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H Vik-Mo

Publications and source records attributed to H Vik-Mo.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effects of impaired lung function and pulmonary regurgitation on maximal exercise capacity in patients with repaired tetralogy of Fallot.

Long-term haemodynamic results and exercise capacity were studied in 34 patients with tetralogy of Fallot (24 men and 10 women) repaired 10.0 +/- 4.9 (mean +/- SD) years previously and compared to 34 healthy matched controls. All subjects were studied by resting spirometry, echocardiography and a symptom limited treadmill exercise test (modified Bruce protocol). The maximal oxygen consumption was 38.2 +/- 8.0 ml.kg-1.min-1 in patients and 48.1 +/- 8.1 ml.kg-1.min-1 in the control group (P < 0.001). Reduced maximal oxygen consumption was found in patients with low vital capacity (VC) and pulmonary regurgitation (PR). The ventilatory anaerobic threshold (VAT) was 23.8 +/- 0.6 ml.kg-1.min-1 and 29.9 +/- 0.6 ml.kg-1.min-1 in patients and controls, respectively (P < 0.001). VC was 3.4 +/- 1.21 in patients and 4.0 +/- 1.31 in controls (P < 0.02). In the patients, maximal ventilation was reduced and at submaximal exercise, the breathing frequency increased. Heart rates during exercise were similar in patients and controls. Tricuspid regurgitation (TR) was detected in 20 patients (58.8%); however, the exercise capacity was not reduced. Thus, impaired exercise capacity in tetralogy of Fallot is partly due to reduced resting lung function, pulmonary regurgitation and low ventilatory anaerobic threshold.

Adolescent↗
PubMed1992

Addition of sodium to the nonionic contrast medium iohexol during coronary angiography in man. Lack of electrocardiographic or hemodynamic effects.

It has recently been claimed that lack of sodium in nonionic contrast media may increase the risk of ventricular arrhythmias during coronary angiography. Thus, the influence of sodium addition to the nonionic contrast medium iohexol was studied in 75 patients with severe coronary heart disease. The study design was randomized, parallel and double-blind, and iohexol was given either with or without addition of NaCl (28 mmol/l). Both formulations induced a transient drop in arterial blood pressure, and prolongation of the QT interval and QRS duration at 10 s only (p less than 0.01). The electrical QRS axis was significantly changed by the coronary artery injections after 10 s, but not later. No differences between iohexol with and without NaCl were observed for any of the variables studied. No serious arrhythmias were observed. Thus, the addition of NaCl (28 mmol/l) to iohexol did not influence the electrocardiographic or hemodynamic changes induced by iohexol during coronary angiography.

Aged↗
PubMed1991

[The usefulness of thallium-201 scintigraphy in the diagnosis of coronary disease].

Stress thallium scintigraphy was performed in 60 patients with chest pain of uncertain origin. Myocardial ischemia was identified in 91% of the 47 patients who had angiographically significant coronary artery stenoses. Sensitivity of thallium scintigraphy was highest in patients with stenosis in the left descending coronary artery (LAD); 91% of the patients had abnormal thallium as compared with 67% of the patients with normal LAD but significant stenoses in the circumflex artery and/or the right coronary artery. Perfusion defects in the circumflex in only 50% of the patients with multiple vessel disease. We conclude that stress thallium scintigraphy is a useful diagnostic procedure in patients with chest pain of uncertain origin and identifies the patients to be selected for coronary artery angiography.

Adult↗
PubMed1991

Respiratory gas exchange during treadmill exercise testing: reproducibility and comparison of different exercise protocols.

Ten subjects performed 4 maximal exercise tests to evaluate reproducibility and effects of treadmill inclination on submaximal and maximal oxygen consumption. They performed a standard Bruce protocol twice, and 1 protocol with progressive speed increase with constant, or without, inclination. At maximal exercise there was no significant difference between the protocols in oxygen consumption, respiratory gas exchange ratio, minute ventilation, plasma lactate, serum potassium or heart rate. Exercise time and treadmill distance were shorter than Bruce protocol with inclination, and considerably prolonged without. Reproducibility for Bruce protocol was good for group comparison of oxygen consumption throughout exercise. The individual variations for oxygen consumption were small at maximal exercise, but were considerable at rest and at the lowest exercise steps, this was slightly improved by analysing longer sampling time. Thus, measurement of oxygen consumption is reliable for group analysis, but interpretation must be careful in individuals unless maximal exercise is obtained. Treadmill inclination may be adjusted according to individual preferences.

Adolescent↗
PubMed1991

Clinical and haemodynamic features in relation to severity of aortic stenosis in adults.

The main symptoms of aortic stenosis (AS), angina pectoris, dyspnoea, and syncope/effort dizziness, are thought to reflect the severity of AS. This assumption is based on studies in relatively young patients, and may not apply to older age groups. Thus, in 100 consecutive adults (age 41-79 years) referred to cardiac catheterization with suspected AS, clinical and haemodynamic variables were assessed in relation to significant (less than or equal to 0.50 cm2 m-2) (n = 70) and nonsignificant AS (n = 30), and to symptoms. Prevalence of symptoms, functional class, and systolic murmur grade greater than or equal to 3, was similar in the groups. However, patients with significant AS more often had an abnormal second heart sound, electrocardiographic left ventricular (LV) hypertrophy with strain, severe echocardiographic aortic valve calcification, and increased LV wall thickness. Multivariate analysis identified an abnormal second heart sound, and aortic calcification grade, as independent predictors of significant AS. When the Doppler mean gradient was added to the analysis, it became the best predictor. Angina pectoris (n = 74) was related to coronary artery disease, but not to severity of AS. However, 31% of patients without angina also had coronary artery disease. Dyspnoea (n = 69) was only related to age, and syncope/effort dizziness (n = 26) was more frequent in women. Functional class grade was not related to severity of AS. Thus, in adults with assumed symptomatic AS, clinical symptoms do not predict severity of AS. Therefore, the decision for valve replacement should rely on Doppler assessment of the severity of AS. Furthermore, in adults with AS, coronary artery disease cannot be excluded without selective coronary angiography.

Adult↗
PubMed1991

Arterial and venous measurement in resting forearm of metabolic indicators during rest and leg exercise.

We compared the levels of various metabolic indicators in arterial and venous forearm blood during maximal treadmill leg exercise, and the subsequent 9 min in nine volunteers aged 31-56 years. At maximal exercise plasma lactate was 13.2 +/- 3.1 mmol l-1 arterially, while venous was 41% lower, but increased more than arterial after exercise. There was a linear relationship between arterial and venous samples during and after exercise, but not at baseline. Plasma pyruvate increased on the arterial side from 49 +/- 8 to 172 +/- 30 mumol l-1 at maximal exercise, maximal venous was 21% lower. Free fatty acids were not different at rest, but decreased during exercise by 52 and 38% on the arterial and venous side. There was no relationship between arterial and venous levels. Changes in these three variables occurred significantly earlier on the arterial side. Arterial cyclic AMP rose from 97.3 +/- 28.4 to 262.7 +/- 67.5 nmol l-1 from rest to exercise, and was linearly inversely related to the decrease in free fatty acids. The mean venous pH was lower than arterial at rest, but was the same as arterial at maximal exercise and after. Thus, venous plasma lactate and pyruvate, but not free fatty acids, are linearly related to arterial measurements during maximal exercise, while pH is identical. Non-working muscle modifies exercise-induced changes, and therefore venous and arterial forearm blood sampling give more information than either alone.

Adult↗
PubMed1991

Compression ultrasonography in hospitalized patients with suspected deep venous thrombosis.

Compression ultrasonography was compared with contrast venography in 215 hospitalized patients (218 limbs) with suspected deep venous thrombosis. All scans were performed using a 5-MHz linear-array scanner. The calf veins were not assessed owing to their small caliber. Distribution of deep venous thrombosis was proximal in 113 of 215 patients (number of limbs with deep venous thrombosis being the same as the number of patients) and limited to the calf veins (distal) in 29 patients. Deep venous thrombosis was detected by compression ultrasonography in 101 of 113 patients (sensitivity, 89%) and falsely diagnosed in two of 76 limbs (73 patients) with negative venographic results (specificity, 97%). The method was less sensitive below the knee, where deep venous thrombosis of the distal popliteal vein was not detected in five of 10 patients as compared with seven of 103 patients with thrombus extension above the knee. Pelvic vein deep venous thrombosis (n = 34) was detected by compression ultrasonography in 71% of the patients. The results of this study indicate that venography may be omitted in patients where compression ultrasonography demonstrates proximal deep venous thrombosis. In patients with negative compression ultrasonographic results, however, venographic verification is needed since venography has a considerably higher sensitivity than compression ultrasonography in detecting isolated iliac and calf vein deep venous thrombosis.

Aged↗
PubMed1990

Influence of low osmolality contrast media on electrophysiology and hemodynamics in coronary angiography: differences between an ionic (ioxaglate) and a nonionic (iohexol) agent.

It has recently been suggested that the addition of sodium to low osmolality contrast media may reduce the incidence of ventricular fibrillation and conduction disturbances during coronary angiography. In a randomized, double blind study of 30 patients undergoing coronary angiography we therefore examined the electrophysiological and hemodynamic effects of the two low osmolality contrast media-ioxaglate (with sodium) and iohexol (without sodium). Standard ECG, aortic blood pressure, and His bundle electrocardiogram were recorded. The contrast media were well tolerated and no serious arrhythmias were observed. Both induced a transient decrement in systolic blood pressure and reduction in heart rate 10 s following contrast injection (all P less than 0.01). Ioxaglate prolonged the QT interval at 10 s (P less than 0.01) and also when analysed for the whole observation period (120 s) (P less than 0.05), whereas iohexol did not cause any significant changes in the QT-interval. The AH-interval was prolonged by ioxaglate at 10 s (P less than 0.01), but not altered by iohexol. Thus, other factors than osmolality and sodium content might contribute to QT prolongation, since only the contrast agents with sodium (ioxaglate) induced QT prolongation in this study.

Adult↗
PubMed1990

Physiological inverse relationship between heart rate and thallium-201 lung uptake, clearance and lung/myocardial uptake ratio.

Increased lung uptake of thallium-201 during exercise has been suggested to indicate left ventricular dysfunction. The normal lung thallium-201 uptake, clearance and lung/myocardial uptake ratio were studied prospectively in 7 healthy men. Initial and delayed (3 h) images were quantitated by computer from regions of interest over the heart and lungs, after three bicycle exercise tests: to maximal, 80% and 60% of predicted maximal heart rate. The initial lung uptake was lowest at peak heart rate, and increased linearly to 121% and 140% of this at 80% and 60% of predicted maximal heart rate. The three delayed lung images were identical. The myocardial activity was highest at maximal exercise, and decreased linearly with heart rate, resulting in a net fall in the sum of initial lung and myocardial activity to 93% and 86% at the two lowest exercise levels. The mean initial lung/myocardial uptake ratio was 0.44, 0.67, and 1.00 from highest to lowest heart rate, and the lung thallium-201 clearance 9%, 21% and 33%. These results suggest that the initial lung thallium-201 uptake, clearance and lung/myocardial uptake ratio are normally inversely related to cardiac output. When used as indicators of left ventricular dysfunction, interpretation should be cautious in patients performing submaximal exercise tests. The lung thallium prognostic indicators seem less specific than previously indicated.

Adult↗
PubMed1989

Factors affecting Doppler echocardiographic valve area assessment in aortic stenosis.

Doppler echocardiographic assessment of the aortic valve area (AVA) using the continuity equation was performed before cardiac catheterization in 100 patients with suspected aortic stenosis. Doppler echocardiographic AVA correlated closely with AVA calculated by the Gorlin equation at catheterization (r = 0.96). However, Doppler echocardiography slightly but systematically underestimated the AVA (p less than 0.001) and did so most markedly in patients with mild stenosis (greater than 1.0 cm2). In multivariate analysis, the difference in AVA by the 2 techniques was positively associated with left ventricular (LV) stroke volume and inversely with the difference between mean catheterization and Doppler gradients, LV ejection fraction and LV outflow tract velocity. Furthermore, the AVA difference also was related to gender, being larger in women. Thus, overall Doppler echocardiography reliably assesses AVA, but the usefulness of the method is somewhat reduced by its underestimation of AVA in mild stenosis. This drawback, however, is usually overcome by taking patients' symptoms into account. Furthermore, lacking a "gold standard," this underestimation need not imply errors of the Doppler echocardiographic method alone, but also may reflect known inaccuracies of the catheterization technique.

Adolescent↗
PubMed1989

[Improved aerobic exercise performance after short-term training of patients with coronary disease].

Maximal oxygen consumption was measured during treadmill exercise in 44 patients with coronary artery disease. Exercise was performed before and after a 4-week course of training. Patients with a previous myocardial infarction and no angina pectoris (n = 27) increased their maximal oxygen consumption by 16% after training. There was no such increase in patients with angina pectoris (n = 17). The subjective feeling of wellbeing after training was the same in both groups of patients. Thus, the advantages of short term training can be both of a symptomatic character and a real improvement in cardiovascular function.

Adult↗
PubMed1989

Physiological effects of short-term training after myocardial infarction.

The effects of a period of 4 weeks training on treadmill exercise performance were evaluated in 27 patients, mean +/- SD age 55 +/- 7 years, who had previously suffered a myocardial infarction (17 Q-wave) 3-24 months (mean 11 +/- 8). To ensure comparability of exercise levels only patients who obtained their predicted maximal heart rate in the initial test were included. All trained 3-4 hours daily 5 days a week at an average maximal intensity of 85% of their initial peak heart rate. They performed 2 maximal exercise tests before and 1 after the training course. Maximal oxygen consumption was 28.1 +/- 5.3 and 28.8 +/- 6.5 ml/kg/minute (NS) before, and increased by 16% to 33.4 +/- 7.2 after training (P less than 0.01). Treadmill exercise distance was 510 +/- 153 and 559 +/- 163 meters (10% increase, P less than 0.01) before, and increased by 14% to 638 +/- 156 after (P less than 0.01). Heart rate, ratio of respiratory gas exchange, and breathing frequency remained unchanged in all three tests at maximal exercise, but were significantly lower at identical submaximal levels after training, while the respiratory tidal volume increased. Resting heart rate decreased by 12% after (P less than 0.01). Thus, aerobic exercise performance is improved by short-term training after myocardial infarction. By the longitudinal design of the study, and the maximal initial exercise test, this physiological improvement can be differentiated from that of increased motivation, and of increased treadmill exercise distance due to improved exercise technique.

Adult↗
PubMed1989

Effects of verapamil on intracellular lipid accumulation in cat hearts with 3 h of regional-ischaemia.

In the regionally ischaemic heart lipid droplet accumulation is found in the ischaemic area and is most pronounced in the periphery. The purpose of the present study is to explore the potential effects of the calcium-channel-blocker verapamil on this accumulation. The drug is known to reduce the intensity of myocardial ischaemic injury. The myocardial ultrastructure was studied in anaesthetized open chest cats with 3 h of coronary artery occlusion. Biopsies were taken from the ischaemic, border and normally perfused myocardium defined in vivo injections of fluorescein and verified by blood flow measurements using radiolabelled microspheres. Arterial concentration of non esterified fatty acids (NEFA) was measured during the ischaemic period. A higher accumulation of lipid droplets was found in the central ischaemic myocardium of verapamil-treated cats than in control animals (p less than 0.05). The normally perfused and borderline areas were unaffected by verapamil as far as lipid accumulation was concerned and showed the same pattern as in the untreated group. The increased accumulation of lipid droplets in the ischaemic myocardium, after treatment with verapamil, may reflect a preserved metabolic activity in the ischaemic tissue or result from a higher supply of fatty acids due to increased perfusion of the central ischaemic tissue.

Animals↗
PubMed1989

Effects of heart rate on myocardial thallium-201 uptake and clearance.

The effects of heart rate on the myocardial uptake and clearance of 201Tl were studied prospectively in seven healthy men, mean age 43 +/- 7 (s.d.) yr. Initial and delayed (3 hr) thallium images were obtained in three views after three bicycle exercise tests: to maximal, 80% and 60% of predicted maximal heart rate. The mean of three views initial myocardial 201Tl uptake was higher at maximal than at both 80% and 60% of predicted maximal heart rate, being 81% (p less than 0.01) and 60% (p less than 0.01) of maximal activity, respectively. The myocardial activity in the delayed images was identical. There was a linear relationship between heart rate and the initial myocardial activity, r = 0.86 (p less than 0.001). The mean (range) 201Tl clearance was 58% (51-65), 47% (34-56), and 34% (22-49) (all differences p less than 0.01), respectively. Concordance among the three individual views in estimating clearance was best for the highest exercise level. There was a linear relationship between heart rate and clearance, r = 0.80 (p less than 0.001). Clearance was altered by only 1.67 x 10%/heart bpm (0.024 hr/heart beat). Clearance in the liver, spleen and lungs increased at submaximal exercise levels. Thus, a linear relationship between heart rate and clearance is the result of changes in the initial exercise myocardial 201Tl activity. Submaximal exercise may reduce reproducibility of clearance estimation, and the change of myocardial clearance with heart rate seems less than previously suggested.

Adult↗