Biomedical subjects

P Carlens

Publications and source records attributed to P Carlens.

10 recordsLinked to original sources

PubMed1991

Effects of exercise on the displacement of the atrioventricular plane in patients with coronary artery disease. A new echocardiographic method of detecting reversible myocardial ischaemia.

The effect of exercise on the displacement of the atrioventricular (AV) plane was studied by echocardiography (echo) in 48 patients with stable angina pectoris without prior myocardial infarction and 20 age-matched healthy subjects. Echo was performed at rest, immediately after and 10 and 30 min after the test. The patients also underwent thallium stress scintigraphy and coronary angiography. From the apical four- and two-chamber views, the atrioventricular plane displacement (AVPD) during the cardiac cycle was recorded at four sites corresponding to the septal, anterior, lateral and posterior walls of the left ventricle and a mean value was calculated (AV-mean). The healthy subjects and patients had almost the same AVPD at all the sites at rest (AV-mean of 14.5 and 14.2 mm respectively). Immediately post-exercise the healthy subjects showed a significant (P less than 0.001) and equally distributed increase in the AVPD at all the sites with an AV-mean value of 19.2 mm. In most of the patients with angiographically confirmed coronary artery disease (CAD), there was a reversible decrease of AVPD (greater than or equal to 3 mm) at one or more of the AV plane sites. The overall sensitivity and specificity were 80% and 100% respectively in identifying CAD patients. The changes correlated well with the reversible ischaemic changes on the thallium scan (sensitivity, 88%, and specificity, 83%). A generalized exercise-induced decrease in AVPD at all the recorded sites had a high specificity (91%) in detecting patients with three-vessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Atrial natriuretic peptide during acute treatment of congestive heart failure.

Atrial natriuretic peptide (ANP) induces potent diuretic/natriuretic, vasorelaxing and aldosterone inhibitory effects. Increased plasma levels in congestive heart failure (CHF) have been reported. The aim of this study was to investigate plasma immunoreactive ANP (ir-ANP) levels during acute treatment of CHF. Seven patients with CHF underwent cardiac catheterization. Ir-ANP plasma levels were followed up to two h after administration of an orally given phosphodiesterase inhibitor (Milrinone); a substance with positive inotropic and peripheral vasodilating properties. In all patients cardiac output increased and cardiac filling pressures decreased markedly. Initially high ir-ANP plasma levels decreased. Our patients did not have an increased blood volume. It is concluded that plasma ir-ANP levels in the pulmonary artery rapidly decrease when atrial pressure is reduced. These data suggest that atrial pressure is the major determinant for release of ir-ANP in man and that the ability to respond quickly to changes in cardiac filling pressures is maintained in patients with severe CHF. Plasma ir-ANP levels may also become useful as an index of the degree of heart failure and serve as a tool in monitoring response to drug therapy.

Adult↗

PubMed1987

Mononitrates as monotherapy in the prophylactic treatment of angina pectoris.

This article reviews the results of double-blind comparative studies on the therapeutic use of isosorbide 5-mononitrate as monotherapy in the prophylaxis of angina pectoris. Isosorbide 5-mononitrate appears at least as effective as the same dosage of isosorbide dinitrate and is probably superior to the calcium antagonists. Recent data have shown that isosorbide 5-mononitrate in a controlled-release formulation given once daily has a significantly better antianginal effect than placebo without inducing the development of tolerance.

Angina Pectoris↗

PubMed1986

The effect of isosorbide-5-mononitrate (5-ISMN) Durules on exercise tolerance in patients with exertional angina pectoris. A placebo controlled study.

Twenty-four patients with stable exercise-induced angina pectoris entered a double-blind cross-over study. Isosorbide-5-mononitrate (5-ISMN) 60 mg in a controlled release formulation (Durules) given once daily was compared with identical placebo. The exercise tolerance was determined by bicycle ergometry before and 3 h after a single dose of 5-ISMN and following one week's treatment with 5-ISMN and placebo. Nineteen patients completed the study. Exercise tolerance until the onset of chest pain and until 1 mm ST segment depression increased significantly 3 h after dose. The same increase was seen both after a single dose and the same dose under steady-state conditions. No increase was seen with placebo. The heart rate and systolic blood pressure reactions in the standing position were less pronounced 3 h after dose in steady-state than after a single dose of 5-ISMN. Headache was the only bothersome side-effect reported. The study demonstrates that 60 mg 5-ISMN in a Durules formulation given once daily has a significant anti-anginal effect and that tolerance does not develop.

Adult↗

PubMed1986

Evaluation of a modified acetylene rebreathing method for the determination of cardiac output.

In order to evaluate a computerized modified acetylene rebreathing method for the determination of cardiac output, 15 healthy subjects were studied at different levels of their maximal oxygen uptake (VO2max). Submaximal exercise was performed on a cycle ergometer and maximal exercise on a treadmill. Oxygen uptake, heart rate, and cardiac output (acetylene method) were determined in all test situations. In seven subjects simultaneous determinations of cardiac output were made by a modified acetylene rebreathing method (QA) and a dye dilution method (QD). Furthermore, a new resting rebreathing technique was used. The methodological error for QA (means of double samples) was 0.37 litre min-1 (2.8%) in the same individual at 150 W. The corresponding values between individuals were 0.71 (rest), 0.41 (50 W), 0.69 (150 W), and 0.40 litre min-1 (VO2max). Thus the methodological error of the modified acetylene method was very low. There was a significant difference (P less than 0.01), however, between the acetylene method and the dye dilution method, which showed a lower value for QA at all levels. This was probably due to the long response time of the mass spectrometer combined with anatomical and physiological arteriovenous shunt effects in the lungs during exercise. When these factors were considered the correcting formula was: QAc = QA + 0.005 X Q2A. There was no significant difference between the corrected cardiac output values (QAc), and the corresponding QD values. In conclusion, this modified acetylene rebreathing method is a very useful non-invasive method for measuring cardiac output at rest as well as during heavy exercise.

Acetylene↗

PubMed1986

The use of invasive techniques to study circulatory effects of nitrates.

The hemodynamic effects of NTG are easily studied with the use of invasive techniques. This article presents and discusses the most commonly used parameters obtained from cardiac catheterization and angiography to describe the effects of nitrates on the central circulation and the left ventricular function.

Cardiac Catheterization↗

PubMed1979

Left ventricular pump function in effort angina.

The successive deterioration of left ventricular pump function during exercise-induced angina pectoris was studied in 20 candidates for aortocoronary bypass surgery. Left ventricular stroke work and power were calculated from continuous left ventricular pressure recordings and repeated measurements of cardiac output every 30 sec using the thermodilution technique. The average left ventricular enddiastolic pressure (LVEDP) increased continuously during exercise whereas stroke work index (SWI) did so only in the beginning of the exercise period up to a maximum value and then fell towards the end of exercise. The onset of angina occurred at an average LVEDP of 34 mm Hg when SWI had already started to fall in most patients. During exercise all patients had markedly lower SWI than normals. Patients with high coronary arteriographic score and patients with a previous myocardial infarction had significantly lower SWI during exercise than those with low score or those without a previous infarct. At rest there were no differences between these groups which emphasises the importance of haemodynamic measurements under stress conditions in patients with ischaemic heart disease.

Adult↗

PubMed1977

Central haemodynamics in the immediate postoperative period after aortic valve replacement.

Twelve patients with aortic valve lesions were studied haemodynamically before operation and on the three consecutive days after uncomplicated aortic valve replacement with a Björk-Shiley tilting disc valve prosthesis. Five patients had pure aortic stenosis, 4 aortic insufficiency and 3 had combined lesions. Cardiac output at rest, which was within normal limits before operation, was unchanged on the first postoperative day, but showed a tendency to increase on the two following days. Heart rate was markedly increased postoperatively with a corresponding decrease in stroke volume. Arteriovenous oxygen difference was slightly higher postoperatively, indicating a more hypokinetic circulation after surgery. Right atrial mean pressure, which was normal preoperatively, increased in average 3 mmHg postoperatively, whereas left atrial mean pressure, which was pathologically elevated in most patients before operation, showed a marked decrease after operation with a corresponding decrease in pulmonary artery pressure. No significant change in radial artery pressure was observed. Pulmonary and systemic vascular resistance did not change significantly after surgery. The causes of tachycardia, decreased left atrial pressure and hypokinetic circulation after operation are discussed. It is suggested that, in spite of a positive fluid and blood balance, a relative hypovolaemia exists with insufficient blood volume in the left atrium, leading to diminished filling of the low-compliant left ventricle.

Adult↗

PubMed1975

Effect of physical exercise on internal carotid artery blood flow after arterial reconstruction.

The effect of physical exercise on internal carotid artery (ICA) blood flow in conscious man was studied with the aid of electromagnetic flowmetry. A flow probe was implanted on the ICA in 25 patients after reconstruction of the artery. ICA mean blood flow and brachial artery mean blood pressure were continuously monitored in supine (25 patients) and sitting (24 patients) position at rest, during 5-6 minutes exercise on a bicycle ergometer and at rest after exercise. Arterial carbon dioxide tension (PaCO2) was studied in 6/25 work tests in supine and 7/24 in sitting position. Cardiac output was measured at rest and during exercise in 10/25 patients in supine and 8/24 patients in sitting position. In the supine group, ICA flow increased significantly within 1 minute and reached a maximal flow 15% above control flow within 2 minutes after the onset of exercise. The ICA flow then gradually declined, but remained almost significantly elevated, 7.5% above control, on termination of exercise. At rest, after exercise, the ICA flow decreased almost significantly to a level of 5% below the control flow within 5 minutes. There was a significant PaCO2 increase of 2.6 mmHg during exercise and a highly significant increase (72%) in cardiac output during exercise. The ICA flow at rest, before exercise, was about 15% lower in the sitting group than in the supine group. It increased in average 11.5% with 2 minutes of exercise and then gradually diminished. At rest, after exercise, ICA flow decreased further to a level of 8% below control flow within 5 minutes. PaCO2 increased significantly in average 1.6 mmHg during exercise. Cardiac output increased highly significantly (85%) during exercise. The ICA flow changes obtained during exercise in the present study indicate the presence of a regulatory mechanism counteracting the increasing perfusion pressure, but it is unable to compensate the decreased perfusion pressure when the body position was altered from supine to sitting. The cerebral vascular bed in the present patient material seems to operate above and below the lower limit of its pressure range for an adequate autoregulation.

Adult↗

PubMed1975

Cardiovascular and renal responses to acute cold exposure in water-loaded man.

Changes in oxygen uptake, cardiac output, heart rate, stroke volume, central blood volume, arteriovenous oxygen difference, aortic, pulmonary arterial, and right atrial blood pressure, systemic vascular resistance, hematocrit, circulating plasma volume, urine flow, fractional sodium excretion, and free water clearance were studied in eight healthy volunteers in stable water diuresis, exposed to cold by means of air at +15 degrees C and at a speed of 0.5 m/sec. A decrease in circulating plasma volume and systemic vascular resistance was found during cold stress. Mean aortic blood pressure, sodium excretion, cardiac output, oxygen uptake, arteriovenous oxygen difference, and hematocrit increased. No changes in urine flow or in clearance of free water could be demonstrated. Heart rate, stroke volume, and central blood volume showed significant increases in cold. The results are interpreted to suggest that exposure to cold raises the arterial blood pressure by an increase in cardiac output, thereby increasing capillary hydrostatic pressure in certain vascular areas, including the renal vascular bed. This negatively affects capillary reabsorption processes in the kidney, causing a reduction in tubular sodium reabsorption, thus giving rise to a natriuresis. In other areas it seems to cause a shift of fluid towards the intersitial space.

Adult↗