pituitrin and Mitral-Valve-Stenosis

Recent work has clarified the relationship between stimulation of left atrial receptors and plasma vasopressin concentration (pAVP) and has allowed a rational explanation of a number of previously anomalous findings. There is now good evidence that mitral obstruction causes a decrease in pAVP and that the decreases in pAVP can occur within a normal range of pAVP in anaesthetized and unanaesthetized animals. A stimulus which is localised to the left atrial receptors also causes a decrease in pAVP and it is likely that this is due to stimulation of the complex unencapsulated endings in the atrium, with myelinated afferent fibres. Evidence is lacking that changes in the stimulus to ventricular receptors or to cardio-pulmonary receptors with C-fibre afferents influences pAVP. The diuretic response to left atrial distension is two-fold, an increase in free water clearance and a natriuresis. The increase in free water clearance is due to the decrease in pAVP; the cause of the natriuresis is unknown. The changes in pAVP occur rapidly in response to atrial distension (within 5 min). The stimulus provided to atrial receptors by atrial distension and the decrease in pAVP is maintained for at least 90 min. pAVP is also modulated in response to small changes in blood volume (+/- 10%). The changes in pAVP that occur over this range of blood volume are likely to be in the range of 1-10 pg/ml and to have their effects on renal water excretion rather than on vascular resistance. The much larger changes in pAVP which occur with greater degrees of blood loss, and which can affect vascular resistance are likely to be produced by changes in the stimulus to other receptors, but a low input from atrial receptors may be permissive for these stimuli to be effective. More work is needed to clarify the relationship between inputs from different receptor types.

Topics: Animals; Blood Volume; Diuresis; Dogs; Heart Atria; Mitral Valve Stenosis; Natriuresis; Pressoreceptors; Pulmonary Circulation; Time Factors; Urine; Vascular Resistance; Vasopressins

Seventy four patients aged 35-74 years who had mitral valvular disease were examined for renin, angiotensin II, aldosterone, and vasopressin, of whom 49 patients were diagnosed as having a mitral valve defect with prevalent stenosis, 25 presented with a mitral valve defect with prevalent heart failure. Circulatory disorders, Stages I-II, were found in 41 patients, Stage IIB in 23, and Stage III in 10 patients. There were no significant differences in the parameters of the renin-angiotensin-aldosterone system (RAAS) and vasopressin in untreated adult and elderly patients with mitral valvular disease at rest. As circulatory disorders progressed, the RAAS parameters significantly increased in all the groups. However, the patients with prevalent stenosis showed higher blood renin levels than did those with prevalent heart failure, irrespective of its severity. In refractory heart failure, the significant differences remained to a greater extent only for renin. The treatment with peripheral vasodilators (isosorbide dinitrate and corinfar) resulted in compensatory activation of the neurohumoral vasoconstrictive system, thereafter the RAAS parameters significantly increased after the drugs.

Topics: Adult; Age Factors; Aged; Hemodynamics; Humans; Middle Aged; Mitral Valve Insufficiency; Mitral Valve Stenosis; Renin-Angiotensin System; Vasopressins

We compared plasma ANP concentration and atrial content of ANP as well as plasma concentrations of other fluid regulating hormones and renal function between the MVR group (n = 12) and the non MVR group (n = 14) during open heart surgery. Preoperatively there was no significant difference in plasma ADH and ACTH between two groups, however plasma ANP was significantly higher in the MVR group (96.9 +/- 16.2 pg/ml) than in the non MVR group (22.8 +/- 8.6 pg/ml) (p less than 0.01). During extracorporeal circulation ANP was at a low level because of aortic clamping. Tissue concentration of ANP in right appendages was higher (p less than 0.02) in the MVR group (61.8 +/- 11.8 nmol/g wet weight) (n = 6) than that in the non MVR group (14.9 +/- 3.1 nmol/g wel weight) (n = 15). Also, concentration in left appendages of the MVR group (50.0 +/- 10.4 nmol/g wet weight) (n = 4) was higher than that in right appendages of the non MVR group (p less than 0.05). From these results it may be concluded that increased secretion of ANP is elicited by left atrial load and probably playing an important role on circulating blood volume regulation.

Topics: Aldosterone; Atrial Natriuretic Factor; Extracorporeal Circulation; Heart Valve Prosthesis; Humans; Kidney; Mitral Valve Insufficiency; Mitral Valve Stenosis; Vasopressins

Topics: Adult; Aged; Anesthesia, Intravenous; Cardiac Surgical Procedures; Catecholamines; Coronary Disease; Humans; Intraoperative Period; Middle Aged; Mitral Valve Stenosis; Vasopressins

1) Plasma ADH levels measured by bioassay in the group with extracorporeal circulation were 2.3 +/- 0.6 muu/ml before surgery and 6.6 +/- 1.8 muu/ml during anesthesia. They increased to 196.5 +/- 62.3 muu/ml or about 100 times greater than before surgery during cardiopulmonary bypass. 2) In the group without extracorporeal circulation, plasma ADH levels were 1.5 +/- 0.9 muu/ml before surgery and increased to 44.1 +/- 15.2 muu/ml during operation. 3) After operation decrease in plasma ADH level was relatively rapid in both groups. It became three times that of the control level in the morning of the next day. 4) Marked increase in plasma ADH level during cardiopulmonary bypass was much the same as it was during hemorrhagic shock in dog experiments. 5) Fall in mean arterial blood pressure and loss of pulsatile blood flow will play main roles in this marked increase in ADH during cardiopulmonary bypass through stimulation of arterial baroreceptors and probably chemoreceptors. 6) In two cases with mitral stenosis, increase in plasma ADH during cardiopulmonary bypass was lesser than the other heart diseases.

Topics: Adult; Animals; Cardiac Surgical Procedures; Dexamethasone; Dogs; Extracorporeal Circulation; Humans; Middle Aged; Mitral Valve Stenosis; Osmolar Concentration; Vasopressins

Topics: Animals; Blood Pressure; Cardiac Output; Disease Models, Animal; Dogs; Heart Atria; Heart Rate; Hemorrhage; Hypothalamo-Hypophyseal System; Mitral Valve Stenosis; Pressoreceptors; Vasopressins

Topics: Adult; Cardiac Surgical Procedures; Female; Heart Septal Defects; Humans; Hypotension; Hypothalamus; Mitral Valve Stenosis; Polyuria; Postoperative Complications; Vasopressins

Topics: Anesthesia; Animals; Blood Pressure; Diuresis; Dogs; Glomerular Filtration Rate; Heart Atria; Homeostasis; Kidney; Kidney Concentrating Ability; Mitral Valve Stenosis; Natriuresis; Osmolar Concentration; Osmotic Pressure; Sensory Receptor Cells; Vasopressins; Wakefulness; Water-Electrolyte Balance

Topics: Adult; Aged; Aldosterone; Arteriosclerosis; Blood Pressure; Blood Volume; Cardiac Output; Chronic Disease; Digitalis Glycosides; Diuretics; Electrocardiography; Female; Heart Diseases; Heart Failure; Humans; Hypertension; Kidney; Male; Middle Aged; Mitral Valve Insufficiency; Mitral Valve Stenosis; Regional Blood Flow; Serum Albumin, Radio-Iodinated; Vasopressins

Topics: Animals; Blood; Blood Pressure; Cardiac Surgical Procedures; Diuresis; Dogs; Female; Heart; Mitral Valve Stenosis; Sensory Receptor Cells; Urination; Vagotomy; Vasopressins