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Biomedical subjects

G R Marx

Publications and source records attributed to G R Marx.

65 records · Page 4Linked to original sources
PubMed1985

Transatrial septal velocity measurement by Doppler echocardiography in atrial septal defect: correlation with Qp:Qs ratio.

Right atrial velocities measured perpendicular to the atrial septum by Doppler echocardiography in patients with atrial septal defects (ASD) have a discernible morphology that may bear a relation to shunt magnitude. The integral of the right atrial Doppler waveform was compared with shunt magnitude measured at cardiac catheterization or nuclear shunt scan in 17 ASD patients. For control subjects, the mean right atrial velocity was 15 +/- 4 cm/s (+/- standard deviation) and that for ASD patients was 41 +/- 11 cm/s (p less than 0.001). Doppler pulmonary-to-systemic flow ratio (Qp:Qs) correlated with catheterization Qp:Qs ratio (n = 9, r = 0.85, SEE = 0.27) and with nuclear Qp:Qs ratios (n = 8, r = 0.60, SEE = 0.51). Mean transatrial septal velocity in ASD patients correlated with catheterization Qp:Qs ratio (n = 9, r = 0.8, SEE = 6.0) and with simultaneous Doppler Qp:Qs ratio (n = 16, r = 0.89, SEE = 4.9, y = 16.2 +/- 8.3). Although Qp:Qs ratio can be approximated by measuring pulmonary and systemic flow by Doppler echocardiography in many ASD patients, this newly described method allows estimation of Qp:Qs ratio. It is useful when these more conventional measurements cannot be performed because of turbulence or when inadequate imaging prevents Doppler pulmonary to systemic flow measurement.

Adolescent↗
PubMed1985

Doppler echocardiographic estimation of systolic pulmonary artery pressure in pediatric patients with interventricular communications.

The purpose of this study was to evaluate a noninvasive method for estimation of pulmonary artery pressures in infants and children with interventricular communications. Systolic pulmonary artery pressures measured by cardiac catheterization were compared with those estimated by Doppler echocardiography. Pressure drops were measured by Doppler study (modified Bernoulli equation) and were referenced to systolic systemic arterial pressure measured by sphygmomanometry. All 25 patients in this study had either a ventricular septal defect or a single ventricle. The systolic pulmonary artery pressure measured by cardiac catheterization ranged from 15 to 100 mm Hg (mean +/- SD 44 +/- 26) and that measured by Doppler echocardiography ranged from 5 to 100 mm Hg (mean 43 +/- 26) (p = NS; r = 0.92; SEE = 9.9; slope = 0.92; y intercept = 4.7). Systolic pulmonary artery to aortic pressure ratio measured by cardiac catheterization ranged from 0.2 to 1.0 (mean 0.5 +/- 0.3) and that measured by Doppler echocardiography ranged from 0.1 to 1.0 (mean 0.5 +/- 0.3) (p = NS; r = 0.94; SEE = 0.09; slope = 0.90; y intercept = 0.04). This study demonstrates that Doppler echocardiography can closely approximate systolic pulmonary artery pressure in patients with interventricular communications.

Blood Pressure↗
PubMed1984

Two-dimensional echocardiographic diagnosis of intracardiac masses in infancy.

Intracardiac masses in infancy are uncommon. Tumors, thrombi and vegetations of bacterial endocarditis are exceedingly rare in this age group. These masses are seldom diagnosed before the infant's death. In a review of two-dimensional echocardiograms performed from May 1979 to January 1981 on 741 infants less than 2 years of age, intracardiac masses were prospectively identified in 6 patients. All six patients presented with unexplained murmurs associated with either hemodynamic instability, arrhythmias or systemic emboli. One patient had a vegetation from bacterial endocarditis, one had an intracardiac thrombus associated with myocarditis, three had rhabdomyomas (two patients with tuberous sclerosis) and one had a fibro-fatty nodule attached to the eustachian valve. Two-dimensional echocardiography not only was important in the diagnosis, but also provided guidance in the medical and surgical treatment of these patients.

Echocardiography↗
PubMed1984

Results of the Senning operation for transposition of the great arteries with intact ventricular septum in neonates.

In spite of an adequate balloon atrial septostomy, some neonates (less than 28 days of age) with transposition of the great arteries and intact ventricular septum (TGA, IVS) remain hypoxemic and acidotic and require operative treatment. Our entire experience with the Senning operation in neonates with TGA, IVS is reviewed. From March 1978 to March 1983 there were 104 infants who underwent the Senning operation for TGA, IVS. Of these, 19 were neonates (18%). The mean age at operation was 12 days (2 to 24) and mean weight was 3.52 kg (3 to 4.38). Two died early (10%) and one died late (5%). The last 16 are alive and well. Causes of early mortality were sepsis and severe obstruction of the superior vena cava. The cause of late mortality was severe pulmonary venous obstruction. Among the 16 survivors, postoperative courses, both early and late, have been remarkably benign. Ten patients have undergone postoperative cardiac catheterization (mean follow up 17 months). Two (12%) had severe pulmonary venous obstruction (one diagnosed by two-dimensional echocardiography), but both were successfully repaired. Atrial shunt was noted in two patients (12%), one of which underwent elective repair. Five infants have dynamic subvalvular pulmonary stenosis of various gradients (9 to 93 mm Hg). One infant has mild tricuspid regurgitation. There are no cases of superior vena caval obstruction or right ventricular dysfunction. Twenty-four hour electrocardiographic monitoring (mean follow-up 25 months) showed predominant normal sinus rhythm in 15 infants and predominant junctional rhythm in one.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1983

Transposition of the great arteries and ventricular septal defect: results with the Senning operation and closure of the ventricular septal defect in infants.

From May, 1978, to July, 1982, 46 infants ranging in age from 12 days to 12 months and in weight from 2.1 to 8.4 kg underwent repair of dextrotransposition of the great arteries (D-TGA) and ventricular septal defect (VSD) using a Senning repair and closure of the VSD. Ventricular septal defects were classified as membranous (47.8%), malaligned (28.3%), atrioventricular (AV) canal type (13.0%), subarterial (2.2%), muscular (2.2%), and multiple (6.5%). Hospital mortality was 15.2% and late mortality, 5.1%. Postoperative complications included tricuspid regurgitation (mild in 3 and severe, requiring tricuspid valve replacement, in 3), residual VSD (pulmonary/systemic flow ratio of greater than 2:1) in 3 patients (2, AV canal type and 1, multiple VSDs), pulmonary venous obstruction in 3 patients, and permanent complete heart block in 4 patients (2, AV canal type of VSD also requiring tricuspid valve replacement). Lung biopsy studies showed reversible Heath-Edwards and morphometric changes. No patient was seen with Heath-Edwards III or greater changes. In 10 patients, right ventricular end-diastolic pressures and pulmonary artery pressures at rest were within normal limits one year after operation. As the operative mortality of atrial inversion and arterial switch operations for D-TGA with VSD tends to become comparable, more extensive follow-up data, including cardiac catheterization and coronary arteriography in a large number of patients, will be necessary to establish the superiority of one approach over the other.

Abnormalities, Multiple↗
PubMedDate not supplied

Aerobic exercise function of patients with persistent coronary artery aneurysms secondary to Kawasaki disease.

Nine patients with persistent coronary artery aneurysms 1.7-14.0 years after an episode of Kawasaki disease underwent progressive bicycle ergometry with expiratory gas analysis. Two of the patients had aneurysms complicated by angiographically documented coronary artery stenosis. Results of the exercise tests were compared to those obtained from a group of age- and gender-matched normal control subjects. The Kawasaki disease patients did not differ significantly from the control subjects with regard to peak oxygen consumption (81 +/- 7% versus 79 +/- 12% predicted), peak workload (75 +/- 13% versus 77 +/- 9% predicted), anaerobic threshold (21.9 +/- 6.5 versus 18.9 +/- 4.0 ml/kg per minute) or oxygen pulse (96 +/- 7% versus 90 +/- 14% predicted). None of the patients developed significant ST segment changes or rhythm disturbances during exercise. The exercise function of the patients with coronary artery stenosis did not differ from that of patients without stenosis. It was concluded that the aerobic exercise function of patients with persistent coronary artery aneurysms after an episode of Kawasaki disease appears to be well preserved. Kawasaki disease patients with significant coronary artery pathology are not accurately identified by a single assessment of aerobic exercise function.

Adolescent↗
PubMedDate not supplied

Three-dimensional echocardiography in congenital heart disease: a continuum of unfulfilled promises? No. A presently clinically applicable technology with an important future? Yes.

Three-dimensional echocardiography has important clinical applications to congenital heart disease. Such applications include assessment of ventricular volumes, and unique imaging planes and projections of septae and atrio-ventricular and semi-lunar valves. Advances in ultrasound and computer technology will improve the process of three-dimensional echocardiography to continue to bring it to everyday clinical utility application.

Artificial Intelligence↗
PubMedDate not supplied

Three-dimensional echocardiographic measurement of left ventricular stroke volume in children: comparison with Doppler method.

Three-dimensional echocardiography (3DE) allows calculation of ventricular volumes without geometric assumption on the ventricular shape. Our aim was to apply 3DE in a normal pediatric population and to compare the left ventricular stroke volume measurements to the Doppler method. Twenty-four normal patients (median age 7 years) underwent Doppler echocardiography and 3DE for left ventricular stroke volume calculation. The left ventricular stroke volume by Doppler method was calculated as the product of the aortic Doppler flow mean velocity and the area of the aortic annulus. The 3DE method was performed using a transthoracic rotational probe (TomTec) and left ventricular volumes were calculated using the Simpson's rule. The mean time for 3DE acquisition was 90 seconds without any sedation. 3DE correlated well with the Doppler method for left ventricular stroke volume measurements (y = 0.8x - 0.2, r = 0.94). The mean difference between the average values of left ventricular stroke volume obtained by Doppler method and 3DE was 5 +/- 4 ml. Intraobserver and interobserver variabilities in the left ventricular stroke volume measurement by 3DE were 2.6% and 4.4%. In conclusion, 3DE compared to the Doppler method is an accurate, noninvasive, and reproducible method to measure the left ventricular stroke volume in normal children.

Adolescent↗
PubMedDate not supplied

Successful placement and re-expansion of a new balloon expandable stent to maintain patency of the ductus arteriosus in a newborn animal model.

OBJECTIVE: We performed this study in order to evaluate the usefulness of a new balloon expandable stent for maintaining ductal patency in a neonatal piglet model and to evaluate the ability to re-expand the stent weeks following initial implantation. BACKGROUND: Maintaining patency of the ductus arteriosus without administration of Prostaglandin E has been reported previously using balloon dilation and stent implantation techniques. However, the experience is limited and the currently available stents are not modified for neonates. METHODS: 14 newborn piglets all at age 12 days and median weight 3.6 Kg (range 2.7-4.3 Kg), underwent initial balloon dilation of the ductus arteriosus. Angiography after dilation demonstrated no significant left to right shunt. All piglets underwent successful stent (3.5 mm x 17 mm) placement in the ductus arteriosus. RESULTS: Percutaneous ductal stent implantation via the arterial route was successful in all piglets with angiographic demonstration of a significant left to right shunt. Follow-up studies at weekly intervals with color flow Doppler were used to confirm patency of the stents. In 3 piglets the stent was not patent at initial follow-up and autopsy revealed sub-optimal stent placement. In two animals the stent was later re-expanded to 4 mm at 22 days, in one to 4 mm at 30 days and in one to 6 mm at 15 days, maintaining flow for an additional period of 15 to 34 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

A new low profile balloon atrial septostomy catheter: initial animal and clinical experience.

OBJECTIVE: To evaluate the safety and efficacy of a new low profile balloon septostomy catheter in neonatal animals as well as in one newborn infant. BACKGROUND: Balloon atrial septostomy remains one of the most commonly performed palliative procedures in pediatric cardiology. The currently available septostomy catheter requires a large introducer sheath (6 or 7F), does not have an end hole for confirmation of position or pressure measurement and is limited in patients with a small left atrium due to its large balloon inflated diameter. METHODS: Four neonatal piglets (average weight 3.9 kg) underwent percutaneous balloon atrial septostomy using the new balloon catheter inflated to 1 cc via a 5F sheath in the femoral vein. Two other piglets (average weight 4.9 kg) underwent septostomy with the conventional catheter inflated to 3.5 cc via a 6 or 7F sheath in the femoral vein. All animals underwent transthoracic echocardiography pre and post septostomy. All animals were sacrificed after the procedure and the size of the atrial defect created was measured. One neonate with Taussig-Bing anomaly underwent septostomy with the new balloon catheter. RESULTS: The left atrium was entered in all piglets. It was easier to enter the left atrium with an end hole catheter which was exchanged over a wire with the septostomy catheter. Septostomy was performed with the new or conventional catheters without complications. Echocardiography demonstrated a very small patent foramen ovale prior to the procedure and a large atrial defect after septostomy. The average size of the defect created by the new catheter was 11.3 x 10 mm in diameter and 11 x 10 mm using the conventional catheter. A 10 x 10 mm atrial communication was created in the neonate. CONCLUSIONS: This study demonstrates the safety and efficacy of this new catheter. This catheter will be of potential importance in patients with a small left atrium and in small neonates with congenital heart disease requiring septostomy.

Animals↗