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

The effects of induced hypocapnia, hypothermia, and hypertension were surveyed in a primate model of acute stroke during and following a 48-hour period of intensive care. The results were compared to a group of nine control animals previously studied. Hypocapnia (PaCO2=25 torr) was examined in five animals and did not appear to alter the expected mortality, degree of neurological deficit, or frequency of infarction. There was, however, a suggestion that the size of infarction may be reduced. Hypothermia (29 degrees C) in five animals had a detrimental effect in that no animals survived following the intensive care period and all had infarction with massive edema. We speculate that hypothermia caused a sufficient increase in blood viscosity as to compromise collateral flow, thereby accounting for this detrimental effect. Induced hypertension (to 20% above control levels) was abandoned after three animals because of severe systemic effects (cardiac failure and pulmonary edema) resulting in death during the period of intensive care.
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PMID:Failure of prolonged hypocapnia, hypothermia, or hypertension to favorably alter acute stroke in primates. 40 43

The alveolar-capillary gas metabolism was studied in 60 patients with acute myocardial infarction. Arterial hypoxemia and hypocapnia were observed in the majority of the patients. Those disturbances are more pronounced in the presence of cardiac insufficiency. The combination of shunt effect with the diminution of cardiac volume is admitted to be the possible pathogenetic mechanism for arterial hypoxemia. The first mechanism is associated with the disturbances of the systemic hemodynamics. Both types of hemodynamic disturbances are conditioned by the weakness of the left ventricle.
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PMID:[Disordered alveolar-capillary gas metabolism in the acute stage of myocardial infarct]. 69 28

The Valsalva manoeuvre was used to examine circulatory reflexes in 22 patients with acute myocardial infarction. Four patients had the 'square wave' response of cardiac failure and two responded normally to the manoeuvre. In the remaining 18 patients there was a 20 per cent or more fall in pulse pressure during the manoeuvre, but no ensuing rise in diastolic pressure, implying impairment of vasoconstriction. This impairment cannot be explained by acidosis, hypocapnia, or arterial hypoxaemia but may be explained by reflex inhibition of vasoconstriction. This abnormal response has important implications when transporting patients; furthermore, it could explain the rapid deterioration sometimes seen in patients with arrhythmias.
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PMID:Circulatory reflexes in myocardial infarction. 83 30

We conducted a retrospective analysis on 311 patients with clinical diagnosis of pulmonary embolism (PE) in a period of 3 years. 163 patients were excluded based on clinical-laboratorial criteria. The remaining 146 patients had a median age of 69 years (range: 30-91 years). 54% of the patients were male. We found dyspnea (94%), abnormal cardiopulmonary observation (89%), risk factors for venous thromboembolism (74%), tachycardia (53%), cyanosis (49%), and neck vein distension (45%) to be the most frequent findings. 64% of the patients had heart failure, 32% had myocardial ischemia, 13% had cancer, and 11% had myocardial infarction. Lactic dehydrogenase (LDH) was higher than two-fold in 54% of the patients. There was severe hypoxemia in 55% of the cases and hypocapnia in 43% of the cases. Creatinine phosphokinase (CPK) was elevated in 16% of the cases. Electrocardiography was suggestive of PE in 37% of the cases. Echocardiography showed right heart dysfunction in 30% of the cases, 92% of the patients were treated with heparin, 37 patients (25%) died, 54% of which during the first 4 days after admittance. Trying to define an index of mortality in PE we evaluated all patients by discriminant analysis coming up with 14 items with good discriminative power. By approximation of their odds-ratios we determined how many points would correspond to each item in the total sum.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Pulmonary embolism--mortality risk]. 147 67

The cardiorespiratory responses to exercise and forced hyperventilation were measured in 17 unselected patients with syndrome X (angina, positive exercise test, normal coronary arteriogram, no other cardiovascular disease) and compared with those in 15 healthy subjects. Forced hyperventilation produced hypocapnia and metabolic alkalosis but no chest pain or electrocardiographic change. Patients with syndrome X showed reduced maximum oxygen consumption with an increased respiratory exchange ratio at peak exercise, confirming that exercise was limited by skeletal muscle perfusion--and thus that the increase in cardiac output with exercise is limited in syndrome X as in heart failure. Arterial carbon dioxide tension (PCO2) homoeostasis during exercise was normal but the ventilatory cost of carbon dioxide excretion was increased in syndrome X (as in heart failure). End tidal PCO2 measurements correlated only poorly with arterial PCO2 in individual patients with syndrome X, providing a possible explanation for previous reports, based on end tidal PCO2 of inappropriate hyperventilation. Patients with syndrome X did not show inappropriate hyperventilation but they did show hyperventilation that was appropriate to maintain normal arterial PCO2 in the face of reduced cardiac reserve.
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PMID:Syndrome X and hyperventilation. 193 59

The effects of "hypocirculation" and "hypercirculation" of the lungs are small. Hypocirculation has an influence of the ventilation/perfusion ratio, and can thus contribute to hypocapnia. In the early stages, hypercirculation--in particular via a left-to-right shung, leads to an increase in diffusion capacity; after a course of many years, a "counter-situation" occurs. Progressive pulmonary hypertension, as is exemplified for mitral stenosis, leads to measurable restrictive and obstructive impairment of function, and possible to unspecific hyper-reaction, as also, over the long-term, to a diminishement in membrane diffusion capacity. Chronic left heart failure is characterised by interstitial oedema at the level of the alveolar and bronchial capillary beds. The results are measurable restrictions in the static volumes, and in particular of the obstruction parameters and the closing volume that involve the small airways. In the individual case, no statement as to the extent of left heart failure is possible. In the passive pulmonary hypertension phase, diffusion capacity increases; in the further course of the disease, with development of interstitial and alveolar oedema, it decreases again. In acute left heart failure, the persistance and/or extent of pulmonary oedema is not determined solely by the magnitude of the pulmonary venous pressure. Permeability oedema--brought about by mediators--would appear to be significant on the basis of animal experiments. Not infrequently, left cardiac failure leads to small pleural effusions which occur in combination with substantial atelectasia, the aetiology of which is unclear. Interpretation difficulties are caused by the clinical findings and function-analytical data obtained in patients with a combination of chronic lung disease and reducted volume storage capacity of the pulmonary circulation and of the left heart failure, a common situation in the elderly patient. Diminished pulmonary function parameters that fail to adequate respond to bronchodilators may be an expression of left ventricular failure.
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PMID:[The lung in heart diseases]. 219 2

The present study was undertaken to examine the effects of changes in PaCO2 and pHa on myocardial blood flow and central hemodynamics during acute ischemic left ventricular failure. Six closed-chest dogs anesthetized with pentobarbital were hyperventilated, and CO2 was added to the inspiratory gas to induce: a) normocapnia, b) hypocapnia, c) hypercapnia, and d) hypercapnia with sodium carbonate given to correct pH. Embolization of the left coronary artery with 50-microns microspheres resulted in deterioration of left ventricular function, as indicated by increased left ventricular end-diastolic pressure and mean pulmonary arterial pressure, while cardiac output decreased. During hypocapnia with left ventricular failure, the central hemodynamics remained unchanged, while a minor but nonsignificant decrease in myocardial blood flow was observed. Hypercapnia aggravated the heart failure, as indicated by increased left ventricular end-diastolic pressure, mean right atrial pressure, and mean pulmonary arterial pressure; however, the pump function of the heart was unchanged, as demonstrated by the unaltered cardiac output, heart rate, and mean aortic blood pressure. The changes in the central hemodynamics were reversed when pH was normalized during hypercapnia. Thus, in the present study pH, and not PaCO2, was responsible for the hemodynamic deterioration observed during hypercapnia in the failing heart.
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PMID:Effects of carbon dioxide and pH on myocardial function in dogs with acute left ventricular failure. 311 92

Changes in the duration and size of the vulnerable period of the myocardium in the presence of respiratory changes were studied in acute experiments on rats. The limits of the vulnerable period were determined by directly stimulating the heart during ventilation via the enlarged respiratory dead space, during hyperventilation and during heart failure. In the control group (normal ventilation without enlargement of the dead space), the vulnerable period lasted 5.7 +/- 0.76 ms. During ventilation via the enlarged dead space, hypercapnic hypoxaemia developed and the vulnerable period was markedly prolonged (18.55 +/- 5.29 ms) by a shift of its inner limit to the left. Hyperventilation caused normoxic to hyperoxic hypocapnia and markedly reduced the duration of the vulnerable period (8.17 +/- 2.21 and 9.31 +/- 2.38 ms respectively). The vulnerable period lengthened the most in heart failure (25.46 +/- 3.93), mainly as a result of a shift of its outer limit. In all the experimental groups there was a shift of the vulnerable period to the right, which was fastest in hypercapnic hypoxaemia and slowest in hyperoxic hypocapnia. The administration of Inderal (3 mg/kg i.p.) or Arfonad (50 mg/kg i.p.) markedly shortened the vulnerable period during hypercapnic hypoxaemia (9.87 +/- 2.78 and 9.32 +/- 2.16 ms respectively), but did not block the shift. Lengthening of the vulnerable period during hypercapnic hypoxaemia was probably due to activation of sympathetic nerves via beta-adrenergic receptors.
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PMID:Changes in the vulnerable period of the rat myocardium during hypoxia, hyperventilation and heart failure. 643 69

A patient with pronounced dyspnoea and cyanosis was found to have severe hypoxaemia with normal spirographic values. His past history included arterial hypertension, myocardial infarction and phlebitis of the lower limb. Airways resistance was normal, but maximal expiratory flow rates at low lung volume (Flow-volume curves) were reduced, suggesting "peripheral" airways obstruction. This was confirmed by the presence of pulmonary hyperinflation and mechanical non-homogeneity accompanied by unevenly distributed ventilation, as shown by alveolar nitrogen gradient. There was marked hyperventilation with hypocapnia. Since transfer values (measured by the CO single-breath method) and lung distensibility values were normal, emphysema could be ruled out as a cause of obstruction. Analysis of pressure-flow relationship confirmed that the obstruction of peripheral airways was "intrinsic" in character. It could be due to an increase in lung extravascular fluid (interstitial oedema due to left cardiac failure), or to repeated micro-emboli in the lungs, or to hypocapnia, these three mechanisms possibly being associated.
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PMID:[Peripheral airway obstruction involving cardiovascular factors. A case report (author's transl)]. 677 51

Varying degrees of respiratory distress developed in 3 dogs in which hyperadrenocorticism was diagnosed. The respiratory distress was attributed to pulmonary artery thrombosis. Radiography revealed pleural effusion, increased diameter and blunting of the pulmonary arteries, lack of perfusion of the obstructed pulmonary vasculature, and overperfusion of the unobstructed pulmonary vasculature. Thrombosis was confirmed by nonselective angiocardiography in each case. In 1 case, selective angiocardiography showed marked reduction of the transit time of contrast medium from the right atrium to the aorta. Hypertension proximal to the site of thrombosis was confirmed in 2 cases by showing increases in the right ventricular systolic pressures (80 mm of Hg in one case and 54 mm of Hg in the other case). In 3 cases, there was moderate hypoxemia with hypocapnia, suggesting a ventilation-perfusion mismatch. Clinical findings other than respiratory distress included hepatomegaly, ventral edema, orthopnea, and a jugular pulse. Pulmonary artery thrombosis, as it occurred in these 3 cases, was compared with the disease in man. It was concluded that pulmonary artery thrombosis should be suspected in cases of intractable dyspnea, right-sided heart failure of unexplained origin, and acute unexplainable death.
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PMID:Pulmonary artery thrombosis in three dogs with hyperadrenocorticism. 723 99


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