Gerhard H. Muelheims

Anomalous inferior vena cava

Abstract Eight patients have been presented with a malformation of the inferior vena cava. The prerenal portion (the portion between the kidney and right atrium) of the inferior vena cava is absent and replaced by the enlarged azygos vein, which opens into the superior vena cava at its usual position. The hepatic venous blood drains directly into the right atrium. This anomaly is referred to in the literature as “absent” inferior vena cava. The embryological development has been described and seems to indicate that the postrenal (lumbar) portion of the inferior vena cava in this entity is more likely normal. Therefore, it is suggested to abandon the term “absent” inferior vena cava in favor of anomalous inferior vena cava with a description of the specific anomaly present. The frequency of this malformation in our laboratory was 1.3 per cent and is attributed to the fact that cardiac catheterization is performed by way of the long saphenous or superficial femoral veins. The diagnosis of an anomalous inferior vena cava might be suspected when the antero-posterior roentgenogram reveals a rounded density in the right superior mediastium representing the enlarged azygos vein as it enters the superior vena cava. When during cardiac catheterization the excursions of the catheter in the area of the right atrium are restricted, an anomalous inferior vena cava should be considered, especially if the oxygen saturations remain identical in what is thought to be the inferior vena cava, right atrium and superior vena cava. The path of the catheter will usually be diagnostic since it cannot enter the right atrium without first passing downward by way of the superior vena cava. Angiocardiography will definitely reveal the presence of this malformation. Open-heart surgery for other cardiac lesions that are usually present with diversion of the venous return to a pump and oxygenator may be extremely difficult. One additional patient has been described with a normal inferior vena cava and a patent azygos vein originating at the renal level and emptying into the superior vena cava at its usual place.

Catecholamine Release After Spinal Cord Section

Summary Cervical spinal cord section causes an immediate rise in CF, MABP, and HR. The increase in these cardiovascular parameters is due to stimulation of the sympathetic nervous system, as indicated by the diminished response after treatment with sympatholytic agents, Hexameton and Guanethidine, and by the rise in blood catecholamines.

Effect of Guanethidine Therapy on Total Blood Volume in Patients With Essential Hypertension

Summary Total blood volume was determined in 5 female patients with essential arterial hypertension during and after treatment with guanethidine. Administration of the drug resulted in a decrease of arterial blood pressure and an increase in total blood volume. The increase in total blood volume was mainly due to an increase in plasma volume.

Increased sensitivity of the heart to catecholamine‐induced arrhythmias following guanethidine

Guanethidine was administered orally to normotensive subjects and the responsiveness of the cardiovascular system to a norepinephrine infusion in increasing concentrations was examined. After guanethidine the infusion of norepinephrine resulted in a higher mean arterial blood pressure and a lower heart rate; cardiac arrhythmias appeared after lower doses of norepinephrine with greater frequency and occasionally were of a type having more serious implication. The almost exclusive development of A‐V nodal beats and A‐V nodal rhythm before as well as after guanethidine suggests the importance of vagal activity reflexly produced by stimulation of the sinoaortic baroreceptors through the rise in blood pressure. However, a direct effect of guanethidine sensitizing the myocardium to norepinephrine cannot be ruled out. It seems advisable to administer norepinephrine to patients receiving guanethidine with even greater caution than usual.

Maturity of The Pituitary-Adrenal Axis in The Newborn Dog

Summary The apparent changes in steroid hormone production and release by newborn canine adrenals following the administration of appropriate agents indicate that the pituitary-adrenal axis is functional at birth in this species, rendering it capable of responding to stress. The newborn dog may be employed as a useful experimental model in exploring the endocrinologic status of the newborn.

EFFECT OF BILATERAL ADRENALECTOMY ON THE CARDIOVASCULAR RESPONSE TO INDUCED TACHYCARDIA.

Summary Relatively short bouts of electrically induced ventricular tachycardia of sufficiently high rate to result at least initially in a marked decrease in cardiac output and mean arterial blood pressure were induced in anesthetized dogs before and immediately after bilateral adrenalectomy. This study reveals that, although adrenalectomy affects the circulation under the experimental circumstances described, the degree of cardiovascular compensation in response to such bouts of tachycardia can remain relatively unaffected by bilateral adrenalectomy. Whether this remains true with bouts of higher rate tachycardia remains to be determined.

Metabolism of progesterone in the canine feto-placental unit.

Abstract Progesterone (P), a major hormone of pregnancy, was selected for study under the conditions of an intact utero-placental-fetal unit. A preparation of the canine gravid uterus, near term, is described and shown to permit observation of the metabolic relationships of the steroid hormone P between maternal and fetal organisms. [1,2-3H] P or [7α-3H]P was injected into pups, while [4-14C]P was injected into the uterine circulation. Perfusion was continued for 1 hr with excellent survival of the pups. Identified metabolites in the fetal and maternal tissues suggest a metabolic pool that is shared throughout the unit.

Adrenal response to hypophysectomy in the newborn dog.

Summary Hypophysectomy in the newborn dog results in a prompt fall in the secretory rate of cortisol during collection of adrenal effluent blood. Due to the rapid rate of clearance of ACTH, lowest secretory rates were expected at 2–5 hr after hypophysectomy but, at 16–20 hr, an even lower rate was found. This unexplained observation was significant. The procedure of hypophysectomy recommends itself as a valuable means of exploring the endocrinologic status of the newborn.

Modification of Norepinephrine Tachyphylaxis by Guanethidine.

Summary Pressor responses to repeated injections of norepinephrine were recorded in a control group of dogs and in dogs pre-treated with guanethidine. The results indicate that guanethidine maintains the pressor response of norepinephrine, i.e., delays tachyphylaxis to norepinephrine.