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Biomedical subjects

J Timisjärvi

Publications and source records attributed to J Timisjärvi.

At least 37 records · Page 2Linked to original sources
PubMed1984

Left ventricular responses to intravenous administration of clonidine in anaesthetized dogs.

We have evaluated left ventricular function in anaesthetized (morphine, pentobarbital), artificially ventilated, normotensive beagle dogs immediately (0 to 30 min) after i.v. bolus injection of clonidine (1, 3, 5, 7, 10 and 15 micrograms/kg of b.w.) using computer assisted catheterization technique. Clonidine decreased heart rate and prolonged pre-ejection, ejection and diastolic periods significantly. Cardiac output, mean systolic ejection rate, left ventricular (LV) dP/dtmax and Vmax decreased (p less than 0.05 to 0.01). LV peak pressure and aortic pressures decreased but the decrease was preceded by an initial rise at doses 5 to 10 micrograms/kg. At dose 15 micrograms/kg the rise persisted through the whole period. LV filling and end-diastolic pressures increased while end-diastolic and stroke volumes decreased. These changes indicate negative chronotropic and inotropic effects and increment in preload with the latter being a situation met in the case of proper LV filling. Tension time index and mean outflow resistance, however, indicate reduction in LV oxygen consumption at doses less than 10 micrograms/kg. It is suggested that enhancement of parasympathetic tone would account for these changes.

Animals↗
PubMed1983

Influence of ethanol on systemic and pulmonary hemodynamics in anesthetized dogs.

Immediate circulatory reactions to acute intragastric ethanol administration were studied by a catheterization technique in spontaneously breathing dogs. Diluted ethanol was given in a dosage of 1 g/kg in test group I (n = 11), and 2/kg in group II (n = 10). The control group (m = 14) received only water. The highest blood ethanol concentration was 0.90 +/- 0.07 mg/ml (mean +/- SE) in group I, and 1.97 +/- 0.10 mg/ml in group II. Heart rate and cardiac output increased (p less than 0.,001), but stroke volume, mean aortic blood pressure and right atrial blood pressure remained practically unchanged. Systemic vascular resistance decreased. Mean pulmonary arterial blood pressure increased markedly in both test groups (p less than 0.001) while pulmonary arterial wedge pressure did not change. The pulmonary arterial resistance increased (p less than 0.01). Changes in respiratory rate or volume and arterial pO2 were negligible in group I, but respiratory minute volume decreased in group II. In conclusion, ethanol in concentrations 0.5 to 2.0 mg/ml increased resistance in the pulmonary arterial tree, indicating pulmonary arterial vasoconstriction, but reduced systemic vascular resistance, thus putting a concept of peripheral vasodilation in favour.

Animals↗
PubMed1980

Effect of smoking on the central circulation at rest and during exercise as studied by radiocardiography.

The pulmonary vessels are the first target of tobacco smoke in the circulatory system, but the functional changes occurring in the pulmonary circulation are poorly understood. Hence 46 volunteers were studied by radiocardiography under the following conditions: 1. At rest before and after smoking 2 cigarettes (15 men); 2. After repeated ergometer exercise (5 min, 100 W) with and without smoking (13 men); and 3. Control experiments under the corresponding conditions without smoking (18 subjects). A significant increase occurred in heart rate, cardiac output and systolic arterial blood pressure after smoking when at rest, but an almost significant decrease in pulmonary dispersion volume , whereas the heart rate and pulmonary capillary pressure attained significantly higher values after than before smoking in the exercise tests, with a significant decrease observed in stroke volume, pulmonary blood volume and pulmonary dispersion volume. It is concluded that smoking impairs physical performance, increases pulmonary capillary pressure and reduces pulmonary blood volume and probably the number of open capillaries.

Adult↗
PubMed1979

Electrocardiogram of the reindeer, Rangifer tarandus tarandus.

Electrocardiograms were recorded for 50 Finnish reindeer of age 1 day to 9 years, using standard and unipolar extremity leads in the frontal plane. The range of heart rate was 40-250 beats per minute. Atrial and ventricular depolarization times were 5-10 ms shorter in newborn calves than in other reindeer, and showed only minor variance with respect to heart rate. The duration of depolarization was dependant on heart rate, and was more rapid in young calves. A-V conduction time decreased with increasing heart rate. The mode of the QRS vector was 280-290 degrees, and the mode of the T vector 200-230 degrees in the older animals, but 100-120 degrees in young calves. The main deflection in the QRS complex was S in the leads II, III and aVF.R was dominant in aVL and I.

Age Factors↗
PubMed1979

Quantitative radiocardiographic evaluation of cardiac dynamics in man at rest and during exercise.

113Inm radiocardiography in conjunction with a gamma camera and a digital computer is applied to measurements of cardiac output, stroke volume, ejection fraction, end-diastolic volume, pulmonary blood volume, pulmonary transfer time and dispersion both at rest and during muscular exercise. A modified gamma function is used in calculations of radiocardiographic curves. In twelve supine male subjects the maximal increase of cardiac output was 220%, stroke volume 30%, ejection fraction 15%, and pulmonary blood volume 30%. The present method provides a non-invasive tool for cardiovascular examinations during exercise.

Adult↗
PubMed1979

[Pulmonary capillary pressure and the exercise test].

In the present work with radiocardiography the change of pulmonary capillary pressure as well as cross correlations of stroke index, cardiac index, pulmonary blood volume, pulmonary arterial pressure and pulmonary dispersion volume which reflects pulmonary capillary volume have been studied during muscular exercise. With increase in cardiac output the mathematical estimation showed decrease in pulmonary capillary pressure while stroke index, pulmonary blood volume and pulmonary dispersion volume increased. The pulmonary arterial pressure also rose but this increase was insignificant. The estimated decrease in pulmonary capillary pressure might be due to decreased resistance, a consequence of recruitment of new capillaries and of increase of cross sectional area of pulmonary vasculature. The radiocardiographic method used here appears to be suitable in exercise studies, and it may further be applicable in clinical studies, e.g. in evaluation of left ventricular failure.

Adult↗
PubMed1979

Observations on circulatory adjustment in newborn reindeer and elk.

Haemodynamics of two reindeer (18 h and 4 days old) and one elk (1 week old) calves were studied by catheterization and angiography. Early closure of foetal shunts, high cardiac output and large ejection fractions were observed in all three animals. Pulmonary arterial blood pressure decreased to the full-grown level during the first days of life in the reindeer. Electrocardiography showed cranial-orientated QRS vector in both species. The cardiovascular system of the Cervidae is well developed at birth and adapts rapidly during the neonatal period.

Age Factors↗
PubMed1978

Renography in the foetal and newborn lamb.

Hippuran renography indicates kidney function as reflected in a substance handled mainly by the tubules. The working conditions of the kidneys undergo a fundamental change at birth with the cessation of placenta circulation, and these organs become responsible for waste elimination. 131I-hippuran renography was performed on foetal and newborn lambs using a gamma camera and a computer. The intervals of the maximum- and half-time renal activity were determined. These decreased by a half from mean foetal value of Tm=7 mi and T12=19 min in 1 to 1.5 days and reached the full-grown level in 2 to 5 weeks. No sudden change occurred as a result of the first breath.

Animals↗
PubMed1976

Haematological values for the Finnish reindeer.

Red blood cell counts, haemoglobin, packed cell volumes and total and differential leucocyte counts as well as E-MCHC, E-MCH, E-MCV values and the osmotic fragility of erythrocytes are described for the Finnish reindeer. The samples were taken in early autumn from 52 reindeer of varying ages.

Animals↗
PubMed1976

Smoking and the subjective health condition among Finnish military conscripts.

Information on smoking habits and a subjective self-estimate of general state of health was collected by means of a questionnaire from 400 conscripts in Northern Finland. The data were treated by factor analysis. Long-term fatigue, frequent headache, insomnia and occasional depression were less frequent among non-smokers than among smokers.

Depression↗
PubMedDate not supplied

Left ventricular volumes and functioning of the reindeer heart.

Left ventricular volumes were measured by cineangiocardiography in 56 sessions on 25 reindeer, together with determinations of arterial pressure and blood oxygen saturation. The heart rate with the animal kept lying on the sternum at rest was 50 b/min, the aortic blood oxygen saturation 94 to 98% and the aortic blood pressure 153/130/115 mm Hg. The left ventricular end-diastolic volume was 3.4 ml/kg of b.w., stroke volume 2.6 ml/kg, cardiac output 133 ml/kg . min, and ejection fraction 76%. If the animal was placed on its side the aortic blood oxygen saturation decreased by 2 to 3 per cent, end-diastolic volume rose 10%, stroke volume 25%, cardiac output nearly 30% and ejection fraction 14%. The heart rate and cardiac output increased in hypoxemia, but the end-diastolic and stroke volumes simultaneously decreased. If the aortic blood pressure rose during hypoxia, the end-diastolic and stroke volumes increased, while the ejection fraction first increased and then decreased again. In normoxia a rise in aortic blood pressure was associated with decreased end-diastolic and stroke volumes and ejection fraction. An increased heart rate at rest was followed by increased cardiac output, but decreased end-diastolic and stroke volumes and ejection fraction.

Animals↗
PubMedDate not supplied

Pulmonary circulation in the reindeer.

Right heart catheterizations were performed in 56 sessions on 25 reindeer with determinations of blood pressure and oxygen saturation. Cardiac output was calculated from cineangiocardiograms. When the animals were placed in prone position, heart rate was about 50/min, mixed venous blood oxygen saturation 68 to 72%, right ventricular systolic pressure 27 mmHg, pulmonary arterial pressure 25/16/11 mmHg, pulmonary arterial wedge pressure 6--8 mmHg and pulmonary transfer time 4 to 5 cardiac cycles. When the animals were placed on their side, the heart rate rose to 90 b/min, mixed venous blood oxygen saturation decreased by about 4% and the right ventricular and pulmonary arterial pressures increased by about 10 mmHg; pulmonary arterial wedge pressure did not change. Hypoxemia led to an increase in heart rate, cardiac output and pulmonary arterial pressure; the latter two measures tended to increase whenever the heart rate increased. Under the conditions stated here, an increased pulmonary vascular resistance was calculated when pulmonary arterial pressure was increased.

Angiocardiography↗
PubMedDate not supplied

Spontaneous oscillations of systemic arterial pressure during cardiopulmonary bypass in man.

Extracorporeal blood circulation (ECC) provides a steady flow and minimal pulmonary circulation in the absence of cardiac function. Oscillations of systemic arterial pressure were observed in 70 patients during ECC. At the onset of oscillations the frequency was as a rule 4 cycles per minute but depended on the temperature and showed a positive correlation with it. Correspondingly, the amplitude was about 6 mm Hg and depended on aortic pressure and showed a positive correlation with it. During the cooling phase of ECC the frequency decreased and the amplitude increased. The oscillations were independent of central venous pressure and ventilation. The oscillations disappeared either at the beginning of restitution of cardiac function or with decreasing arterial pressure caused by drug administration or rewarming. Arterial blood pressure oscillations have been described in experimental animals under various conditions but also in conscious man. The mechanisms underlying these oscillations are suggested to be nervous in origin, as is possible also in the present findings.

Adult↗
PubMedDate not supplied

Mean outflow resistance as a marker of left ventricular afterload.

The changes of mean outflow resistance (MOR) (defined as the ratio between mean aortic ejection pressure and mean ejection rate) and of total peripheral resistance (TPR) together with their relations to some circulatory parameters and to each other were studied under control (NaCl) and six different loading conditions on anesthetized closed chest dogs. Phenylephrine increased both MOR and TPR (ca. 160%, max), pacing increased MOR (p less than 0.01) but not TPR. Isoproterenol and dextran infusion decreased TPR (p less than 0.001) but not MOR. Calcium chloride decreased MOR (p less than 0.05) but increased TPR (NS). The relationship between MOR and TPR was linear in each case (r from 0.63 to 0.91). Both MOR and TPR showed either positive or negative linear correlations with volume and pressure parameters although MOR appeared to be more sensitive to the administered interventions. The present results suggest that, when referring to the pulsatile and discrete nature of the blood-flow-pressure output from the left ventricle, MOR seems to be a more useful measure than TPR in the assessment of the left ventricular afterload.

Animals↗
PubMedDate not supplied

Spontaneous oscillation of the systemic arterial pressure during cardiopulmonary bypass in man. The effects of some drugs used during the operation.

Despite the fact that the blood flow maintained during cardiopulmonary bypass is rather steady in the extracorporeal pump output, the arterial pressure under high-dose fentanyl anaesthesia quite often shows sinusoidal oscillations. In the present study the duration of an oscillatory cycle was on average 17.6 +/- 3.6 s, its amplitude 7.3 +/- 1.6 mm Hg and mean systemic arterial pressure 75 +/- 12 mm Hg. The oscillation is affected by the drugs used under bypass conditions. In our series of clinical observations the blood pressure oscillation disappeared under the influence of chlorpromazine, phentolamine, droperidol, and enflurane, and it disappeared or at least was distinctly attenuated under fentanyl, thiopental, diazepam, sodium nitroprusside, nitroglycerin, acebutolol, and potassium chloride. Pancuronium, atropine and furosemide appeared to be practically ineffective. In spite of the fact that the drugs used affected several sites of the sympathetic efferent chain, the disappearance and attenuation of the oscillation were associated with a simultaneous decrease of blood pressure. Hence, it is suggested that the occurrence of the oscillations requires some level of peripheral vascular tone.

Adrenergic beta-Antagonists↗