Primary care physicians' use of screening echocardiography.

OBJECTIVE: To survey primary care physicians to understand their reasons for using echocardiography to screen for congenital heart disease in children and to assess their understanding of the costs associated with cardiology services. DESIGN: A questionnaire. PARTICIPANTS: Eight hundred sixty-seven pediatricians and family physicians in our region were surveyed, 494 (57%) responded and 466 were used for the analysis. RESULTS: The majority of pediatricians and family physicians in our area do not know the relative costs associated with cardiology consultation and echocardiography. They also believe it likely that a cardiologist will routinely obtain an echocardiogram as part of their evaluation of a child with a murmur, although this is not the case. The availability and convenience of specialist appointments was found to significantly influence the decision to order an echocardiogram. Family physicians were significantly more likely than pediatricians to order an echocardiogram for a variety of clinical indications. CONCLUSIONS: Improving primary care physicians' knowledge of the costs associated with cardiology services and current cardiology practice patterns, in addition to improving the availability of cardiology referrals, may reduce the number of expensive and unnecessary echocardiograms. echocardiography, heart murmur, congenital heart disease, cost-effectiveness.

Growth of the right heart after balloon valvuloplasty for critical pulmonary stenosis in the newborn.

Eight newborns with critical pulmonary stenosis and intact ventricular septum underwent successful percutaneous balloon dilation. Follow-up using echocardiography showed sustained relief of the obstruction across the pulmonary valve and excellent growth of the right heart structures.

Cardiac effects of dexamethasone in very low birth weight infants.

OBJECTIVE: To characterize the cardiac effects of dexamethasone in very low birth weight infants. DESIGN: Prospective, randomized, placebo-controlled, double-blind trial. Enrolled subjects were randomized to receive either a 42-day tapering course of dexamethasone or a saline placebo. Echocardiographic measurements were obtained on days 0, 7, 14, 28, and 42. SUBJECTS: Thirteen infants received dexamethasone and 13 a saline placebo. The two groups were similar in birth weight, gestational age, age at enrollment, and sex/ race composition. RESULTS: Patients receiving dexamethasone had a significantly larger increase in septal thickness on days 7, 14, and 28 and left ventricle (LV) posterior wall thickness on day 14. A significantly lower left ventricular end-diastolic dimension in the dexamethasone group was initially noted on day 7 and persisted until day 42. With the reduced left ventricular end-diastolic dimension, no significant differences in LV mass were noted, despite the increased wall thickness. No differences in LV systolic function, as assessed by area shortening, were seen. Assessment of diastolic function showed a significant increase in the atrial portion of mitral inflow in dexamethasone patients on day 14, as well as a significant prolongation in isovolumic relaxation time on days 7, 14, and 28. CONCLUSIONS: Infants receiving dexamethasone developed evidence for impaired LV filling with a lager increase in wall thickness but no increase in LV mass, asymmetric septal hypertrophy, or augmented systolic function. This suggests that alterations in left ventricular filling play an important role in the development of hypertrophy seen with dexamethasone administration.

Cardiovascular function during rest and exercise in patients with sickle-cell anemia and coexisting alpha thalassemia-2.

Cardiac function was measured at rest and during exercise in 9 patients with sickle-cell anemia (SS) and coexisting homozygous alpha thalassemia-2 (alpha thal-2). Results were compared with 18 sickle cell patients with normal alpha globin genes, who were matched to the study group by age, gender, and size, and to published normal values. SS alpha thal-2 patients were less anemic: 9.9 +/- 1.0 vs 8.2 +/- 1.2 gm/dl for SS alone (P<.05). Left ventricular dimensions were normal in SS alpha thal-2 (4.9 +/- 0.7 cm), but increased in SS (5.4 +/- 0.7, cm P=.05) (normal range, 3.7-5.6 cm). Left ventricular wall thickness was, however, dramatically increased in the SS alpha thal-2 patients (free wall, 1.8 +/- 0.6 cm; septum, 1.6 +/- 0.4 cm), though SS controls had normal wall thickness (free wall, 1.0 +/- 0.2 cm; septum, 1.0 +/- 0.2 cm, P<.001) (normal range, 0.6-1.1 cm). At rest, Doppler indices of systolic function were not significantly different between sickle groups and normal values. SS alpha thal-2 patients did have abnormal diastolic filling at rest, as evidenced by a reduced ratio of early/late diastolic filling, 1.4 +/- 0.3 vs. 2.0 +/- 0.5 for SS controls (P<.01), and 1.8 +/- 0.4 for normals. An analysis of covariance suggested that this abnormality persisted after taking into account the previously demonstrated hypertrophy. During exercise, SS alpha thal-2 patients had higher heart rates and blood pressures than SS controls in spite of performing the same or less work. This resulted in a higher double product (an estimate of oxygen consumption) in SS alpha thal-2 patients (37,470 +/- 2,310 mm Hg-BPM) than in SS controls (33,310 +/- 1,490 mm Hg-BPM, P<.01). Work capacity, peak heart rate, and blood pressure were all abnormally decreased in both sickle-cell groups when compared to normal. Cardiac abnormalities noted at rest and during exercise in SS alpha thal-2 patients suggest a role of microvascular occlusion and a protective effect of decreased hemoglobin.

The heart in sickle cell anemia. The Cooperative Study of Sickle Cell Disease (CSSCD).

The objective of this study was to obtain representative echocardiographic measurements of cardiac size and function in stable patients with sickle cell disease. This prospective, multicenter study utilized central reading of echocardiograms by an investigator blinded to other patient data. Stable outpatients from a balance of inner city and rural settings with SS phenotype and a broad age range were selected, because conflicting results from earlier studies were believed to be due to these patient selection criteria. Right and left ventricular dimensions and wall thickness, left atrial and aortic root dimensions, and systolic time intervals were measured. Body surface area indexed chamber dimensions and septal thickness were significantly increased from normal. Except for the right ventricle, chamber dimensions and wall thickness were inversely correlated with hemoglobin. The relationship between left ventricular dimension and hemoglobin was significantly dependent on age. Systolic time interval ratios were normal though left ventricular ejection time was prolonged. Shortening fraction was normal but velocity of circumferential fiber shortening was abnormally low. Stable patients with sickle cell disease have dilated chambers, septal hypertrophy, and normal contractility. Though left ventricular dilatation was inversely related to hemoglobin, age (duration of illness) was an important factor in that relationship. No specific cardiomyopathy was associated with sickle cell anemia.

A mutation in FBN1 disrupts profibrillin processing and results in isolated skeletal features of the Marfan syndrome.

Dermal fibroblasts from a 13-yr-old boy with isolated skeletal features of the Marfan syndrome were used to study fibrillin synthesis and processing. Only one half of the secreted profibrillin was proteolytically processed to fibrillin outside the cell and deposited into the extracellular matrix. Electron microscopic examination of rotary shadowed microfibrils made by the proband's fibroblasts were indistinguishable from control cells. Sequencing of the FBN1 gene revealed a heterozygous C to T transition at nucleotide 8176 resulting in the substitution of a tryptophan for an arginine (R2726W), at a site immediately adjacent to a consensus sequence recognized by a cellular protease. Six other individuals in the proband's family had the FBN1 mutation that segregated with tall stature. None of the affected individuals have cardiac or ocular manifestations of the Marfan syndrome. This mutation identifies a putative site for profibrillin to fibrillin processing, and is associated with isolated skeletal features of the Marfan syndrome, indicating that the FBN1 gene is one of the genes that determines height in the general population. The cellular effect of the mutation may be equivalent to a "null" FBN1 allele and may define the phenotype associated with FBN1 "null" alleles.

Echocardiographic demonstration of a ventriculocoronary artery communication in a neonate with hypoplastic left heart syndrome.

A neonate diagnosed with aortic atresia and mitral hypoplasia had a ventriculocoronary artery communication demonstrated by use of echocardiography. These communications have been noted by angiography and on pathologic specimens in the past, but their clinical importance in the surgical management of these patients remains unclear. The ability to noninvasively identify these communications and study their flow characteristics would help to define their impact on surgical outcome.

Fetal cardiovascular hemodynamics in the presence of complete atrioventricular block.

OBJECTIVE: Our purpose was to follow serially the hemodynamic adaptation to a congenital complete heart block in a human fetus. STUDY DESIGN: Longitudinal and serial M-mode and Doppler echocardiography over a 10-week span were performed on a fetus affected by complete heart block. Ventricular fractional shortening, size, and flow across the atrioventricualr valves and outflow tracts were determined starting at 20 weeks up to the time of delivery. Neonatal Doppler follow-up was performed at 2 days of life after implantation of a temporary pacemaker. RESULTS: The right and left ventricles were able to adapt to sustained bradycardia by increasing their size. This ventricular dilatation was also associated with an increase in fractional shortening, which was associated with ventricualr free wall hypertrophy. When ventricualr heart rate decreased to 38 beats/min, fractional shortening decreased, this was associated with the rapid onset of ascites and pericardial effusion. CONCLUSION: In the presence of sustained bradycardia ventricular output can increase, because this fetus was able to increase ventricular size and fractional shortening and wall thickness.

Najjar syndrome revisited.

We describe 2 brothers with cardiomyopathy and hypergonadotropic hypogonadism and conclude that this is the first description of the Najjar syndrome in the United States. The inheritance may be autosomal recessive.

The significance of ductal shunting during extracorporeal membrane oxygenation.

The purpose of this study was to evaluate the significance and direction of shunts at the level of the foramen ovale or ductus arteriosus in full-term newborns with neonatal respiratory failure who were placed on extracorporeal membrane oxygenation (ECMO). A decrease in left ventricular dimension was expected when infants were placed on ECMO but did not occur. A left-to-right shunt was demonstrated at the ductal level in nine of 12 infants early in the course of ECMO before pulmonary resistance decreased. Presumably, the lack of change in the left ventricular dimension when infants were placed on bypass was due to a left-to-right shunt at the ductal level with ductal flow replacing the right heart output, being drawn into the bypass circuit.

Left ventricular filling in sickle cell anemia.

M-mode echocardiography was performed on 11 normal black subjects and 38 patients with sickle cell anemia while they were at rest to evaluate their left ventricular (LV) systolic and diastolic function. The patients with sickle cell anemia were also evaluated by radionuclide exercise tests and, based on their ejection fraction (EF) response, were separated into 2 groups: a group with a normal EF response to exercise (73 +/- 9%, mean +/- standard deviation) and a group with an abnormal EF response to exercise (53 +/- 9%). Computer-assisted analysis of the M-mode echocardiograms identified abnormalities of diastolic function (impaired left ventricular filling) in patients with sickle cell anemia compared with the normal subjects. The abnormal EF response group had significantly more impaired diastolic function and did less exercise than the normal EF response group. Both groups of patients had a decrease in left ventricular end-diastolic volume during exercise. The patients with sickle cell anemia had abnormalities of systolic and diastolic function on echocardiographic and radionuclide testing. The abnormalities in diastolic and systolic function assumed greater significance at the increased heart rates associated with exercise, accounting for the decrease in left ventricular end-diastolic volume and the abnormal EF response, and contributed to exercise intolerance in patients with sickle cell anemia.

The conduction system in patients with a prolonged QT interval.

The conduction system and the myocardium of five patients with Romano-Ward syndrome and one patient with the Jervell and Lange-Nielsen syndrome were studied to determine the cause of the prolonged QT interval. The patients were 9 and 15 months and 2, 5 and 19 years of age, respectively. All had a prolonged QTc interval. A sixth patient was a 16 year old girl who died suddenly; several members of her family had a prolonged QT interval. The only common finding in the conduction system in all cases was marked fatty infiltration in the approaches to the atrioventricular (AV) node. In four, the AV bundle was lobulated, with loop formation in one. In four, the AV bundle and bundle branches showed fibrosis. The ventricular myocardium in all cases was chronically inflamed. In two cases, the AV node was partially embedded in the central fibrous body. It is not clear how these changes are related to the disturbance in the repolarization process and the prolongation of the QT interval. However, it is interesting that all patients had an abnormality in the conduction system.

Longitudinal exercise hemodynamics in children with sickle cell anemia.

To define further the natural history and causative factors in exercise-related cardiac dysfunction in children and adolescents with sickle cell anemia (SS), we studied the results of 74 patients' initial and follow-up exercise tests. The follow-up study was done one to three years after the first study in 36 children and four to seven years after initial testing in 38 children. Split-plot analysis of covariance did not show any temporal deterioration in exercise hemodynamic variables. Correlation analysis defined hemoglobin and hematocrit levels as critical determinants of cardiac functional reserve capacity in these patients. Several exercise ECG patterns, formerly considered abnormal in children with SS, are now considered to be variants of normal. Studies are presently in progress that should further define the nature and severity of the cardiac impairment during exercise in children with SS.