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G R Marx

Publications and source records attributed to G R Marx.

At least 19 recordsLinked to original sources
PubMed2001

Three-dimensional echocardiography of the atrial septum.

This article details the important contribution of three-dimensional echocardiography for catheterization device closure of secundum atrial septal defects. Aspects presented include three-dimensional echocardiographic application in preselection of patients and in selection of the type and size of the atrial septal occluder devices. Unique three-dimensional echocardiographic imaging planes are shown that depict the size and shape of the defect, the important rim tissue surrounding the defect, and the images that demonstrate successful device placement. Details of the acquisition phase, digital reformatting, and the eventual rendering of standard three-dimensional echocardiographic imaging planes of the atrial septum are shown. Three-dimensional echocardiography not only provides important additional information, but also enhances understanding of standard two-dimensional studies.

Cardiac Catheterization↗
PubMed2001

Valve-sparing operation for balloon-induced aortic regurgitation in congenital aortic stenosis.

OBJECTIVE: Aortic regurgitation after balloon dilation of congenital aortic stenosis may be treated with valve repair as an alternative to replacement. METHODS: Charts and echocardiograms of all patients undergoing aortic valve operations after balloon dilation of congenital aortic stenosis at our institution between January 1988 and December 1999 were reviewed. RESULTS: Twenty-one patients underwent valvuloplasty for predominant aortic regurgitation 9 months to 15 years (mean, 6.1 years) after balloon dilation. The mean +/- SD age at the time of the operation was 11 +/- 7 years. Aortic regurgitation was caused by a combination of commissural avulsion (10), cusp dehiscence with retraction (9), cusp tear (5), central incompetence (2), perforated cusp (1), or cusp adhesion to the aortic wall (1). Repair techniques included commissural reconstruction with a pericardial patch (8), pericardial patch cusp augmentation (6), primary suture repair (6), raphae release and debridement (4), commissurotomy (4), commissural resuspension with sutures (3), and cusp release (1). There were no deaths. At a mean follow-up of 30.1 months (range, 9 months-8 years), all patients were asymptomatic, and the grade of aortic regurgitation had been significantly reduced (P <.001). Left ventricular end-diastolic dimension z scores and proximal regurgitant jet/aortic anulus diameter ratios were significantly reduced (P <.001) and remained so over time. Freedom from reoperation for late failure was 100%, and overall freedom from reintervention was 80% at 3 years. CONCLUSION: Aortic valve repair for balloon-induced aortic regurgitation is reproducible and durable at medium-term follow-up.

Adolescent↗
PubMed1999

Echocardiographic characteristics of successful deployment of the Das AngelWings atrial septal defect closure device: initial multicenter experience in the United States.

The AngelWings device is a newer transcatheter device used for closure of secundum atrial septal defects (ASD) and patent foramen ovale (PFO), which consists of a self-centering, 2-disk system. Transesophageal echocardiography (TEE) plays a pivotal role in the deployment of the 2 disks of this device, on the appropriate sides of the atrial septum. The objective of this study is to describe the echocardiographic findings associated with successful deployment of the AngelWings device for closure of ASD and PFO. We evaluated the TEE studies of 70 patients enrolled in 4 United States centers, for closure of ASD and PFO with the AngelWings device. The TEE characteristics of successful and unsuccessful deployments were analyzed. Residual shunts across the atrial septum were assessed by TEE at the end of the procedure, 24 hours later by transthoracic echocardiography, and at 6 months by TEE. The deployment of the device was successful in 65 patients (93%). In the unsuccessful group, ASD size by TEE was larger (13.4 +/- 3.1 vs 8.9 +/- 4.7 mm, p <0.05). TEE was successful in identifying snagging of the device by intracardiac structures and prolapse of corners of the left or right atrial disk through the ASD, features that were difficult to identify by fluoroscopy. The echocardiographic characteristics outlined here are important guidelines for successful deployment of the AngelWings device.

Adolescent↗
PubMed1998

New insights and observations in three-dimensional echocardiographic visualization of ventricular septal defects: experimental and clinical studies.

BACKGROUND: The positions, sizes, and shapes of ventricular septal defects (VSDs) can be difficult to assess by 2-dimensional echocardiography (2DE). Volume-rendered 3-dimensional echocardiography (3DE) can provide unique views of VSDs from the left ventricular (LV) side, allowing complete assessment of their circumference and spatial orientations to other anatomic structures. METHODS AND RESULTS: Seventeen experimentally created defects of various locations, sizes, and shapes were imaged and reconstructed in 9 explanted porcine hearts. From an en face projection, major and minor axis diameters of the defects were measured, and these data were compared with direct anatomic measurements. Optimal reconstructions of the VSDs were obtained in all heart specimens, accurately depicting their positions and shapes. The correlations between 3DE and anatomy for the VSD major and minor axis diameters were y=1.0x+0.3 (r=0.88, P<0.001) and y=1.0x-1.4 (r =0.89, P<0.001), respectively. Good agreement between the 2 methods was demonstrated for all measurements. Our experience from the in vitro model was then applied to patient studies. Optimal LV en face reconstructions were obtained in 45 of 51 patients, permitting detailed assessment of the positions, sizes, and shapes of the VSDs. In the 25 patients with comparative surgical measurements, the correlations between 3DE and surgery for the VSD major and minor axis diameters were y =0. 81x+2.1 (r=0.92, P<0.001) and y=0.73x+2.0 (r=0.91, P<0.001), respectively. Good agreement was demonstrated between measurements made by 3DE and those obtained at surgery. CONCLUSIONS: 3DE provides excellent visualization of various types of VSDs. From an LV en face projection, the positions, sizes, and shapes of VSDs can be accurately determined. Such precise imaging will be beneficial for surgical and catheter-based closure of difficult perimembranous and singular or multiple muscular VSDs.

Adolescent↗
PubMed1998

Effect of pulmonary artery stenoses on the cardiopulmonary response to exercise following repair of tetralogy of Fallot.

Data from exercise tests, echocardiograms, and lung perfusion scans were analyzed to determine whether the excessive minute ventilation (VE) often encountered among patients with tetralogy of Fallot is due to ventilation-perfusion mismatch secondary to branch pulmonary artery stenoses. Patients with branch PA stenoses had lower peak oxygen consumptions and higher VE during exercise than did patients without stenoses, and a strong correlation existed between the degree of pulmonary blood flow maldistribution on lung perfusion scan and the amount of excessive VE during exercise.

Adolescent↗
PubMed1998

Transoesophageal echocardiography during scoliosis repair: comparison with CVP monitoring.

PURPOSE: Accurate haemodynamic assessment during surgical repair of scoliosis is crucial to the care of the patient. The purpose of this study was to compare transoesophageal echocardiography (TEE) with central venous pressure monitoring in patients with spinal deformities requiring surgery in the prone position. METHODS: Twelve paediatric patients undergoing corrective spinal surgery for scoliosis/kyphosis in the prone position were studied. Monitoring included TEE, intra-arterial and central venous pressure monitoring (CVP). Haemodynamic assessment was performed prior to and immediately after positioning the patient prone on the Relton-Hall table. Data consisted of mean arterial blood pressure (mBP), heart rate (HR), CVP, left ventricular end-systolic and end-diastolic diameters (LVESD and LVEDD respectively) and fractional shortening (FS). Right ventricular (RV) function and tricuspid regurgitation (TR) were assessed qualitatively. Analysis was performed using descriptive statistics, Student's t test, sign rank, and correlation analysis. RESULTS: There was an increase in CVP (8.7 mmHg to 17.7 mmHg; P < .01), and decreases in LVEDD (37.1 mm to 33.2 mm; P < .05), and mean blood pressure (75.0 mmHg to 65.7 mmHg; P < .05) when patients were placed in the prone position. Fractional shortening, LVESD, and HR did not change from the supine to the prone position. Right ventricular systolic function and tricuspid regurgitation were unchanged. CONCLUSION: These data indicate that the CVP is a misleading monitor of cardiac volume in patients with kyphosis/scoliosis in the prone position. This is consistent with previous studies. In this clinical situation, TEE may be a more useful monitoring tool to assess on-line ventricular size and function.

Adolescent↗
PubMed1998

Cardiac dysfunction in twin-twin transfusion syndrome: a prospective, longitudinal study.

OBJECTIVE: To use serial echocardiography to evaluate prospectively the cardiac dysfunction in twin-twin transfusion syndrome and determine its clinical course and outcome. METHODS: Twin pregnancies presenting in the second trimester with sonographic evidence of twin-twin transfusion syndrome were managed with therapeutic reduction amniocenteses. Gestational age at diagnosis and delivery, number of amniocenteses performed, volume of amniotic fluid withdrawn, placentation, birth weight, hemoglobin at delivery, and perinatal outcome were recorded. Serial fetal echocardiography was carried out in a single tertiary center. Echocardiographic assessments included cardiac anatomy, chamber size, cardiothoracic ratio, interventricular septal thickness, ventricular systolic function, and the presence and severity of atrioventricular valve regurgitation. Postnatal echocardiograms were obtained on the surviving twins. RESULTS: Twelve cases of twin-twin transfusion syndrome were evaluated with serial echocardiography. Evidence of cardiac dysfunction was present prenatally in 10 recipient twins. All of the donor twins had normal fetal echocardiographic assessments. The most common abnormalities detected prenatally in recipient twins were decreased ventricular function, tricuspid regurgitation, and cardiac chamber enlargement. A deterioration of cardiac function was observed in seven recipient twins with increasing gestational age. Four of the eight surviving recipient twins had persistent postnatal echocardiographic abnormalities on follow-up examinations after the first 28 days of life. CONCLUSION: Prenatal cardiac dysfunction is common in recipient twins and can be transient, progressive, or persistent beyond the neonatal period.

Female↗
PubMed1998

MRI and echocardiography in children: how do they compare?

Clearly, both echocardiography and MRI play vital roles in the diagnosis and management of children with congenital heart defects. 2-D Doppler echocardiography is very easy to use in a vast array of clinical situations. The accuracy of the anatomic and hemodynamic findings are well accepted. In comparative studies, 2-D Doppler echocardiography appears preferable for intracardiac anatomy, whereas MRI appears preferable for extracardiac anatomy. In certain patients, Doppler echocardiography may not be able to optimally obtain the anatomic or hemodynamic information, and MRI should be used in these particular cases.

Child↗
PubMed1998

Neonatal radiofrequency catheter ablation of junctional tachycardias.

Junctional tachycardias comprise several arrhythmia types with differing mechanisms, principally involving the region of the atrioventricular (A-V) junction. Neonatal radiofrequency catheter ablation has typically been reserved for life-threatening, drug-refractory cases due to the unique concerns regarding patient size and development. We performed radiofrequency catheter ablation on two neonates with incessant, rapid junctional tachycardias and hemodynamic compromise after failing conventional medical therapy. This report describes 2 neonates who underwent emergent radiofrequency catheter ablation, and compares these two patients to a larger pediatric catheter ablation patient cohort. Both neonates had an acutely successful outcome and were able to be discharged within a week of the ablation procedure. Fluoroscopy time and total procedure time were shorter in these two patients than in the course of the average pediatric catheter ablation. Though long-term developmental consequences of neonatal catheter ablation are yet unknown, in unique extreme situations, radiofrequency catheter ablation can be performed in neonates, as in older children and adults, without excessive acute morbidity.

Adult↗
PubMed1998

Transcoronary ethanol ablation of the atrioventricular node in a young patient with tricuspid atresia.

Catheter ablation of AV conduction with radiofrequency energy can be challenging in the presence of structural abnormalities of the AV junction, either congenitally or after reconstructive surgery. We used transcoronary ethanol to ablate the AV node in a patient with classic tricuspid atresia and refractory intraatrial reentry tachycardia. This approach provides an alternative means of creating complete heart block with catheter-based techniques, when radiofrequency catheter ablation is technically impossible or ineffective.

Adult↗
PubMed1997

Fate of mitral regurgitation following repair of atrioventricular septal defect.

The purpose of this study was to evaluate the fate of mitral regurgitation (MR) following repair of atrioventricular septal defects (AVSDs). Echocardiograms of all survivors of isolated AVSD surgery between 1986 and 1996, who had had > or =2 postoperative color Doppler studies (39 patients), were reviewed. On each study, MR severity was graded on a 1+ to 4+ scale, based upon the size of the MR jet. Median age at surgery was 9 months (range 3 to 169); median age at postoperative follow-up was 45 months (range 3 to 107). Mild deterioration of mitral valve function was fairly common. MR severity increased by > or =1 grade in 16 patients (41%) during the course of the study. However, the deterioration in mitral valve function occurred primarily during the early postoperative time intervals. After the initial 32 postoperative months, MR worsened on only 4 occasions and in each instance worsened by only 1 grade. Deterioration to 4+ MR occurred in only 3 patients, and was not observed after the initial 30 postoperative months. Survival curve analysis predicted a 90% probability of not having severe (4+) MR after 30 months (lower 95% confidence bound: 80%). Postoperative MR remains fairly stable following AVSD repair. Serious deterioration is rare, especially after the initial 30 postoperative months.

Child, Preschool↗
PubMed1997

Two- and three-dimensional transesophageal echocardiography in patient selection and assessment of atrial septal defect closure by the new DAS-Angel Wings device: initial clinical experience.

BACKGROUND: Transcatheter closure of atrial septal defects (ASDs) has been feasible and successful. Two-dimensional echocardiography (2DE) was applied to patients before selection and during device deployment. Three-dimensional echocardiography (3DE) can provide unique anatomic perspectives that might aid in improving device closure of ASDs. METHODS AND RESULTS: Twenty-two consecutive patients were enrolled in an initial protocol for ASD device closure by the new DAS-Angel Wings occluder device. On the basis of transesophageal (TEE) 2DE and 3DE, 13 patients were considered eligible for device closure (9 secundum ASDs and 4 with patent foramen ovale associated with a cerebral vascular accident). Maximal ASD diameter and surrounding rim tissues were compared by TEE 2DE and 3DE and with balloon sizing measurements at catheterization. ASD size measured by TEE 2DE and 3DE correlated well (y = 1.0x + 0.049, r = .95), with good limits of agreement. However, balloon-stretched diameter measurements were systematically larger than echocardiographic measurements. Rim tissue measurements correlated well; however, TEE 3DE could demonstrate the entire shape and perimeter of the defect. Two-dimensional imaging provided reliable information during device deployment and for closure of small ASDs. However, 3DE was superior for imaging the device, especially when abnormally placed. CONCLUSIONS: Three-dimensional imaging provides unique images and projections that were essential for understanding the spatial relationship of the device to the atrial septum. Three-dimensional echocardiography significantly enhanced our understanding of two-dimensional images and provided an imaging conceptualization that should aid in future development of device closures.

Echocardiography↗
PubMed1997

Intraoperative discovery of neuroblastoma in an infant with pulmonary atresia.

There have been 28 previously reported cases of neuroblastoma associated with congenital heart disease. Because many of these have been defects of the conotruncal region, it has been proposed that abnormal neural crest cell migration or maturation may be a factor that links these normally disparate pathologic conditions. Most neuroblastomas in these cases have been detected at autopsy or by radiologic studies conducted in the evaluation of the cardiac anomalies. Recently, we discovered an occult posterior mediastinal neuroblastoma in a patient undergoing a unifocalization procedure for tetralogy of Fallot with pulmonary atresia and major aortopulmonary collaterals. The tumor was resected, and the patient has demonstrated no evidence of residual or metastatic neuroblastoma.

Female↗
PubMed1997

Excessive anaerobic metabolism during exercise after repair of aortic coarctation.

OBJECTIVES: To determine whether survivors of surgery for coarctation of the aorta (CoA) have an excessive reliance on anaerobic metabolism during exercise. BACKGROUND: Patients with peripheral vascular disease cannot increase blood flow to their muscles normally during exercise. Consequently they acquire an early, excessive reliance on anaerobic metabolism and have depression of the ventilatory anaerobic threshold (VAT) and of the slope of the oxygen consumption-work rate relationship (delta VO2/delta WR). We speculated that the capacity to augment blood flow to the lower extremities during exercise may be impaired after CoA surgery and would result in similar metabolic disturbances. STUDY DESIGN: Progressive exercise tests were performed on 15 patients (ages 19 +/- 7 years; range, 10 to 32) after successful repair of CoA (residual resting gradient, 7.7 +/- 7.1 mm Hg; range, 0 to 18), 15 age- and sex-matched healthy control subjects, and 10 patients (ages 13 +/- 3 years; range, 10 to 20) who had undergone ligation of a patent ductus arteriosus. RESULTS: The CoA patients' VAT averaged 14.8 +/- 3.8 ml O2/kg per minute versus 19.3 +/- 3.1 ml O2/kg per minute for the control subjects (p < 0.01), and their delta VO2/delta WR averaged 8.2 +/- 1.8 ml/watt compared with 10.1 +/- 1.4 ml/watt for control subjects (p < 0.01). Furthermore, 10 of 15 CoA patients had a VAT of less than 40% of predicted maximal oxygen consumption, and 9 of 16 had a delta VO2/delta WR of less than 8.7 ml O2/watt (generally accepted abnormal values). Patients with patent ductus arteriosus resembled the healthy control subjects with regard to anaerobic metabolism during exercise. CONCLUSIONS: Patients who have had CoA repairs commonly manifest an excessive reliance on anaerobic metabolism during exercise. This phenomenon may result from persistent blood flow abnormalities across the aortic arch during exercise, which may be present even after apparently successful surgery.

Adolescent↗
PubMed1997

Electrocardiographic markers of late sudden death risk in postoperative tetralogy of Fallot children.

Following surgery for tetralogy of Fallot (TOF), children may develop late onset ventricular arrhythmias. Many patients have both depolarization and repolarization abnormalities, including right bundle branch block (RBBB) and QT prolongation. The goal of this study was to improve prospective risk-assessment screening for late onset sudden death. Resting ECG markers including QRS duration, QTc, JTc, and interlead QT and JT dispersion were statistically analyzed to identify those patients at risk for ventricular arrhythmias and sudden cardiac death. To determine predictive markers for future development of arrhythmia, we examined 101 resting ECGs in patients (age 12 +/- 6 years) with postoperative TOF and RBBB, 14 of whom developed late ventricular tachycardia (VT) or sudden death. These ECGs were also compared with an additional control group of 1000 age- and gender-matched normal ECGs. The mean QRS (+/- SD) in the VT group was 0.18 +/- 0.02 seconds versus 0.14 +/- 0.02 seconds in the non-VT group (P < 0.01). QTc and JTc in the VT group was 0.53 +/- 0.05 seconds and 0.33 +/- 0.03 seconds compared with 0.50 +/- 0.03 seconds and 0.32 +/- 0.03 seconds in the non-VT group (P = NS). There was no increase in QT dispersion among TOF patients with VT or sudden death compared with control patients or TOF patients without VT, although JT dispersion was more common in the TOF groups. A prolonged QRS duration in postoperative TOF with RBBB is more predictive than QTc, JTc, or dispersion indexes for identifying vulnerability to ventricular arrhythmias in this population, while retaining high specificity. The combination of both QRS prolongation and increased JT dispersion had very good positive and negative predictive values. These results suggest that arrhythmogenesis in children following TOF surgery might involve depolarization in addition to repolarization abnormalities. Prospective identification of high-risk children may be accomplished using these ECG criteria.

Child↗
PubMed1997

Supraventricular tachycardia in the fetus: conservative management in the absence of hemodynamic compromise.

The purposes of this study were to assess the natural history of isolated fetal supraventricular tachycardia and to evaluate the role of conservative management without medical therapy in the absence of hemodynamic compromise. Spontaneous resolution of supraventricular tachycardia occurred in eight of nine fetuses followed expectantly with serial evaluations. These data suggest that the spontaneous resolution of isolated fetal supraventricular tachycardia may be a common occurrence. Although conservative management may prove to be a reasonable option for fetuses with isolated supraventricular tachycardia, this approach must be balanced against the lack of reliable predictors for the development of hemodynamic compromise.

Female↗