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Biomedical subjects

L R Smith

Publications and source records attributed to L R Smith.

At least 181 records · Page 10Linked to original sources
PubMed1981

Midazolam versus diazepam: different effects on systemic vascular resistance. A randomized study utilizing cardiopulmonary bypass constant flow.

In 43 patients electively scheduled for myocardial revascularization surgery, a hemodynamic comparison of 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-a][1,4] benzodiazepine (midazolam, Ro 21-3981, Dormicum) and 7-chloro-1,3-dihydro-1-methyl-5-phenyl-(2H)1,4-benzodiazepin-2-one (diazepam) was made during cardiopulmonary bypass. Midazolam and diazepam were compared in patients with ischemic heart disease to determine the effects of the drugs on systemic vascular resistance at constant flow (cardiac output) and temperature. Diazepam (0.3 mg/kg) produced significantly greater decreases in perfusion pressure, systemic vascular resistance, and venous reservoir volume than did midazolam (0.2 mg/kg). It was concluded that there are subtle differences in the pharmacologic actions of both midazolam and diazepam. When used with constant flow on cardiopulmonary bypass, diazepam causes more pronounced arterial and venous dilation. These data are at variance with the findings in intact man.

Anesthetics↗
PubMed1980

Pathogenesis of paroxysmal hypertension developing during and after coronary bypass surgery: a study of hemodynamic and humoral factors.

A prospective study of hypertension first appearing during and after saphenous vein bypass coronary surgery was performed in 28 patients to examine the incidence, hemodynamics and mechanism of this problem. In 15 patients (54 percent) new hypertension developed (mean arterial pressure greater than 107 mm Hg), characterized by increased peripheral vascular resistance and unchanged cardiac output within 1 hour after surgery. These 15 patients had a longer history of angina of greater severity, but also had relatively well preserved ventricular myocardium. Because plasma renin activity was depressed in patients in the hypertensive group, activation of the renin-angiotensin system was not important in the pathogenesis of this postoperative hypertension. The expected decrease in total peripheral resistance at the onset of cardiopulmonary bypass was observed in all patients, but later during bypass the peripheral resistance increased in all patients in association with a rise in plasma epinephrine levels. Patients who had hypertension postoperatively had a greater increase in arterial pressure and total peripheral resistance during cardiopulmonary bypass than did those with normal postoperative blood pressure. An elevation in plasma epinephrine and norepinephrine concentration, suggesting enhanced sympathoadrenal responsiveness to the challenge of cardiopulmonary bypass, was characteristic of the hypertensive group. This evidence of enhanced sympathetic activity during surgery may be a useful predictor of the development of postoperative hypertension.

Blood Pressure↗
PubMed1980

Lymphangitis of the anterior chest wall.

Lymphangitis of the anterior chest wall in children is an unusual finding and may be a diagnostic enigma. The following case report describes a five year old boy who presented with this condition. The diagnosis was somewhat elusive until a history of an antecedent insect bite was obtained. Lymphangitis should therefore be considered in the differential diagnosis when perplexing erythematous chest wall lesions are present in children.

Child, Preschool↗
PubMed1980

[Coronary morphology in patients with unstable angina pectoris. Quantitative analysis of coronary angiograms before and after one year of medical treatment (author's transl)].

The purpose of this study was to quantify coronary morphology under medical therapy in patients with initially unstable angina pectoris (Propranolol, long-term nitrates). In 25 patients the extent of 69 coronary stenoses was exactly quantified with a vernier caliper (accuracy: 0.05 mm) in two successive coronary angiograms performed in each patient at approximately one year interval. The validity of the measuring technique was assessed in nine hearts in which 19 coronary stenoses were measured in the intravital coronary angiogram and then compared with the post mortem planimetric measurements of the same cross-sections after pressure fixation. This relation yielded a correlation coefficient of r = 0.87. In the patients with initially unstable angina the average degree of the stenoses in the three major coronary branches did not change significantly over the one year interval: In 27 stenoses of the right coronary artery the mean degree of obstruction averaged 79% in the initial angiogram and 84% in the second angiogram. In 26 stenoses of the left anterior descending artery the degree of obstruction was 78% and 77%, respectively and in 16 stenoses of the left circumflex artery 73% and 83%, respectively. Only 14 out of 69 stenoses (= 20%) showed a distinct progression of more than 20% area obstruction. All stenoses of 90% or more in the first angiogram (n = 6) progressed to complete obstruction within one year. In contrast, in five other stenoses we measured a regression in the degree of obstruction of more than 20%. We conclude from these quantitative measurements that the severity and the distribution of coronary lesions are similar in patients with stable or unstable angina pectoris. Coronary anatomy showed no significant change after one year of medical treatment in patients with unstable angina.

Angina Pectoris↗
PubMed1979

Effect of filming projection and interobserver variability on angiographic biplane left ventricular volume determination.

Although biplane right anterior oblique-left anterior oblique (RAO/LAO) quantitative left ventricular (LV) angiography is commonly performed, justification of LV volume calculation using the area length method (originally formulated from anteroposterior-lateral (AP/LAT) angiograms) has been limited. To assess whether RAO/LAO and AP/LAT LV volumes are similar when computed by the area length method formula, we performed biplane cine LV angiography in both RAO/LAO and AP/LAT projections in random sequence in 21 patients and four LV models of known volume. LV silhouettes were drawn independently by two trained observers. Calculated angiographic volume of the models correlated almost exactly with their true volume (r = 0.999), establishing the absolute accuracy of this system. Rotation of the LV models through 90 degrees of obliquity at 10 degree increments demonstrated a mean change from true volume of only -5.4 +/- 0.7% (p less than 0.001). In the patient studies, rotation to the 30 degree RAO/60 degree LAO position was associated with significant changes in magnitude of biplane areas and long axes, but area length volume estimates were unchanged. Excellent correlation was found between area length calculated AP/LAT and RAO/LAO volumes with r = 0.90, 0.97, and 0.91 for end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF), respectively. Furthermore, interobserver agreement in volume assessment was excellent, with r = 0.98, 0.99, and 0.94 between observers for EDV, ESV, and EF, respectively. Interobserver and inter-method variability for estimates of LV volume and EF ranged from 5--10%. We conclude that when using RAO/LAO LV angiography, volume calculation by the area length method is justified.

Angiocardiography↗
PubMed1979

Perifollicular fibroma.

Perifollicular fibroma is a very unusual lesion and infrequently seen. The present report describes a thirty-two year old white man with unusual manifestations of this condition which usually presents as a small number of lesions on the head and neck, most often in adults. It has a characteristic pathologic picture of perifollicular fibrosis. The origin of this lesion is uncertain, but most probably represents a tumor of the connective tissue sheath of the follicle.

Adult↗
PubMed1978

Changes in left ventricular segmental wall motion following randomization to medicine or surgery in patients with unstable angina.

Twenty-six patients with unstable angina pectoris had biplane left ventricular (LV) angiograms and coronary arteriograms (CAGs) initially and at a median of 1 year following randomization to medical (15 patients) or surgical 11 patients) therapy. Left ventricular segmental wall motion was analyzed by a digital computer yielding segmental ejection fraction for 10 zones along the LV perimeter. Baseline and follow-up CAGs were analyzed simultaneously by one observer, and changes in LV segmental coronary perfusion were estimated. Left ventricular angiograms were analyzed separately from CAGs and independently of knowledge of changes in estimated segmental coronary perfusion. Left ventricular segmental wall motion was more frequently improved in surgical patients than in medical patients. Furthermore, in surgical patients there was a significant correlation between changes in LV segmental wall motion and perfusion to LV segments supplied by the left anterior descending coronary artery, whereas no such correlation for any segment was found in the medical group. Thus, this prospective randomized study suggests that, in patients with unstable angina, coronary revascularization may significantly improve LV segmental wall motion compared to medically treated patients. In the surgical group, improvement in LV wall motion relates to improvement in coronary perfusion to the segments supplied by the left anterior descending artery.

Adult↗
PubMed1977

Correlation of angiographic estimates of myocardial infarct size and accumulated release of creatine kinase MB isoenzyme in man.

Accumulated creatine kinase MB isoenzyme release (sigma CK-MB) during acute myocardial infarction was correlated with biplane left ventricular (LV) angiographic estimates of percent abnormally contracting segment (%ACS) and ejection fraction (EF) in 35 patients who underwent diagnostic angiography at a mean of 33 +/- 4 days post myocardial infarction (MI). Of the 35 patients, 18 had no evidence of prior MI and their sigma CK-MB showed good correlation with %ACS (r = 0.84) and with EF (r = - 0.78). An additional two patients with first (inferior) infarct secondary to stenosis of the right coronary artery proximal to the origin of the right ventricular arterial blood supply had disproportionately large sigma CK-MB, suggesting a combination of LV and RV necrosis. In the 15 patients with prior infarct, there was no significant correlation between sigma CK-MB and %ACS or EF. However, in the subgroup of patients with anterior MI, %ACS correlated with sigma CK-MB, both in patients with no prior MI (r = 0.88, N = 12) and in patients with prior MI (r = 0.69, N = 9). These independent angiographic and enzymatic data suggest that enzymatic infarct size estimates utilizing accumulated CK-MB release may be a valid and reliable clinical measure for assessing the extent of LV necrosis in the setting of acute anterior myocardial infarction. However, limitations may exists in certain cases of inferior MI, probably because of concomitant right and left ventricle necrosis.

Angiocardiography↗
PubMed1976

Erythema chronicum migrans.

Erythema chronicum migrans is characterized by an expanding erythematous band about an arthropod bite. While rare, it is an important disease to recognize because of its rapid response to even modest doses of antibiotics. This response and the association with arthropod bites suggest a microbial vector. Richettsial titers have been demonstrated in several cases but we were unable to show them in our patient, who we believe is the second reported case of erythema chronicum migrans incurred by an American without traveling abroad.

Adult↗
PubMed1975

Skin changes secondary to hydroxyurea therapy.

Hydroxyurea is an effective agent in the treatment of chronic myelogenous leukemia. The toxic reactions have included myelosuppression and megaloblastosis. During long-term maintenance therapy, dermatologic alterations occurred in seven of 20 patients and consisted of partial alopecia, increased pigmentation, scalings, atrophy of the skin and subcutaneous tissues, nail changes, and erythema of the face and hands. The histologic changes were similar to those seen in lichen planus. These observations were a factor leading to the use of hydroxyurea in the treatment of psoriasis.

Administration, Oral↗