Biomedical subjects
Publications and source records attributed to G R Marx.
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We describe two brothers with congenital lymphedema of lower limbs, atrial septal defect (ASD), and similar facial appearance. A sister had severe hydrops fetalis, ASD, omphalocele, and other anomalies. This combination of congenital lymphedema and ASD differs from other reported cases of congenital lymphedema and most likely constitutes a previously unrecognized autosomal recessive syndrome.
Our objective was to assess the immediate and short-term results of stent implantation to relieve pulmonary artery stenosis (PAS). Thirty-seven patients underwent an attempt at stent implantation at a median age of 7.0 years (range, 0.8-31.4 years) and a median weight of 20.5 kg (range, 7.4-85 kg). Twenty-two patients had previous tetralogy of Fallot repair. A total of 55 stents were implanted successfully in 36 patients. The peak systolic gradient across the stenotic segment decreased from a mean of 43 +/- 20.4 mmHg prestent to 13 +/- 13.9 mmHg (P < 0.001) poststent. The diameter of the narrowest segment increased from a mean of 4.8 +/- 1.6 mm to 10.5 +/- 2.6 mm (P < 0.001). The right ventricular-to-aortic mean systolic pressure ratio decreased from 0.74 +/- 0.2 to 0.52 +/- 0.19 (P < 0.001). Complications included balloon rupture prior to full stent expansion in 4 patients (in 2 patients the stent was positioned in the superior vena cava, and in 2 in the inferior vena cava), distal migration of a stent which was successfully retrieved at surgery 1 mo later in 1 patient, and tethering of the stent to the balloon requiring surgical removal in 1 patient. One patient died several hours after stent placement. Sixteen patients underwent repeat catheterization at a mean follow-up interval of 0.9 +/- 0.5 years (range, 0.2-2.0 years). The mean gradient across the stent for these 16 patients was 26.7 +/- 19.8 mmHg, and there was no change in the mean diameter (9.4 +/- 3.2 mm). Two patients developed stenosis related to neointimal proliferation at the stent site which was redilated successfully. In conclusion, stent implantation is generally safe and effective in relieving PAS.
A 61-year-old woman with levo-transposition of the great arteries, double-inlet single left ventricle, and valvar and subvalvar pulmonary stenosis presented with a large pulmonary valve vegetation unresponsive to antibiotic therapy. The diagnostic evaluation and the surgical management are discussed. At operation the pulmonary valve was excised and an abscess cavity was obliterated with a pericardial patch. She is currently doing well 3 years after the operation.
OBJECTIVES: This study attempted to determine the site, relative size and dynamic geometry of atrial septal defects using dynamic three-dimensional echocardiography. BACKGROUND: Recent studies have demonstrated the feasibility of dynamic three-dimensional echocardiography. Images are acquired from computerized reconstruction of sequential, tomographic ultrasound "slices" of the heart. Ultrasound images can be obtained by linear progression of a transducer within a transesophageal imaging probe. In small infants and children the large transducer size has not allowed transesophageal placement, and the probe has been placed on the thorax or in the subcostal position. Other scanning devices, housed in plastic containers, acquire images in a rotational format and can also be placed in a transthoracic or subcostal position. METHODS: Specially designed transesophageal probes and a dedicated computer unit were used for two-dimensional image retrieval and reconstruction of three-dimensional images. Sixteen patients with atrial septal defects were studied (median age 18 months, range 1 day to 18 years). In one patient, images were obtained by transesophageal probe placement; in the other 15 patients, the probe was placed in the transthoracic or subcostal position. RESULTS: A dynamic three-dimensional echocardiogram of the atrial septal defect could be obtained in 13 of the 16 patients. The distinguishing features of the atrial septal defects and their spatial orientation could be visualized in unique three-dimensional views. CONCLUSIONS: Dynamic three-dimensional imaging could be applied to the specific evaluation of atrial septal defects. Unique views of the heart allowed for spatial comprehension of the defects, rendering potentially important clinical information.
Miniaturization of echocardiographic transducers, improved crystal technology, and enhanced digital processing of ultrasound signals have resulted in newer, more sophisticated equipment and imaging techniques. These technologic advances include transesophageal echocardiography, stress echocardiography (both pharmacologic and exercise), intravascular and intracardiac ultrasound, and three-dimensional echocardiography. Magnetic resonance imaging is also becoming increasingly important in the visualization of specific pathologies. These advances in cardiac imaging are discussed, with prime emphasis placed on present and future clinical applications in congenital heart disease.
Doppler color flow imaging has become indispensable in the diagnosis and management of patients with congenital heart disease. Certain defects may not be possible, or may be very difficult to diagnose by two-dimensional echocardiography alone. Such examples include multiple ventricular septal defects, anomalous pulmonary venous connection, coronary artery malformations, and the hypertensive patent ductus arteriosus. Additionally, color flow Doppler echocardiography significantly provides additional information, and reduces the time for fetal and transesophageal echocardiographic studies. Doppler color flow imaging has become an essential part of the echocardiographic examination. Experience has broadened the use of this important technological advance, with anticipation of an ever expanding future for its clinical application.
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OBJECTIVES: The aim of this study was to determine whether persistent coronary aneurysms in patients with Kawasaki disease are associated with altered myocardial perfusion and function. BACKGROUND: Some patients with Kawasaki disease have died suddenly because of severe coronary artery stenosis; others have chronic coronary aneurysms. METHODS: Eleven patients with chronic coronary aneurysms were enrolled in the study. The size of the aneurysms and the degree of associated stenosis were determined by angiography in nine patients and by echocardiography in two. All patients underwent simultaneous function and myocardial perfusion assessment during symptom-limited exercise by echocardiography and technetium-99m sestamibi imaging, respectively. RESULTS: Of 33 vascular territories, 18 contained coronary aneurysms measuring 3.5 to 10 mm. Three aneurysms were associated with significant stenosis as detected by angiography. Of the 18 vascular territories, 13 were normal, and 5 manifested stress-induced perfusion defects; of the latter 5 areas, 4 had associated wall motion abnormalities. The three territories supplied by stenotic coronary arteries had both abnormal regional function and perfusion demonstrated during exercise. CONCLUSIONS: Patients with chronic coronary aneurysms may have associated stenosis, as detected by angiography, with a subjacent myocardium that is subject to abnormal perfusion and function. However, the majority of coronary aneurysms are associated with normal regional coronary flow reserve, as assessed by myocardial perfusion imaging, and even giant coronary aneurysms may be associated with normal coronary flow reserve and preserved regional myocardial function during stress.
Three-dimensional cardiac reconstruction generated from transesophageal interrogation can be performed using an integrated unit that captures, processes, and postprocesses tomographic parallel slices of the heart. This probe was used for infants and young children in the transthoracic position to evaluate the feasibility of producing three-dimensional cardiac images with capability for real-time dynamic display. Twenty-two infants and children (range 1 day-3.5 years) underwent image acquisition using a 16 mm 5 MHz 64 element probe placed over the precordium. Two infants were also imaged from the subcostal position. Data was obtained and stored over a single cardiac cycle after acceptable cardiac and respiratory gating intervals were met. The transducer was advanced in 0.5-1 mm increments over the cardiac structures using identical acquisition criteria. The images were reconstructed from the stored digital cubic format and could be oriented in any desired plane. In 9 of the 22 infants the images obtained were of optimal quality. The images obtained displayed normal cardiac structures emphasizing depth relationships as well as visualization of planes not generally demonstrated by two-dimensional imaging. Several lesions were also depicted in a unique fashion using this technique. Though the method employed was limited by movement artifact and reconstruction time, the quality of the three-dimensional display was excellent and enhanced by real-time demonstration. The transthoracic approach was successful in capturing sufficient data to create three-dimensional images, which may have further application in more accurate diagnosis of complex cardiac abnormalities and generation of planes of view which could duplicate surgical visualization of a lesion. Further assessment of the technique in infants with congenital heart disease is warranted.
Exercise testing of children differs from adult exercise testing in many ways beyond the technical issues related to test performance that are addressed in this report. Disease processes that produce myocardial ischemia are relatively rare in children compared with adults. Exercise testing may be useful in these cases, but the use of testing to assess functional capacity or cardiac rhythms will be encountered more often. Although the precise role of exercise testing in patient evaluation or long-term management of the cardiac patient will vary somewhat from center to center, exercise testing is often essential to diagnose and to direct treatment in a wide variety of clinical problems. An understanding of the role of exercise testing for children with known or suspected heart abnormalities is an essential part of the training of pediatric cardiologists. The staff of the pediatric exercise laboratory should be available to discuss with the clinician when a test might be of value in a specific case in addition to providing advice about the specifics of the performance of the test and offering age- and size-appropriate normal data from the laboratory with test interpretation.
Although a great deal of controversy surrounds the concept of routine ultrasound screening, 70% of pregnant women in this country undergo ultrasound examination. Assessment of the fetal heart including a four-chamber view is recommended when ultrasound scans in the second and third trimester are performed. The accurate diagnosis of structural heart disease and cardiac dysrhythmias is now possible with advances in ultrasound and fetal echocardiography. Increased prenatal screening and genetic counseling have improved the management of these complicated pregnancies. It is hoped that the detection of significant congenital heart disease will continue to increase leading to further advances in medical and surgical treatment, improved patient care, and favorable perinatal outcomes.
We performed a randomized, controlled trial of intravenous immune globulin (respiratory syncytial virus [RSV] neutralizing [Nt] antibody titer of 1:950 in 5% solution) to evaluate protection against RSV-induced disease over two respiratory virus seasons. Forty-nine children (mean age at enrollment, 4.5 months) with severe congenital heart disease or bronchopulmonary dysplasia were randomized as follows. Twenty-four patients were followed as controls and received no immune globulin. Twenty-five patients received monthly infusions of immune globulin at a dose of 500 mg/kg of body weight. There was a similar distribution between groups of patients with heart disease and bronchopulmonary dysplasia. There were 12 culture-proven RSV infections, 6 in the prophylaxis group and 6 in the control group. There was a trend toward less severe RSV illness in immune globulin recipients, as measured by length of hospitalization. Four of the six immune globulin recipients were hospitalized for a total of 35 days (mean, 8.8 +/- 5.0 days) because of RSV illness, in contrast to 51 hospital days (mean, 12.8 +/- 7.6 days) among RSV-infected controls. We conclude that monthly infusions of standard immune globulin containing RSV Nt antibodies may be safely administered to high-risk children, but that standard intravenous immune globulin does not contain sufficient RSV Nt antibody titer to fully protect against severe RSV illness.
BACKGROUND: Peak dP/dt is a good index of ventricular performance that is not influenced by afterload, wall motion abnormalities, or the variations in ventricular anatomy and morphology commonly encountered among patients with congenital heart disease. Unfortunately, the clinical utility of peak dP/dt has been limited by the fact that its measurement generally requires an intraventricular catheter. However, peak dP/dt occurs during isovolumetric contraction, and the pressure rise during isovolumetric contraction is almost linear. Therefore, the mean dP/dt during isovolumetric contraction (mean dP/dtic), ie, the ratio of the rise in pressure during isovolumetric contraction (aortic diastolic pressure minus the systemic ventricular end-diastolic pressure [VEDP]) over the isovolumetric contraction time, should provide a good estimate of peak dP/dt that could be generated noninvasively. METHODS AND RESULTS: Echo/phonocardiography was used to measure the isovolumetric contraction time and a blood pressure cuff to estimate aortic diastolic pressure of 27 patients (age, 1 day to 77 years) with congenital or acquired heart disease. VEDP was determined by three methods: (1) intraventricular catheter, (2) assumed VEDP of 10 mm Hg, and (3) assignment of a normal or elevated value on the basis of clinical history. The three estimates of mean dP/dtic thus generated were compared with simultaneous measurements of peak dP/dt obtained during cardiac catheterization. Invasively measured peak dP/dt correlated well with the indirect determinations (r = .95, .89, and .92 for methods 1, 2, and 3, respectively; P < .0001). CONCLUSIONS: Echo/phonocardiography can be used in conjunction with a blood pressure cuff and indirect estimates of VEDP to generate mean dP/dtic, an index of ventricular function that approximates and closely correlates with peak dP/dt. This noninvasive measurement can be obtained in almost any patient and may be useful in the assessment of ventricular performance in a variety of cardiovascular disorders.
BACKGROUND: Severe pulmonary regurgitation (PR) and associated right ventricular (RV) dilatation are late complications of surgical repair of tetralogy of Fallot (TOF). For the past several years, we have restored pulmonary valve competence with the exclusive use of cryopreserved allografts. METHODS AND RESULTS: Sixteen patients with symptoms of diminished exercise tolerance and echocardiographic evidence of progressive PR with severe RV dilatation underwent placement of allografts in the RV outflow tract at a median age of 12 years (10 years after TOF repair). Abnormal exercise tolerance tests were documented in 10 patients. Additional surgical procedures included pulmonary artery augmentation (n = 6), closure of residual left to right shunts (n = 3), and subendocardial resection for monomorphic ventricular tachycardia (n = 1). Six patients had either preoperative or postoperative balloon dilations of pulmonary artery stenoses. All patients had symptomatic improvement after allograft insertion. At a mean follow-up of 26.4 +/- 3.4 months, the severity of PR improved in all but one patient. In 12 patients (group 1), conduit regurgitation was either trace (n = 11) or mild (n = 1). Four patients (group 2) had moderate conduit regurgitation. In a retrospective analysis, pulmonary artery diameters and cross-sectional areas were significantly smaller in the group 2 patients compared with the group 1 patients. With the exception of one patient, RV end-diastolic diameter (RVEDD/BSA) fell after allograft insertion in each patient (P < .01). The reduction in RVEDD/BSA was significantly greater in group 1 than in group 2 (31.8 +/- 3.4% versus 21.4 +/- 11.0%, P < .05). CONCLUSIONS: Thus, restoration of the pulmonary valve with cryopreserved allografts improved exercise tolerance and diminished RV volume overload in patients with severe PR after previous repair of TOF. Optimal results were achieved in patients who did not have significant residual pulmonary artery distortion.
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The influence of pulmonary regurgitation (PR) on exercise capacity is unknown. The hemodynamic responses to exercise in postoperative patients with PR was determined using Doppler-measured regurgitant fraction to indicate PR severity. Maximal heart rate, oxygen consumption and workload capacity were measured during upright cycle ergometry. Cardiac output was measured at rest and during submaximal supine cycle ergometry by pulsed Doppler echocardiography. Oxygen consumption was simultaneously measured and exercise factor was calculated as the change in cardiac output per change in oxygen consumption. Twenty-seven patients were compared with 17 age-, size- and sex-matched control subjects. Patients with PR had larger right ventricles (p less than or equal to 0.001), lower heart rate response (p less than or equal to 0.05), lower maximal oxygen consumption (p less than or equal to 0.005) and lower workloads (p less than or equal to 0.005) when compared with normal control subjects during maximal exercise testing. Exercise factor was the same for both groups. Patients with PR were then separated into mild, moderate and severe groups. Patients with mild PR had a normal response to exercise. However, patients with moderate and severe PR had lower maximal oxygen consumptions and maximal workloads than control subjects. Control, mild and moderate PR groups had similar exercise factors. Patients with severe PR had markedly low cardiac output responses. PR is associated with reduced exercise capability, which is related to the severity of the PR.