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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal osmoregulation is maintained by the proper function and interplay of factors influencing thirst, renal water metabolism, and vasopressin secretion. In pathophysiologic states, body water homeostasis is disrupted and hyponatremia ensures. Hyponatremia associated with cardiac failure, hepatic failure, respiratory failure, diabetes mellitus, the postoperative state, and other disorders is commonly found in the critical care setting. The pathophysiology, diagnosis, and treatment of hyponatremia are discussed.
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PMID:Disordered water metabolism: hyponatremia. 333 23

Arginine vasopressin levels in 17 neonates with cardiac disease were compared with control levels in 10 healthy newborn infants. Infants with congestive heart failure who were free of left ventricular outflow tract obstruction had a mean level of 80 +/- 18 pg/ml, which was significantly greater than the mean control level (p less than 0.001). Infants with congestive heart failure and left ventricular outflow tract obstruction had a mean vasopressin level of 3 +/- 0.7 pg/ml, which was lower than the mean control level of 6 +/- 0.7 pg/ml (p less than 0.05). The data suggest that impaired forward flow to high pressure sinoaortic and ventricular baroreceptors is necessary for vasopressin release in congestive heart failure. In left ventricular outflow tract obstruction with heart failure these receptors may be impaired or absent, leading to decreased vasopressin release. Low plasma arginine vasopressin may adversely affect circulatory homeostasis.
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PMID:Variable arginine vasopressin levels in neonatal congestive heart failure. 334 66

Vasopressin's role as a vasoconstrictor in chronic heart failure, was examined in rabbits with adriamycin cardiomyopathic congestive heart failure. Chronic adriamycin treatment resulted in a decrease in cardiac output (829 +/- 38-610 +/- 36 ml/min, P less than 0.005) and blood pressure (83 +/- 2-76 +/- 3 mmHg, P less than 0.01), and an increase in peripheral resistance (8,377 +/- 381-10,170 +/- 657 dyn-s-cm-5, P less than 0.05). Plasma renin activity (4.7 +/- 0.6-10.9 +/- 2.8 ng angiotensin I/ml X h) and norepinephrine (0.7 +/- 0.1-1.3 +/- 0.2 pmol/ml, P less than 0.05) increased while plasma vasopressin levels did not change. Vasopressin infusion, however, produced significantly greater increases in peripheral resistance in animals with heart failure than in controls. Moreover, a specific vasopressin vascular antagonist reduced blood pressure (7 +/- 3%) and peripheral resistance (14 +/- 4%) and increased cardiac output (10 +/- 3%) in animals with heart failure but had no cardiovascular effects in normal rabbits. These results suggest that vascular sensitivity to vasopressin is increased in heart failure, and that it contributes significantly to the increased afterload in heart failure despite normal plasma levels. In this model of severe, chronic heart failure the sympathetic, renin-angiotensin, and vasopressin systems all appear to be activated.
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PMID:Vasoconstrictor role for vasopressin in experimental heart failure in the rabbit. 352 20

Neurohumoral factors were assessed in 14 subjects with chronic, stable New York Heart Association functional class II or III congestive heart failure and nine comparably aged normal subjects at rest and during moderate (50 W) and strenuous (100 W) upright exercise. Heart failure was associated with elevated plasma renin activity and plasma antidiuretic hormone (ADH) concentrations at rest. However, plasma renin activity almost doubled (from 4.7 +/- 0.6 to 8.4 +/- 1.1 ng/ml per hour) during strenuous exercise in subjects with heart failure, and changed only minimally in normal control subjects. Plasma ADH concentration did not change during exercise in the presence of heart failure, but rose in normal subjects during strenuous exercise to levels comparable to those of subjects with heart failure. Similar plasma osmolality values were present in both groups. Circulating norepinephrine concentrations were insignificantly elevated by heart failure both at rest and during exercise, and plasma epinephrine concentrations were similar. These findings suggest independent neurohumoral activation during exercise in the presence of congestive heart failure, with predominant activation of the renin-angiotensin-aldosterone axis.
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PMID:Neurohumoral activation during exercise in congestive heart failure. 353 88

Mechanically and chemically sensitive receptors in the ventricle have been described histologically and electrophysiologically. Early experiments documented the hypotension and bradycardia that resulted from the intracoronary administration of one of the veratrum alkaloids (the Bezold-Jarisch reflex). Mechanical distension of the ventricles also results in a reflex decrease in heart rate and a reduction in peripheral resistance. Skeletal muscle and coronary vascular resistance appear to be most prominently affected by stimulation of ventricular receptors. Coronary ischemia has also been shown to evoke reflex effects which are attributable to stimulation of ventricular receptors. The resultant bradycardia can be especially ominous in acute myocardial infarction. Changes in myocardial inotropic state have been shown to alter ventricular receptor discharge in experimental animals. This stimulus may evoke reflex changes in peripheral hemodynamics. A variety of humoral substances can alter ventricular receptor discharge and evoke Bezold-Jarisch like responses. These include bradykinin and prostaglandins. PGI2, when given intracoronary in small doses or intravenously in larger doses will lower blood pressure while inhibiting the baroreflex induced tachycardia. It has also been shown in some experiments that PGI2 and arachidonic acid can evoke overt bradycardia and hypotension via a reflex mechanism. The role of prostaglandins in cardiovascular reflex control may be important in pathophysiologic states such as coronary ischemia and heart failure. Ventricular receptors can interact centrally with the arterial baroreceptors to attenuate the baroreflex control of both heart rate and peripheral resistance. Finally, the stimulation of ventricular receptors can alter a variety of humoral substances which are important regulators of cardiovascular and fluid volume homeostasis. These include vasopressin, renin and catecholamines. Those studies which have been done within the last 10 years or so, especially in unanesthetized animals, have demonstrated that the Bezold-Jarisch reflex is more important to cardiovascular control than previously thought. Future work will be necessary to determine the precise role ventricular receptors play in various pathological situations.
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PMID:Left ventricular receptors: physiological controllers or pathological curiosities? 354 77

Chronic administration of intravenous adriamycin (1 mg . kg-1 twice weekly for 8 weeks) to rabbits resulted in a cardiomyopathy which was similar to that occurring in patients with adriamycin cardiotoxicity. We studied systemic and renal haemodynamics and the activation of vasoconstrictor mechanisms reflected by changes in plasma renin activity (PRA), noradrenaline (NA) and vasopressin (AVP) levels during the development of heart failure in this animal model. By 8 weeks cardiac failure was clearly established. At postmortem all animals had dilated hearts, pleural and pericardial effusions, ascites and hepatic congestion. Heart weights were increased (8.1 +/- 0.7 g in treated animals n = 9 vs 6.0 +/- 0.2 g in controls n = 9 p less than 0.05). Cardiac output (measured by thermodilution) fell at 8 weeks from 799 +/- 61 ml . min-1 to 624 +/- 44 ml . min-1 (n = 6 p less than 0.05) with a parallel fall in mean blood pressure from 85 +/- 2 mmHg to 75 +/- 4 mmHg. Total peripheral resistance rose in four of the six rabbits. Renal blood flow fell from 108 +/- 4 ml . min-1 to 61 +/- 6 ml . min-1 (p less than 0.05) by 8 weeks. Renal vascular resistance increased in all animals. PRA increased from 5.1 +/- 0.5 ng AI . ml-1 . h-1 to 11.6 +/- 2.6 ng AI . ml-1 . h-1 by 4 weeks (p less than 0.05) and remained elevated thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adriamycin cardiomyopathy in the rabbit: an animal model of low output cardiac failure with activation of vasoconstrictor mechanisms. 401 15

Hamsters of the BIO 14.6 strain characteristically develop cardiomyopathy as they age, and hamsters of this strain have overt signs of heart failure by 11 months of age. Plasma levels of the posterior pituitary hormone arginine-vasopressin (AVP) were found to be elevated (approximately 2-fold) in 11 month old BIO 14.6 hamsters, compared to age-matched hamsters of a control strain. AVP appeared inappropriately elevated in these animals, since they were neither hyperosmotic nor markedly hypotensive. The elevated levels of AVP observed in these animals appears to contribute to vasomotor tone, since intravenous administration of a specific antagonist of the vasoconstrictor action of AVP [d(CH2)5Ome(TYR)AVP] elicited a fall in arterial pressure (9 +/- 2 mm Hg, n = 6, p less than 0.05). The AVP antagonist had no effect on arterial pressure in hamsters of a control strain, and vehicle administration had no effect on arterial pressure in either strain. These data indicate that inappropriately elevated levels of AVP contribute to the cardiovascular state of myopathic hamsters. Since elevated plasma AVP has been noted in human congestive heart failure, these results suggest that AVP may contribute to the cardiovascular status during congestive heart failure.
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PMID:Elevated plasma vasopressin in cardiomyopathic hamsters. 406 3

1. Study of the delayed responses to lethal doses of endotoxin in cats is complicated by acute pulmonary vasoconstriction which results in hypotension, cardiac failure and pulmonary oedema. This acute response is abolished if the animal is pretreated with aspirin (10-100 mg/kg). In these cats, pretreated with aspirin, arterial pressure and right atrial pressure remain unchanged in the first 2 h after administration of endotoxin. Later, arterial pressure falls and the animals die but no haemorrhagic lung lesions are visible.2. These results confirm our previous conclusion that the delayed lethal response to endotoxin is an independent action and not a secondary consequence of the acute response. The mechanism of the action of aspirin is discussed and it is suggested that it prevents the release by endotoxin of vasoactive substances, possibly from platelets.3. In cats pretreated with aspirin, administration of endotoxin results in a marked mesenteric vasoconstriction. Although arterial pressure does not decrease significantly, superior mesenteric arterial flow decreases to 20% of control in the first hour after endotoxin and remains at this low level until the animal dies. Mesenteric ischaemia may contribute to the cat's death.4. The mesenteric vasoconstriction is not reduced by prior administration of phenoxybenzamine and is only slightly reduced after phenoxybenzamine, hypophysectomy and nephrectomy. It is concluded that catecholamines, vasopressin and angiotensin play at most a minor role in the mechanism of this vasoconstriction and that other unknown factors are predominant.
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PMID:Mesenteric vasoconstriction after endotoxin administration in cats pretreated with aspirin. 433 2

Persistent secretion of vasopressin and/ or diminished distal fluid delivery have been proposed to explain the impaired water excretion associated with low-output cardiac failure. In the present investigation cardiac output (CO) was diminished in anesthetized dogs undergoing a water diuresis by constriction of the thoracic inferior vena cava (TIVC). In intact animals (group I) acute TIVC constriction decreased CO from 3.5 to 2.2 liters/min (P < 0.005) as urinary osmolality (U(osm)) increased from 103 to 543 mosmols/ kg (P < 0.001) and free water clearance (C(H2o)) decreased from 2.1 to -0.6 ml/min (P < 0.001). This antidiuretic effect was disassociated from changes in renal arterial and venous pressures, glomerular filtration rate, solute excretion, and renal innervation. To examine the role of vasopressin in this antidiuresis, studies (group II) were performed in acutely hypophysectomized, steroid-replaced animals. In these animals TIVC constriction decreased CO to a similar degree from 3.4 to 2.1 liters/min (P < 0.001). However, the effects on U(osm) (87-104 mosmols/kg) and C(H2o) (2.1-1.6 ml/min) were significantly less than in intact dogs. In another group of hypophysectomized animals, (group III) renal arterial and venous pressures were not controlled, and the effect of TIVC constriction on U(osm) was not significant (65-79 mosmols/kg) although C(H2o) decreased from 3.3 to 1.9 ml/min (P < 0.001). In both the group II and III studies, there were linear correlations between the changes in C(H2o) and the urine flow. Studies were also performed in baroreceptor-denervated animals with intact hypothalamo-neurohypophyseal tracts, and acute TIVC constriction altered neither U(osm) nor C(H2o) when renal arterial pressure was controlled. These results therefore indicate that the effect of TIVC constriction on U(osm) is primarily vasopressin mediated while the effect on C(H2o) is mediated both by vasopressin release and diminished distal fluid delivery. A decrease in renal arterial pressure, or some consequence thereof, seems to be an important determinant of the latter effect.
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PMID:Mechanism of effect of thoracic inferior vena cava constriction on renal water excretion. 443 43

To define the short-term haemodynamic, hormonal and electrolyte effects of enalapril in chronic heart failure, we administered it to nine patients. The first dose (5 mg) induced a gradual reduction in plasma angiotensin II, systemic vascular resistance, arterial pressure, heart rate and right heart pressures, the maximum effects occurring within 4-8 h. Angiotensin II levels were still suppressed 24 h after the initial dose, but haemodynamic indices had returned almost to control values by this time. Dose-related increases in cardiac index and plasma renin, and decreases in angiotensin II, systemic vascular resistance and urine aldosterone excretion were seen with 5, 10 and 20 mg enalapril. Cumulative balances for sodium and potassium were positive, plasma potassium increased and plasma antidiuretic hormone fell. After 4-8 weeks of enalapril therapy, clinical status and exercise tolerance improved in the patients who were most severely restricted initially. Enalapril may be useful in the treatment of chronic heart failure.
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PMID:Acute haemodynamic, hormonal and electrolyte effects and short-term clinical response to enalapril in heart failure. 610 Jun 4


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