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M J Lipton

Publications and source records attributed to M J Lipton.

At least 145 records · Page 8Linked to original sources
PubMed1981

Evaluation of coarctation of the aorta by computed tomography.

We used computed tomography (CT) after contrast medium administration to evaluate three adult patients with coarctation of the aorta. In preoperative scans, CT showed the aortic narrowing and deformity and the poststenotic dilation associated with coarctation. In postoperative examinations, CT was used to check for residual or recurrent narrowing and for the development of complications such as aneurysm or dissection. Since CT is noninvasive, it can be performed as an outpatient procedure. Its potential applications and its limitations with respect to aortography are discussed.

Adult↗
PubMed1981

Detection of intraventricular thrombi by computed tomography.

Intraventricular thrombosis (usually occurring after myocardial infarction) can lead to embolization, with serious consequences. Angiocardiography and two-dimensional echocardiography both are limited in their ability to detect intraventricular thrombi. Computed tomography (CT) with intravenous administration of contrast material gave excellent definition of intraventricular thrombi in three patients with recent myocardial infarctions and in one patient with a pericardial patch of the right ventricular apex. A ventricular mural thrombus was detected in a dog after an experimentally induced myocardial infarction. CT offers some advantages over contrast ventriculography and echocardiography in detecting intraventricular thrombosis.

Animals↗
PubMed1981

Computed tomography for follow-up of chronic aortic dissections.

Patients who have chronic dissections of the aorta are prone to re-dissection, extension of dissection, aortic aneurysm, and aortic rupture. Computed tomography (CT) with contrast enhancement provides a convenient, noninvasive method for follow-up of these patients. We used CT in a group of twelve patients who were treated for aortic dissection. CT demonstrated re-dissection, aneurysmal dilation of the aorta, and delayed filling of the false lumen. CT also showed persistent patency of the false lumen in almost all of the postoperative cases.

Aortic Dissection↗
PubMed1981

Detection and quantitation of myocardial infarction in vivo using transmission computed tomography.

In vivo studies were performed on 28 dogs to evaluate the usefulness of transmission computed tomography (CT) in the detection and quantitation of experimentally induced myocardial infarction. Intravenously administered contrast material was required to define the internal structure of the heart and to differentiate normal from infarcted tissue. Transmural infarcts with homogeneous central regions were visualized as areas of diminished contrast enhancement compared with the normal myocardium. All transmural infarcts of at least 24 hours' duration showed a surrounding border zone of patchy necrosis that was variable in size and had high CT numbers due to slow washout of the contrast material from this region. Infarct area determined from the images for individual slices correlated well (r = 0.976) with that calculated using pathology. The technique is very sensitive and can detect infarction within a papillary muscle. Nontransmural or patchy infarcts show up as areas of diffuse contrast enhancement without a central core of diminished enhancement. The distribution of the contrast material is similar to that of technetium-99m pyrophosphate in the border zone of the infarct in infusion studies, but in bolus studies it behaves more like thallium-201.

Animals↗
PubMed1981

Ventricular diastolic pressure-volume relations and the pericardium. Effects of changes in blood volume and pericardial effusion in dogs.

We investigated the role of the pericardium in the mechanism of shifts in the left ventricular (LV) diastolic pressure-volume relation produced by changes in circulating blood volume and by pericardial effusion. Twelve closed-chest anesthetized dogs were instrumented with pericardial and pleural balloons and intracardiac catheters for pressure measurements. We measured the volumes of the pericardium and the left and right ventricles by computed tomography (CT), integrating the area of CT cross-sections measured at 1-cm intervals from the cardiac apex to the aortic arch. The volumes of the pericardium and the cardiac chambers were changed by infusing 40 and 80 ml of dilute contrast medium into the pericardial space, by bleeding, and by rapidly infusing saline intravenously. Pericardial effusions of 80 ml reduced mean right ventricular volumes to 59% of control, whereas LV volumes were less severely compromised (81% of control). Total pericardial volume and pressure increased. Intravenous saline infusions, which raised right atrial pressure 10-15 mm Hg, produced increases of this magnitude in pericardial pressure. This was also the magnitude of the upward displacement in the LV diastolic pressure-volume relation after infusion. However, LV diastolic transmural pressure-volume coordinates fell along a single curve. Similar behavior was observed for the right ventricular diastolic pressure-volume relation. Pericardial transmural pressure-volume curves were described. When cardiac volume was altered by volume load and pericardial effusion, acute shifts in the LV diastolic pressure-volume relation were caused by changes in pericardial pressure, which, in turn, corresponded to changes in pericardial volume.

Animals↗
PubMed1981

Myocardial infarction in dogs, demonstrated by non-enhanced computed tomography.

The capability of non-enhanced and enhanced CT scanning of the heart without ECG gating to detect myocardial infarction in living dogs was explored. CT findings were correlated with those at post mortem. In large transmural infarctions, areas of lower attenuation were detected without contrast medium enhancement and appeared as defects when intravenous contrast medium was administered. The infarct size as estimated on each CT scan correlated closely with post mortem values.

Animals↗
PubMed1981

Validation of geometric methods for estimating segmental myocardial motion of the left ventricle at cineangiography.

Functional myocardial changes which result from ischemia are typically local rather than total. For assessing such regional changes quantitatively, left ventricular angiography has been used. The ventricular image has been divided into several components which can be measured individually. In order to test the validity of such methods, left ventricles of 5 dogs were labeled with endocardial tantalum markers and the segmental myocardial motion was estimated using cineangiography. Variance analysis of beat to beat measurements of total ejection fractions was performed. Total ejection fraction demonstrated the least variation with an average 3.5 per cent, segmental myocardial shortening 15 and regional stroke volumes 13 to 18 per cent. Intermethodologic variation with different regional volume measurements was 11 to 13 per cent. Regional stroke volume calculations showed large methodologic variations in beat to beat analysis. Conclusions and clinical decisions based on such measurements should be drawn with caution.

Animals↗
PubMed1980

Estimation of pulmonary artery wedge pressure from chest radiograph in patients with chronic congestive cardiomyopathy and ischaemic cardiomyopathy.

In order to define the relation between chest x-ray findings and the level of pulmonary artery wedge pressure in patients with chronic congestive cardiomyopathy, 82 patients had chest radiographs before undergoing 92 haemodynamic studies. The studies were divided into three groups according to the level of pulmonary artery wedge pressure (PAWP) (group 1: less than 15 mmHg, group 2: 15 to 24 mmHg, group 3: greater than or equal to 25 mmHg. Venous distribution, interstitial oedema, pleural effusions, left atrial enlargement, and right ventricular enlargement each occurred in less than 10 per cent of group 1 studies. Radiological abnormalities generally distinguished group 1 from group 2, but none except cardiothoracic ratio distinguished group 2 from group 3. Cardiothoracic ratio correlated best with pulmonary artery wedge pressure (r = 0.70). Alveolar oedema was uncommon when PAWP greater than or equal to 25 mmHg, occurring in 32 per cent of group 3 studies. Stepwise multiple linear regression analysis showed that cardiothoracic ratio, alveolar oedema, interstitial oedema, and left atrial size each contributed independently to the prediction of PAWP. The regression analysis improved the accuracy of the estimation of PAWP from the findings noted on standard chest radiographs.

Aged↗
PubMed1980

Evaluation of catheter thrombogenicity in vivo with indium-labeled platelets.

Platelets labeled with a lipid-soluble indium-111 8-hydroxyquinoline (oxine) complex were evaluated as an agent to measure the rate and degree of in vivo platelet accumulation on catheters. Polyethylene catheters and Teflon-coated guidewires were inserted into the femoral arteries or veins of dogs that had been injected with indium-labeled platelets. The catheters were passed to either the abdominal aorta or inferior vena cava and left in situ for 30 minutes to three hours. Images were obtained every five minutes with a gamma camera. This labeling technique is reproducible, allows multiple testing with a single preparation, and is relatively noninvasive. The results are easily quantitated to allow testing of different materials and coatings.

Animals↗
PubMed1980

Evaluation of dissections and aneurysms of the thoracic aorta by conventional and dynamic CT scanning.

Conventional computed tomography (CT) with intravenous contrast injection effectively demonstrates the features of aneurysms of the thoracic aorta (dilatation, calcification, intraluminal thrombus, and displacement and erosion of adjacent structures). In aortic dissection, CT can establish the diagnosis by demonstrating (a) double channels with an intimal flap or (b) displaced intimal calcifications if one channel is thrombosed. Dynamic CT following a contrast bolus shows the relative rate of filling of the true and false channels and demonstrates the intimal flap with optimum clarity. Reformatted CT images (paraxial and oblique) display the entire thoracic aorta in the plane of the arch, resembling an aortogram. CT is noninvasive and can be easily repeated to assess progress. Although aortography is still required prior to surgery in some cases, CT is a safe screening procedure that may avoid some invasive angiographic procedures.

Adult↗
PubMed1980

Detection of patent coronary bypass grafts by computed tomography. A preliminary report.

Twenty-three coronary bypass graft patients were evaluated by a contrast-enhanced computed tomography (CT) technique to determine graft patency. Four to six 4.8-second sequenced scans with a 1-second interscan interval were obtained in each patient during the hand injection of 25-30 ml of contrast medium in a peripheral vein. Patency of grafts was determined by a characteristic contrast enhancement. The CT technique correlated with angiographic assessment of graft patency in 59 of 62 grafts (95%). We conclude that this relatively noninvasive technique shows promise as a method for determining coronary bypass graft patency.

Adult↗
PubMed1980

[Experience with computed transmission tomography of the heart in vivo].

Cardiac computed tomography in its present form provides useful information about the heart for clinical use in patients with heart disease and for investigative work in such patients and living animals. Its great reconstructive power and unmatched density resolution are particularly advantageous in the study of ischemic heart disease. Because of its non-invasive character cardiac computed tomography has the potential of becoming an effective screening tool for large numbers of patients with suspected or known coronary heart disease. Other cardiac conditions such as valve disease and congenital lesions can also be examined with high diagnostic yield. However presently available scanners suffer from low repetion rate, long scan times and the fact that only one transverse cardiac level at a time can be obtained. The development which must be accomplished in order to eliminate these weaknesses is technically feasible. The availability of a dynamic cardiac scanner would greatly benefit the treatment of patients with heart disease and facilitate the inquiry into the pathophysiology of such diseases.

Angina Pectoris↗
PubMed1980

Radiography of acute myocardial infarction.

In conclusion, the plain radiograph provides an insight into the hemodynamic severity of myocardial infarctions and the effected patient's ultimate prognosis. It may also be the initial indicator of one of the several complications that may accompany the evolution of an acute myocardial infarction.

Arrhythmias, Cardiac↗
PubMed1980

Evaluation of ischemic heart disease by computerized transmission tomography.

As the technology of CTT advances in speed and resolution, a new clinical applications of this modality for noninvasive evaluation of ischemic heart disease should emerge. This modality has already advanced to the stage at which it can compete with echocardiography in producing static images of cardiac structures. The ability of CTT to quantitate regional blood flow using dynamic densitometry is a unique capability of this modality. Although cardiac scintigraphy provides excellent density sensitivity using small amounts of radioactive tracers, it currently lacks the spatial fidelity needed to differentiate many anatomic structures in the heart. Thus, CTT will likely complement the capabilities of other noninvasive imaging modalities. In the future, ultra high-speed CTT scanners will be developed that should provide a multi-section capacity for true three-dimensional imaging. Such scanners will enable many of the cardiac CTT techniques described in this article to advance from the experimental laboratory stage into the mainstream of clinical practice.

Aortic Dissection↗
PubMed1979

Gated cardiac scanning: canine studies.

Retrospective electrocardiograph gating of data from a rotating detector fan beam computed tomography system was employed to produce end systolic and end diastolic images of the beating heart in a series of normal and experimentally infarcted canines. The gating window was typically less than 20% of the cardiac cycle, and the gated images showed superior spatial resolution compared with ungated images of the same cross section. Comparison of the scans of the normal and of the infarcted animals shows abnormal contrast enhancement of the myocardium in the region of the infarct, and the gating studies demonstrate dyskinetic behavior of the infarct zone.

Animals↗
PubMed1979

Isolated single coronary artery: diagnosis, angiographic classification, and clinical significance.

Isolated single coronary artery is a rare congenital anomaly occuring in approximately 0.024% of the population. This entity can be diagnosed during life only by coronary angiography. Ten patients with isolated single coronary artery are reported. Based on angiographic analysis, a new classification is proposed, according to the site of origin and anatomical distribution of the branches. Typical angina did not occur with single coronary artery in the absence of coexisting coronary artery disease or aortic stenosis. No correlation was apparent between the type of anomalous patterns and the symptoms of angina.

Adult↗