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Biomedical subjects

D J Sahn

Publications and source records attributed to D J Sahn.

305 records · Page 17Linked to original sources
PubMedDate not supplied

Ketone bodies maintain normal cardiac function and myocardial high energy phosphates during insulin-induced hypoglycemia in vivo.

It has been suggested that myocardial utilization of ketone bodies might cause deterioration of cardiac function. Therefore, the influence of ketonemia (mean: 1.3 and 3.3 mM) in the presence of hypoglycemia (mean: 33 mg/dl) on cardiac function, substrate utilization and myocardial high energy phosphate levels was studied in 10 mongrel dogs. Hypoglycemia alone led to a significant increase of mean aortic pressure, total peripheral resistance and myocardial oxygen consumption, but other hemodynamic parameters and regional myocardial function were not changed. Additional infusion of 3-hydroxybutyrate did not affect hemodynamic variables significantly. During both metabolic interventions in vivo phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy showed stable levels of myocardial Pi, PCr, ATP, as well as PCr/Pi (3.2-3.4) and PCr/ATP (3.0-3.2) ratios. Biochemical measurements revealed that ketonemia led to significant alterations in arterial concentrations and arterio-coronary venous differences of selected citric acid cycle intermediates, thus confirming previous reports which suggested a blockade of the 2-oxoglutarate-dehydrogenase reaction induced by ketone body oxidation. However, despite this blockade, the energy supply to the heart was not impaired as shown by normal NMR spectroscopy and cardiac performance. It is speculated that the blockade might be due to an enhanced NADH/NAD ratio.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Serial two-dimensional echocardiography for detection of coarctation of the aorta in the postnatal period.

We describe the ultrasound appearance of postnatal development of an angiographically proven coarctation of the aorta in a full-term infant. The diagnosis of a discrete coarctation was subsequently supported on a repeat two-dimensional echocardiogram, after an initial clinical and two-dimensional study at 6 h of age that had revealed only minimal juxtaductal aortic deformity. We stress the importance of two-dimensional echocardiography as a reliable noninvasive method for detecting the change in aortic contour occurring with ductal closure in infants with predisposing aortic anatomy who will go on to develop coarctation of the aorta.

Aortic Coarctation↗
PubMedDate not supplied

Giant blood cyst of the aortic valve.

Beyond infancy, blood cyst of the aortic valve is not known to occur. We describe a 16-year-old girl who had aortic valve stenosis and regurgitation and giant blood cyst of the aortic valve. Serial echocardiograms over a 12-year period demonstrated gradual enlargement of the cyst.

Adolescent↗
PubMedDate not supplied

Color flow Doppler mapping studies of "physiologic" pulmonary and tricuspid regurgitation: evidence for true regurgitation as opposed to a valve closing volume.

Color flow Doppler mapping using either an Aloka 880 or a Toshiba SSH65A system was performed in 39 normal subjects (aged 13 to 45 years) and 43 patients (aged 13 to 82 years) with pathologic tricuspid or pulmonary regurgitation to evaluate the incidence of "physiologic" regurgitation of right heart valves and to determine the differentiating characteristics in the spatial distribution and velocity encoding of "normal" and "pathologic" regurgitant jets. In the normal subjects, tricuspid and pulmonary regurgitation were documented in 32 (83%) and 36 (93%), respectively, and were unrelated to the system being used. Flow acceleration and aliasing were imaged on the right ventricular side of the tricuspid regurgitant orifice and on the pulmonary artery side of the pulmonary valve (in both normal subjects and patients), and indicated flow convergence for true regurgitation through an orifice as opposed to blood being driven retrogradely by the closing valve. Such proximal acceleration was documented in all patients with pathologic tricuspid regurgitation, in 31/32 of the normal subjects with tricuspid regurgitation, and was also observed in 12/15 (80%) of the patients and 4/12 (33%) of normal subjects with pulmonary regurgitation who were examined with the Toshiba system. The dimensions (mean +/- SD) of tricuspid regurgitant jets (length [JL] and area [JA]) were consistently larger in the patients than in the normal subjects [JL: 3.4 +/- 0.9 vs 1.2 +/- 0.5 cm, p less than 0.001; and JA: 5.7 +/- 2.0 vs 1.4 +/- 0.7 cm2, p less than 0.001) as were the pulmonary regurgitation jet dimensions (JL: 1.8 +/- 0.4 vs 0.9 +/- 0.08 cm, p less than 0.001; JA: 1.8 +/- 0.7 vs 0.3 +/- 0.08 cm2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Prenatal detection of restrictive foramen ovale.

The foramen ovale is an important communication between the two sides of the heart prenatally, allowing the left ventricle to carry its share of the prenatal circulation and providing flow for growth of left ventricular structures. Restriction of the foramen ovale appears to be a serious disorder of the fetus and can be associated with fetal hydrops, arrhythmias, and other signs of major fetal compromise. This article reviews our experience with restriction of the foramen ovale and provides a summary of the pathologic and echocardiographic literature related to the etiology and effects of restrictive foramen ovale in the fetus.

Echocardiography↗
PubMedDate not supplied

Echocardiographic imaging techniques with subcostal and right parasternal longitudinal views in detecting sinus venosus atrial septal defects.

Sinus venosus atrial septal defects are frequently missed and difficult to visualize with conventional two-dimensional echocardiographic views. Using modified subcostal and right parasternal longitudinal views, nine patients were found to have a sinus venosus atrial septal defect. The modified subcostal view showed a sinus venosus atrial septal defect in all nine patients; three patients had secundum atrial septal defects as well. The right parasternal view detected only six patients with sinus venosus atrial septal defect. Partial anomalous pulmonary venous return was diagnosed in seven patients using these views. The combination of subcostal and right parasternal longitudinal imaging views will improve the detection of sinus venosus atrial septal defects.

Adolescent↗
PubMedDate not supplied

Quantification of mitral flow by Doppler color flow mapping.

This study was performed to develop and validate Doppler color flow methods for quantifying forward transmitral flow rates and volumes with isovelocity aliasing contours. We undertook computer modeling of flows and studied an animal model with strictly controlled mitral flows. Finite element analysis was first used to establish the isovelocity surface contours reconstructed from the magnitudes and directions of the velocity vectors proximal to the normal mitral orifice. We modeled finite element-simulated Doppler color flow isovelocity surfaces and computed non-angle-dependent simulated isovelocities to compare them. Then 24 pharmacologically induced hemodynamic states in six sheep in which mitral regurgitation had been previously created surgically were studied. Three methods were used for peak flow (PF) computation: (1) the classic hemispheric methods: PF = 2 pi r2.aliasing velocity; (2) a modified hemispheric method: PF = 2 pi r2.aliasing velocity Vo/Vo-aliasing velocity; and (3) a new segment of sphere method: PF = pi p2.aliasing velocity, where p is the chord from the zenith of the first aliasing contour to the circumference at its base. Mean volume flow was also calculated in combination with phasic flow information from continuous-wave Doppler echocardiography: mean volume flow = PF.VTI/Vmax.heart rate, where VTI and Vmax are the velocity-time integral and maximal velocity of mitral inflow by continuous-wave Doppler echocardiography. Compared with the flow rates obtained by electromagnetic flowmeters, different correlations and agreements were achieved for these methods. Correlation (r = 0.86) and agreement were best for the segment of sphere method for computation of forward mean volume flows in our model. Color flow Doppler quantitation with a segment of sphere or modified hemispheric method appears applicable for quantification of forward transmitral valve flow rates and volumes with reasonable accuracy.

Animals↗
PubMedDate not supplied

Graphical and stereolithographic models of the developing human heart lumen.

Scaled physical models can be useful in analyzing stage-specific hemodynamics in the embryonic human heart to address correlations between early physical stressors and myocardial wall responses. We generated models of the cardiac blood space from reconstructions of four digitized human embryo images from Carnegie Collection at the Armed Forces Institute of Pathology. From physical scale models manufactured by stereolithography, compliant sleeves can be created for flow dynamics studies. This novel use of Carnegie collection images and graphical modeling software provides tools for broadening our understanding of normal and aberrant heart formation.

Embryonic and Fetal Development↗
PubMedDate not supplied

Evaluation of double aortic arch and aortic coarctation by intravenous digital subtraction angiography (IV DSA).

Eleven pediatric patients with congenital aortic anomalies were evaluated using intravenous digital subtraction angiography (IV DSA). Excellent correlation was found between IV DSA, other imaging studies, and operative findings. Ten of 11 patients studied (90.9%) were correctly diagnosed using this technique. Intravenous DSA may be the procedure of choice in assessing aortic arch anomalies in selected patients.

Adolescent↗
PubMedDate not supplied

[Clinical applications of Doppler echocardiography].

In this review, we demonstrate the normal patterns of flow and some quantitative applications of Doppler echocardiography combined with two-dimensional imaging. Flow information can be accurately measured and valve gradient calculations can be made in patients with stenotic diseases. Further corroborative work in this area is necessary before definitive statements can be made, but this appears to be a promising noninvasive technique which can be applied at the bedside or in an ambulatory setting with a fair degree of confidence.

Atrial Function↗
PubMedDate not supplied

[Two-dimensional echocardiography in the study of aneurysms of the membranous interventricular septum].

Seven patients with angiographically proven aneurysm of the membranous interventricular septum associated with membranous ventricular septal defect were studied by two-dimensional echocardiography. In all patients a curvilinear, dome-shaped echo arising from the upper ventricular septum and bulging toward the right ventricular cavity in systole was identified. This finding was detected in all long axis views (7/7), and 4/7 short axis views, in 4/6 apex four chamber views and in 3/6 subcostal four chamber views. Two-dimensional echocardiographic studies in forty patients with angiographically proven membranous ventricular septal defect, but not septal aneurysm, revealed only one case with similar findings, suggesting ventricular septal aneurysm, in the long axis and apex four chamber views. We conclude that two-dimensional echocardiographic imaging of a curvilinear echo in the proximal interventricular septum, bulging toward the right ventricle in systole and visualized in different planes, is very suggestive of aneurysm of the membranous ventricular septum. Two-dimensional echocardiography appears to have acceptable specificity for the diagnosis of aneurysms of the ventricular septum.

Child↗