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Biomedical subjects

H Ihlen

Publications and source records attributed to H Ihlen.

71 records · Page 4Linked to original sources
PubMed1983

Haemodynamic and metabolic effects of timolol (Blocadren) on ischaemic myocardium.

The effects of timolol (2.5 mg i.v.) on coronary haemodynamics and myocardial metabolism were studied in 26 patients with angina pectoris. Cardiac venous flow (CVF) was measured by thermodilution technique. Blood was sampled for metabolic studies. Angina pectoris was induced by atrial pacing and the same heart rate was regained after timolol. Metabolic ischaemia was defined as reduction in myocardial lactate extraction ratio (MLE) by at least 50% and to a ratio below 0.15. The study was completed in 22 patients, 9 of whom fulfilled the metabolic criteria for ischaemia. This subgroup did not differ from the total group in any other respect than in lactate metabolism. Beta-adrenergic blockade reduced myocardial oxygen consumption (MVO2) and CVF significantly at rest, but MVO2, CVF, myocardial glucose uptake and MLE were unchanged during pacing despite a decrease in systolic aortic pressure, ejection time and reduced myocardial free fatty acid uptake. Conclusively, timolol did not reduce MVO2 and metabolic ischaemia during pacing-induced angina.

Angina Pectoris↗
PubMed1983

Reproducibility of ischaemic lactate metabolism during atrial pacing in man.

The reproducibility of myocardial ischaemia provoked by atrial pacing was studied in two groups of patients. The heart rate was slowly increased (10 beats per fourth min) until angina in group A, and quickly increased (10 beats per 20 s) in group B. Cardiac venous flow was measured by thermodilution and blood was sampled for metabolic studies at rest and during the maximum obtained heart rate and repeated after 20 min of rest. Ischaemia was defined as a reduction in myocardial lactate extraction ratio by 50% and to a ratio lower than 0.15. Lactate metabolism changed from production (-0.06 +/- 0.05) during the first pacing to extraction (0.05 +/- 0.05) during the second in group A (p less than 0.02). Lactate metabolism was quite reproducible in group B. All the other metabolic and haemodynamic parameters were unchanged in both groups. We conclude that the duration of atrial pacing is important for the reproducibility of pacing-induced myocardial ischaemia.

Cardiac Pacing, Artificial↗
PubMed1983

Myocardial lactate metabolism during pacing induced angina pectoris.

Myocardial lactate metabolism was studied in 20 patients with coronary heart disease during and immediately after slight angina pectoris induced by atrial pacing. Myocardial lactate extraction ratio (MLE) decreased from 0.27 +/- 0.03 (SEM) before angina to 0.01 +/- 0.06 during angina, and further to -0.32 +/- 0.11 at 15 sec after pacing. Lactate production was found to occur in eight patients during pacing and 13 patients after pacing. Cardiac venous flow was measured by thermodilution in eight of these patients. 'Net ischaemic lactate efflux' increased by 23 +/- 4 mumol/min 15 sec after pacing, whereas 'lactate uptake in non-ischaemic regions' diminished by 11 +/- 2 mumol/min. Lactate production 15 min after pacing was revealed in all patients with subtotal stenosis of the left anterior descending coronary artery (LAD), whereas it was less frequently observed in patients with occluded LAD and collaterals to the post-stenotic area. Increased washout of metabolites from the ischaemic myocardium during the early recovery period is the main reason for the rather high sensitivity of ischaemia detection by this procedure. This permits shorter pacing periods and less pain than in earlier studies. Both MLE and electrocardiographic changes were equally reproducible after 20 and 45 min recovery period.

Angina Pectoris↗
PubMed1982

Effects of red rest and prazosin in congestive heart failure.

Twelve patients with congestive heart failure were monitored with invasive and noninvasive techniques to evaluate the effect of vasodilator treatment. During the 18 hours of strict bed rest before administration of prazosin, the hemodynamics improved substantially while only small and transient heModynamic changes were observed after introduction of prazosin. At 6 weeks' control the effect of vasodilator treatment with prazosin, 3 mg x 4, was lost. The beneficial results often credited to vasodilators in studies on congestive heart failure might in part be due to the concomitant bed rest introduced during the monitoring of the patients.

Adult↗
PubMedDate not supplied

Intraventricular early diastolic velocity profile during acute myocardial ischemia: a color M-mode Doppler echocardiographic study.

The aim of the study was to investigate the effect of acute myocardial ischemia on the early diastolic mitral-to-apical velocity profile. Intraventricular filling velocities were measured by color M-mode Doppler echocardiography, which allows simultaneous measurements of velocities at multiple sites. Twenty patients were examined during angioplasty and eight dogs during transient coronary artery occlusion. Velocities at each 0.46 cm level from the mitral tip toward the apex were determined at the time of peak early transmitral velocity. Before angioplasty, early diastolic flow velocities decreased progressively from the mitral tip toward the apex. During angioplasty, intraventricular velocities showed a more abrupt decrease from the middle region toward the apex (p < 0.05). A similar change in the mitral-to-apical profile was found during myocardial ischemia in dogs (p < 0.05). Also, there was a decrease in peak early transmitral velocity (p < 0.01) and peak early transmitral pressure gradient (p = 0.06). Volume loading and constriction of the caval veins performed in the nonischemic ventricle did not appear to change the mitral-to-apical velocity profile. Regional myocardial ischemia was associated with a change in the mitral-to-apical velocity profile as measured by color M-mode Doppler echocardiography. The altered filling pattern could not be explained by changes in loading conditions and may reflect impaired relaxation of the ischemic ventricle.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

The influence of atrioventricular conduction and heart rate on the pulmonary venous flow pattern.

The pulmonary venous flow (PVQ) pattern usually has two antegrade flow waves, corresponding to ventricular systole and diastole, respectively, and is used to assess left atrial pressure. To study the effects of atrioventricular conduction (AVD) and heart rate (HR) on the PVQ pattern, transthoracic pulsed Doppler recordings of pulmonary venous, transmitral, and aortic flow were made in five healthy subjects with dual-chamber pacemakers. Recordings were made at HRs of 80, 100, and 120 beats/min, with AVDs of 75, 150, and 220 msec at each HR. When the AVD was increased, the biphasic PVQ changed to a monophasic pattern in which a single flow wave covered the transition between ventricular diastole and systole. There was a shift of flow from ventricular systole to diastole. When HR was increased, the systolic fraction of the PVQ increased as a result of an increase in the relative duration of systole. In conclusion, AVD and HR influenced the PVQ pattern in subjects without signs of ventricular dysfunction. This may be a limitation to the use of the flow pattern to assess left atrial pressure.

Adolescent↗