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Biomedical subjects

C B Higgins

Publications and source records attributed to C B Higgins.

At least 433 records · Page 24Linked to original sources
PubMed1983

Nuclear magnetic resonance imaging of the cardiovascular system: normal and pathologic findings.

Whole body nuclear magnetic resonance (NMR) imaging of the cardiovascular system was carried out in early clinical trials in 244 volunteers and patients using a 3.5 KGauss (0.35 T) unit. The spin echo technique with multiple imaging parameters was used. Blood vessels were clearly discriminated from solid organs and lesions because little or no intraluminal signal is seen with laminar blood flow at normal velocities, whereas a more intense image is generated by solid organs. Characteristic flow signals were observed in normal patients and were accentuated by varying the imaging parameters. Cardiac chambers were well delineated in some patients on nongated images. In one case, internal topography of the ventricles was exquisitely displayed on a gated image. Intraluminal pathology, such as dissection of the aorta, aneurysms of the aorta and left ventricle, and aortic atheroma, was clearly demonstrated. Patency of coronary arterial bypass grafts was shown. Abnormal flow patterns due to slow or turbulent flow were accentuated on images using the second spin echo. This preliminary experience indicates the considerable potential of NMR imaging in the evaluation of cardiovascular diseases.

Blood Flow Velocity↗
PubMed1983

Nuclear magnetic resonance imaging of the infarcted muscle: a rat model.

Eleven Sprague-Dawley rats with experimentally produced infarction of the lower extremities were imaged by nuclear magnetic resonance (NMR) immediately after infarction, and 6 and 24 hours later. Contrast between the infarcted and control muscles was noted immediately and continued to increase through 24 hours. These changes corresponded to a significant increase in the water content of the infarcted extremity at 24 hours. These results suggest promise for NMR imaging in the identification of myocardial infarction and should encourage further investigation in this area.

Animals↗
PubMed1983

Nuclear magnetic resonance imaging of atherosclerotic disease.

Nuclear magnetic resonance (NMR) images of 93 patients undergoing studies of the abdomen and pelvis were studied for evidence of lesions of the aorta and the iliac and femoral arteries; atherosclerotic lesions were present in 13 of them. The lesions consisted of eccentric and concentric mural thickening with luminal narrowing and discrete plaques protruding into the vessel lumen. This appearance was distinctly different from the morphology of the internal vessel surface and uniformly thin vessel wall in normal patients and volunteers under the age of 30 years. Intraluminal flow signals observed in atherosclerotic and nonatherosclerotic subjects could be distinguished from mural lesions because of their lack of contiguity with the vessel wall and variation in appearance on multiple images obtained with the first and second spin echo. This initial experience suggests a potential role for NMR in the noninvasive imaging of atherosclerotic lesions. The natural contrast between flowing blood and the vessel wall indicates a distinct advantage of NMR for vascular imaging.

Abdomen↗
PubMed1983

The cardiovascular effects of metrizamide in infants.

A prospective study was performed in 30 children under 3 years of age to compare the cardiovascular effects of a nonionic contrast material of low osmolality, metrizamide, with those of a conventional ionic contrast material, meglumine sodium diatrizoate. Left ventricular end-diastolic pressure, left ventricular peak systolic pressure, heart rate, echocardiographically obtained end-diastolic and end-systolic dimension, and blood chemistries were obtained before and after angiography. Neither contrast material changed serum sodium, potassium, or creatinine levels. However, serum osmolality rose significantly following injection of diatrizoate, but not metrizamide. Both end-diastolic and end-systolic dimensions increased after diatrizoate injection. However, end-diastolic dimension was unchanged and end-systolic dimension fell after metrizamide infusion. Both contrast materials raised left ventricular peak systolic pressure and left ventricular end-diastolic pressure after injection; the magnitude of these pressure changes was the same for both agents. Heart rate increased with diatrizoate to a significantly greater degree than with metrizamide. There was no difference in the quality of radiographic opacification. It is concluded that although the effects on intracardiac pressures are similar for both contrast materials, metrizamide may be advantageous in the critically ill infant because it causes a smaller increase in osmolality, fewer changes in cardiac dimensions, and a reduced heart rate challenge.

Angiocardiography↗
PubMed1983

Effects of contrast media on pulmonary hemodynamics: comparison of ionic and non-ionic agents.

Hemodynamic effects of pulmonary arterial injections of ionic (sodium methylglucamine diatrizoate) and non-ionic contrast media (iohexol) were compared in 9 anesthetized dogs which were maintained with an open thorax in a resting control state. Both were found to increase pulmonary arterial pressure and cardiac output. In addition, both resulted in decreased systemic vascular resistance, though the effect was significantly less with the non-ionic agent. Aortic pressure did not change with the non-ionic agent but fell drastically with the ionic agent. Contrary to prevailing beliefs, the predominant response of the pulmonary circulation to contrast media was a fall rather than a rise in pulmonary vascular resistance.

Animals↗
PubMed1983

Extravascular lung water: effects of ionic and nonionic contrast media.

The effects of right atrial injections of Renografin 76 (meglumine diatrizoate), hypertonic (5%) sodium chloride, and iohexol, a new nonionic contrast medium, on sequential measures of left atrial pressure and extravascular lung water in anesthetized dogs were studied. Renografin 76 caused significant transient elevations of extravascular lung water; control levels were reestablished at 15-20 minutes after injection. These changes occurred in the absence of significant changes in left atrial pressure. Iohexol reduced extravascular lung water slightly while hypertonic saline transiently increased it. The increased extravascular lung water after right atrial injections of ionic contrast medium can only partially be explained by the tonicity of the medium. This increase was not observed with nonionic medium, suggesting that nonionic media may be preferable imaging agents in patients with underlying lung or heart disease, and may be more suitable for digital intravenous examinations.

Animals↗
PubMed1983

In vivo assessment of left ventricular wall and chamber dynamics during transient myocardial ischemia using prospectively ECG-gated computerized transmission tomography.

Seven dogs were evaluated with prospective ECG-gated computerized transmission tomography (CTT) to analyze left ventricular (LV) wall thickness and cross-sectional chamber area after acute occlusion of the left anterior descending coronary artery (LAD). ECG-gated CTT scanning during i.v. administration of contrast material was performed over the mid-left ventricle at rest, after acute occlusion of the LAD and 30 minutes after release. The extent of systolic wall thickening (EWTh) of the anterior (potentially ischemic) segment was 39.8 +/- 8.8% (SEM) in the control state and -26.0 +/- 4.7% during LAD occlusion (p less than 0.01). The nonischemic septum demonstrated a compensatory increase in EWTh, from 28.6 +/- 3.5% to 46.4 +/- 6.1% during LAD occlusion (p less than 0.05). The end-diastolic LV luminal area (LVA) increased from 17.4 +/- 0.8 cm2 in the control state to 21.0 +/- 1.1 cm2 during LAD occlusion (p less than 0.01). End-systolic LVA also increased, from 11.0 +/- 0.9 to 15.2 +/- 1.1 cm2 (p less than 0.01). In addition, the percent change in LVA from end-diastole to end-systole declined from 37.4 +/- 3.8% during control to 28.0 +/- 2.6% during LAD occlusion (p less than 0.02). In conclusion, gated CTT demonstrates that the alterations in acute ischemia are characterized by changes in regional wall thickening dynamics, consisting of wall thinning during systole in the jeopardized segment and compensatory increase in the extent of systolic thickening in the normal segment, and changes in global LV function, consisting of an increase in the LVA and a decrease in the percent change of LVA during systole. Gated CTT may be useful for monitoring regional and global effects of ischemia when subjects can be studied in the supine position and with respiration suspended for 45 seconds.

Animals↗
PubMed1983

Pulmonary edema formation with myocardial infarction and left atrial hypertension: intravascular and extravascular pulmonary fluid volumes.

The response of pulmonary blood volume (PBV) and extravascular lung water (EVLW) was examined by indicator-dilution techniques in 14 "open chest" dogs, seven that underwent coronary occlusion (group 2) and seven that served as controls (group 1). Data were obtained in a control stage (control stage 1) 45 min after coronary ligation (control stage 2), and 90 min after the left atrial pressure had been increased to approximately 35 mm Hg with a left atrial balloon. In group 2 animals, EVLW increased after coronary ligation without a marked change in left atrial pressure (6.9 +/- 0.4 to 8.2 +/- 0.5 ml/kg mean +/- SD; p less than .05) and increased to 20.1 +/- 1.4 ml/kg after the production of left atrial hypertension (p less than .005 vs control and vs coronary ligation). In the control dogs, EVLW was unchanged 45 min after the initial data had been collected (7.1 +/- 0.7 to 7.0 +/- 0.8 ml/kg). After the production of left atrial hypertension in these dogs, EVLW rose (14.8 +/- 1.2 ml/kg; p less than .005 vs control stage 1 and control stage 2, p less than .01 vs group 2 dogs). PBV did not change significantly with ligation and increased similarly in both groups during left atrial hypertension. We conclude that coronary ligation can increase EVLW, independent of microvascular hydrostatic pressure. During the production of left atrial hypertension there was greater transcapillary fluid flux in group 2 dogs at matched levels of left atrial pressure elevation. This may be due to an alteration in the permeability of the pulmonary capillary membrane during myocardial infarction and provides a partial explanation for the occasional disparity between left heart dynamics and the chest radiograph in acute myocardial infarction.

Animals↗
PubMed1983

Inflammatory constriction following complete pericardiectomy in tuberculous constrictive pericarditis.

A 13-year-old boy with active tuberculous constrictive pericarditis underwent complete pericardiectomy together with antituberculous therapy and a short course of steroids. Six weeks following the surgery, he was seen with clinical and hemodynamic findings of recurrent pericardial constriction, presumably due to an inflammatory collection around the heart. Symptoms gradually resolved within six months with resumption of steroid therapy. Repeat hemodynamic study showed normal hemodynamics. The case demonstrates the production of cardiac constriction by nonpericardial inflammatory tissue and the possible benefits of steroid therapy in the treatment of tuberculous constrictive pericarditis.

Adolescent↗
PubMed1983

Misdiagnosis of aortic atresia due to catheter malposition.

A single film portable aortogram through a highly placed umbilical artery catheter suggested aortic atresia, but subsequent study revealed a normal aorta and a patent ductus arteriosus. This demonstrates the importance of proper catheter placement in single film portable aortography, which is a reliable diagnostic tool in the evaluation of distressed neonates.

Aorta↗
PubMed1983

Intravenous vs. left ventricular injection of ionic contrast material: hemodynamic implications for digital subtraction angiography.

Because of the increased use of intravenous injection of contrast material for the evaluation of cardiac structure and function by digital subtraction techniques, a study was done to assess the hemodynamic effects of contrast material when used in this fashion in man. In 10 patients, with each serving as his own control, the effects of intravenous and intraventricular injections of sodium meglumine diatrizoate (Renografin 76) in the same dose were compared. There was no difference between these two methods with respect to changes in pulmonary wedge pressures, systemic pressures, and pulmonary vascular resistance. The elevation of mean pulmonary artery and right atrial pressure was greater after the intraventricular injection (p less than 0.05). The elevated cardiac output and systemic vascular resistance returned to control values somewhat more quickly after the intravenous injection (p less than 0.001 and p less than 0.05, respectively); and the increase in cardiac output was greater after the intravenous injection at 1 min (p less than 0.05), but less than after the intraventricular injection at 2 min (p less than 0.05). Despite the detection of these statistically significant differences, the magnitude and timing of these differences are too small to justify the notion that imaging by intravenous injections of standard ionic contrast media provides any substantial hemodynamic benefits or decreased risk to the patient.

Aged↗
PubMed1983

Nuclear magnetic resonance imaging of vasculature of abdominal viscera: normal and pathologic features.

Nuclear magnetic resonance (NMR) imaging of intraabdominal vascular anatomy and the effect of various lesions on retroperitoneal and splanchnic vessels was assessed in 67 patients and volunteers using a superconducting magnet (0.35 tesla) and the spin-echo imaging techniques. Because of the low signal generated by flowing blood in most images, blood vessels, including intraparenchymal vessels, were well demonstrated. Clear delineation of the splenic vein facilitated visualization of the normal pancreas and pancreatic masses. Variation in the size and shape of the inferior vena cava and portal venous system reflected constricting and mass lesions. Preliminary observations from this initial experience suggest conspicuity of splanchnic vessels out of proportion to the current spatial resolution of NMR imaging due to the marked natural contrast between flowing blood and solid organs.

Abdomen↗
PubMed1983

Nuclear magnetic resonance imaging in retroperitoneal fibrosis.

Three patients with biopsy-proven idiopathic retroperitoneal fibrosis were studied by computed tomography (CT) and nuclear magnetic resonance (NMR). The nuclear magnetic resonance images revealed the extent of the fibrous mass or plaque and showed that it involved the periaortic area in each case. The diagnostic information regarding the extent of the disease was similar to that derived from the x-ray CT. The NMR images demonstrated the relation of the fibrosis to the major retroperitoneal vessels in a fashion superior to CT. Furthermore, variation in intraluminal signals on multiple spin-echo parameters suggested the presence of abnormal flow in the vessel constricted by retroperitoneal fibrosis.

Aorta↗
PubMed1983

CT scanning of the heart.

It is generally agreed that all present diagnostic cardiac methods including echocardiography, nuclear medicine, and coronary arteriography have significant limitations. Nuclear cardiology provides excellent diagnostic sensitivity using small amounts of radioactive tracers, but it currently lacks the spatial fidelity needed to differentiate many anatomic structures in the heart. CT complements the capabilities of these alternative imaging modalities. Computed tomography offers accurate reconstruction of the whole myocardium with far greater spatial and density resolution in three dimensions. CT may eventually find its most important and clinically useful application in the diagnosis and management of heart disease.

Animals↗
PubMed1983

Computed tomography. The technique and its use for the evaluation of cardiocirculatory anatomy and function.

Computed tomography, a promising new imaging technique, has not yet been widely applied to cardiac disease. There is, furthermore, very little experience with CT scanning for patients with congenital cardiovascular malformations. Nevertheless, early studies with this remarkable modality indicate great promise for future application at low levels of radiation--approximately 10 to 15 per cent that of a conventional angiogram. The feasibility studies so far performed should be considered in that context. Nevertheless, relatively slow, whole body CT scanners can contribute useful clinical diagnostic information in patients with heart disease. Cardiac CT scanning is presently limited, as were all other conventional x-ray techniques at first, by relatively long exposure times. CT scan technology has made dramatic strides during its short existence of one decade, and there is strong evidence that this trend will continue in conjunction with rapid advances in high technology.

Calcinosis↗