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P G Avery

Publications and source records attributed to P G Avery.

11 recordsLinked to original sources
PubMed1998

Randomized, double-blind crossover study to investigate the effects of amlodipine and isosorbide mononitrate on the time course and severity of exercise-induced myocardial stunning.

BACKGROUND: Myocardial stunning may cause prolonged left ventricular dysfunction after exercise-induced ischemia that can be attenuated by calcium antagonists in animal models. To assess their effects in humans, we performed a randomized, double-blind crossover study comparing the calcium antagonist amlodipine (10 mg once daily) versus isosorbide mononitrate (ISMN, 50 mg once daily) on postexercise stunning. METHODS AND RESULTS: Twenty-four men with chronic stable angina and normal left ventricular function underwent serial quantitative exercise stress echocardiography after 3 weeks on each treatment to assess the degree of postexercise stunning with simultaneous sestamibi single-photon emission computed tomography perfusion scans at peak stress to quantify the ischemic burden. Exercise time (P=1), maximum ST depression (P=0.48), and sestamibi single-photon emission computed tomography scores (P=0.17) were unchanged between treatments. Stunning occurred more often with ISMN than amlodipine (82% versus 48%). The global and segmental stress echocardiography parameters of stunning were attenuated in patients while taking amlodipine compared with ISMN. Shortening fractions and ejection fractions were less impaired 30 minutes after exercise in patients receiving amlodipine (3.5+/-1.4% versus 2.5+/-1.4%, P=0.014, and 59.7+/-5.4% versus 54.5+/-8%, P<0.001); similarly, the isovolumic relaxation period was less prolonged with amlodipine (93+/-15.5 versus 106.3+/-14.9 ms, P=0.018). CONCLUSIONS: Despite comparable levels of ischemia, amlodipine attenuated stunning when compared with ISMN. This beneficial effect may relate to a prevention of the calcium overload implicated in the pathogenesis of stunning.

Aged↗
PubMed1993

Xamoterol in sinus node disease.

A pharmacological alternative to pace-maker implantation would be useful in some patients with sinoatrial disorder particularly since the single lead ventricular system usually fitted has disadvantages. Xamoterol, a cardioselective beta-receptor partial agonist, has been shown to increase heart rate both in animals and in man. We, therefore, studied the effects of Xamoterol in patients with sinoatrial disease in a double blind, cross-over trial in 10 patients. Mean heart rates and number and duration of pauses were compared during the treatment phases of the trial with Holter monitoring. Mean heart rates were significantly increased between 01:00 h and 05:00 h (P < or = 0.02) and between 05:00 h and 09:00 h (P < or = 0.01) on Xamoterol. The number of sinus pauses were eliminated or reduced on Xamoterol in six patients, but there was an increased frequency in three patients. Xamoterol, therefore, does increase the heart rate and reduce the number of pauses in sinoatrial disorder, but only in some patients.

Adult↗
PubMed1993

Assessment of myocardial perfusion and function using gated methoxy-isobutyl-isonitrile scintigraphy to detect restenosis after coronary angioplasty.

BACKGROUND: Technetium-99m-methoxy-isobutyl-isonitrile (MIBI) has been shown to be a useful perfusion agent, and its improved imaging characteristics also allow evaluation of myocardial function. We evaluated the use of gated MIBI scintigraphy in patients undergoing percutaneous transluminal coronary angioplasty to show improvements in myocardial perfusion and function and to detect restenosis. METHODS: Gated MIBI scintigraphy was performed in a preliminary study in 25 patients before angioplasty. Twenty-one patients who had undergone a successful procedure were re-examined 3 months later. Myocardial perfusion was evaluated and function measured using myocardial profiles along four axes. RESULTS: Before angioplasty, 18 out of 21 patients had a reversible perfusion defect, and computer analysis of fractional shortening showed 19 out of 21 had abnormalities of left ventricular function during exercise. Only 11 out of 21 had a positive stress test. Mean global fractional shortening before angioplasty was 27.3% at rest and 26.6% during exercise (not significant). After angioplasty, left ventricular function was improved during exercise, with global fractional shortening increasing from 26.6% to 32.7% (P < 0.001). Repeat angiography was performed in 16 patients. Lesions in four patients had restenosed, in 11 they had not, and in one a different artery was occluded. Three of the four patients with restenosed lesions were identified using repeat perfusion imaging, and all four from abnormalities in left ventricular function. An abnormality in a new region was detected using both methods in the patient with the new occlusion. Normal perfusion and function were found in nine of the 11 patients without restenosed lesions. Two patients continued to have a positive stress test: one with a restenosed lesion and one with new disease. CONCLUSION: Dual assessment with gated MIBI scintigraphy provides useful data in patients undergoing angioplasty and may help in the selection of patients for repeat angiography.

Adult↗
PubMed1993

Management of hospital survivors of pre-hospital ventricular fibrillation.

The objective of our study was to characterise 52 hospital survivors of pre-hospital ventricular fibrillation and record their initial management in hospital. A retrospective review was undertaken of ambulance report forms, hospital notes, and electrocardiograms, in one teaching hospital and three district general hospitals in South Wales, of 53 patients discharged from hospital between February 1987 and April 1992 after resuscitation from pre-hospital ventricular fibrillation by ambulance personnel. Twenty patients showed evidence of acute myocardial infarction (group 1), eight patients had a diagnosis of 'possible acute myocardial infarction' (group 2), and 25 patients had no evidence of acute myocardial infarction (group 3). Nineteen patients in group 1 experienced chest pain before collapse compared with only six patients in group 3 (p < 0.001). Five patients in group 1 had a previous history of ischaemic heart disease compared with 17 patients in group 3 (p < 0.01). A greater proportion of patients in group 3 were taking diuretic medication (15 of 25 vs 4 of 20: p < 0.01) but there was no difference in potassium levels on admission to hospital. Cardiologists were involved in the management of a minority of patients (21 of 53); only eight patients underwent cardiac catheterisation; and only three were referred for electrophysiological studies. Patients in group 3 were more likely to be discharged taking empiric antiarrhythmic drugs (13 of 25) than patients in group 1 (2 of 20) (p < 0.01). Not enough use is made of noninvasive and invasive investigations in the management of survivors of pre-hospital ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Gated technetium-99m methoxy-isobutylisonitrile perfusion imaging.

Technetium-99m methoxy-isobutylisonitrile, has been shown to be a useful perfusion agent for detecting coronary artery disease. Gated acquisition of perfusion images may remove motion artefact and improve detection. We compared the results of sensitivity and specificity for detecting coronary artery disease using perfusion images from the whole cardiac cycle (ungated) or from end-diastolic (gated) frames in 46 subjects, 31 with significant coronary disease and 15 with normal coronary arteries. There was no significant difference in detection of patients with coronary disease between the ungated and end-diastolic images: 25/31 with the ungated image and 28/31 with the end-diastolic. An improvement was made in detecting defects in the left anterior descending artery territory: 17/20 with the end-diastolic vs 11/20 with the ungated image (P less than 0.05) and in the right coronary artery region: 16/21 vs 10/21 (P less than 0.05), with an overall improvement in detecting regions supplied by stenosed coronary arteries: 45/55 end-diastolic vs 31/55 ungated (P less than 0.01). These results suggest use of the end-diastolic frame can significantly enhance the diagnostic capacity of methoxy-isobutylisonitrile perfusion imaging.

Adult↗
PubMed1992

Cardiac failure secondary to hypocalcaemia of nutritional osteomalacia.

A 41-year-old Asian woman presented with mild congestive cardiac failure, initially controlled with a small dose of diuretic. Subsequently there was a marked deterioration in her condition with severe cardiac failure resistant to treatment. At this time biochemistry revealed a hyperphosphataemic variety of osteomalacia. Her cardiac failure improved promptly on correcting the hypocalcemia. Although hypocalcaemia is a recognised cause of cardiac failure it has not been described in privational osteomalacia.

Adult↗
PubMed1992

Evaluation of changes in myocardial function on exercise in patients with coronary artery disease using gated MIBI scintigraphy.

Technetium-99m-methoxy-isobutyl-isonitrile (MIBI) is a myocardial perfusion agent which allows simultaneous assessment of left ventricular function. We evaluated left ventricular (LV) function with exercise using a new method of myocardial profiling in 43 patients with chest pain. Twenty-eight had significant coronary artery disease and 15 were normal on coronary angiography. Results were compared to equilibrium radionuclide ventriculography. MIBI fractional shortening (FS) correlated well with ejection fraction (EF) on exercise (r = 0.79, P = less than 0.001). There was also a good correlation between changes in global function from rest to exercise (r = 0.82, P = less than 0.001) with a sensitivity of diagnosing CAD of 71% and specificity of 80%. New regional wall abnormalities were detected in 25/28 with CAD with a sensitivity of 89% and specificity of 60%. There was also a close correlation between mean diameters measured with gated MIBI scans and volumes measured with RNV, end-diastolic diameter (EDD) versus end-diastolic volume (EDV) r = 0.78 (P = less than 0.001) at rest and r = 0.74 (P = less than 0.001) on exercise and end-systolic diameter (ESD) versus end-systolic volume (ESV) r = 0.72 (P = less than 0.001) at rest and r = 0.72 (P = less than 0.001) on exercise. This produced a sensitivity for detecting CAD of 79% and a specificity of 73%. These results show that gated MIBI scanning on exercise provides information comparable to RNV so enhancing the diagnostic usefulness of MIBI.

Adult↗
PubMed1991

Gated 99Tcm-MIBI myocardial function imaging.

The introduction of the 99Tcm isonitrile perfusion agents has provided improved myocardial image quality with conventional imaging equipment allowing improved edge definition on gating. We evaluated left ventricular wall motion in 46 patients using gated 99Tcm-2-methoxy-2-methyl-isopropyl-1-isonitrile (MIBI) scintigraphy. Using a method of myocardial profiles in four axes, global and regional fractional shortening (FS) were assessed. A good correlation was found between FS in the left anterior oblique (LAO) 40 degrees projection and ejection fraction (EF) on gated radionuclide ventriculography (r = 0.81, P less than 0.001). This was improved by using FS in two planes, LAO 40 degrees and anterior (r = 0.88, P less than 0.001). There was also a good correlation between FS in two planes and EF on cine-angiography (r = 0.72, P less than 0.001). There was good intra- and interobserver agreement with the studies. Assessment of myocardial function using gated MIBI imaging and myocardial profiles provides useful additional information to the perfusion scan, thus enhancing the diagnostic usefulness of the agent.

Adult↗