Left ventricular filling and stress response pattern in essential hypertension
Article Abstract:
The response of the cardiovascular system to stress is often assessed by having patients do isometric exercise or passively tilting the head up. However, patient responses to these tests are not uniform. Blood pressure increases in normal subjects by an increase in cardiac output (the volume of blood pumped), while patients with heart dysfunction who can not do so tend to increase blood pressure by increasing the resistance (constriction) of peripheral vessels. In addition, chronic hypertension may restrict the filling capacity of the left ventricle, but how these subtle changes influence response to isometric stress or head-up tilt (orthostatic stress) is unclear. These responses were studied in 32 patients (8 female), all of whom had hypertension. Of these patients, 17 had impaired left ventricular filling, established by echocardiography. Isometric stress caused a significant increase in heart rate, cardiac output, and peripheral resistance in all patients, and this was associated in an increase in blood levels of adrenaline and a related hormone (a stress response). Although blood pressure increased similarly in both groups, the group with impaired ventricular filling had only a minor increase in cardiac output and more than double the increase in peripheral resistance of the other group. The lower cardiac output was significantly associated with a lower peak filling rate of the heart and significantly higher levels of noradrenaline. Overall responses to head-up tilt were not as uniform; blood pressure was increased in 11 patients, maintained in 16 patients, and decreased in three. Cardiac output decreased significantly in all patients, due to a reduction in stroke volume, while heart rate and peripheral resistance increased significantly. Patients with impaired filling had a greater decrease in stroke volume and cardiac output and more extreme changes in peripheral resistance. The study indicates that patients with impaired left ventricular filling have altered responses to isometric and orthostatic stress testing, which take the form of increased peripheral vessel constriction and higher hormonal responses. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Pulmonary dysfunction in advanced liver disease: frequent occurrence of an abnormal diffusing capacity
Article Abstract:
Lung and breathing abnormalities are often seen in patients with severe liver disease. These include hypoxemia (decreased oxygenation of arterial blood) and restricted breathing. There are a number of possible underlying causes of these problems, yet few studies have examined lung problems found in such patients. Severe liver disease can now be treated by liver transplantation. A positive outcome requires complete evaluation of preoperative health status to determine postoperative care requirements. These evaluations include pulmonary (lung) function testing. This study examined the results of such testing in patients with liver failure to characterize the abnormalities found. The subjects examined were 116 patients suffering from liver failure who were being evaluated as candidates for liver transplantation. Results showed that 55 percent of the patients were current or former smokers. Shortness of breath (dyspnea) was reported during exercise by 39 percent, and at rest by 14 percent of the patients. The underlying liver disease varied among the subjects. Diffusing capacity for carbon monoxide (DLco; the ability of the lungs to reduce the concentration of carbon monoxide in the blood) was found to be abnormally low in many subjects, with 48 percent of nonsmokers, 71 percent of smokers, and 45 percent of former smokers having abnormally low DLco values. Restricted breathing capacities were found in a third of the subjects with abnormally low DLco values. In all, 29 subjects had restrictive abnormalities, of which 86 percent showed abnormalities on lung X-rays. The ability of the lungs to properly oxygenate the blood was impaired in 45 percent of the patients. These results indicate that patients with severe liver disease often have one or more types of lung abnormalities. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Left ventricular diastolic dysfunction and cardiovascular regulation in hypertension
Article Abstract:
Hypertension, or abnormally high blood pressure, is associated with abnormalities in the function of the left ventricle during diastole or the relaxation phase of the heart cycle. Such disorders include altered relaxation of the left ventricle muscle, early filling of the ventricle with blood, and reduced compliance, which is the ability of the volume of the ventricle to change in response to changes in pressure. Under normal conditions, a decreased pressure in the veins returning blood to the heart causes a reflexive constriction of blood vessels, in order to maintain the rate at which the heart fills with blood. However, this reflex blood vessel constriction in response to a reduced venous pressure is impaired in patients with abnormal left ventricle filling, because of the loss in sensitivity of the reflex responses of the cardiovascular system. The failure of left ventricle function during relaxation is associated with difficulty breathing and lung congestion. Other factors that may cause impaired left ventricle function include altered blood flow to the heart and changes in the calcium movements within the heart cells. The causes and consequences of decreased diastolic function of the left ventricle must be clarified in order to provide effective treatment of hypertension. The effects of various antihypertensive agents, such as methyl-dopa, hydralazine, and calcium entry blockers, on left ventricle filling are reviewed. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1989
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