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Biomedical subjects

R R Smith

Publications and source records attributed to R R Smith.

At least 145 records · Page 8Linked to original sources
PubMed1982

The three phases of vasospasm.

We propose the theory that prolonged cerebral vasospasm involves three phases: (1) the initial muscular contraction of the arterial wall; (2) a secondary injury to the artery that consists of endothelial desquamation with adherence of platelets to te denuded internal elastic lamina and mural thrombus formation; and (3) the repair process, which is the proliferative endarteropathy that has been observed in autopsy specimens. Cerebral ischemia can be the end product of any of these three conditions. We have postulated a possible subcycle in the overall scheme by which adherence of platelets to the denuded internal elastic lamina of the artery provide a continuously replenishing supply of spasmogenic chemical factors to the mural receptors and stimulate prolonged contraction of the muscular layer. We propose that this cycle may be interrupted by the administration of heparin. To test this hypothesis, the records of 112 consecutive patients who received systemic heparin in conjunction with carotid ligation were compared with the results of carotid ligation reported in the Cooperative Study, in which heparin was not used. The incidence of ischemic complications in the group of patients receiving heparin was 6%, as compared to 23% in control group, with a concomitant reduction in mortality from 16% to 10%. The incidence of recurrent subarachnoid hemorrhage was slightly less in the patients receiving heparin than in patients in the Cooperative Study. We conclude that the data provide support for our hypothesis of the mechanism of prolonged cerebral vasospasm and cerebral ischemia associated with subarachnoid hemorrhage, and that systemic heparin may be used with relative safety in patients in whom the aneurysm if protected by partial carotid ligation.

Animals↗
PubMed1982

Homozygous alpha thalassemia/Hb G Philadelphia.

Microcytic red cells from a 70 year old Negro man with mild anemia contained only hemoglobin G-Philadelphia. Red cells from all of his children had low-normal MCV's, and contained 32-34 percent of the abnormal hemoglobin. Oxygen affinity of his blood and stability of his hemolysate were normal, suggesting that his mild anemia was not caused by the the abnormal hemoglobin. Restriction endonuclease analyses of DNA from the proband and his offspring showed that the alpha G-Philadelphia globin gene exists in only one copy per chromosome. The new gene was probably created by an unequal cross-over which deleted an alpha globin coding sequence (derived from one or both alpha globin genes), as well as some or all of the DNA sequence between those genes.

Aged↗
PubMed1982

Spontaneous resolution of occlusive lesions of the carotid artery.

The authors review the literature concerning spontaneous resolution of occlusive lesions involving the carotid artery. They add four cases illustrating three pathological vascular processes that may resolve spontaneously, namely, arterial dissection, atheromatous lesions at the carotid bifurcation, and an arteriopathy involving the intracranial vessels which is poorly understood at this time.

Adult↗
PubMed1982

Pulmonary artery atherosclerosis: correlation with systemic atherosclerosis and hypertensive pulmonary vascular disease.

Atherosclerosis of the pulmonary arteries is a common autopsy finding and is associated with a variety of clinical conditions. To delineate the morphologic changes associated with pulmonary artery atherosclerosis, autopsies of 337 consecutive adults (greater than 15 years of age) were studied. For each, 35 features were studied, including age, coronary vascular disease, cardiac chamber hypertrophy and dilation, pulmonary artery and aortic atherosclerosis, and pulmonary thromboemboli and emphysema. These were compared using correlation coefficients and forward and backward stepwise regression procedures for selected variables. Pulmonary artery atherosclerosis correlated significantly with age, right ventricular dilation and hypertrophy, pulmonary emphysema, and aortic atherosclerosis. Regional evaluations of systemic and pulmonary atherosclerosis showed highly significant internal correlations. In the ligamentum arteriosum, the intensity of atherosclerosis over the aortic insertion correlated with the severity of a similar atheroma at the pulmonary artery insertion. With the multiple-regression procedure, pulmonary artery atherosclerosis was a significant predictor of aortic atherosclerosis, right ventricular hypertrophy, and pulmonary embolization. Our study shows that pulmonary embolization. Our study shows that pulmonary embolization. Our study shows that pulmonary artery atherosclerosis is accelerated in patients with atherosclerosis of the systemic arteries and the pathologic lesions associated with hypertensive pulmonary vascular disease.

Adolescent↗
PubMed1982

Percutaneous transluminal angioplasty in subclavian steal syndrome: recurrent stenosis and retreatment in two patients.

Two patients with proximal subclavian artery stenosis and "subclavian steal syndrome" by clinical and arteriographic criteria were treated with percutaneous transluminal balloon catheter angioplasty. Successful dilatation was obtained, but stenoses recurred at or near the dilated segments in both cases, necessitating repeat transluminal angioplasty. One patient eventually underwent surgical carotid-subclavian grafting. Factors influencing recurrent stenosis after transluminal angioplasty are discussed, including the choice of an optimal balloon inflation diameter, the pathophysiology of angioplasty, and the role of anticoagulation. Transluminal angioplasty may be a viable therapeutic alternative to operation in selected patients with occlusive subclavian disease.

Angioplasty, Balloon↗
PubMed1982

Fibromuscular dysplasia of the internal carotid artery: a long term follow-up.

The natural course of fibromuscular dysplasia (FMD) of the internal carotid artery (ICA), a stenosing angiopathy associated with cerebrovascular insufficiency, has been described. A search of medical records located 16 female patients with angiographically demonstrated FMD of the ICA. The identical twin of 1 patient was included in the registry on the basis of noninvasive studies consistent with FMD of the ICA. The mean age at diagnosis was 58 years. Follow-up examinations were performed an average of 3.8 years after diagnosis (range, 1 to 9 years); the evaluation included clinical, angiographic, and Doppler studies. Fifteen patients showed no evidence of progression of FMD, whereas 2 patients with coincident atherosclerotic disease had suffered strokes. One patient had undergone surgical dilatation of the ICA, 3 had received oral anticoagulants, and 13 had received either aspirin or no specific therapy. In light of the apparently benign clinical course of uncomplicated FMD of the ICA, it is concluded that dilatation is rarely warranted.

Adult↗
PubMed1982

Hyperbaric oxygen after circulatory arrest: modification of postischemic encephalopathy.

Cats were subjected to circulatory arrest of 5 minutes duration by occlusion of the ascending aorta and the superior and inferior venae cavae. After perfusion was re-established by release of the occluding clamps, one group of animals was placed in a hyperbaric chamber and ventilated with oxygen at 1.5 atmospheres absolute pressure for 2.5 hours. Control animals were ventilated with oxygen at ambient atmospheric pressure. The time for electroencephalographic recovery was significantly shortened (P = 0.002) and the cerebrospinal fluid lactate change (2.5-hour value minus the preclamp value) was reduced (P = 0.008) in the animals receiving hyperbaric oxygen. The data indicate that hyperbaric oxygen administered after global cerebral ischemia modifies favorably both postischemic functional impairment and metabolic derangement. Possible mechanisms for the modification of postischemic encephalopathy are discussed.

Animals↗
PubMed1981

Radionuclide salivary imaging usefulness in a private otolaryngology practice.

Radionuclide salivary gland scans were performed on 44 patients using sodium pertechnetate Tc 99m. The accuracy of the scans and their usefulness in the clinical treatment of the patients were reviewed. The scan provided helpful information in 31 of 38 (82%) cases in which adequate follow-up data were available, although it proved diagnostic in only six patients. It was particularly useful in the evaluation of primary salivary gland neoplasms, acute and chronic sialadenitis, and sialolithiasis, as well as in the differential diagnosis of xerostomia. The value of this procedure in the elucidation of a variety of morphologic and functional diseases of these glands warrants its greater application in private otolaryngologic practices.

Acute Disease↗
PubMed1981

Fatal pulmonary tumor embolization following peritoneovenous shunting for malignant ascites.

A 44-year-old white male with pseudomyxoma peritonei and intractable malignant ascites is described. This patient underwent three peritoneovenous shunt procedures utilizing first the LeVeen shunt and finally the Denver shunt in a surgical attempt at palliative decompression of his malignant ascites. The peritoneovenous shunts resulted in massive tumor embolization to the pulmonary vasculature, clinically asymptomatic disseminated intravascular coagulation, and partial thrombosis of the superior vena cava. The pulmonary tumor embolization was manifest clinically as moderate pulmonary hypertension with increased pulmonary vascular resistance and persistent hypoxia.

Adenocarcinoma, Mucinous↗
PubMed1981

Further experience with the two-stage anatomic correction of simple transposition of the great arteries.

Between May 1976 and January 1981 a two-stage anatomic correction was performed in 25 patients with simple transposition of the great arteries, ranging in age from 41/2 to 46 1/2 months (mean 14.8). A first-stage operation, consisting of banding of the pulmonary artery to redevelop the left ventricle, including a Blalock-Taussig-anastomosis in 4 patients was performed prior to anatomic correction. Of 33 patients, who underwent first-stage correction there were 3 early deaths (9%). The interval between the first and second stages was 5 weeks to 9 months (mean 4.3 months). After the first-stage operation, the peak systolic left ventricular pressure rose from 34 +/- 11 mmHg to 80 +/- 16 mmHg with no significant change in enddiastolic pressure. After anatomic correction there were 5 early deaths (20%) of whom 4 were due to left heart failure. There was no correlation between death and the age of the patients at the time of anatomic correction. By our current criteria the ventricles were not adequately prepared for correction in these four patients. The coronary arteries, with different types of origin, could be reimplanted to the posterior vessels without kinking, tension or torsion in all cases. After correction, the ECG and vectorcardiogram rapidly changed toward normal. The arterial oxygen saturation was higher than 95% in all patients. Recatheterization performed in 11 patients, 3 weeks to 27 months after correction, showed normal left ventricular pressure at rest in all children, except in 2 recatheterized early after correction, who had moderately elevated left ventricular enddiastolic pressure. Right ventricular peak systolic pressure decreased to normal limits. The aortic and coronary anastomoses showed normal growth in cineangiography. Although the two-stage corrections of simple TGA may have its own problems, investigation suggests that results are encouraging.

Child, Preschool↗
PubMed1981

Recent developments in brain rehabilitation.

This paper introduces the new area of neuropsychologic rehabilitation. Procedures have been developed that can improve some verbal and nonverbal skills impaired by stroke and other brain insults. Technics are described that are now available to remediate perceptual problems such as spatial neglect, cognition difficulties, and recent memory deficits in people with brain injury.

Brain Diseases↗