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Biomedical subjects

E Sowton

Publications and source records attributed to E Sowton.

At least 91 records · Page 5Linked to original sources
PubMed1983

"Crown of thorns" single pass lead--clinical results.

Twenty-four patients have been treated for periods of up to two years (mean 14 months) with this single pass electrode for physiological pacing. Manufacturing refinements now allow percutaneous insertion into the subclavian vein. Pacing thresholds and sensing signals from both atrium and ventricle have remained satisfactory for a wide variety of different physiological pacemakers. No complications specifically related to the lead have occurred in a total of 277 patient months. We conclude that this single pass electrode is suitable for long-term implantation and can provide physiological pacing with present day stimulators.

Adult↗
PubMed1983

Transcatheter occlusion of coronary to bronchial anastomosis by detachable balloon combined with coronary angioplasty at same procedure.

The first case of non-operative occlusion of a large coronary to bronchial anastomosis is described. The patient who had severe angina had also a critical stenosis of the anterior descending coronary artery which was successfully dilated by an angioplasty procedure. An occluding balloon was detached in the large distal circumflex coronary artery, beyond all the normal branches. At a repeat catheterisation study seven months later the balloon was intact and in position, and the anastomosis remained occluded.

Aged↗
PubMed1982

Successful late non-surgical removal of intracardiac catheter fragment.

A patient was discovered to have a retained intracardiac catheter fragment more than two years after successful aortic valve replacement. During this time the patient had had extensive investigations and several hospital admissions for suspected subacute bacterial endocarditis, as well as for episodes of supraventricular tachycardia. The catheter fragment was successfully removed via a percutaneous catheter approach despite the very long interval that had elapsed since its detachment.

Cardiac Catheterization↗
PubMed1981

Programmed stimulation for long-term treatment and non-invasive investigation of recurrent tachycardia.

Eleven patients with recurrent tachycardia refractory to drugs were treated by a pacemaker system that consisted of an implanted QRS triggered stimulator activated by the application of stimuli to the patient's skin. These skin stimuli are derived by a small control box carried about in the pocket or handbag and which the patient holds in his hands to make contact with the electrode plates during a tachycardia attack. If the heart rate is higher than the preset value on the control box, timed stimuli are delivered to the skin. The tachycardia is stopped by a premature ventricular contraction induced during the "termination window", a period that occurs very soon after the refractory period. The skin impulses continue to be delivered until the tachycardia stops. The eleven patients were followed up for more than 2 1/2 years and about 2000 episodes were reliably stopped by this pacemaker system. Patients do not feel the skin stimuli and there were few complications.

Adult↗
PubMed1981

Treatment of paroxysmal nodal tachycardia by dual demand pacemaker in the coronary sinus.

A patient with refractory paroxysmal atrioventricular nodal re-entrant tachycardia had required direct current cardioversion to terminate attacks on 83 occasions. A dual demand pacemaker was implanted to sense and interrupt attacks of tachycardia automatically. The pacing electrode was positioned in the proximal coronary sinus near to the atrioventricular node; a site from which fixed rate underdrive pacing successfully interrupted attacks throughout a trial period of one week, with a lead left in this position on a temporary basis. Complete control of the arrhythmia was obtained in the six months after pacemaker implantation.

Aged↗
PubMed1981

Segmental quantitative analysis of digital thallium-201 myocardial scintigrams in diagnosis of coronary artery disease. Comparison with rest and exercise electrocardiography and coronary arteriography.

One hundred and forty-nine patients with suspected ischaemic heart disease were evaluated by exercise thallium-201 myocardial scintigraphy (201Tl SMS), single lead exercise electrocardiography, and coronary arteriography. Myocardial distribution of tracer was assessed semi-quantitatively from digital 201Tl scintigrams and compared with tracer distribution in subjects with normal hearts. Fifty-two of 54 (96%) patients with normal coronary arteries had normal myocardial scintigrams whereas three patients had a positive ischaemic exercise electrocardiogram and were scan normal. Conversely, 36 of 95 (38%) patients with coronary artery disease had a positive ischaemic electrocardiogram compared with 94 of 95 (99%) patients who had a positive myocardial scintigram. Disease in specific coronary arteries could be deduced from the topography of myocardial tracer deficit. Disease was predicted correctly in 76 out of 80 (95%) of left anterior descending coronary stenoses, in 48 out of 64 (75%) of right coronary artery stenoses, and in 55 out of 64 (85%) of left circumflex coronary artery stenosis, despite the presence of infarcted myocardium in other territories. Similarly, single vessel disease was predicted correctly in 14 out of 17 (82%) patients and multiple vessel disease in 64 out of 77 (83%) patients. 201Tl SMS with segmental quantitative analysis is a highly sensitive and specific technique in the diagnosis of coronary artery disease and may be useful screening procedure to select patients for further investigation, particularly those with evidence of life-threatening severe left coronary artery disease.

Adult↗
PubMed1981

Double-blind trial of nifedipine in angina patients with normal coronary arteries.

A double-blind trial was carried out in 33 patients with the syndrome of angina and normal coronary arteries, comparing the effects of nifedipine and placebo on the frequency and severity of anginal attacks, glyceryl trinitrate consumption and exercise tolerance. Electrocardiograms were abnormal at rest in 16 and normal in 17 patients. Five patients developed electrocardiographic changes suggestive or myocardial ischaemia on exertion. Exercise thallium 201 scintigraphy showed evidence of regional myocardial ischaemia in 4 patients. Of 30 patients who completed the trial, 16 reported fewer, less severe anginal attacks on nifedipine than on placebo; glyceryl trinitrate consumption was lower during nifedipine thn during placebo therapy. However, the reduction in angina and glyceryl trinitrate consumption in the group as a whole was not statistically significant; the results from 1 particular patient heavily influenced the statistical analysis against significant benefit from nifedipine. Exercise tolerance was similar on nifedipine and placebo. Two-thirds of the patients reported unwanted effects from nifedipine; 3 patients withdrew because of intolerable side-effects. It is concluded that nifedipine may reduce the frequency and severity of anginal attacks in some patients with angina and normal coronary arteries but the high incidence of side-effects may limit its usefulness.

Adult↗
PubMed1980

Functional significance of coronary collateral circulation during dynamic exercise evaluated by thallium-201 myocardial scintigraphy.

Sixty-five patients with angiographically documented coronary artery disease were investigated by thallium-201 (201Tl) scintigraphy to determine the role of the collateral circulation during dynamic exercise. Fifty-three patients had complete proximal occlusion of at least one major coronary artery. One patient had total occlusion of all three major coronary arteries. Sixty-four collateral channels were identified, graded, and compared with corresponding regions of the myocardial scintigram. Tracer uptake was also graded and classified as various degrees of protection from ischaemia. A significant correlation between good collaterals with complete protection and poor or absent collaterals with no protection was noted. Seventeen patients (20 occluded vessels) had total coronary occlusion without myocardial infarction. Collaterals conferred protection in 9/15 occlusions whereas no protection was seen in five occlusions without collaterals. There was no difference in the protective role of homocoronary and heterocoronary collateral vessels. Hypertrophy of the first septal left anterior descending perforator conferred significant protection from ischaemia in contrast to bridging collaterals and ghosting. During exercise the right coronary bed is preferentially protected from ischaemia, in contrast to the left anterior descending territory. This probably reflects the direction of a transmural flow gradient between left and right ventricles during exercise.

Adult↗
PubMed1980

Exercise thallium-201 myocardial scintigraphy in the follow-up of aortocoronary bypass graft surgery.

The predictive accuracy of exercise thallium-201 (201Tl) myocardial scintigraphy in the evaluation of aortocoronary bypass graft surgery was assessed in 48 patients undergoing angiographic investigation 15 months (mean time) after myocardial revascularisation. 201Tl scintigrams detected 61 out of 77 (79%) patent grafts but only 21 out of 42 (50%) occluded grafts, though, for grafts supplying non-infarcted myocardium, the predictive accuracy of graft patency and graft occlusion was 85 per cent and 81 per cent, respectively. Stress electrocardiography failed to detect 15 out of 21 patients with scintigraphic evidence of regional myocardial ischaemia. Residual ischaemia in the proximal left anterior descending coronary distribution was commonly detected in 201Tl scintigrams despite a patent, well-functioning left anterior descending graft to the distal coronary segment. Additional residual ischaemia attributable to ungrafted coronary disease was detected by scintigraphy in 32 (67%) patients and most commonly occurred in the distribution of the diagonal branch of the left anterior descending especially in the presence of a patent distal left anterior descending graft. Thus, independent grafts to the diagonal branch of the left anterior descending are recommended at the time of aortocoronary bypass graft surgery.

Adult↗
PubMed1980

Cardiac tumours: non-invasive detection and assessment by gated cardiac blood pool radionuclide imaging.

Four patients with cardiac tumours were investigated by gated cardiac blood pool radionuclide imaging and echocardiography. Contrast angiocardiography was performed in three of the cases. Two left atrial tumours were detected by all three techniques. In one of these cases echocardiography alone showed additional mitral valve stenosis, but isotope imaging indicated tumour size more accurately. A large septal mass was detected by all three methods. In this patient echocardiography showed evidence of left ventricular outflow obstruction, confirmed at cardiac catheterisation, but gated isotope imaging provided a more detailed assessment of the abnormal cardiac anatomy. In the fourth case gated isotope imaging detected a large right ventricular tumour which had not been identified by echocardiography. Gated cardiac blood pool isotope imaging is a complementary technique to echocardiography for the non-invasive detection and assessment of cardiac tumours.

Adult↗
PubMed1980

New intervention in mitral valve prolapse. Use of cold pressor test during echocardiography.

A study was performed in 13 patients with idiopathic mitral valve prolapse and in 21 control subjects to assess the effect of the cold pressor test on systolic motion of the mitral valve. A significant increase in blood pressure occurred in 10 patients with mitral valve prolapse and in 19 controls after immersion of one hand in ice-cold water. M-mode echocardiographic recordings from the mitral valve were obtained in all patients before, during, and after the cold pressor test, together with simultaneous phonocardiograms in selected patients. Nine out of 10 patients with mitral valve prolapse and a hypertensive response to the cold stimulus showed a significant increase in the depth of mitral valve prolapse during the cold pressor test whereas in three patients with mitral valve prolapse and no hypertensive response the depth of mitral valve prolapse did not change during cold stimulation. Three patients with previously demonstrated mitral valve prolapse had equivocal resting echocardiograms but developed diagnostic evidence of mitral valve prolapse during the cold pressor test. No evidence of mitral valve prolapse was seen in any of the control subjects before, during or after the cold pressor test. In four patients with mitral valve prolapse and a hypertensive response to cold stimulation the systolic click was delayed by the cold pressor test, whereas the time of the systolic click remained constant in the three patients whose blood pressure did not increase. It is concluded that the cold pressor test provides a stimulus sufficient to delay the onset and increase the depth of mitral valve prolapse, thereby enhancing the diagnostic sensitivity of echocardiography in this condition.

Adult↗
PubMed1980

Assessment of chest pain in hypertrophic cardiomyopathy using exercise thallium-201 myocardial scintigraphy.

Exercise thallium-201 myocardial scintigraphy was performed in 23 patients with hypertrophic cardiomyopathy. Eighteen patients presented with chest pain which was a persistent symptom in 11. Selective coronary arteriography was performed in 16 patients and showed normal coronary arteries in 15 and insignificant luminal irregularities in one patient. Eighteen patients had abnormal scintigrams. Three had an abnormal distribution of tracer entirely attributable to asymmetric septal hypertrophy, whereas 15 had discrete tracer uptake defects which could not be explained solely by myocardial hypertrophy. In this latter group of patients three scintigraphic patterns were identified: (1) in 10 patients defects were seen in scintigrams immediately after exercise but not in delayed images obtained four to six hours later. Eight of these patients had chest pain. (2) Four patients had uptake defects seen in both initial and delayed images. One patient had chest pain. (3) In three patients, one of whom had chest pain, tracer defects were seen only in delayed images and were not apparent in the initial scintigrams. Chest pain occurred in eight out of 10 patients with scintigraphic evidence of myocardial ischaemia but was present in only three out of 13 patients with non-ischaemic scintigrams. The value of exercise thallium-201 myocardial imaging as a diagnostic technique in hypertrophic cardiomyopathy appears limited. Scintigraphic evidence of regional myocardial ischaemia in the absence of significant coronary artery disease, however, contributes to an understanding of the mechanism of angina production in patients with hypertrophic cardiomyopathy.

Adult↗
PubMed1980

Early occlusion and late stricture of normal coronary arteries following blunt chest trauma.

A 27-year-old man had inferior myocardial infarction following superficial chest trauma. Coronary arteriography documented an isolated total occlusion of the right coronary artery, probably caused by localized extra-coronary compression, and no other evidence of intrinsic coronary disease. The left anterior descending artery later developed a localized proximal stenosis, most likely due to mural thrombus, which progressed rapidly to cause anterior myocardial infarction despite coronary artery surgery. The etiology of this lesion is discussed and support given to the "encrustation" hypothesis of human atherosclerosis. Exercise thallium scintigraphy proved helpful in the management of this case.

Adult↗
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

Cold-pressor test.

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Cold Temperature↗
PubMed1979

[Method for long-term pacemaker treatment of refractory reentry tachycardias].

A new method for pacemaker treatment of refractory reentry tachycardias has been developed which in 5 patients proved effective over a period of up to ten months. The system consists of a modified QRS-synchronous pacemaker and an external trigger unit. During tachycardia the external unit senses pacemaker spikes and by timed skin stimulation activates the implanted pacemaker to provoke the ventricular premature beats necessary for interruption of the tachycardia. The system also allows repetitive non-invasive programmed stimulation of the heart.

Adult↗