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Biomedical subjects

D S Dymond

Publications and source records attributed to D S Dymond.

65 records · Page 4Linked to original sources
PubMed1980

Assessment of function of contractile segments in patients with left ventricular aneurysms by quantitative first pass radionuclide ventriculography. Haemodynamic correlation at rest and exercise.

Thirteen patients with left ventricular aneurysms complicating myocardial infarction were studied by contrast angiography and by first pass radionuclide ventriculography. The ejection fraction of the contractile segment (EFCS) was measured from both studies using a double hemishperoid model, and the values correlated closely. There was a monotonic relation between EFCS and stroke volume index measured from thermodilution cardiac outputs carried out simultaneously with the radionuclide study. When radionuclide ventriculography was performed at submaximal supine exercise, changes in EFCS paralleled changes in the total left ventricular ejection fraction in 10 of the 13 cases. In nine patients, changes in EFCS paralleled changes in stroke volume index and the relation between EFCS and stroke volume index was maintained at exercise. After administration of the vasodilator isosorbide dinitrate to 12 patients, repeat exercise radionuclide ventriculography showed an improvement in left ventricular ejection fraction and in eight patients EFCS improved. First pass radionuclide ventriculography can accurately estimate EFCS, which may be an important factor in predicting the likely response to aneurysmectomy. Changes in EFCS on exercise are reflected in changes in total left ventricular ejection fraction and stroke volume index. Isosorbide dinitrate may improve contractile segment function on exercise.

Adult↗
PubMed1980

Radionuclide and hemodynamic assessment of left ventricular functional reserve in patients with left ventricular aneurysm and congestive cardiac failure. Response to exercise stress and isosorbide dinitrate.

The hemodynamic response to exercise stress was assessed in 17 patients with left ventricular (LV) aneurysm, demonstrated by contrast left ventriculography, and congestive cardiac failure (CCF) before and after sublingual isosorbide dinitrate (ISDN). Radionuclide ventriculography was performed at rest and during exercise in 14 patients. ISDN increased mean exercise LV stroke work index (LVSWI) from 31 to 39 g-m/m2 (p less than 0.001) and reduced mean exercise LV filling pressure from 38 to 25 mm Hg (p less than 0.001). Using the combined criteria of LVSWI and ejection fraction of the contractile section of the left ventricle (EFCS), no patient with rest EFCS of less than 40% achieved a good absolute response to exercise in LV performance with or without ISDN. Of the six patients with rest EFCS greater than or equal to 40% only three achieved a good response. While rest EFCS less than 40% indicates poor LV functional reserve, good LV functional reserve is not always indicated by rest EFCS greater than or equal to 40%.

Adult↗
PubMed1979

Cardiac emission tomography in patients using 201thallium. A new technique for perfusion scintigraphy.

The distribution of 201thallium (Tl) in the myocardium has been studied by the new technique of emission tomography, and compared with standard gamma camera images in 5 patients. Tomographic imaging was carried out using a dual-detector scanner operated under the single-photon technique. Initial results have been promising, with visualisation of resting perfusion defects in patients with recent infarction and those with ventricular aneurysms. Emission tomography has also been performed at exercise, and has shown tracer deficits in the distribution of significant coronary stenoses. This new approach to myocardial perfusion scintigraphy may lead to improved sensitivity for detecting apical and inferior wall abnormalities by providing depth information not available from a conventional two-dimensional image.

Coronary Disease↗
PubMed1979

Detection of postinfarction left ventricular aneurysms by first pass radionuclide ventriculography using a multicrystal gamma camera.

Eighteen patients with a history of previous anterior myocardial infarction and suspected left ventricular aneurysms were studied both by contrast left ventriculography and by first pass radionuclide ventriculography using Technetium99m and a computerised multicrystal gamma camera. The radionuclide study successfully identified all 14 patients with aneurysms and all 4 with diffusely hypo-kinetic ventricles. Ejection fraction calculated from the change in radioactive counts in the left ventricle correlated well with that calculated from the area-length method from the contrast angiogram (r = 0.83). Ventricular volumes calculated from the area-length formula for both contrast and radionuclide angiograms correlated closely (r = 0.85 and r = 0.89 for end-systolic and end-diastolic volumes, respectively). In the patients with aneurysms, there was a close correlation between the extent of akinesis, as assessed by the two methods (r = 0.94). The ability of the radionuclide ventriculogram to provide accurate information on global and segmental ventricular function, and to differentiate between segmental and diffuse ventricular dysfunction, enables the method to act as a screening procedure in the investigation of patients with suspected left ventricular aneurysms.

Adult↗
PubMed1979

Detection of a false left ventricular aneurysm by first-pass radionuclide ventriculography.

A false left ventricular aneurysm complicating an inferior myocardial infarction was successfully identified by computerized first-pass radionuclide ventriculography using a multicrystal gamma camera. The aneurysmal chamber exhibited paradoxical systolic expansion, a pattern of contraction confirmed by contrast cineangiography. Because of the propensity of false aneurysms to rupture, early noninvasive firm diagnosis is desirable and may be accomplished by first-pass radionuclide angiography.

Cineangiography↗
PubMed1978

Positive myocardial scintigraphy at the bedside--evaluation using a portable gamma camera.

A study was undertaken to evaluate the role of positive infarct scintigraphy in the diagnosis of acute myocardial infarction (AMI), using Technetium99m stannous pyrophosphate (Tc-PYP) and a portable gamma camera. Sixty-one patients admitted to the Coronary Care Unit (CCU) with a presumptive diagnosis of AMI or ischaemic cardiac pain were studied. Positive scans were present in 24/25 (96%) patients with AMI and new Q waves, and in 10/12 (83%) patients with AMI and no Q waves. Nine of eleven (82%) patients with chest pain and no infarction had negative scans. Of thirteen patients with unstable angina, ten (77%) had positive scans. A further eight patients undergoing coronary artery bypass surgery for angina pectoris were studied pre- and postoperatively. Two patients had strongly positive postoperative scans. The Tc-PYP scan is valuable in the detection of peri-operative infarction following coronary artery surgery, and in patients with unstable angina the technique may detect small amounts of myocardial necrosis undetectable by more conventional means. When the diagnosis of infarction is obvious from the ECG, enzymes, or a combination of the two, the Tc-PYP scan provides no extra information helpful in patient management.

Acute Disease↗
PubMedDate not supplied

Myocardial revascularisation in elderly patients with refractory or unstable angina and advanced coronary disease.

BACKGROUND: Elderly patients with ischaemic heart disease are often treated more conservatively and for longer than younger patients, but this strategy may result in subsequent invasive intervention of more advanced and higher risk coronary disease. METHODS: We performed a retrospective analysis of 109 patients aged > or = 70 years (mean age 74 years, 66% men), who presented with angina refractory to maximal medical treatment or unstable angina over a 2-year period (1988-1990), to compare the relative risks and benefits of myocardial revascularisation [coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA)] in this higher-risk age group. RESULTS: Sixty patients underwent CABG and 49 patients PTCA. There were eight periprocedural deaths in total (six in the CABG group, and two in the PTCA group, P = 0.29). Six patients in the CABG group suffered a cerebrovascular accident (two fatal). Acute Q-wave myocardial infarction occurred in one patient in the CABG group and in two patients in the PTCA group. The length of hospital stay was longer for the CABG group (CABG group 11.4 +/- 5.4 days, range 7-30 days, PTCA group 7.4 +/- 7.6 days, range 1-39 days, P = 0.01). Outcome was assessed using the major cardiac event rate (MACE; i.e. the rate of death, myocardial infarction, repeat CABG or PTCA). The cumulative event-free survival in the CABG group in 1, 2 and 3 years was 87, 85 and 85%, respectively. In contrast, in the PTCA group it was 55, 48 and 48% (P = 0.0001). Age, sex, number of diseased vessels, degree of revascularisation and left ventricular function were not predictive of the recurrence of angina in both groups. Actuarial survival (total mortality, including perioperative mortality) was lower at 1 year in the CABG group due to the higher perioperative mortality, but similar in both groups after the second year (P = 0.62). CONCLUSIONS: Elderly patients with refractory or unstable angina who are revascularised surgically have a better long-term outcome (less frequent event rate of the composite end-point--myocardial infarction, revascularisation procedures and death) compared with those who are revascularised with PTCA. This benefit is been realised after the second year. Total mortality is similar in both groups after the second year. Therefore elderly patients who are fit for surgery should not be denied the benefits of CABG. PTCA may be regarded as a complementary and satisfactory treatment, especially for those whose life expectancy is limited to less than 2 years. The use of stents may improve outcome in the PTCA group and this needs to be evaluated.

Aged↗
PubMedDate not supplied

The role of balloon angioplasty in the management of coronary artery disease.

PTCA is a new technique for the treatment of certain patients with coronary artery disease. It involves dilatation of stenotic segments of artery using a balloon catheter, and is carried out in cardiac catheterization laboratories. If successful, the need for coronary bypass surgery may be removed, although some patients with initially successful PTCA will come to surgery eventually. Successful PTCA is associated with relief of angina, improved angiographic appearances and coronary perfusion. The primary success rate is between 65% and 80%, and the restenosis rate approximately 25%. 80% of patients will be angina free one year after PTCA. In this paper the indications, contraindications, technology, results and complications are discussed.

Angina Pectoris↗