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Biomedical subjects

M J Lipton

Publications and source records attributed to M J Lipton.

At least 181 records · Page 10Linked to original sources
PubMed1975

Correction of absence of the aortopulmonary septum by creation of concentric great vessels.

An 18-year-old patient is reported who had simultaneous occurrence of aortopulmonary septal absence, complete interruption of the aortic arch, and patent ductus arteriosus. This is the only known patient who has had total anatomical correction of this combination of defects. Correction was accomplished by staged procedures; the first stage consisted of obliteration of the patent ductus and establishment of aortic continuity; this was followed one year later by the second stage, which included a unique method for repair of absence of the aortopulmonary septum. The surgical desirability and embryological implications of criteria for differentiating truncus arteriosus from aortopulmonary septal defect are presented. Follow-up physiological evaluations and the patient's death from the effects of increasing pulmonary vascular disease (despite early symptomatic improvement) approximately two years after completion of the repair underscore the importance of early diagnosis and operative intervention.

Adolescent↗
PubMed1975

Aneurysms of the coronary arteries in the adult. Clincial and angiographic features.

One thousand coronary arteriograms were reviewed to determine the incidence, clinical presentation and angiographic features of aneurysms of the coronary artery (ACA) in adults with angina. Criteria for the angiographic diagnosis are described and the angiographic aspects are emphasized. The incidence of ACA was 1.1%. Saccular and fusiform aneurysms were seen. Single aneurysms were present in 7 patients. One patient had an abdominal aneurysm. Five patients underwent surgery; two had postoperative selective coronary angiography one year later and all five underwent follow-up left ventricular angiography. The most likely etiology of the aneurysms in this series is atherosclerosis.

Adult↗
PubMedDate not supplied

Differentiating between T1 and T2* changes caused by gadopentetate dimeglumine in the kidney by using a double-echo dynamic MR imaging sequence.

Dynamic MR images of the passage of gadopentetate dimeglumine through the kidneys of normal rats are obtained using a dual gradient-echo sequence. The amplitudes of gradient echoes are defined by local T1 and T2* values in the tissue. The ratio of these amplitudes, primarily defined by local T2*, can be used to differentiate between T1 and T2* effects. This is particularly important with regard to renal studies because, due to a highly inhomogeneous distribution of gadopentetate dimeglumine in the kidney, T2* shortening can impede MR data analysis. To study changes in the observed signal caused by gadopentetate dimeglumine, curves of MR renal intensity versus time were obtained in the cortex and medulla after administration of the contrast agent. Using T2* compensation, distinct temporal peaks were observed in the cortex and outer medulla, indicating a high concentration of gadopentetate dimeglumine in the vascular phase. The authors conclude that this technique can be a useful tool for studying renal function noninvasively.

Animals↗
PubMedDate not supplied

Dangers of left main coronary artery lesions: angiographic technique and evaluation.

Five hundred consecutive coronary arteriograms were reviewed to evaluate left main coronary artery lesions. This entity has been associated with a high incidence of angiographic deaths. Clinical signs claimed to be diagnostic were analyzed together with the value of various projections for making the diagnosis. Pressure damping was a vital sign, and when persistent, it required 3-5 mm to be cut from the catheter's tip for a safe study to be performed. Shallow 10-15 degrees oblique and AP projections were found to be essential for a complete evaluation of the left main trunk. Marked ST depression or hypotension during treadmill exercise testing, as well as the presence of coronary calcification were not statistically significant in anticipating this lesion. The incidence of left main lesions nearly 15% (74/500) in this series is higher than previously reported (2.4-5.9%); however, in 8% (40/500), the stenosis was 75% or greater in degree which more closely approximates to the incidence previously reported in the literature. This may be the result of the additional projections recommended, but is probably also related to the population studied. No complications occurred in this series.

Angiography↗
PubMedDate not supplied

The effect of contrast media on the isolated perfused canine heart.

The intravascular injection of contrast medium produces a rise of ventricular filling pressure which may reflect blood volume expansion, a negative inotropic effect on the myocardium, and/or a decrease in ventricular diastolic compliance. This phenomenon was studied by randomly infusing three substances, Renografin-76, 1% saline and 38% sucrose, into the aortic root of the isolated perfused canine heart. The preparation was modified by having an inflated ballon within the left ventricular cavity so that the end diastolic ventricular volume and afterload were fixed. A dose-related depression of left ventricular systolic pressure and peak dP/dt due to contrast media occurred, without a significant change in the left ventricular diastolic pressure. This decrease in ventricular contractility due to Renografin-76 could not be attributed entirely to either a saline or an osmotic effect. No significant changes were observed in left ventricular diastolic compliance. Sucrose was found to exhibit a marked positive inotropic effect.

Animals↗
PubMedDate not supplied

The effects of orientation on volume measurements of human left ventricular casts.

Biplane angiocardiography has emerged as a standard method for calculating left ventricular volume measurements. Validation of such measurements has separately been made for several projections of silicone casts of the left ventricle. This study was undertaken to establish and compare the regression lines for left ventricular cast volume measurements in the commonly used angiographic projections. Once established, any ventricular volume can be calculated from the slope and intercept of the regression line obtained from the appropriate angiographic projection.

Angiocardiography↗
PubMedDate not supplied

Measurement of cardiac output by computed transmission tomography.

The capability of computed tomography (CT) scanning to measure cardiac output was explored using ten anesthetized dogs, and the results were compared with those obtained by thermodilution. Dynamic CT scans were performed at the level of the aortic root while small peripheral intravenous boluses of contrast medium were injected. Time/density curves were generated using a gamma variate fitting program. These were used to estimate cardiac output by applying indicator dilution principles. CT results correlated favorably (r = 0.86) with those of thermodilution. This feasibility study indicates the utility of CT for obtaining physiologic measurements of cardiac function and should encourage further studies to develop the potential of CT for cardiovascular diagnostic purposes.

Animals↗
PubMedDate not supplied

Assessment of human right ventricular cast volume by CT and angiocardiography.

Angiocardiographic methods available for cardiac chamber volume measurements have been shown to be less accurate although more practical than CT for the evaluation of the LV. To explore the capability of CT for RV volume measurements, silastic casts of seven normal RV were measured by a displacement method, conventional angiocardiographic biplane methods, and CT. The displacement method used degassing beneath vacuum to remove air trapped in the casts, and the actual volumes, which varied between 62 and 188 cc, were measured by Archimedes' principle. Cast volumes measured by biplane angiogram methods displayed a varying degree of spread around the regression line, caused by the chamber's irregular shape and its variation in orientation relative to the x-ray beams. CT measurements were in all aspects significantly more accurate.

Angiocardiography↗