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Biomedical subjects

E Rowland

Publications and source records attributed to E Rowland.

123 records · Page 7Linked to original sources
PubMed1981

Role of calcium antagonists in cardiovascular therapy.

The development of drugs which selectively block the "slow" channels by which calcium enters the cell (calcium antagonists) has provided valuable information about the role of transmembrane calcium exchange in man and has offered new therapeutic approaches. The principal effect on the cardiovascular system is relaxation of vascular smooth muscle but some of these drugs also have electrophysiological effects, especially slowing of conduction in the atrioventricular node; verapamil is the agent of choice in supraventricular tachycardia. Significant myocardial depression does not usually occur with doses used clinically. The calcium antagonists have specific value in variant angina. By causing peripheral vasodilatation they are also effective hypotensive agents and do not cause reflex tachycardia in chronic use. Their value in hypertrophic cardiomyopathy and in the protection of ischaemic myocardium remains to be proven.

Angina Pectoris↗
PubMed1980

Sudden death in hypertrophic cardiomyopathy: associated accessory atrioventricular pathways.

Sudden death is a known but unpredictable complication of hypertrophic cardiomyopathy. We describe two patients who both had a strong family history of the disorder complicated by sudden death. Necropsy disclosed accessory bypass tracts, concealed in one and previously suspected in the other. One died from ventricular fibrillation and the other, who died outside hospital, had previously complained of palpitation. Arrhythmia complicating pre-excitation appears to be one of the factors responsible for sudden death in hypertrophic cardiomyopathy.

Adolescent↗
PubMed1980

Electrophysiological manifestations of non-penetrating cardiac trauma.

Electrophysiological disturbances were observed in four cases of non-penetrating cardiac trauma. Ventricular tachycardia occurred both as an early and late complication in three, responding to medical treatment in two; it was cured by cryoablation in the other case. The fourth patient developed an isolated conduction defect associated with anteroseptal myocardial infarction, the coronary arteries and left ventricular function being normal.

Adult↗
PubMed1980

Electrophysiological assessment of amiodarone in treatment of resistant supraventricular arrhythmias.

Oral amiodarone has been used to treat 21 patients with various supraventricular arrhythmias; 13 had Wolff-Parkinson-White syndrome, which was complicated by atrial fibrillation and re-entry atrioventricular tachycardia in four, and re-entry tachycardia alone in the other nine. The remaining eight patients had paroxysmal atrial fibrillation or flutter without pre-excitation. All were refractory to conventional treatment and had undergone intracardiac electrophysiological study. Fifteen have been controlled with amiodarone, this treatment proving most effective in atrial fibrillation or flutter with or without pre-excitation. Amiodarone was successful in only four of the nine patients with re-entry atrioventricular tachycardia. In two patients who responded well the drug had to be discontinued because of side effects.

Adult↗
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↗
PubMed1979

Effect of nifedipine on atrioventricular conduction as compared with verapamil. Intracardiac electrophysiological study.

Intravenous nifedipine, a powerful calcium antagonist, had no obvious effect on atrioventricular conduction when administered to 11 patients during routine intracardiac electrophysiological studies. Verapamil on the other hand showed potent antiarrhythmic properties, depressing atrioventricular nodal conduction. Nifedipine thus appears safe in patients with angina pectoris who have disorders of atrioventricular nodal conduction, and in those receiving beta-adrenergic blocking drugs. There appear to be differential effects on the slow inward channels of cardiac cells with different 'calcium antagonists'.

Adolescent↗
PubMed1979

Electrophysiological effects soon after intravenous beta-methyldigoxin.

The digitalis derivative beta-methyldigoxin has been shown to be quickly and well absorbed from the gut and, in hemodynamic studies, to start acting rapidly after intravenous administration. However, when tested on 6 patients suffering from paroxysmal reciprocating atrioventricular tachycardia, or having an accessory pathway who might develop this disorder, there was no effect on induced tachycardias or on AV conduction during rapid atrial pacing or the extrastimulus test. One of the 6 patients showed some increase in refractoriness of conduction through the AV node within 25 min after the injection. Beta-methyldigoxin does not appear to be a satisfactory alternative to other effective agents available for the prompt correction of paroxysmal reciprocating atrioventricular tachycardia.

Adolescent↗
PubMed1979

'Bradycardia-tachycardia' syndrome 8 yr after correction of Fallot's tetralogy.

A 13-yr-old boy presented with atrial flutter 8 yr after surgical correction of tetralogy of Fallot; antiarrhythmic therapy caused depression of the sinoatrial node, with syncope. Disordered sinoatrial function and intraventricular conduction were demonstrated by intracardiac electrography, and appear to have resulted from the operation. Sinoatrial disease may be responsible for supraventricular arrhythmias or syncope long after operative correction of Fallot's tetralogy and may be one of the explanations for the tendency of such patients to die suddenly.

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↗
PubMedDate not supplied

Inappropriate shocks in patients receiving internal cardioverter-defibrillators for malignant ventricular arrhythmias.

Implantation of internal cardioverter defibrillators (ICDs) for treatment of malignant ventricular arrhythmias is complicated by failure of therapy or inappropriate shocks. We studied 81 patients (age range 16-72 years; mean 48 +/- 13 years) who underwent ICD implantation for device therapy. The underlying aetiology was ischaemic heart disease (39%), cardiomyopathies (32%) and others (28%). Information regarding shocks was collected using Holter monitoring, telemetry or device memory (stored electrograms) and lastly by clinical follow-up. Fifty-eight patients completed 36 months of follow-up. Thirty-five patients experienced 337 spontaneous shocks, appropriate in 21, inappropriate in 12, and both in two patients. Of the 74 episodes of inappropriate discharges for rhythms other that ventricular tachycardia (VT) or ventricular fibrillation(VF), 55 percent were due to supraventricular arrhythmias (atrial flutter or fibrillation). Lead malfunction occurred in four and the device was replaced in two. Additional drugs controlled AF in one. There was no mortality in any of the 81 patients. The frequency of shocks was highest in the first six months after implantation and atrial fibrillation remains the main cause. In conclusion, inappropriate shocks are frequent in patients undergoing ICD implantation.

Adolescent↗