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Biomedical subjects

N S Talner

Publications and source records attributed to N S Talner.

72 records · Page 4Linked to original sources
PubMed1968

Vasomotor responses in the hind limbs of foetal and new-born lambs to asphyxia and aortic chemoreceptor stimulation.

1. Hind limb blood flow was measured in lambs of from 91 days gestation (delivered by Caesarean section) to 1 month after birth (term is about 147 days), under chloralose anaesthesia. Vascular resistance/100 g wet wt. increased progressively with age. There was reflex femoral vascular tone from the earliest age studied, as shown by vasodilatation on cutting the sciatic nerve.2. On asphyxia by cord occlusion reflex femoral vasoconstriction began earlier and was somewhat greater in older foetal lambs. At all ages, and after denervation of the hind limb, there was vasodilatation after local ischaemia, and a vasoconstriction of delayed onset during asphyxia attributed to release of noradrenaline into the circulation. The vasoconstrictor effect of noradrenaline in immature lambs was at least as great as at term or in the new-born.3. Injections of minimal effective doses of cyanide were used to localize possible chemoreceptor sites in foetal lambs. Injection into the left atrium caused a rise of arterial pressure, femoral vasoconstriction and a complex change in heart rate (usually bradycardia) but rarely any respiratory movement. After atropine, cyanide caused a large tachycardia. All responses were much reduced or abolished by cervical vagotomy.4. Injection of the same doses of cyanide into a jugular vein, the right ventricle, pulmonary or common carotid arteries of foetal lambs caused negligible cardiovascular or respiratory effects, whereas injection into the carotids of new-born lambs caused a profound hyperpnoea.5. It is concluded that the aortic chemoreceptors are active in the foetus, are supplied from the left heart, and that they probably represent the primary defence in blood gas homeostasis by their effects on the circulation.

Acetylcholine↗
PubMedDate not supplied

Fetal echocardiography--applications and limitations.

Fetal echocardiography has been a useful technique for demonstrating the anatomy of the developing human heart. M-mode echocardiography may be used to provide rhythm diagnosis in the absence of high-fidelity transabdominal fetal electrocardiograms. The information so generated may be applied to plan the management of pregnancy and delivery in a population at "high risk" for structural or functional heart disease and may provide the impetus for developing in utero treatment programs. For this reason, a high degree of sensitivity and specificity must be asked of the technique and of the personnel performing the examination. "Major" malformations which impart marked hemodynamic and structural alterations on the fetal heart may be reliably diagnosed. Diseases which must be identified on the basis of direct recognition of subtle abnormalities of structure, with little impact on fetal flow patterns (e.g. mild semilunar valve stenosis of perimembranous ventricular septal defect) have been more problematic. Before effective screening and treatment programs for the fetal heart can be developed, a cooperative effort between cardiologists and perinatologists is essential in order to gain facility with imaging as well as familiarity with the natural history of these conditions.

Echocardiography↗
PubMedDate not supplied

Chest pain in the adolescent and young adult.

Pediatric cardiologists and cardiologists who examine adults frequently receive referrals of adolescents and young adults with chest pain. Chest pain in this age group is most likely noncardiac in origin, which often creates a diagnostic dilemma for the consultant in terms of the etiology and extent of evaluation. This review presents the noncardiac and cardiac etiologies of chest pain in adolescents and young adults, as well as the key features of a patient's history and physical examination that help delineate cardiac from noncardiac chest pain. In addition, we present recommendations for the cardiac consultant regarding the evaluation and management of adolescents and young adults referred with the complaint of chest pain.

Adolescent↗