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Biomedical subjects

H Grendahl

Publications and source records attributed to H Grendahl.

At least 37 records · Page 2Linked to original sources
PubMed1979

Influence of high plasma concentrations of free-fatty acids on heart rhythm in healthy fasting men.

Ten healthy male student in regular sinus rhythm fasted for 66 hours. Their overnight fasting plasma concentration of free fatty acids (FFA) was 455 +/- 104 micro mol/1 (mean +/- S.E.M., n=7), the reference value of our laboratory, measured in another normal population of young men, being 344 +/- 28 micro mol/1 (n=10). After 42 and 66 hours of fasting, the plasma concentration of FFA rose to 1198 +/- 181 (p less than 0.01, n=10) and 1471 +/- 89 micro mol/1 (p less than 0.001, n=10), respectively. During the last 24 hours of fasting, the heart rate rhythm was monitored continuously by means of a Holter recorder and computer. No arrhythmias were observed, indicating that elevated plasma concentrations of FFA, exceeding those reported in patients with acute myocardial infarction, are well tolerated by the healthy human myocardium.

Adult↗
PubMed1979

Escape rhythm in complete A-V block. The recovery phase after overdrive suppression from artificial ventricular suppression from artificial ventricular pacing.

In 60 patients with third degree A-V block, recovery of escape rhythm from overdrive suppression after ventricular pacing has been studied. Implanted unipolar VVI pacemakers were inhibited by chest wall stimuli. A total of 165 rhythmograms were studied. In 37, the rate was irregular, in the other 128 the escape rate increased gradually, following an exponential curve until stabilization after 3 minutes. In 29 of these rhythmograms, a possible exit block of the first escape impulse was observed. In 99 rhythmograms without exit block, escape rhythm recovery time was an average 1.45 times basal escape RR intervals. Overdrive suppression was most marked in patients with a slow escape rhythm.

Cardiac Pacing, Artificial↗
PubMed1978

Overdrive suppression of implanted pacemakers in patients with AV block.

Patients being permanently paced for symptomatic AV block were studied by overdrive suppression of the QRS-inhibited pacemaker, in order to observe the underlying heart rhythm. The chest wall stimulation method was used. In complete AV block the escape rhythm recovery time proved highly reproducible on repeated testing on the same day, and in many patients remained so over months or years. Occasionally, a doubling of the escape rhythm recovery time was seen, suggesting initial exit block of the escape focus. Resetting of the escape rhythm usually followed an exponential curve until stabilisation after about 3 minutes. An early escape rhythm with a recovery time of less than 4 seconds was found on every occasion in 21 of 58 patients with complete AV block, and inconstantly in 23 more; in 14 it was never observed. Accidental pacing failure was seen in 15 patients. The overdrive suppression test was helpful in selecting pacemaker dependent patients.

Aged↗
PubMed1976

Pacemaker wires and electrodes. A follow-up study.

In 362 patients on permanent pacing, a follow up with regard to pacemaker electrode function time and connection to pulse-generators has been carried out. In 12 patients Elema epicardial electrode were used with an average function time of 3.8 years. 232 Elema EMT 588 endocardial electrodes were used in 216 patients. Average observation time for the electrodes was 3.3 years. Sixty-eight electrodes have been followed for more than 5 years. Early electrode complications comprise 10 per cent of displacements before implantation of the pulse-generator and another 6 per cent of electrode displacements within the first 3 months after implantation. Eleven per cent of the electrodes had to be corrected due to high threshold value before implantation and another 6 per cent during the first 3 months after implanattion of pulse-generator. On hundred and fifty-five unipolar electrodes of the types Cordis, Medtronic, Elema EMT 282, and Stanium were implanted in 149 patients. Average observation time for the electrodes were 1.2 years. During the first 3 months after pacemaker implant 7 per cent of the electrodes were dislocated, 5 per cent failed due to high threshold value. Three perforations of the right ventricle occurred, without serious complications. Late complications i.e. after 3 months, for EMT 588 electrode included 4 per cent electrode dislocations, 4.5 per cent failure due to high threshold, 3 cases of wire break and 4 defects in the insulation. Many of the late electrode complications were probably caused by replacement operations for pulse-generators. The most frequent late complications for the conventional unipolar electrode was wire break which occurred in 5 cases.

Arrhythmias, Cardiac↗
PubMed1976

Routine pacemaker control, and selective replacement of pulse generators. A cost/benefit analysis.

Two hundred and fifty patients with permanent pacemaker have been followed up with routine pacemaker controls in a pacemaker clinic for a 21 months period 1/3-73 to 1/1-75. Ninety-five pulsegenerators were replaced. Sixty-two of the replacements were due to impending battery exhaustion, nine elective and 24 for other reasons. Signs discovered by the patients led to replacements in 21 cases for impending battery exhaustion and in 17 cases for other reasons. Forty-one replacements for impending battery exhaustion and 7 other replacements followed a scheduled visit to the pacemaker clinic. The selective replacement policy resulted in an average gain of pulsegenerator lifetime of 6.5 months, compared to a 24 minths elective replacement policy. Increased safety is obtained by routine control of pacemaker patients in a pacemaker clinic.

Action Potentials↗
PubMed1976

Diazepam in acute myocardial infarction. Clinical effects and effects on catecholamines, free fatty acids, and cortisol.

Diazepam is a valuable drug in cases of acute myocardial infarction. The 10 mg intravenous loading dose and the subsequent 15 mg oral dose of diazepam administered three times daily produced safe, pleasant sedation, and reduced the need for analgesics. A much reduced excretion of catecholamines was recorded. It is presumed that diazepam causes a lower stress reaction, which is beneficial in diminishing the incidence of malignant arrhythmias and preventing the existing myocardial injury from spreading.

Adult↗
PubMed1975

Registration of sinus node recovery time in patients with sinus rhythm and in patients with dysrhythmias.

Sinus node recovery time (SRT) after rapid atrial pacing has been recorded in 66 patients, 28 with coronary heart disease, 11 with advanced AV block, 10 with sick sinus syndrome and 17 with paroxysmal tachyarrhythmias. In patients with a normal functioning sinus node SRT was related to the basal heart rate. On an average SRT was 130% of the basal P-P interval with an upper limit of 160%. In patients with a presumed normal atrial function the mean SRT was found to be 1 080 msec, with an upper limit of 1 500 msec. This corresponds with previously published observations. In all 5 patients examined, beta-receptor blockade (propranolol 5 mg i.v.) prolonged SRT. The prolonged SRT was related to sinus bradycardia. Verapamil (Isoptin 5 mg i.v.) had no effect on SRT in the 7 patients examined. The observation of an SRT of more than 1 500 msec indicates a poor sinus node function. Recording of a normal SRT, however, cannot exclude a sinus node dysfunction, as normal SRT is occasionally found even in patients with a clinically proved dysfunction.

Arrhythmia, Sinus↗
PubMed1975

The effect of propranolol and verapamil on atrial and atrioventricular refractory periods in man.

The atrial effective (ERP) and relative (RRP) refractory periods were examined at high atrial pacing rates in 12 patients before and after intravenous injection of propranolol, and in 5 patients before and after injection of verapamil, using the technique of paired pacing. Seven of the patients had A-V block grade II-III and 10 patients had sinus rhythm. The range of atrial ERP in all patients was found to be 200 to 270 msec. and the range of atrial RRP was 230 to 330 msec. The atrial ERP and RRP were longer at a pacing rate of 160 per minute than at a pacing rate of 240 per minute. The conduction delay between the second impulse and the atrial depolarization was found to be due to increased interval between the stimulus and the start of the depolarization wave. The atrial ERP increased after injection of propranolol in 8 of 12 patients, decreased in 3 patients and was unchanged in one patient. The atrial RRP increased in 7 patients, decreased in one patient and was unchanged in 4 patients. In all patients the changes were of moderate degree. The conduction delay between the stimulating impulse and the atrial response was shorter after propranolol in 7 patients, longer in one patient and unchanged in 4 patients. The ERP of the atrioventricular conducting tissue was 220 to more than 380 millisec. After injection of propranolol it increased in all of 3 patients in whom it could be measured. After injection of verapamil no significant effects on the atrial ERP and RRP were found. ERP of the atrioventricular conducting tissue was lengthened in 4 of 5 patients, and the degree of A-V block during rapid atrial pacing increased after injection of verapamil. It is suggested that the effect of propranolol on atrial arrhythmias is due to its effect on ectopic pacemaker activity rather than any effect on the refractory period of the atrium. The effects of verapamil on the atrioventricular conducting tissue may explain some of the antiarrhythmic effects of this drug.

Adult↗