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Biomedical subjects

D M Krikler

Publications and source records attributed to D M Krikler.

14 recordsLinked to original sources
PubMed1979

Dual-demand pacing for refractory atrioventricular re-entry tachycardia.

An automatic dual-demand pacemaker has been used in six patients to treat refractory attacks of paroxysmal re-entry atrioventricular tachycardia that occurred in the Wolff-Parkinson-White syndrome. The pacemaker was designed to pace at a fixed rate of 70 beats per minute when sensed heart rates were either below this rate or above 150 beats per minute; in the latter case, it would compete with the paroxysmal tachycardia and interrupt it after a short period of random scaning. The best location for the permanent pacing electrode and the feasibility of using the pacemaker were tested in each case during a detailed preliminary intracardiac electrophysiological study. The permanent pacing electrode was positioned in the coronary sinus in three patients and was attached to the epicardium of either the left or right ventricle in another three. All patients were given regular oral doses of verapamil or propranolol to enhance the effectiveness of the pacemaker system and, with the latter, to prevent pacemaker activation during sinus tachycardia. Over a follow-up period of between 11 and 47 months, the pacemaker system remained completely effective in three patients, but developed unreliable sensing in another two (one coronary sinus and one left ventricular lead). In the sixth patient the pacemaker was only effective when the rate of the tachycardia remained below 170 beats a minute, as when she was resting supine; when sitting or standing, however, her tachycardia rate considerably exceeded this value and the pacemaker was ineffective. Explantation of the pacemaker and either successful cryosurgical ablation of the accesory AV pathway or treatment with amiodarone was undertaken in the three patients in whom the pacemaker had failed.

Adult↗
PubMed1978

Clinical value of tests of sino-atrial function.

Sinus node recovery times and the premature atrial stimulus test were studied in 36 patients, seven with gross sinus node disease, 25 with possible sinus node disease and four with no clinical evidence of sinus node disease. The corrected sinus node recovery time proved of most value in predicting which patients needed and would benefit from permanent pacemaker implantation, though there was one false negative diagnosis and two patients with abnormal corrected sinus node recovery times were asymptomatic. The premature atrial stimulus test usually proved to be of no practical value once severe sinus node disease was present and, in the group of patients with suspected sino-atrial disease, only 13 of 25 graphs could be analysed due to gross "scatter" in the others. When patients with symptoms have unequivocal evidence of sino-atrial dysfunction, invasive study seems unnecessary. With lesser degrees of sino-atrial disease, premature atrial stimulation may provide confirmatory evidence; but when sinus arrhythmia, atrial escape beats, or more marked dysfunction are present, one is likely to encounter useless "scatter" graphs. In the absence of regular sinus rhythm on the ECG, overdrive sinus node suppression in the only invasive study worth attempting.

Adolescent↗
PubMed1978

The relationship between posture, blood pressure and electrophysiological properties in patients with paroxysmal supraventricular tachycardia.

In 9 patients with paroxysmal supraventricular tachycardia the effects of tilting the body on the blood pressure and on responses during tachycardia or pacing revealed important effects that could influence the clinical presentation and the treatment required. Assessment of these reflex responses adds a major dimension to the understanding of the patient with supraventricular tachycardia.

Atrioventricular Node↗
PubMed1977

A spectrofluorometric method for the determination of ajmaline in plasma.

1 Ajmaline was found to have maximum fluorescence at neutral pH with 300 nm excitation and 365 nm emission wavelengths (corrected). 2 The fluorescence intensity had a linear relationship to concentration up to 50 microgram ml-1 and the recovery of ajmaline after extraction from plasma was 92.5 +/- 3%. 3 Extraction of drug-free plasma and of samples containing known concentrations of ajmaline showed that drug levels in the range found clinically could be measured accurately by fluorimetry. 4 Serial plasma ajmaline concentrations were measured in a subject after intravenous injection of ajmaline (50 mg). The rates of plasma clearance of the drug were found to be similar to those obtained in previous studies.

Ajmaline↗
PubMed1976

"Torsade de pointes" initiated by electrical ventricular stimulation.

Four cases are described in which electrical stimulation of the right ventricle produced the ventricular arrhythmia known as "torsade de pointes". This arrhythmia has previously been described as classically occurring in the context of the chronic bradycardias, particularly when there is also hypokalemia and a long QT interval, being most frequently initiated by a ventricular extrasystole occurring relatively late during ventricular repolarization. One patient had suffered a recent anterior myocardial infarction and developed the arrhythmia during rapid pacing for atrial flutter, when the electrode catheter had inadvertently entered the right ventricle. In the other three patients the arrhythmia was produced during the ventricular extrastimulus test performed during routine diagnostic electrophysiological investigation.

Adult↗
PubMed1975

[Verapamil in the study and treatment of supraventricular tachycardias, with special reference to pre-excitation].

Verapamil is a novel antiarrhythmic agent which appears to act as a calcium-ion antagonist, blocking calcium transport across the myocardial cell membrane. It was given intravenously, in a dose of 10 mg, to thirty-two patients suffering from paroxysmal supraventricular tachycardia, and sinus rhythm was achieved promptly in all. Identical results were obtained in a further ten patients with supraventricular tachycardias associated with the Wolff-Parkinson-White or other pre-excitation syndromes. In a separate group of eighteen patients in whom A-V junctional tachycardias were induced during intracardiac electrography, conversion to sinus rhythm was achieved in fifteen patients, with prolongation of the cycle length in the others. Circus-movement tachycardias were induced in eight patients with the Wolff-Parkinson-White syndrome, and conversion to sinus rhythm was achieved in seven. The results were less consistent in patients with other supraventricular arrhythmias including ectopic atrial tachycardia and atrial flutter, and, in the single patient with supraventricular and ventricular tachycardias, only the former was controlled. In the single patient with atrial fibrillation complicating the wolff-Parkinson-White syndrome who received Verapamil, sinus rhythm was restored. Side effects were few and mild, with rare exceptions of profound hypotension, bradycardia and asystole; their management is discussed, and reasons are advanced why their occurrence is likely to be related either to the concomitant administration of beta-adrenergic blockers or to the presence of sinoatrial disease. It appears that Verapamil is particularly suitable for the treatment of supraventricular tachycardias due to a circus movement as calcium antagonism is likely to be most effective in the N region of the atrioventricular node.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Paroxysmal reciprocating sinus tachycardia.

We present clinical and electrophysiological data on 9 patients with paroxysmal reciprocating sinus tachycardia (PRST) of whom only 6 described palpitations. Sinus node disease was present in 5 and cardiac ischemia and/or hypertension in another 3; the remaining case had apparently coincidental Wolff-Parkinson-White (WPW) syndrome. PRST could be initiated in all cases, and terminated in the 4 in whom it was sustained, by suitably timed atrial premature beats over a zone that was dependent on the effective atrial extrastimulus coupling interval (A1-A2) in the high right atrium (HRA). The sequence of atrial depolarization during PRST was similar to that of sinus beats although minor changes in both the P wave and the configuration of the HRA electrogram were observed in half the cases. During paroxysms, cycle length variation and sensitivity to alterations in vagal tone were common. In 6, paroxysms could be initiated by moderately rapid atrial pacing. Repetitive attacks were usually initiated by increases in the sinus rate and not be an antecedent premature atrial extrasystole. Verapamil suppressed sinus node reentry in 5 patients while small doses of atropine favored initiation in 3. PRST was seen in association with AV reentry tachycardias in the patient who had the WPW syndrome.

Adult↗