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Biomedical subjects

D J Sahn

Publications and source records attributed to D J Sahn.

At least 235 records · Page 13Linked to original sources
PubMed1982

Range gated echo-Doppler velocity and turbulence mapping in patients with valvular aortic stenosis.

Flow beyond a stenotic aortic valve (AS) is dynamically complex. Numerous hydraulic studies have demonstrated that at least four well-known major flow areas occur distal to a stenotic valve. These include a jet, an area alongside the jet (the parajet), an area of flow disturbance, and an area in which disturbed flow again becomes laminar downstream. Of these, only the flow disturbance area has markedly turbulent flow, although some turbulence can be at times detected in the area beside the jet. The purpose of this investigation was to test a technique of patient examination that might allow a range-gated pulsed Doppler to detect each of these known areas in the aorta (Ao) of valvular AS patients. A method for mapping flow in the lumen of the Ao root and ascending Ao is detailed. The transverse Ao arch was studied in the standard manner. With this mapping method, 14 patients with AS were studied. We were able to identify the jet in 13 of 14 as a high velocity, narrow-width signal in the Ao root. The parajet area was characterized by no detectable or low flow in 12 of 14, but two patients had late systolic flow disturbance in the parajet area. All patients had a strong flow disturbance detected; 3 of 14 were first detected in the Ao root and the remainder were first detected higher in the ascending Ao. The area of relaminarization was not addressed in this study. This investigation demonstrates that a proper interpretation of range-gated pulsed Doppler recordings from areas distal to AS requires knowledge of flow dynamics beyond an obstruction and a methodical range-gated pulsed Doppler examination technique.

Aorta↗
PubMed1982

High predictive accuracy for detection of left main coronary artery disease by antilog signal processing of two-dimensional echocardiographic images.

Two-dimensional echocardiography has been used to image the left main coronary artery. We have successfully imaged the left main coronary artery in 16 of 19 patients with left main coronary artery disease (LMCAD) and in 14 of 18 control patients using a dynamically focused 3-1/2 MHz experimental phased array sector scanner. Images were displayed with standard logarithmic compression grey scale allocation and with a modified antilog curve which enhances high intensity echoes. All of the 16 patients with LMCAD were identified from the antilog processed image. Only 1 of the 18 control patients had a false positive study. Modified antilog processed images provide high sensitivity (100%) and specificity (93%) for detecting LMCAD. This noninvasive technique could be used to screen patients for the presence or absence of LMCAD.

Adult↗
PubMed1982

Two dimensional echocardiography and intravenous digital video subtraction angiography for diagnosis and evaluation of double aortic arch.

Two infants and one 7 year old child with double aortic arch are described in whom subcostal two dimensional echocardiography identified the bifurcation of the aorta high within the thorax and imaged the proximal portions of the right and left aortic arches. In one of the infants and in the 7 year old child, the diagnosis was confirmed using intravenous digital video subtraction angiography, thus avoiding aortography and permitting accurate evaluation of the anatomic features. All cases were confirmed surgically. If X-ray examination after barium swallow and clinical history are suggestive of double aortic arch, two dimensional echocardiography is useful in verifying this possibility. Intravenous digital video subtraction angiography provides the capability for precise documentation of the anatomic features.

Angiography↗
PubMed1982

Two dimensional Doppler echocardiographic/M mode echocardiographic and phonocardiographic method for study of extracardiac heterograft valved conduits in the right ventricular outflow tract position.

Significant concern exists over the long-term results of right ventricular outflow tract repair using heterograft valved conduits. Because these conduits and valves are difficult to image using ultrasound, a serially applicable two dimensional Doppler echocardiographic, M mode echocardiographic and phonocardiographic method for noninvasive investigation was developed and applied in 15 children. The method provides two dimensional echocardiographic imaging of valve contour and motion, as well as M mode and phonocardiographic analysis and quantitative range-gated Doppler information about the timing of flow through the conduit. Conduit diameter in two dimensional echocardiographic images correlated well with known conduit size (r = +0.96). A thickened and stenosed heterograft valve was predicted in two patients before hemodynamic investigation. This new method provides serially obtainable information to aid in the management of children and infants with a valved conduit placed for repair of congenital heart malformations and aids in planning the timing of hemodynamic follow-up studies.

Adolescent↗
PubMed1982

Effect of beam directional alterations on left ventricular shortening fraction.

In this study, the dependence on beam direction of the echocardiographically derived fractional shortening of the left ventricular minor axis was evaluated. A directionally oriented, steerable cursor was used to select M-mode lines from a 2-dimensional image at the chordal level. Seven M-mode traces were derived from each image, 1 along the true ventricular meridian and 3 at known deviations on either side of the meridian. M-mode traces, thus derived, all appeared acceptable for measuring wall or cavity dimensions. Results indicate a progressive increase in shortening fraction (p less than 0.05) for deviations more than 25% of the distance between the meridian and the lateral or medial papillary muscle heads. Decreases in left ventricular dimensions in diastole and systole with progressive deviation from the meridian accounted for the decrease in shortening fraction. Spatial orientation is required for reproducible shortening fraction measurements.

Adolescent↗
PubMed1982

Ultrasonic imaging of the coronary arteries in open-chest humans: evaluation of coronary atherosclerotic lesions during cardiac surgery.

We explored techniques that would allow the surgeon to localize coronary artery lesions demonstrated angiographically or to supplement angiographic information in patients who are undergoing coronary artery bypass procedures by intraoperative scanning of the coronary arteries using ultrasound. A 9-MHz electronically focused water-path ultrasound scanner was first used to image the coronary arteries in three anesthetized, open-chest sheep. In a subsequent study, 10 human subjects undergoing cardiac surgery for valve replacement who had normal coronary angiograms were scanned during heart surgery to provide images of normal coronary arteries. The ultrasound probe was sterilized with gas and placed directly on the beating heart by the surgeon. In the third phase of this study, 21 patients with coronary artery disease were scanned and the ultrasonic appearance of their imaged coronary lesions was compared to independently interpreted angiographic estimates of percent obstruction, with close correlation (r = 0.91). The ultrasound scan could be used to identify lesions in vessels beyond proximal occlusions, which are not visualized well angiographically, and could localize the site of lesions to determine placement of saphenous vein bypass grafts. This new technique may provide a method for evaluating coronary atherosclerotic lesions during coronary artery surgery and aid decisions regarding placement of saphenous vein grafts.

Animals↗
PubMed1982

Cross-sectional echocardiographic diagnosis and subclassification of univentricular hearts: imaging studies of atrioventricular valves, septal structures and rudimentary outflow chambers.

We reviewed anatomic observations (surgical or autopsy), angiograms and echocardiograms from 44 patients with documented univentricular hearts. Thirty-three patients had univentricular heart of left ventricular type with an outflow or rudimentary chamber. Five had univentricular heart of right ventricular type, and six had univentricular heart of indeterminate types without a rudimentary chamber. Univentricular heart was correctly diagnosed by two-dimensional echocardiography in all but two of the 44 patients, including 25 of 27 double-inlet univentricular hearts, all five with absent left and all 12 with absent right atrioventricular connection. One of the two blind trabecular pouches was missed on echocardiography; the other was not seen on the angiogram but was present at autopsy. In 30 of 33 patients, univentricular heart of left ventricular type was correctly identified by imaging an anterosuperior and leftward or rightward outlet chamber, and in four of five patients with univentricular heart of right ventricular type, the anomaly was correctly identified by imaging the inferior and posterior position of the rudimentary outflow chamber near the crux of the heart. Two-dimensional echocardiography provides detailed analysis of atrioventricular connections, main chamber morphology, and rudimentary chamber size and position of noninvasive diagnosis and anatomic subclassification of univentricular hearts.

Adolescent↗
PubMed1982

Serial two-dimensional echocardiography in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy (DMD) are known to have progressive epicardial fibrosis of the free wall of the left ventricle, but standard noninvasive M-mode echocardiographic tests of left ventricular function are relatively insensitive detectors of this cardiomyopathy. We therefore used two-dimensional echocardiography to record three short axis levels of the left ventricle in 13 Duchenne patients. Serial studies were separated by 2 years for most patients. The two-dimensional echocardiographic technique allows qualitative evaluation of segmental contraction of the left ventricle. Four general principles were found during this study: (1) Obvious contraction abnormalities of the left ventricle were present in most patients with DMD. (2) In most patients, the contraction deficit was first noted in the left ventricular posterior free wall behind the mitral valve. (3) Once a contraction deficit was observed, the area of abnormal contraction progressed inferiorly to include additional areas of the left ventricular posterior free wall. (4) Standard M-mode left ventricular function techniques were unreliable for detecting individuals with segmental contraction abnormalities.

Adolescent↗
PubMed1982

Residual shunting in the early postoperative period after closure of atrial septal defect: echocardiographic comparison of patch materials.

Residual shunting after surgical closure of septal defects is a common postoperative complication. In this study, contrast echocardiography was used to assess the effect of different surgical patch materials on early postoperative residual shunting. The study consisted of 44 patients (aged 3 days to 64 years) with simple or complex atrial septal defects. Total pulmonary-to-systemic flow ratios ranged form 1.8:1 to 4.0:1. Three methods were used to close the atrial septal defects: primary suture closure (n = 7), patching with thin, knit Teflon fabric (n = 13), and patching with thicker, low porosity, knit Teflon fabric (n = 24). Contrast echocardiographic injections were performed through central venous and left atrial lines positioned at operation for monitoring purposes. Ten of the 44 patients had residual shunts. In five of them, daily contrast studies showed progressive diminution in shunting with eventual resolution, but in the other five patients, shunting persisted beyond the first 5 postoperative days. Three of the latter five required reoperation for actual residual anatomic defects. No patient whose atrial septal defect was closed by either direct suture or thick, low porosity Teflon fabric had shunting detected at any time postoperatively. Our data confirmed temporary leakage across newly implanted intracardiac patches. However, shunts that persist beyond the first postoperative week indicate true anatomic residua and not porous patch material. If a patient's recovery is complicated, use of contrast echocardiography can determine whether a residual shunt is a causative factor. In patients with complex lesions in whom continued shunting during the early postoperative period may cause serious hemodynamic consequences, heavier, low porosity patch material can be useful.

Adolescent↗
PubMed1981

Evaluation of the cardiac effects of doxorubicin by serial echocardiography.

Serial echocardiographic studies were performed on 48 children who received chemotherapy with doxorubicin hydrochloride (Adriamycin). For the group as a whole, no correlation could be made between the cumulative dose of doxorubicin administered and left ventricular systolic function as measured by the fractional shortening of the left ventricle (delta s). Two asymptomatic patients, however, demonstrated depressed delta s and abnormal results from radionuclide studies at cumulative doxorubicin doses of less than 430 mg/sq m. Differentiation of the echoderived curve of left ventricular minor axis dimension indicated that these two patients had abnormalities in both diastolic and systolic function. Good correlation was demonstrated between echocardiographic and radionuclide studies in eight patients, including the two with depressed function. Inherent variability limits the sensitivity of echocardiographic functional studies, but serial studies are helpful in the evaluation of cardiac function in children who receive doxorubicin.

Adolescent↗
PubMed1981

Accuracy of two-dimensional echocardiography in the detection of aneurysms of the ventricular septum.

Eight children with angiographically proven aneurysm of the membranous ventricular septum (AVS) associated with ventricular septal defect were studied by real-time cross-sectional echocardiography. A curvilinear, sickle (dome-shaped), or irregular echo arising from the interventricular septum and bulging toward the right ventricle in systole was visualized in all patients. This finding was detected in 7 of 8 long axis views, 5 of 8 short axis views, 5 of 7 apex four-chamber views, and 4 of 7 subcostal four-chamber views. In addition, real-time cross-sectional echocardiograpic studies were performed in 40 patients with angiographically proven membranous ventricular septal defect without AVS; in only one patient was the abnormal echo suggesting aneurysm of the ventricular septum detected in the long axis and apex four-chamber views. Our echo study suggests that two-dimensional echocardiography has acceptable specificity for the diagnosis of AVS.

Child↗
PubMed1981

Range gated Doppler ultrasound detection of contrast echographic microbubbles for cardiac and great vessel blood flow patterns.

Ultrasonic contrast techniques allow tracking of blood flow in patients with cardiac malformations. One problem often encountered in M-mode contrast is inability to generate adequate microbubbles for recording. Theoretically, echo Doppler should be more sensitive for detection of microbubbles. To test this hypothesis, results of 75 saline injections were studied at catheterization in 16 patients by simultaneously recording contrast M-mode and echo Doppler studies. For this part of the investigation, an ATL 500 system was utilized. The M-mode of this system was found to provide identical information to that of SmithKline. Records were evaluated without identification of the patient. In all instances (n = 20) in which microbubbles were not expected on the basis of flow patterns, none were detected by Doppler. One error occurred for M-mode. Contrast in the direction of flow was visualized in 50 of 55 injections by echo Doppler. In these, a frequency dispersion was present, but even more striking was a marked rise in the time interval histographic input signal strength indicator. Only 40 of 55 simultaneous M-mode echoes showed a contrast effect (p less than 0.05). Doppler microbubble detection was usually represented by a much stronger signal than was M-mode contrast. This investigation demonstrates that range gated Doppler is an effective method for microbubble detection.

Child↗