Biomedical subjects

P Carlens

Publications and source records attributed to P Carlens.

4 recordsLinked to original sources

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↗