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Biomedical subjects

O Edhag

Publications and source records attributed to O Edhag.

At least 91 records · Page 5Linked to original sources
PubMed1982

Ankylosing spondylitis: an important cause of severe disturbances of the cardiac conduction system. Prevalence among 223 pacemaker-treated men.

The cause of severe disturbances of the cardiac conduction system is seldom possible to establish clinically at pacemaker implantation, apart from cases of acute myocardial infarction or digitalis intoxication and in relatively rare cases of inflammatory disorders such as sarcoidosis and systemic sclerosis. Since cardiac manifestations, mainly conduction disturbances, occur in patients with ankylosing spondylitis, the prevalence of this disease was determined using radiologic screening for sacroiliitis in a population of 223 men who had permanently implanted pacemakers. Sacroiliitis was found in 19 men (8.5 percent), 15 of whom fulfilled the diagnostic criteria for ankylosing spondylitis. In six patients, sacroiliitis was asymptomatic and two of the patients were completely free of symptoms other than those originating from their heart manifestations. In seven of the 15 patients with ankylosing spondylitis and in the four patients with sacroiliitis without clinical criteria of ankylosing spondylitis, the diagnosis was previously unknown. Uveitis and aortic regurgitation occurred in five patients each, while peripheral arthritis was twice as common. The prevalence of sacroiliitis and ankylosing spondylitis of 8.5 and 6.7 percent, respectively, differ significantly (p less than 0.01) from the frequencies found in general Caucasian populations of 1 to 2 and 0.1 to 0.5 percent, respectively. HLA B27 was present in more than 80 percent of the patients with sacroiliitis and/or ankylosing spondylitis, compared with 8 to 10 percent in the general population. This strong association is in accordance with previous studies of patients with symptomatic sacroiliitis and/or ankylosing spondylitis. Thus sacroiliitis, diagnosed by x-ray, can be considered a marker for this relatively common rheumatic cause of severe disturbances of the cardiac conduction system.

Adolescent↗
PubMed1981

Associated conduction disturbances in patients with symptomatic sinus node disease.

Electrophysiological investigations were performed in 30 patients with symptomatic sinus node disease (SND) to assess the extent and distribution of associated functional disturbances in the conduction system. The tests were performed before and after inhibition of autonomous tone with propranolol, 0.1 mg/kg, and atropine, 0.02 mg/kg. Surface ECG had shown bundle branch blocks (BBB) in 5 patients and fascicular blocks in 2. AV block I had been recorded in 4 patients, while none had shown high-degree AV block. Malfunction was most often detected in the AV junction, 17 patients showing a prolonged conduction time or an abnormal effective AV node refractory period. Intraventricular conduction delay was present in 7 patients, with a prolonged HV interval in 3 and a complete permanent BBB in the others. Rate-dependent BBBs were demonstrated in a further 4 patients. Long cardiac arrests following interruption of atrial pacing, suggesting impaired automaticity also of subsidiary escape pacemakers, were seen in 11 patients. Only 6 patients, 20%, showed no signs of associated malfunction of the conduction system. Thus, detailed electrophysiological assessment demonstrated associated conduction abnormalities in the majority of these SND patients. The results agree with histopathological studies and show that sinus node malfunction is often the clinically apparent manifestation of a widespread degenerative process in the cardiac conduction system.

Adult↗
PubMed1981

Digital pulse volume in the evaluation of haemodynamic effects of cardiac pacing.

Some artificially paced patients experience symptoms referrable to competition between spontaneous and pacemaker-induced heart activity. Haemodynamic studies are necessary to establish a relationship. Non-invasive techniques are desirable. Because of the considerable variations in haemodynamic variables from one beat to another it seems necessary to do beat-to-beat analysis. In the present study a comparison has been made between digital arterial pulse amplitude (DAPA) and central haemodynamic parameters in six patients at different pacing modes. A good correlation was found between DAPA and arterial pulse pressure (r = 0.83-0.99). The mean difference in cardiac output between atrio-ventricular pacing and ventricular pacing with atrial activation in early systole was 1.11 /min (P less than 0.01). A mean increase of 70% in DAPA was found at optimal PR-time as compared to simultaneous atrial and ventricular activation; wide individual variations were, however, seen. The results presented indicate that peripheral pulse volume registrations may be helpful in evaluating the consequences of atrial contractions for haemodynamic variables and to find those paced who may benefit from atrial or bifocal heart stimulation.

Aged↗
PubMed1980

Diagnostic capacity of sinus node recovery time after inhibition of autonomous neural tone.

Symptomatic arrhythmias often occur intermittently in patients with sinus node dysfunction. A diagnostic test with ability to reveal latent sinus disease has therefore been much sought for. Determinations of sinus node recovery time (SNRT) and corrected sinus node recovery time (CSNRT) have been attempted but limitations in their diagnostic power are well recognized. To eliminate a possible masking effect of autonomous neural tone, propranolol 0.1 mg/kg and atropine 0.02 mg/kg was administered to 30 patients with established symptomatic sinus bradydysrhythmias (SSBD) and to a control group of 18 age-matched healthy volunteers. In addition the same procedure was applied to 9 patients with symptoms suggesting SSBD in whom, however, this cause was later excluded. The upper normal limit of CSNRT defined by the control group was 545 msec before and 505 msec after drugs. In the SSBD group, CSNRT was falsely negative in 8 of the 30 patients. Repeated testing after drug inhibition reduced this number to 2 patients. Thus, the sensitivity increased from 73% to 93%. CSNRT determinations were normal in the non-SSBD patients, specificity remaining at 100%. Thus, the discriminative power of electrophysiologic testing for sinus node disease was found to be high when CSNRT determinations were performed both before and after drug inhibition of autonomous neural tone.

Aged↗
PubMed1979

Long-term observation of pacemaker electrodes. A follow-up study of 328 consecutive patients treated between 1959 and 1967.

Epicardial electrodes implanted in 20 patients between 1959 and 1962 had a short-term effectiveness. A change to endocardial stimulation was later necessary in 15 of these patients. Endocardial electrodes inserted between 1962 and 1967 in 306 patients were included in this study; 121 (40%) of these patients survived for 10 years or more. Seventy-five (62%) of the long-term survivors had no problems with their electrodes. In 39 of these patients the stimulation thresholds were measured after both 5 and 10 years and found to be 2.3 +/- 0.6 volts and 2.2 +/- 0.8 volts, respectively. Hence, long-term complication-free endocardial pacing can be accomplished.

Adult↗
PubMed1979

Heart rhythm during permanent cardiac pacing.

Heart rhythm was analysed with regard to spontaneous or pacemaker-induced heart activity, in a consecutive series of 282 patients paced for at least 1 year. The mean duration of pacing was 59 (13 to 180) months. The mean age of the patients was 76 (39 to 93) years. Spontaneous heart activity at all routine examinations was found in 33 (12%) of the patients. Pacemaker-induced rhythm only was recorded in 42 per cent of the patients whereas the remaining 46 per cent had varying electrocardiographic patterns. Of the patients with spontaneous rhythm at each visit, 10 had had complete heart block before pacing. Regular sinus activity was recorded at every routine examination in 74 per cent of the patients paced for reasons other than the sick sinus syndrome. This indicated that a substantial number of paced patients might be candidates for atrial triggered pacing. Patients treated with digitalis more often had asystole at the time of replacement of the pacemaker (32%) than those not so treated (19). This suggests an increased risk of sudden death in paced patients on digitalis if the pacemaker fails.

Adult↗
PubMed1978

Non-invasive methods for evaluating the importance of heart rate and atrial activity in cardiac pacing. Results of ballistocardiography and digital plethysmography studies in six patients with heart block.

Ultralow frequency ballistocardiography (UFB) and digital pulse plethysmography (DPP) were performed in six patients with an external artificial pacemaker system. UFB was used mainly to evaluate the force of contraction of the left ventricle (IJ amplitude) and DPP for evaluating relative changes in the peripheral pulse volume. Four patients were studied at 40, 50, 60, 70, 80, 90 and 100 beats/min. There was a significant decrease (p less than 0.001) in LJ and pulse amplitudes when the heart rate increased from 40 to 100 beats/min. A positive correlation between relative IJ and pulse amplitude was observed in all cases studied. In beat-to-beat analysis it was found that the importance of the PR interval for the IJ and pulse amplitudes varied between patients. It is concluded that both UFB and DPP may be of value in clinical practice for evaluating hemodynamics in patients with slow spontaneous heart rate. The methods may be of help in selecting the most effective type of pacemaker for the individual patient.

Aged↗
PubMed1978

Influence of output capacitor, electrode and pulse width on power consumption in cardiac pacing.

Three different types of unipolar endocardial electrodes--47 in all--were compared in regard to power consumption at stimulation threshold with six different output capacitors and seven pulse widths. Fifteen were conventional large surface electrodes (area 47 mm2); 18 were conventional small surface electrodes (area 6 mm2), and 14 had a specially designed tip with a large area but small active surface of 8 mm2. Pulse widths ranged from 0.15 to 2.0 msec and output capacitors from 1.0 to 22.0 microFarads. All in all about 2,000 measurements were performed. The average current drain to the pacemaker output stage was measured and power consumption was calculated for each electrode--pulse width--output capacitor combination. In all combinations, the two small surface electrodes consumed approximately the same amount of power and, in both cases, significantly less than the larger one. With regard to power economy at stimulation threshold, the pulse width of choice was about 0.5 msec and, furthermore, power consumption decreased with increasing capacitor size. The optimal combination was a small surface electrode, an output capacitor of 22 microF and a pulse width of 0.5 msec.

Adult↗
PubMed1978

Complete heart block due to granulomatous giant cell myocarditis: report of 3 cases.

3 patients with chronic complete AV block were found at autopsy to have granulomatous giant cell myocarditis (GGCM). In 1 patient an unusual clinical course led to more extensive investigation including echocardiography which revealed ventricular septal abnormalities. A review of the literature is presented. Although GGCM is a rare disease echocardiography may be a useful screening procedure in patient with AV block especially in the presence of immunological disorders.

Adult↗