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Biomedical subjects

D E Ward

Publications and source records attributed to D E Ward.

At least 163 records · Page 9Linked to original sources
PubMed1988

Initial clinical experience with a minute ventilation sensing rate modulated pacemaker: improvements in exercise capacity and symptomatology.

A minute ventilation sensing rate modulated pacemaker was implanted in nine patients with bradycardia. Minute ventilation is sensed in this pacemaker by means of a standard bipolar pacing electrode. Compared with exercise in the constant rate ventricular pacing (VVI) mode at 1 month after pacemaker implantation, rate responsive pacing resulted in an improvement of exercise capacity of 33 +/- 5% (from 437 +/- 42 s in the VVI mode to 593 +/- 57 s in the rate modulated mode, P less than 0.01, Bruce protocol). This improvement was maintained in the seven patients in whom an exercise test was repeated at 3 months after implantation. The pacing rate was significantly correlated with oxygen consumption (r = 0.84 +/- 0.04) and measured minute ventilation (r = 0.76 +/- 0.06). Symptomatology in these patients was assessed by means of self-assessment questionnaires in a double blind, randomized cross-over study in which the pacemaker was alternatively programmed into the VVI and rate modulated modes. Significant improvements in "shortness of breath" and "energy during daily activities" were documented during rate modulated pacing and "palpitations" and "chest pain" were not worsened. Most patients preferred the rate modulated mode during the study. In conclusion, rate modulated pacing by sensing minute ventilation resulted in better exercise capacity and symptomatology. The pacing rate also showed good correlation with the individual's oxygen requirement.

Adult↗
PubMed1988

High gain signal averaged electrocardiogram combined with 24 hour monitoring in patients early after myocardial infarction for bedside prediction of arrhythmic events.

The value of the high gain, signal averaged electrocardiogram combined with 24 hour electrocardiographic monitoring in the prediction of arrhythmic events was assessed in 159 patients in the first week after myocardial infarction. Eleven patients (7%) suffered arrhythmic events during a mean (SD) of 12 (6) months of follow up (range 2-22, median 13 months). The combination of high gain, signal averaged electrocardiography and 24 hour electrocardiographic monitoring was more accurate than either technique alone or than clinical information collected during admission in predicting these events. The combination identified a high risk group of 13 (8%) patients, with an arrhythmic event rate of 62% and a low risk group with an event rate of 2%. The combination of high gain, signal averaged electrocardiography and 24 hour electrocardiographic monitoring in the first week after myocardial infarction provides a rapid, cheap, and non-invasive bedside method for the prediction of arrhythmias.

Adult↗
PubMed1988

Automatic implantable defibrillators.

The automatic implantable defibrillator was developed in the USA by Mirowski. This device automatically detects ventricular fibrillation or ventricular tachycardia and delivers a low energy (30 J) shock directly to the myocardium via patch electrodes on the epicardial surface or through a combination of a pericardial patch and an endocardial wire. These devices are being implanted in large numbers in the USA and represent a major contribution to the management and refractory ventricular arrhythmias. Unfortunately their high cost has limited their use in this country despite impressive clinical results.

Electric Countershock↗
PubMed1987

Rapid and safe termination of supraventricular tachycardia in children by adenosine.

Adenosine (0.05-0.25 mg/kg intravenously) successfully terminated resistant supraventricular tachycardia (SVT) in three seriously ill newborn infants and one older child. Termination of tachycardia was achieved in each case within 20 s. Adenosine, unlike many other anti-arrhythmic agents, has no substantial negative inotropic effect under these circumstances and may become the drug of choice in haemodynamically compromised children with SVT. However, it has no value in prophylaxis against recurrent SVT.

Adenosine↗
PubMed1987

The QT and QS2 intervals in patients with mitral leaflet prolapse.

The QT interval was plotted against the R-R interval in 92 patients with mitral prolapse and 92 age- and sex-matched control subjects. Ten patients (11%) lay above the upper 95% confidence limit for the control group, and analysis of variance confirmed a small group effect (p less than 0.05). Despite this, the mean QT intervals in the two groups differed by only 7 msec and a t test showed no significant difference between the groups. The prevalence of QT prolongation was exaggerated by Bazett's rate correction formula (62%) or historical control groups published by Simonson (58%) or Ashman (70%). Simultaneous QT and QS2 intervals were measured in 67 patients with mitral prolapse. Inversion of the normal QT:QS2 relationship occurred in nine patients (13%) and was more common in the presence of severe mitral regurgitation. It was not associated with an increased prevalence of absolute QT prolongation and was therefore thought to be caused by relative shortening of the QS2 interval. In conclusion, the prevalence of QT prolongation in mitral prolapse is low (11%). The QT:QS2 ratio is unlikely to be a reliable indicator of QT prolongation in these patients.

Arrhythmias, Cardiac↗
PubMed1987

A severe case of myopotential interference in a patient with a respiratory-dependent rate modulated pacemaker.

Symptomatic myopotential interference was observed in a patient with a respiratory-dependent rate modulated pacemaker (RDP3). During treadmill exercise, prolonged interference suspended the rate responsive function and resulted in reversion to the interference mode with the pacing rate falling back to the basic frequency during the interference. This loss of rate response resulted in severe impairment of exercise tolerance and reduction in cardiac output during exercise. The unit was replaced with a bipolar activity sensing rate modulated pacemaker.

Equipment Failure↗
PubMed1987

Long-term transvenous pacing in children weighing ten kilograms or less.

Long-term transvenous endocardial pacing was performed in 5 children each of whom weighed 10 kg or less at the time of implantation. At implantation, using the direct subclavian puncture method, no technical problems were encountered. During follow-up, complications occurred in two patients. In one child recurrent threshold rises were overcome using a steroid-eluting lead. Erosion of the unit in another child required revision of the system with a satisfactory long-term result. Thus, permanent transvenous pacing in small children is feasible and safe and may be preferable to open-chest surgery.

Body Weight↗
PubMed1987

Isolated coronary ostial stenosis: observations on the pathology.

A 54 year old woman with isolated stenosis of the left coronary ostium died following cardiac catheterisation and emergency coronary artery bypass surgery. Histological examination showed the ostial narrowing to be a local and discrete plaque of atherosclerosis. Like most reported cases this patient was a young woman whose disease pursued an aggressive course.

Constriction, Pathologic↗
PubMed1987

Treatment of refractory supraventricular arrhythmias with flecainide acetate.

We treated 13 children aged 0.2 years to 15.7 years (median 7.1 years) with flecainide acetate for refractory symptomatic supraventricular tachycardia. Six children had direct atrioventricular accessory pathways, of whom four had overt Wolff-Parkinson-White syndrome on the 12 lead electrocardiogram, while in the other two the accessory pathway was concealed. Three children had nodal atrioventricular re-entrant tachycardia, two had a re-entrant tachycardia, the exact mechanism of which was not known, one child had ectopic atrial tachycardia, and one had atrial flutter associated with an atrial septal defect. The remaining 12 children had structurally normal hearts. Flecainide (2 mg/kg intravenously) resulted in termination of the tachycardia in 11 of the 12 children treated during tachycardia. In 11 of the children successful prophylaxis was achieved with oral flecainide. Side effects occurred in two children during intravenous administration, but there were no side effects with oral treatment. This experience indicates that flecainide, which has not been used extensively in children, is an effective and safe antiarrhythmic agent, capable of terminating and controlling supraventricular tachycardia in children. Furthermore, flecainide may be successful where conventional agents fail.

Administration, Oral↗
PubMed1987

Accurate detection of triple vessel disease in patients with exercise induced ST segment depression after infarction.

The severity of coronary artery disease is an important determinant of prognosis after acute myocardial infarction. The ability of a symptom limited exercise test to predict the presence of triple vessel disease was assessed in 221 patients three weeks after infarction. Coronary angiography was performed in patients with exercise induced ST segment depression. The presence of ST segment depression alone was poorly indicative of triple vessel disease; however, some specific features of ST segment changes on exercise were of predictive value. Downsloping ST segment configuration alone or horizontal ST segment depression associated with an early onset and a late recovery time after exercise correctly identified 30 (90%) of 33 patients with triple vessel disease whereas it incorrectly identified only 6 (15%) of 39 patients with single and double vessel disease. An abnormal blood pressure response was also predictive. In patients with ST segment depression after infarction triple vessel disease can be detected accurately by a combination of the electrocardiographic and haemodynamic variables attained on exercise.

Adrenergic beta-Antagonists↗
PubMed1986

Usefulness of noninvasive Doppler measurement of ascending aortic blood velocity and acceleration in detecting impairment of the left ventricular functional response to exercise three weeks after acute myocardial infarction.

Left ventricular (LV) function was assessed by Doppler ultrasound measurement of ascending aortic blood velocity and maximal acceleration in 165 patients 3 to 4 weeks after acute myocardial infarction (AMI); all were undergoing routine 12-lead electrocardiogram exercise stress testing. Patients were grouped according to electrocardiographic stress test response; a positive response was defined as at least 1 mm of ST-segment depression in any lead. The Doppler velocity signal yielded 3 variables of interest: peak velocity, maximal acceleration (an index of inotropic state) and the systolic velocity integral (an index of stroke volume). All 3 Doppler ejection variables were significantly lower at peak exercise in patients with a positive electrocardiographic stress test response than in those with negative response, with maximal acceleration showing the most significance (p less than or equal to 0.001). Coronary angiography was performed in 63 of the 67 patients with positive responses, and patients were separated into 2 groups according to extent of coronary artery disease (CAD): 1- and 2-vessel or 3-vessel CAD. Peak velocity and maximal acceleration were significantly lower in patients with 3-vessel CAD than in those with 1- and 2-vessel CAD (p less than or equal to 0.01 and p less than or equal to 0.01). Discriminant analysis showed maximal acceleration and peak velocity values at peak exercise to be 65% predictive of 3-vessel CAD, onset time to ST-segment depression was 74% predictive and the combination of Doppler and electrocardiographic variables increased 3-vessel CAD predictive value to 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Use of flecainide acetate for refractory junctional tachycardias in children with the Wolff-Parkinson-White syndrome.

The response of sustained supraventricular tachycardia to intravenous and oral flecainide acetate was investigated in 5 children, aged 5.5 to 11.5 years, who had tachycardias associated with Wolff-Parkinson-White syndrome. All children had failed to respond to at least 2 conventional agents. The effect of flecainide was studied using intracardiac techniques. Intravenous flecainide terminated tachycardia in all 5 patients. After drug infusion, slow, sustained tachycardia could be initiated in 1 patient. With oral treatment, slow, sustained tachycardia was started in 2 children and nonsustained in 2. One child had no inducible tachycardias. In 4 of 5 patients, long-term treatment has reduced the frequency of episodes and the drug is well tolerated. Thus, flecainide may be used to terminate and suppress junctional tachycardias in children who have failed to respond to conventional therapy.

Administration, Oral↗