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J L Caplin

Publications and source records attributed to J L Caplin.

At least 19 recordsLinked to original sources
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↗
PubMed1989

Influence of respiratory variations on right ventricular function.

Respiratory effort during inspiration, expiration, and the Valsalva manoeuvre changes right ventricular preload and afterload. On inspiration these changes should improve systolic emptying of a larger end diastolic volume and so increase the ejection fraction, whereas on expiration the reverse should be true. The resting right ventricular ejection fraction was measured by first pass radionuclide angiography with gold-195m (half life 30.5 s) in 17 individuals at maximal inspiration and expiration and in eight at rest and during the strain phase (phase 2) of the Valsalva manoeuvre. The right ventricular ejection fraction was significantly lower during expiration than during inspiration. There were, however, no significant differences in bolus duration or right ventricular transit time. The Valsalva manoeuvre, in contrast, significantly increased the ejection fraction and also significantly prolonged both the bolus duration and right ventricular transit time. The conformation of the bolus curves during the Valsalva manoeuvre suggested the development of tricuspid regurgitation. These data suggest that relative influences of venous return, pulmonary arterial pressure, pulmonary vascular resistance, and possible functional tricuspid regurgitation vary during inspiration, expiration, and the Valsalva manoeuvre and can affect the right ventricular ejection fraction. Changes in right ventricular function on exercise assessed by first pass radionuclide angiography must be interpreted with caution because maximal respiratory effort may alter the right ventricular ejection fraction independently of ischaemia or other non-ischaemic factors.

Blood Pressure↗
PubMed1988

Nonischemic changes in right ventricular function on exercise. Do normal volunteers differ from patients with normal coronary arteries?

Factors other than ischemia may alter right ventricular function both at rest and on exercise. Normal volunteers differ from cardiac patients with normal coronary arteries with regard to their left ventricular response to exercise. This study examined changes in right ventricular function on exercise in 21 normal volunteers and 13 patients with normal coronary arteries, using first-pass radionuclide angiography. There were large ranges of right ventricular ejection fraction in the two groups, both at rest and on exercise. Resting right ventricular ejection fraction was 40.2 +/- 10.6% (mean +/- SD) in the volunteers and 38.6 +/- 9.7% in the patients, p = not significant, and on exercise rose significantly in both groups to 46.1 +/- 9.9% and 45.8 +/- 9.7%, respectively. The difference between the groups was not significant. In both groups some subjects with high resting values showed large decreases in ejection fraction on exercise, and there were significant negative correlations between resting ejection fraction and the change on exercise, r = -0.59 (p less than 0.01) in volunteers, and r = -0.66 (p less than 0.05) in patients. Older volunteers tended to have lower rest and exercise ejection fractions, but there was no difference between normotensive and hypertensive patients in their rest or exercise values. In conclusion, changes in right ventricular function on exercise are similar in normal volunteers and in patients with normal coronary arteries. Some subjects show decreases in right ventricular ejection fraction on exercise which do not appear to be related to ischemia.

Adult↗
PubMed1987

Duration of action of tiapamil in stable exercise induced angina.

The duration of action of tiapamil was assessed in ten patients with stable exertional angina. Maximal symptom-limited treadmill exercise electrocardiography was performed before and at 1, 3, 6 and 9 h after therapy. Significant differences were only found at 1 h after tiapamil with increases in mean exercise duration (312 vs 399 s), the time to onset of angina (221 vs 310 s) and exercise work load (5.9 vs 7.3 METS). Tiapamil had no significant effect on the exercise heart rate but increased the resting heart rate by 6 beats/minute. The resting systolic blood pressure fell by 17 mmHg (p less than 0.01), and the diastolic blood pressure by 14 mmHg. Exercise systolic and diastolic blood pressures fell by 19 and 17 mmHg respectively. Side-effects were short-lived and attributable to vasodilatation. Tiapamil is effective for the relief of angina with minimal side-effects, but its duration of action is short. For effective chronic oral use, a sustained release preparation is required.

Adult↗
PubMed1987

Effects of nisoldipine on left ventricular function during exercise or cold pressor stress.

The effects of a single oral dose of nisoldipine, 10 mg, were investigated in two groups of patients. Firstly, the effects of nisoldipine on exercise left ventricular function were assessed in 20 patients with chronic stable angina and coronary disease. Secondly, the effects of nisoldipine on the left ventricular response to cold pressor stimulation were examined in 12 patients with normal coronary arteries, who presented with typical ischaemic chest pain and abnormal exercise tests. All studies were performed using first pass radionuclide angiography and the new short half-life radiopharmaceutical, gold-195m. In patients with coronary disease, mean exercise time improved after nisoldipine (P less than 0.01). Both at the identical workload to that before treatment, and at a new peak workload, mean exercise left ventricular ejection fraction (LVEF) improved significantly after nisoldipine (P less than 0.01 and P less than 0.05 vs pretreatment levels, respectively). At the identical workload to that before treatment, 10 of 16 patients, who had initially developed angina, did not develop angina after nisoldipine, and 23 of 46 exercise-induced regional left ventricular abnormalities had normalized. In the patients with normal coronary arteries undergoing cold pressor stimulation, imaging was carried out at rest, and after 1 and 2.5 minutes of cold stimulation, before and one hour after oral nisoldipine. LVEF fell significantly during cold stimulation before nisoldipine administration, with 10 of the 12 patients showing an abnormal response. Nisoldipine did not lead to any attenuation of the heart rate and blood pressure response to cold, but mean LVEF did not fall at any cold pressor stage and only three patients showed an abnormal response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Sex differences in exercise induced left ventricular dysfunction in patients with syndrome X.

Clinical, electrocardiographic, and scintigraphic data were reviewed from 32 patients (18 men and 14 women) who had syndrome X (chest pain, evidence of ischaemia, and normal coronary arteries without coronary vasospasm). The mean (SD) resting left ventricular ejection fraction, determined by first pass radionuclide angiography was 62.6 (9.2)% and was greater than 50% in all subjects. There was no significant difference between men and women. On exercise, left ventricular ejection fraction decreased significantly to 57.4 (13.0)%. In 17 of 32 subjects there was a fall in left ventricular ejection fraction of greater than 5%, and regional wall motion abnormalities developed in 12 subjects. The fall in left ventricular ejection fraction on exercise was significant in women (from 61.9 (8.5)% at rest to 54.0 (9.8)% on exercise) but not in men (from 63.2 (9.8)% at rest to 60.0 (14.8)% on exercise). Exercise left ventricular ejection fraction fell by greater than 5% in 10 (71%) of 14 women and in seven (39%) of 18 men. Dyskinetic segments developed in eight (57%) of 14 women and only four (22%) of men. Exercise duration in women was significantly shorter than in men (4.1 (1.5) vs 6.6 (2.1) minutes) and was the only one of several clinical and scintigraphic variables that correlated with the change in left ventricular ejection fraction on exercise. In this selected group of subjects with chest pain and angiographically normal coronary arteries, exercise induced left ventricular dysfunction, as shown by a fall in ejection fraction or the development of regional abnormalities, is a common finding. These are more likely to occur in women than men and are associated with a lower exercise capacity. The data suggest that the sex of the patient is important in the interpretation of the non-invasive evaluation of subjects suspected of having syndrome X.

Adult↗
PubMed1987

Global and regional right ventricular function after acute myocardial infarction: dependence upon site of left ventricular infarction.

The relation of global and regional right and left ventricular function during the acute phase after a first myocardial infarction was assessed by first pass radionuclide angiography in 20 patients (10 after anterior and 10 after inferior myocardial infarction). The right ventricular ejection fraction did not differ significantly between the groups, but left ventricular ejection fraction was significantly depressed after anterior myocardial infarction. There was evidence of right ventricular dilatation and impaired transit in the group with inferior infarction. Five patients with anterior infarction and six with inferior infarction had abnormal right ventricular ejection fractions. Right ventricular wall motion abnormalities affected the septal wall in the group with anterior infarction and the free wall in the group with inferior infarction. The relation between right and left ventricular ejection fractions was markedly different in the two groups. In the group with anterior infarction there was a significant linear relation between right and left ventricular ejection fraction, whereas in the group with inferior infarction there was not. Thus right ventricular dysfunction commonly occurs after both anterior and inferior myocardial infarction. Right and left ventricular impairment are related after anterior myocardial infarction, but are independent after inferior myocardial infarction. Finally, the different effects of anterior and inferior myocardial infarction on right ventricular function may be explained by differences in septal and free wall involvement.

Adult↗
PubMed1986

The adequacy of radioisotope mixing from bolus injections in first-pass radionuclide angiographic assessment of right ventricular function: a study using gold-195m.

The adequacy of radioisotopic mixing in first-pass radionuclide studies of right ventricular function was assessed in 27 patients using multiple injections of gold-195m (half-life 30.5 sec). A theoretical disadvantage of the first-pass technique is inadequate mixing of the injected bolus with blood prior to entry into the right ventricle. Since the calculation of ejection fraction is based on the assumption of complete mixing, this would lead to errors. In order to assess the effects of bolus injection rates and bolus duration on the calculation of right ventricular ejection fraction, multiple, rapid, sequential studies were performed using gold-195m at four bolus injection rates (10, 5, 2 and 1 ml/sec). Slowing the injection rate caused a significant increase in bolus duration, and a significant increase in the number of cardiac cycles available for analysis. Mean ejection fraction, however, was not significantly changed. There was good correlation between right ventricular ejection fraction at all injection rates when compared to 10 ml/sec, and no injection rate led to a consistent over or underestimate of right ventricular ejection fraction. There was no significant relationship between change in bolus duration and variation in ejection fraction. These data indicate that mixing is adequate for first-pass studies of right ventricular function using a rapid bolus.

Cardiac Output↗
PubMed1986

Relation between coronary anatomy and serial changes in left ventricular function on exercise: a study using first pass radionuclide angiography with gold-195m.

Serial changes in left ventricular function on exercise were assessed by first pass radionuclide angiography with gold-195m (half life 30.5 s) in 25 men with known coronary anatomy. In the seven patients with three vessel disease, abnormalities of global left ventricular function and regional wall motion occurred earlier during exercise, were of greater extent at peak exercise, and persisted longer after exercise than in the 11 patients with one and two vessel disease or the seven with normal coronary arteries. Although there were significant differences between the groups in absolute change in ejection fraction and the rate of change in ejection fraction related to exercise duration and heart rate, a considerable overlap of values between groups precluded the accurate prediction of coronary anatomy in individuals. These data suggest that the amount of myocardium at risk from ischaemia in some patients with one and two vessel disease may resemble that in patients with three vessel disease. This study shows that an anatomical classification based solely on the number of diseased vessels will not predict the extent of the impairment of left ventricular function on exercise.

Blood Pressure↗
PubMed1986

Gated right ventricular studies using krypton-81m: comparison with first-pass studies using gold-195m.

Krypton-81m, given by continuous i.v. infusion, has been successfully used for the equilibrium ECG-gated assessment of right ventricular function. We compared gated studies with 81mKr (half-life 13 sec) with first-pass studies using 195mAu (half-life 30.5 sec). Krypton studies analyzed using variable regions of interest (ROIs) led to a significantly higher calculated right ventricular ejection fraction (RVEF) than with a fixed ROI, both with and without background correction. The differences between first-pass studies and gated studies without background correction were significant (p less than 0.01), whereas they were not with background correction. These data suggest that large systematic errors exist in the calculation of RVEF depending on the analysis method and that background correction is important when different techniques are compared.

Adult↗
PubMed1985

The acute changes in serum binding of disopyramide and flecainide after myocardial infarction.

In the serum basic drugs are principally bound to alpha1-acid glycoprotein (AAG). Following acute myocardial infarction it has been shown that the levels of AAG rise. The serum levels of total protein, albumin, AAG and the protein binding of 2 antiarrhythmic drugs which are bases, disopyramide and flecainide, was measured in vitro with blood samples from eleven patients taken over the first 5 days following myocardial infarction. Mean AAG levels significantly increased from 1.04 g/l on Day 1 to 1.80 g/l on Day 5. The binding of disopyramide, which is highly bound, rose from 80% to 87%, representing a 35% decrease in free drug concentration. In contrast the binding of flecainide fell from 61% to 53%, a 20% increase in free drug concentration. These data suggest that although the binding of strongly bound drugs responds appropriately to increases in binding protein after acute myocardial infarction, poorly bound drugs are displaced from binding sites possibly by endogenous substances. Since the pharmacological effects of a drug are related to its free (unbound) concentration, the changes in the proportions of free to bound drug after myocardial infarction may have important clinical implications.

Aged↗
PubMed1985

Effects of projection and background correction method upon calculation of right ventricular ejection fraction using first-pass radionuclide angiography.

There is no consensus as to the best projection or correction method for first-pass radionuclide studies of the right ventricle. We assessed the effects of two commonly used projections, 30 degrees right anterior oblique and anterior-posterior, on the calculation of right ventricular ejection fraction. In addition two background correction methods, planar background correction to account for scatter, and right atrial correction to account for right atrio-ventricular overlap were assessed. Two first-pass radionuclide angiograms were performed in 19 subjects, one in each projection, using gold-195m (half-life 30.5 seconds), and each study was analysed using the two methods of correction. Right ventricular ejection fraction was highest using the right anterior oblique projection with right atrial correction 35.6 +/- 12.5% (mean +/- SD), and lowest when using the anterior posterior projection with planar background correction 26.2 +/- 11% (p less than 0.001). The study design allowed assessment of the effects of correction method and projection independently. Correction method appeared to have relatively little effect on right ventricular ejection fraction. Using right atrial correction correlation coefficient (r) between projections was 0.92, and for planar background correction r = 0.76, both p less than 0.001. However, right ventricular ejection fraction was far more dependent upon projection. When the anterior-posterior projection was used calculated right ventricular ejection fraction was much more dependent on correction method (r = 0.65, p = not significant), than using the right anterior oblique projection (r = 0.85, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

DNA polymorphisms in the apolipoprotein C-III and insulin genes and atherosclerosis.

A total of 167 patients undergoing investigation for suspected coronary artery disease (CAD) were genotyped for restriction fragment length polymorphisms (RFLP) at the apo A-1/C-III locus and the insulin gene locus using cloned human apo A-1 and insulin gene probes. The study group was subdivided into patients with absent or minimal CAD, intermediate CAD and severe obstructive CAD. An Sst-1 polymorphism located in the 3' non-coding region of the apo C-III gene identifies two alleles. One of the alleles (S2) showed a significantly increased frequency in the subjects with severe obstructive CAD (18%) compared with patients with minimal or absent CAD (6%) (P less than 0.025) and normolipidaemic control subjects. This A-1/C-III polymorphism may be a marker for an abnormality in the A-1/C-III genes predisposing to atherosclerosis. In contrast to a previous report, we found no increase in the frequency of the Class 3 insulin alleles in subjects with severe CAD.

Adult↗
PubMed1985

Pulmonary mycotic aneurysms secondary to infective endocarditis in a patient with a persistent ductus arteriosus and partial anomalous pulmonary venous drainage.

Mycotic aneurysms are a rare but recognized complication of infective endocarditis. Aneurysms of the pulmonary artery are usually associated with infected congenital heart lesions and especially with persistent ductus arteriosus. This report deals with a patient with a persistent ductus who developed multiple mycotic aneurysms in the right lung following infective endocarditis, and whose management was complicated by anomalous venous drainage of most of the contralacteral lung. Surgical closure of the ductus to reduce pulmonary blood flow failed to prevent haemoptysis, and further surgery to ligate the feeder arteries to the aneurysms was required.

Adult↗
PubMed1985

Improved cardiac function after renal transplantation.

There are few reports of the outcome of renal transplantation in patients with severe left ventricular (LV) impairment. We describe three men with chronic disabling heart failure associated with LV dysfunction in whom a remarkable improvement in cardiac function followed renal transplantation. Transplantation may offer the prospect of successful rehabilitation in these circumstances. Undue pessimism as to the prognosis in such patients is unwarranted.

Adult↗