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Biomedical subjects

M Viitasalo

Publications and source records attributed to M Viitasalo.

65 records · Page 4Linked to original sources
PubMed1992

Exclusion of coronary artery disease by exercise thallium-201 tomography in patients with aortic valve stenosis.

In many patients with valvular aortic stenosis (AS), management decisions may be possible without invasive studies if coexistent coronary artery disease (CAD) can be ruled out noninvasively. The use of thallium-201 single-photon emission computed tomography to the exclusion of CAD was studied in 44 patients aged 41 to 78 years with AS. In addition to cardiac catheterization and selective coronary angiography, patients underwent a cardiac ultrasound study and thallium-201 myocardial perfusion imaging at rest and after bicycle ergometer exercise. Two thirds of the patients had critical AS (valve area index less than or equal to 0.5 cm2/m2) but none had left ventricular systolic dysfunction. Twenty-one patients had angiographically significant CAD (greater than or equal to 50% diameter stenosis in greater than or equal to 1 coronary artery), whereas 23 had either a fully normal angiogram (n = 17) or mild (less than 50%) stenoses (n = 6). Each patient with significant CAD had an abnormal thallium-201 tomogram, either a strictly segmental perfusion defect (n = 19), or a patchy nonsegmental abnormality (n = 2); however, 10 of 23 patients free of significant CAD had similar results. Thus, the sensitivity and specificity of an abnormal scintigram were 100 and 57%, respectively. If only segmental perfusion defects typical of CAD had been considered abnormal, then the sensitivity of the test would have been 90% and the specificity 70%. Patients with false abnormal scintigrams had more severe AS and more angiographically nonsignificant CAD than those with true normal findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Stenosis↗
PubMed1992

The performance of the probability density function in differentiating supraventricular from ventricular rhythms.

The ability of the probability density function (PDF) of an automatic implantable cardioverter defibrillator (AICD) to reject supraventricular arrhythmias being recognized as ventricular was evaluated in 12 patients who were treated with an AICD (Ventak P 1600). The PDF criterion was monitored via telemetry with the sinus rate during exercise test. PDF was satisfied in seven patients at a rate of 75-144/min (mean 109/min), and not in the remaining five patients (mean rate 141/min). PDF was fulfilled in five of ten patients at a lower heart rate than predicted by the duty cycle index, derived from the ventricular patch lead electrogram at the implantation. Thus PDF is often fulfilled already at a moderately elevated sinus rate. If used to prevent inadvertent AICD discharges during rapid supraventricular rhythms, its performance should be tested in the individual patient.

Electric Countershock↗
PubMed1992

QT intervals at heart rates from 50 to 120 beats per minute during 24-hour electrocardiographic recordings in 100 healthy men. Effects of atenolol.

BACKGROUND: Conflicting reports about changes in QT intervals suggest that QT values should be compared at similar heart rates. METHODS AND RESULTS: Relations between QT and RR intervals were determined after measurement of QT values by Holter recording at heart rates of 50, 60, 70, 80, 90, 100, 110, and 120 beats per minute in 100 healthy young men. Fifteen men underwent a second recording during acute treatment with the beta-blocking agent atenolol. At heart rates between 80 and 120 beats per minute, the QT interval was significantly longer (from 9 to 16 msec), and at a heart rate of 50 beats per minute significantly shorter (26 msec), than values calculated from Bazett's formula. Sleep prolonged QT values by 18 msec at a heart rate of 60 beats per minute and by 21 msec at a heart rate of 50 beats per minute compared with the waking state. Atenolol lengthened QT intervals significantly (by 11-14 msec) at heart rates between 90 and 110 beats per minute and shortened them (by 12 msec) at a heart rate of 60 beats per minute. During sleep, QT intervals were the same before and after atenolol. CONCLUSIONS: The method of plotting QT against RR intervals after measurement of QT values at similar stable spontaneous heart rates before and after intervention allows changes in autonomic state and heart rate to be taken into account. By this method, QT values can be compared without distortion effects caused by correction formulas.

Adrenergic beta-Antagonists↗
PubMed1991

Sleep and cardiac rhythm in healthy men.

Cardiac rhythm during sleep was analysed in 168 healthy men aged 19 to 30 (mean 21.8) years using continuous nocturnal ECG recordings. Thirty five of the subjects were endurance athletes; 99 were recorded at home and 69 at a garrison during military service. The number of short term (less than one min) accelerations of heart rate of more than ten beats per minute ranged from 1.3 to 14.3 per hour; the number or accelerations (greater than one min) of more than 25 beats per minute typical of nocturnal restlessness ranged from zero to 6.1 per hour. The accelerations indicating nocturnal restlessness were more common during recordings done at the garrison than at home (2.2 per hour vs 1.3 per hour, P less than 0.01), whereas the short term accelerations were not (5.8 per hour vs 5.1 per hour, NS). Sinus pauses exceeding 2.00 sec occurred in 17 men (13 in athletes), occasional second degree atrioventricular block in 19 (eight in athletes) and ventricular premature beats in 37. Eighty-two per cent of sinus pauses, 83% of second degree atrioventricular blocks, and 81% of ventricular premature beats (when less than ten in the same subject) were associated with short term changes in heart rate. In conclusion, rapid changes in heart rate, presumably as a results of autonomic activation, are closely associated with most arrhythmias in healthy men during sleep, whereas changes in heart rate typical of nocturnal restlessness have little arrhythmogenic effect.

Adult↗
PubMed1986

Fever and cardiac rhythm.

To study the effect of fever on cardiac rhythm and conduction, we recorded 24-hour electrocardiograms in 27 young men during an uncomplicated acute febrile infection (12 patients had adenovirus, four had influenza, three had Mycoplasma pneumoniae, and eight were undefined) and after recovery. During the first 24-hour recording period, the mean axillary temperature in the whole group was 38.4 degrees C. The mean heart rate during the febrile period was 84.0 beats per minute. After recovery, it was 66.5 beats per minute. When the temperature rose by 1 degree C, the heart rate increased on the average by 8.5 beats per minute. During the febrile period, the heart rate remained high, even during sleep. The PR interval shortened significantly at a heart rate of 60 beats per minute and occasional first- or second-degree atrioventricular blocks were rarer. The QT interval shortened significantly at heart rates of 60, 80, and 100 beats per minute. Simple and complex ventricular extrasystoles were not increased by fever. In contrast, frequent supraventricular extrasystoles developed in two patients during high fever, but not during the control recording. If an acute febrile infection induces a prolongation of the atrioventricular conduction or the QT interval, or if frequent ventricular extrasystolic beats are triggered, complications must be suspected.

Acute Disease↗
PubMed1984

24-Hour electrocardiographic recordings in mild acute infectious myocarditis.

Arrhythmias and even sudden death may be caused by acute infectious myocarditis. We therefore recorded 24-hour electrocardiograms in 26 myocarditis patients both one week and two to three months after the detection of myocarditis. Two of the patients were also monitored on the first day of their symptomatic myopericarditis . Twenty-eight control subjects had recordings one to two weeks after the onset of acute uncomplicated infections. One of the two patients monitored during the first day of myopericarditis had repetitive, asymptomatic bursts of ventricular tachycardia. In the 1-week recordings 27% of the myocarditis patients and 7% of the control subjects (p less than 0.06) had complex ventricular premature beats; these occurred in only 8% of the myocarditis patients during the late recording. However, the overall number of ventricular premature beats was low in both groups and recordings. A lengthening of the QT interval was related (p less than 0.05) to the occurrence of complex premature beats in repeated recordings in the same individuals. The heart rate was higher (p less than 0.02) in myocarditis patients, but no significant difference was noted in the frequency of conduction defects. We conclude that there seems to be no reason for a prolonged restriction of physical activity during clinically uncomplicated recovery from mild acute myocarditis. However, potentially dangerous arrhythmias may occur during the very first days of the disease.

Acute Disease↗