PubMed Health⌕ Search

Biomedical subjects

G C Kaye

Publications and source records attributed to G C Kaye.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cardiac syncope due to transient coronary artery occlusion: the role of percutaneous angioplasty.

A case of cardiac syncope is presented, associated with single vessel coronary disease. The mechanism of the syncope would appear to be a ventricular arrhythmia with transmural myocardial ischaemia due to transient occlusion of the diseased coronary artery. The symptoms and electrocardiographic abnormalities were reproduced and subsequently abolished by percutaneous coronary angioplasty.

Angina Pectoris, Variant↗
PubMed1998

Epidemiology and management of failed sudden cardiac death.

With increasingly successful resuscitation many patients survive to reach hospital after a cardiac arrest but few survive to be discharged. Work on the investigation and treatment of such patients has begun to influence the outcome. This article reviews the epidemiology, mechanisms and management of failed sudden cardiac death, specifically in ischaemic heart disease.

Anti-Arrhythmia Agents↗
PubMed1997

Femoral complications and bed rest duration after coronary arteriography.

This randomized study using a pneumatic compression device found no significant difference in the femoral complication rate between 4 and 6 hours of bed rest after Judkin's coronary arteriography. The positive implications for the organization of an efficient service in busy tertiary centers include reduced patient discomfort, earlier ambulation and discharge, efficient staff deployment, and enhanced throughput.

Adult↗
PubMed1997

Failure of plasma atrial natriuretic peptide levels to increase during exercise in patients with chronic atrial fibrillation.

It is generally accepted that plasma atrial natriuretic peptide release occurs secondary to atrial stretch. The influence of coordinated atrial contraction (AC) upon this process is not fully appreciated. The aim of the study was to determine the importance of coordinated AC upon peripheral atrial natriuretic peptide levels (alpha-hANP) during exercise. Peripheral alpha-hANP levels were measured at rest and during exercise in 12 patients with complete heart block (CHB) and permanent rate responsive pacemakers. Seven patients had coordinated AC and five had chronic atrial fibrillation (AF). Each patient performed three treadmill exercise tests. Maximal inspired oxygen volume (VO2 max) was determined during test 1. Tests 2 and 3 were performed to 70% VO2 max, the pacemaker being programmed to either VVI or VVIR mode. Plasma alpha-hANP was measured using a two-site immunoradiometric assay. At rest there was a small but significant difference between the two patient groups: AF 60.2 pg/mL versus AC97.6 pg/mL; P = 0.03. During exercise in the AC patients, there was a significant increase in alpha-hANP levels, in VVIR mode, to 238.4 pg/mL, and in VVI mode, to 207.9 pg/mL, P = 0.002 and 0.003, respectively. In those patients with chronic AF, there was no significant rise or fall in alpha-hANP levels in either pacing mode, VVIR 65.2 pg/mL, VVI 46.6 pg/mL. Previous workers have suggested that alpha-hANP release by nonfunctioning atria is normal. We have shown that the presence of coordinated AC is required for the release of alpha-hANP during exercise in patients with CHB, and that this appears to be independent of ventricular rate.

Adult↗
PubMed1995

Stress echocardiography.

Stress echocardiography has now emerged from the days of research and clinical evaluation to take its place alongside other non-invasive imaging methods in coronary artery disease. It is safe, versatile, and clinically accurate. It has been validated against radionuclide perfusion imaging; the cost and convenience advantages for echocardiography must be balanced against the greater automaticity and probable sensitivity (in single-vessel disease) of perfusion imaging. There is a definite 'learning curve' for stress echo--both in the practice of image acquisition and in interpretation. The choice between these two techniques will often be determined by local availability and demand. However, the addition of a stress echo service to a modern ECG department is likely to be considerably cheaper than the cost of a new gamma camera and radio-pharmacy service. A recent editorial called for a 'critical reappraisal' of stress echo and its application in the UK. The increasing availability of the necessary hardware and software for the newer echocardiography machines is likely to accelerate this process in the near future. A more recent application for the technique is in the determination of contractile reserve and 'viability' in patients with poor LV function and IHD, using low-dose dobutamine regimens. Stress echocardiography is therefore likely to occupy an expanding role in the management of patients with coronary artery disease, as an adjunct to the exercise ECG.

Echocardiography↗
PubMed1994

Clinical evaluation of a dual sensor, rate responsive pacemaker.

UNLABELLED: Dual sensor pacemakers should respond more appropriately during differing exercise modes than a single sensor device. The Topaz model 515 (QT and activity count [ACT] sensing) pacemaker shows appropriate rate response during treadmill exercise testing. We postulated that adjustments to relative sensor contribution should allow fine tuning of the onset of rate response. Eleven patients with this pacemaker were studied. Three standard exercise tests were performed with adjustment of sensor blending and activity threshold between each one. We also assessed the response to isometric exercise and a false positive activity signal. RESULTS: Times to 100 ppm (3.7 +/- 1.3, 4.4 +/- 2.0, 5.3 +/- 1.5 mins), times to peak rate (6.1 +/- 1.6, 5.6 +/- 1.4, 6.5 +/- 1.3 mins) and accelerations to peak (9.0 +/- 2.4, 9.2 +/- 5.3, 7.7 +/- 2.8 ppm/min) were measured in all three different sensor settings (QT = ACT, QT < ACT, and QT = ACT with decreased activity threshold). No significant difference in onset of rate response was seen between the three settings. Tapping (false-positive activity) provided a rapid rise in paced rate to 79 ppm from a resting value of 65 ppm. This came down to 71 ppm demonstrating satisfactory sensor cross-checking. Isometric exercise induced a moderate response from 65 ppm at rest to 74 ppm after 3 minutes. CONCLUSIONS: Satisfactory rate response was demonstrated in most patients to treadmill testing and to isometric exercise. However, small adjustments to relative sensor contributions do not predictably alter the onset of rate response.

Aged↗
PubMed1993

The response of implanted dual chamber pacemakers to 50 Hz extraneous electrical interference.

Twenty-two patients with dual chamber pacemakers with interchangeable lead configuration were exposed to 50 Hz electromagnetic interference. Current, at corporeal levels from 0-600 microA, was applied between electrodes on shoulders and feet using a bedside injection unit. Pacemaker behavior was monitored with telemetered event markers and intracardiac electrograms. In bipolar mode, noise reversion mode was induced in all except two Medtronic units at high (> 170 microA) levels of corporeal current. In the Intermedics, Siemens Pacesetter, and Telectronics models, onset of noise reversion mode was preceded by a window of inappropriate function, characterized by rate acceleration due to atrial malsensing, or pacemaker inhibition due to ventricular malsensing. In unipolar mode, pacemaker malfunction occurred at much lower current levels. Inappropriate behavior preceded the onset of protective noise reversion mode. During current injection, all pacemakers could be interrogated and reprogrammed, and intracardiac telemetry was reliably obtained except in two Medtronic units at high current levels. No pacemaker was reset by the electrical interference, and no cross-talk was seen. Use of bipolar mode confers a high degree of protection from extraneous electrical interference, but in unipolar mode pacemakers may be inhibited by small amounts of corporeal current, potentially encountered in every day life. The current injection unit allows safe, controllable, and quantifiable investigation of the effects of the electric field induced by a current on implanted pacemakers. Telemetry of annotated intracardiac signals during electromagnetic interference clarifies observations of pacemaker acceleration and inhibition.

Adult↗
PubMed1992

Effect of induced supraventricular tachycardias on changes in urine output and plasma hormone levels in man.

1. A symptomatic diuresis, polyuria, sometimes accompanies paroxysmal tachycardias in man. A study was undertaken in patients with inducible supraventricular tachycardia, irrespective of the symptom of polyuria, to measure simultaneous changes in urine output and plasma hormone levels during the arrhythmia. 2. During 14 episodes of induced tachycardia in 10 patients, there was a significant increase in mean urine flow, which was independent of the state of patient hydration. During a mean tachycardia duration of 30 +/- 3 min, the mean group urine flow increased from 3.2 +/- 2.3 ml/min to 7.6 +/- 3.7 ml/min (P less than 0.001). This was characterized by a consistent increase in free water excretion and a variable increase in sodium excretion. 3. The plasma atrial natriuretic peptide level (five patients) significantly increased from 7.6 +/- 4.6 pg/ml to 34.6 +/- 21.7 pg/ml (P less than 0.02) during the arrhythmia. There was no significant change in the plasma arginine-vasopressin level and a non-significant reduction in plasma renin activity. 4. This study has shown that induced supraventricular tachycardias in man are accompanied by a significant diuresis. The mechanisms responsible remain unknown, but do not appear to involve the plasma arginine-vasopressin level alone.

Adult↗
PubMed1991

Tachycardia recognition and diagnosis from changes in right atrial pressure waveform--a feasibility study.

Implantable defibrillators either monitor heart rate or use a probability density function to detect ventricular fibrillation/tachycardia. As a result, they are unable to discriminate sinus tachycardia and atrial arrhythmias from malignant ventricular rhythms. We have assessed high fidelity fiber-optic pressure recordings in the right atrium during cardiac arrhythmias in 23 patients (mean age 44 years, 11 females) undergoing electrophysiological study. The unfiltered pressure signal was amplified and recorded on paper. During sinus rhythm, a constant amplitude deflection occurred during atrial systole (a wave). A characteristic waveform pattern was observed during each of the studied tachyarrhythmias, which included atrial flutter and fibrillation, atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and ventricular tachycardia with and without ventriculoatrial conduction. The waveform pattern allowed clear visual discrimination of the underlying arrhythmia. Mean atrial pressure was increased during all arrhythmias and did not allow discrimination of the nature of the tachycardia. High fidelity pressure recordings produced characteristic appearances for pattern recognition of each arrhythmia studied. They allowed determination of the temporal relation between electrical and mechanical cardiac events and may have potential in the detection and recognition of cardiac arrhythmias.

Adult↗
PubMed1990

Acute electrophysiologic effects of an HT2-serotonin antagonist, ketanserin, in humans.

The acute electrophysiologic effects of an intravenous bolus of ketanserin, a 5HT2 serotonin blocker, were studied in ten patients (four females, six males) during invasive electrophysiology. Following baseline electrophysiologic measurements during sinus rhythm and fixed-rate atrial pacing at 600 ms, a bolus of 0.2 mg/kg ketanserin was given over a 3-minute period. After 30 minutes all measurements were repeated. Systemic blood pressure was measured at regular intervals throughout. During sinus rhythm, there was no significant change in the basic cycle length or in the PA, AH, HV, QRS, QT, and QTc intervals. During atrial pacing there was a nonsignificant increase in the QT interval, from 342 +/- 13 ms to 366 +/- 16 ms, and a significant increase in the QTc interval, from 422 +/- 27 ms to 449 +/- 29 ms (p less than 0.05). There was no reduction in blood pressure. Thus ketanserin produced a significant prolongation of the QTc interval, in the absence of hypokalemia, in humans.

Adult↗
PubMed1990

Bacterial endocarditis of the tricuspid valve after insertion of a central venous catheter.

Central venous cannulation is a commonly used technique in the management of seriously ill patients. In experienced hands, the complication rate is low and primarily includes sepsis, thrombosis and local trauma. For chronic indwelling central venous catheters, thrombus formation within the right atrium has been described, particularly in premature infants, and a recent case has been reported in an adult. Valvular damage in the right heart is recognised and more often diagnosed at autopsy. This report describes the presence of tricuspid vegetations in a diabetic woman, related to the insertion of a central venous cannula.

Catheterization, Central Venous↗
PubMed1990

Fatal right ventricular thrombus secondary to Hickman catheterisation.

Complications arising from central venous cannulation include sepsis, thrombosis and trauma. Total parenteral nutrition via a Hickman catheter is an accepted therapeutic technique. Cases of catheter-related thrombus within the right atrium have been described, primarily in premature infants, although a recent case has been reported in an adult. We describe the presence of a fatal right ventricular thrombus in a female with an infected Hickman catheter.

Adolescent↗
PubMed1989

Can central neuropeptides be implicated in carotid sinus reflex hypersensitivity?

Carotid sinus reflex hypersensitivity involves profound and intermittent changes in heart rate and blood pressure associated with symptoms of dizziness and syncope. This involves a reflex arc in which the main defect is believed to lie within the central nervous system. The discovery of classical and peptidergic neurotransmitters within the same neurone, and the presence of these peptides within the central nervous system raises the possibility that carotid sinus reflex hypersensitivity may be related to an abnormality of peptide distribution or function.

Carotid Sinus↗
PubMed1988

The effect of 50 Hz external electrical interference on implanted cardiac pacemakers.

The effects of injected 50 Hz alternating current on the function of cardiac pacemakers has been observed in 18 patients with implanted unipolar VVI units. Current, in the range 0-600 microA was applied via electrodes attached to the patients' upper body and feet and fed from a specially designed current injection unit at the bedside. Most implanted pacemakers reverted to interference mode in the current range 29-250 microA. At current levels just below the reversion current all units developed irregular and inappropriate pacing. This current level was pacemaker dependent and varied in the range 27-246 microA. The total reversion current depended on the location of the injecting electrodes and on the patients' posture. The sensitivity of the units to injected interference was increased by deep inspiration. Temporary pacing catheters fitted to an additional ten patients were used to monitor the interference voltage which would be sensed by an implanted unit. This voltage was similarly dependent on patient posture and on deep respiration. Current injection has proved to be a safe, controllable and reproducible method of testing the sensitivity of implanted pacemakers to 50 Hz external interference.

Aged↗
PubMed1986

Isolated atrial amyloid contains atrial natriuretic peptide: a report of six cases.

Twenty five specimens of the human right atrial appendage were examined for immunoreactivity to alpha human atrial natriuretic peptide. In the electron microscope characteristic amyloid fibrils were identified around small blood vessels and adjacent to atrial muscle cells in eight of the surgical cases and in two necropsy cases. In six cases, four surgical and two necropsy, these fibrils contained immunoreactive alpha human atrial natriuretic peptide. Amyloid is known to occur in peptide secreting endocrine tumours and immunoreactive peptide may be incorporated in the amyloid matrix. The demonstration of atrial amyloid containing immunoreactive alpha human atrial natriuretic peptide suggests that some deposits of cardiac amyloid are of a type analogous to that found in other endocrine organs.

Adult↗