Biomedical subjects

E Sowton

Publications and source records attributed to E Sowton.

At least 73 records · Page 4Linked to original sources

PubMed1986

Early results after percutaneous transluminal coronary angioplasty in 400 patients.

In a consecutive series of 400 patients treated by percutaneous transluminal coronary angioplasty 212 had single vessel disease, 142 had multivessel disease with only one vessel dilated, and 46 had multivessel dilatation. In addition sequential stenoses were dilated in the same vessel in all groups. There was no mortality among patients with single vessel disease. Success rates varied from 83% to 90% according to the artery in which angioplasty was attempted. Urgent surgery was required by 3.8%. Primary success was lower (74%) in the presence of multivessel disease and complications were more frequent, with four deaths (2.8%). In 46 patients with multivessel disease in whom all important lesions were dilated during the same procedure the overall primary success rate was 76% and within the last year of the study it was 91%. One (2%) patient died and three (7%) required urgent surgery. Twelve (86%) out of 14 stenosed vein grafts were successfully dilated and eight (53%) chronically occluded vessels were re-opened; in both groups there were no deaths, no infarctions, and no need for urgent surgery. In all groups symptoms improved greatly and predischarge exercise tests showed that there was no reversible ischaemia in 94% of patients with single vessel disease or in 65% of patients with incomplete revascularisation. Six months after the procedure 95% of the patients had improved symptomatically and 80% had normal exercise tests after one year. Percutaneous transluminal coronary angioplasty is the method of choice in single vessel disease and its use also results in a high proportion of other patients becoming symptom free. Complication rates are low and for selected patients results that are equivalent to those of cardiac surgery are obtained.

Adult↗

PubMed1985

Effects of oral prajmaline bitartrate on exercise test responses in patients with coronary artery disease.

The safety, tolerability and haemodynamic effects of oral prajmaline bitartrate were assessed in a double-blind, randomized, placebo-controlled, crossover trial in 21 patients with stable angina pectoris and coronary artery disease. No serious side-effects occurred. Prajmaline bitartrate produced no statistically significant changes in resting heart rate or systolic blood pressure or in work capacity on the treadmill, or in heart rate or systolic blood pressure at maximum exercise compared to placebo values. No new arrhythmias or conduction abnormalities were produced in any patient. We conclude that oral prajmaline bitartrate is well tolerated and can be given safely to patients with coronary artery disease without producing deleterious haemodynamic effects or changes in exercise capacity.

Administration, Oral↗

PubMed1985

Stress testing predischarge and six weeks after myocardial infarction to compare submaximal and maximal exercise predischarge and to assess the reproducibility of induced abnormalities.

Submaximal and maximal treadmill exercise tests were performed predischarge in 64 patients after acute myocardial infarction to assess the relative yield of residual ischaemic abnormalities. The reproducibility of individual abnormalities resulting from maximal stress tests performed predischarge and 6 weeks after infarction was also assessed in 55 of these patients. Compared with predischarge submaximal exercise testing, a maximal exercise test identified a significantly greater number of patients with residual myocardial ischaemia (26 vs. 15, P less than 0.05) and this was associated with a significantly longer average maximal exercise duration (P less than 0.001), and a higher rate-pressure product (P less than 0.001). Among the 55 patients who had maximal stress tests both predischarge and 6 weeks after infarction, there was a significant lack of reproducibility in the occurrence of exercise induced angina (P less than 0.01) and an abnormal blood pressure response (P less than 0.02). In contrast, exercise induced ST segment depression and elevation and ventricular arrhythmias were relatively reproducible. More patients had an ischaemic test result (ST depression or angina) at the later test compared to the predischarge test (33 vs. 25 patients) but this increase was not statistically significant. There were, however, significant increases at the later test in mean maximal exercise duration (P less than 0.001). mean maximal heart rate (P less than 0.001) and heart rate-systolic blood pressure double product (P less than 0.001). The majority of patients who had a cardiac event in the period between the two tests had a predischarge test abnormality. We conclude that a significantly greater number of patients with residual reversible myocardial ischaemia after infarction will be identified by symptom limited exercise testing compared with a submaximal predischarge test. Because ST depression and elevation appear reproducible, patients who develop these abnormalities during a predischarge test do not, for prognostic reasons, need retesting 6 weeks after infarction. Exercise induced angina pectoris and an abnormal blood pressure response, however, are highly variable and in these patients a repeat test may be useful.

Adult↗

PubMed1985

Identification of pacemaker dependent patients by serial decremental rate inhibition.

In a study of the concept of pacemaker dependence, 86 patients who had permanent ventricular demand (VVI) pacemakers implanted for more than six months and were in predominantly paced rhythm underwent repeated interruption of pacing both abruptly and after gradual reduction of paced rate. Non-invasive pace slowing was accomplished by timed inhibiting pulses applied to the chest wall. The results identified a small group (A) of patients, 8% of those tested, who consistently failed to develop an adequate escape rhythm and may thus be considered highly pacing dependent. A second group B, 26%, developed an adequate intrinsic rhythm with serial decremental rate inhibition (SDRI) but suffered symptoms with abrupt complete inhibition (ACI). The remaining 66%, group C, developed no symptoms in any test. Analysis of clinical pre-test data showed that syncope, atrioventricular block and a low rate prior to implant, and a long duration of pacing were associated with a higher degree of pacing dependence, but were not reliably predictive. The clinical significance and value of the results are discussed. We conclude that SDRI is a reliable test for the high degree of pacemaker dependence and can be helpful especially in planning a procedure which may involve interruption of pacing.

Adult↗

PubMed1985

Diurnal variation in symptom-limited exercise test responses six weeks after myocardial infarction.

Diurnal variation of exercise test responses occurring during symptom-limited treadmill exercise testing was investigated in 45 patients six weeks after myocardial infarction. Each patient was exercised using a Naughton protocol before 8 a.m. and after 6 p.m. on the same day. No complications arose. There was no significant diurnal variation of any of the analysed exercise induced ischaemic abnormalities (angina pectoris or ST segment shift) or of the mean maximal exercise durations and achieved workloads. Mean maximal heart rates and heart rate-systolic blood pressure double products were similar in both tests. ST segment depression occurred in 21 patients and was totally consistent in both tests. An abnormal blood pressure response occurred in 14 patients in the morning test and in 18 patients in the evening test but this discordance did not reach statistical significance. Similarly there was no significant diurnal variation in exercise induced ventricular arrhythmias, although only three of the 11 patients in whom they occurred had this abnormality on both tests. We conclude that in this group of patients, no significant diurnal variation was observed in either exercise induced ischaemic abnormalities or in exercise haemodynamics during symptom-limited exercise tests performed six weeks after myocardial infarction. These data increase the confidence in clinical management decisions based on the results of this test.

Adult↗

PubMed1985

Low energies and Helifix electrodes in the successful ablation of atrioventricular conduction.

High energies delivered via standard pacing catheter electrodes produce permanent atrioventricular conduction block and generate high pressures. We investigate the use of lower energies and an active fixation electrode. Ten patients with refractory supraventricular tachycardias (six with paroxysmal atrial fibrillation, three with dual AV nodal pathways, and one with a concealed accessory atrioventricular pathway) were treated. A 6F Vitatron Helifix electrode was positioned to give the maximum His bundle deflection. Four shocks of only 50 joules each were delivered at 1-minute intervals. Long-term follow-up showed that seven patients (70%) had persistent complete heart block and two had atrial fibrillation with slower ventricular rates. Nine patients (90%) were symptom-free without antiarrhythmic therapy. Permanent pacemakers were implanted in eight patients. There were no complications resulting from the procedure. Transvenous ablation of atrioventricular conduction can be safely achieved using a Vitatron Helifix electrode and much lower energy values than have been previously employed.

Adult↗

PubMed1985

Submaximal exercise testing early after myocardial infarction. Difficulty of predicting coronary anatomy and left ventricular performance.

Impaired left ventricular function and extensive coronary artery disease are important determinants of prognosis after acute myocardial infarction. The ability of clinical and predischarge submaximal exercise test variables to predict multivessel coronary artery disease and impaired left ventricular function was assessed in 62 survivors of acute myocardial infarction. Abnormal exercise blood pressure response and short exercise performance were predictors of multivessel disease, but exercise induced ST segment changes and clinical variables were not. Q wave infarction, high grade Killip classification, and exercise induced ST segment elevation predicted statistically significant impairment of resting left ventricular function, whereas other clinical and exercise test variables did not. Exercise induced ST segment changes were therefore of little value in detecting extensive coronary disease, although exercise induced ST elevation was an indicator of poor resting left ventricular function. Although abnormal exercise haemodynamics may detect extensive coronary artery disease, other physiological markers of reversible myocardial ischaemia are probably necessary to plan optimal management in these patients.

Adult↗

PubMed1985

Effect of exercise on ventricular response to atrial fibrillation in Wolff-Parkinson-White syndrome.

Ten patients with Wolff-Parkinson-White syndrome underwent cardiac electrophysiological study extended to include the induction of atrial fibrillation at maximum exercise in the upright position. This was performed using a new temporary bipolar lead with a helical active fixation tip for atrial pacing. The highest rate of atrioventricular conduction via the accessory pathway was greater during exercise than at rest in all 10 patients (mean increase 28%). In three cases the resulting ventricular rate exceeded 300 beats/min, but no patient had severe symptoms or ventricular arrhythmias. The exercise induced enhancement of accessory pathway conduction may significantly but unpredictably affect the risk from spontaneous atrial fibrillation especially in patients with coronary artery disease or in those taking antiarrhythmic drugs. The test procedure was sufficiently simple and well tolerated to be included in our routine electrophysiological investigation.

Adolescent↗

PubMed1984

DHM 32-550 in patients with angina and normal coronary arteries: dose/response relationship.

This is the first report of the use of DHM 32-550 a dehydrogenated peptide ergot alkaloid with both alpha and beta adrenoceptor blocking activity, in patients with angina-like chest pain. Five patients were studied to assess a dose/response relationship. No deleterious effects on blood pressure occurred at either rest or on effort. The frequency of angina attacks and the number of glyceryl trinitrate tablets needed per week was appreciably reduced during treatment with both 'high' and 'low' dosages of the agent compared with placebo. The duration of treadmill exercise was appreciably prolonged. Within the limitations of this small, open pilot study, it appears that oral DHM 32-550 could be used safely in patients with chest pain due to cardiomyopathy or to coronary spasm.

Aged↗

PubMed1984

Safety, tolerability and efficacy of PN 200-110, a new calcium antagonist in patients with angina and coronary heart disease.

The safety, tolerability and efficacy of PN 200-110, a new calcium antagonist with minimal negative inotropic effects, were studied in twelve patients with stable angina pectoris and coronary artery disease. The study design was single-blind and placebo-controlled and increasing doses of the drug were used on consecutive days to investigate a dose response relationship. Eleven patients completed the trial. Response to the drug was evaluated using symptom limited cycle ergometric exercise. PN 200-110 in all three tested doses of 2.5 mg, 5.0 mg and 10.0 mg significantly increased the resting heart rate (p less than 0.02) and the exercise time to the onset of angina pectoris (p less than 0.02). Doses above 2.5 mg did not appear to improve the exercise parameters evaluated. Four patients had side effects probably due to PN 200-110 but these were mild and included dizziness, headache and flushing. There were no abnormal results from haematological and biochemical screening or from urine testing. We conclude that PN 220-110 can be given safely to patients with coronary artery disease without producing deleterious effects on blood pressure either at rest or during exercise.

Angina Pectoris↗

PubMed1984

Acute haemodynamic effects of ajmaline and prajmaline in patients with coronary heart disease.

Thirty patients undergoing cardiac catheterisation for coronary artery disease received parenteral ajmaline (15 patients) or prajmaline (15 patients). There were no statistically significant induced changes in left ventricular systolic or end diastolic pressures, indirect left atrial pressure, pulmonary artery mean pressure, cardiac output or left ventricular ejection fraction compared to control values. Intravenous prajmaline bitartrate in 15 patients with angina did not significantly alter work capacity, maximum exercise heart rate or systolic blood pressure compared to control values. Five patients developed transient minor conduction defects ( 2LBBB , 1 RBBB, 2 prolonged PR interval): all five were also receiving long-term treatment with beta blockers and nifedipine.

Adult↗

PubMed1984

A comparison of the Naughton and modified Bruce treadmill exercise protocols in their ability to detect ischaemic abnormalities six weeks after myocardial infarction.

Symptom-limited Naughton and modified Bruce treadmill exercise protocols were compared in 20 patients to assess their ability in detecting additional ischaemic abnormalities six weeks after myocardial infarction. Eleven patients had a result indicating reversible myocardial ischaemia on both tests while the other nine had no ischaemic abnormality during either of the two protocols. The only significant difference between the two protocols was the longer exercise duration resulting from the Naughton protocol (17.3 +/- 5.0 vs. 14.8 +/- 2.8 mins, P less than 0.01). The mean maximum heart rates, rate-pressure products and achieved workloads did not differ significantly. We conclude that even though the Naughton protocol resulted in a significantly longer mean maximum exercise duration, the protocols were equally effective in detecting additional ischaemic abnormalities six weeks after myocardial infarction.

Aged↗

PubMed1984

Successful treatment of ventricular tachycardia by physiological pacing.

The case is presented of a young patient with atrioventricular (AV) block but no evidence of other disease; in this patient exercise or stress-related syncope continued after implantation of a ventricular inhibited (VVI) pacemaker. Investigation revealed exercise-induced limited rapid multiform ventricular tachycardia (VT) which was associated with faintness or syncope. Temporary atrial triggered ventricular inhibited ventricular (VDD) pacing resulted in enhanced exercise tolerance with no significant arrhythmia. A permanent full function dual chamber (DDD) pacemaker was implanted and prevented the VT. There have been no further exercise-related symptoms during two years of follow up.

Adams-Stokes Syndrome↗

PubMed1984

Clinical results with the Tachylog antitachycardia pacemaker.

Tachylog is an implantable automatic multi-function device with several antitachycardia modes including "intelligent" search which is not preodained. Twenty-five patients have received Tachylog stimulators in England since December, 1982. Sixteen had supraventricular tachycardia with a mean rate of 220/minute and nine had ventricular tachycardia with mean rate in excess of 180/minute. Four patients with ventricular tachycardia died of poor coronary artery disease and two patients with WPW underwent bypass tract division because of very rapid atrial fibrillation on effort. Clinical control of all arrhythmias has been achieved in the remaining 19 patients. Eighty per cent of those with SVT and two out of five of those with VT need no drug therapy. Problems have been confined to sensing difficulties with early units.

Adult↗

PubMed1984

Comparative trial of iohexol 350, a non-ionic contrast medium, with diatrizoate (Urografin 370) in left ventriculography and coronary arteriography.

In a prospective double blind randomised study in 25 consecutive patients a conventional ionic contrast medium (Urografin 370) was compared with the new non-ionic medium iohexol 350 ( Omnipaque ) in left ventriculography and coronary arteriography. In left ventriculography there was a clear patient preference for iohexol by both a visual analogue scale and independent observer assessment. Iohexol also induced a smaller increase in heart rate or decrease in systolic blood pressure than Urografin. In coronary arteriography iohexol resulted in a smaller reduction in heart rate and systolic blood pressure, a smaller maximum increase in RR interval, less prolongation of the PQ and QT intervals and QRS duration, and a lower incidence of induced chest pain, ST segment depression, or T wave deflection.

Adult↗

PubMed1984

Submaximal exercise testing early after myocardial infarction. Prognostic importance of exercise induced ST segment elevation.

Seventy four patients (66 men, eight women; mean age 54.3 years) underwent submaximal exercise testing 7-23 days (mean 10.7) after acute myocardial infarction. Follow up was a mean period of 11.3 months. When compared with patients with no exercise induced abnormality, ST segment elevation, ST shift (depression or elevation or both), ST depression, inability to complete five metabolic equivalents, and inadequate blood pressure response to exercise were predictive of subsequent cardiac events (cardiac death, left ventricular failure, recurrent myocardial infarction, angina). When the presence or absence of specific variables was assessed, only ST elevation and ST shift predicted subsequent cardiac events. The presence of exercise induced ST elevation was the only exercise test variable which predicted cardiac death. ST segment elevation was, therefore, the exercise induced abnormality which best predicted the risk of future complications.

Adrenergic beta-Antagonists↗

PubMed1984

Diurnal variation and reproducibility of predischarge submaximal exercise testing after myocardial infarction.

Diurnal variation and reproducibility of abnormalities occurring during predischarge postinfarction treadmill exercise testing were investigated in 41 patients. Each patient was exercised using a limited Naughton protocol before 0800 and after 1800 h on two consecutive days. No complications arose. Individual ischaemic abnormalities were poorly reproducible in any patient. No abnormality and no patient showed significant diurnal variation. When the presence of any one of three ischaemic abnormalities (ST segment depression or elevation and angina) was analysed the reproducibility of an ischaemic result in the two morning and the two evening tests was 72% and 95% respectively with no significant difference between the two. The reproducibility of an ischaemic result in all four tests was 66%. The reproducibility of the test for either the presence or absence of an ischaemic result was 71%. No training effect could be shown either for the group as a whole or for any individual patient. There were no appreciable differences in either the heart rates or systolic blood pressures during exercise among those patients with non-reproducible ischaemic test results. Thus it is concluded that an assessment of any one of three ischaemic abnormalities improves the reproducibility of the result of submaximal exercise testing after infarction. Mechanisms other than increased myocardial oxygen consumption related to increased heart rate and systolic blood pressure at submaximal exercise tolerance are needed to explain non-reproducible ischaemic test results.

Adult↗

PubMed1983

Clinical evaluation of a single-pass implantable electrode for all modes of pacing. The "Crown of Thorns" lead.

Physiological pacing was instituted in 17 patients (11 men and 6 women), mean age 67 years (range 33-77 years), using a variety of multiprogramable generators attached to a permanent single-pass dual chamber electrode. Eleven patients were paced in VAT mode (Cordis 208A or Siemens-Elema 625 generator), two patients in DVI mode (Intermedics Cyberlith IV generator) and four patients in DDD mode (Siemens-Elema 664/P33 or Telectronics Autima unit). Mean intracardiac P wave amplitude was 2.0 mV +/- 0.78/SD, range 0.7-3.6 mV. and mean atrial and ventricular pacing thresholds were 1.0 V and 0.5 V, respectively. Fourteen patients had completely successful A-V pacing during a follow-up period of 4-13 months (mean 7 +/- 2.7 months). Two failures were associated with malposition of the atrial crown and occurred exclusively with the Cordis 208A generator. In both patients generator replacement using a more sensitive unit (Siemens-Elema 625) resulted in successful VAT pacing for most of the time. Complete failure of A-V pacing occurred in only one patient who died from coronary artery disease after four months of follow-up. Thus, all of the remaining 16 patients achieved long-term (6 months) satisfactory physiological pacing using this new lead. We conclude that the "Crown of Thorns" electrode is a successful single-pass unipolar lead and can be used with all types of dual chamber generator for all modes of pacing.

Adult↗