examinations. Of these, 115 were in the medically treated group, and 210 had undergone a previous operation. Patients in the valvotomy group had a higher incidence of right ventricular dysfunction and a larger right ventricular diastolic dimension. The valvotomy group had a lower pulmonary valve mean gradient and a lower right ventricular systolic pressure than the medically treated group. For all patients, there was no significant correlation of the echocardiographic variables with the presence or absence of symptoms, reflecting the low incidence of patients with cardiac decompensation. CONCLUSIONS: These observations provide an objective measurement for assessing the status of the pulmonary valve and right ventricular response in patients with pulmonary stenosis. Limitations of echocardiography in this study are discussed.

Second natural history study of congenital heart defects. Ventricular septal defect: echocardiography.

BACKGROUND: Two-dimensional and Doppler echocardiography can provide structural and hemodynamic information for patients with ventricular septal defects (VSDs). Therefore, two-dimensional and Doppler echocardiographic examinations were performed on patients with VSDs returning for the Second Natural History Study of Congenital Heart Defects. METHODS AND RESULTS: Five hundred fifty-six patients with VSDs underwent two-dimensional and Doppler echocardiographic examinations. Three hundred twenty-four patients were in the medically treated group, and 232 had undergone a previous operation. The location of the VSD was classified in 235 patients. Several Doppler measurements were used to calculate pulmonary artery pressures: tricuspid regurgitation peak systolic velocity, peak systolic velocity of VSD jet, pulmonary regurgitation end-diastolic velocity, and pulmonary artery acceleration time. The two methods that were found to be reliable consisted of the tricuspid regurgitation peak systolic velocity and the pulmonary regurgitation end-diastolic velocity. These measurements were obtained in only 26% of patients at all centers. At one center in which adult and pediatric echocardiography was performed in a single laboratory, these values were obtained in 60% of patients. CONCLUSIONS: Two-dimensional and Doppler echocardiography has the ability to provide a noninvasive method of assessing morphology and hemodynamics in patients with VSDs. However, the reliability and accuracy of hemodynamic measurements are dependent on operator experience.

Pulmonary arteriovenous malformation in the newborn: a familial case.

Pulmonary arteriovenous malformation (PAVM) is a rare cause of cyanosis in the newborn with nine previously reported cases. Typical signs at presentation include cyanosis, murmur, and congestive heart failure. Abnormality on chest x-ray is common with cardiomegaly, oligemia, and focal pulmonary density. There is a male predominance, unlike older children and adults with PAVM. Familial cases of PAVM have been reported with Osler-Weber-Rendu syndrome. We report a familial case of PAVM presenting in the newborn.