Biomedical subjects
Publications and source records attributed to C Ilsley.
Sensor cross-checking within dual sensor rate responsive pacemakers is designed to reduce the incidence of inappropriate rate response. We describe a patient in whom sensor cross-checking prevented the occurrence of angina during automotive transport.
OBJECTIVE: To evaluate a clinic set up specifically to assess patients with recent onset chest pain, particularly those presenting with a normal resting electrocardiogram. DESIGN: Retrospective review of case notes. SETTING: Cardiac department of a tertiary referral cardiothoracic centre. PATIENTS: 250 consecutive patients with recent onset chest pain seen within 24 hours of general practitioner referral. OUTCOME MEASURES: Clinical diagnosis and management. RESULTS: 40% of patients were seen within seven days of the onset of symptoms. Twenty seven per cent had non-cardiac symptoms and could be discharged while 60% were considered to have cardiac pain. Sixty six patients (26%) were admitted directly from the clinic and 48 of these underwent coronary angiography within three weeks. Seventy patients (28%) have so far undergone intervention (angioplasty or coronary artery surgery), 22 within one month of presentation. One hundred and nine patients (44%) presented with a normal resting electrocardiogram, 21 of whom were considered to have unstable angina. Forty one of these patients were investigated of whom 37 were found to have significant coronary disease and 26 have undergone intervention. CONCLUSIONS: This experience highlights the inadequacy of a routine electrocardiogram reporting service in patients with recent onset of chest pain. An alternative facility offering immediate and complete cardiac assessment produced patient benefit with early diagnosis and intervention. Investigation of these patients, however, accounted for 5% of cardiac catheterisation laboratory throughput; this was a significant additional and unscheduled workload.
An acute thrombotic occlusion of a mitral prosthesis in a hemodynamically compromised patient was successfully lysed with intravenous streptokinase. Unfortunately, the patient had a major cerebral embolus, from which she died several days later. A review of the current literature reveals that thrombolytic therapy successfully relieves the obstructing thrombus in 73% of cases, while it is partially successful in another 16% allowing deferral of surgical repair to a more optimal time. Mortality from thrombolytic therapy is 14% while hemorrhage or cerebral emboli occur in a further 11%. Reports of surgical intervention have shown an operative mortality rate of 25%, in those fit to undergo surgery. If hemodynamically unstable patients unfit for surgery are included on an intention to treat basis, overall mortality is 42%. Thus, thrombolytic therapy should be considered primarily in those compromised patients who have a thrombotic occlusion of a valvular prosthesis with a greater risk of operative mortality. Low dose, prolonged infusions should be favoured over rapid, high concentration infusions currently employed for coronary thrombolysis, as the latter regime could have contributed to the fatal cerebral embolus in our patient.
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Since May 1981 39 men and 11 women (mean age 55 years) have undergone percutaneous transluminal coronary angioplasty at Dunedin Hospital. Angioplasty was performed in 34 (68%) patients with stable angina, 13 (26%) with unstable angina and in three (6%) patients with acute myocardial infarction. Primary success (reduction in angiographic stenosis without associated myocardial infarction or emergency coronary bypass) was achieved in 77% of those patients with single vessel coronary disease (27 of 35 procedures) and of 62% in those patients with multiple vessel disease (16 of 26 procedures). Successful angioplasty was obtained in 81% (25/31) of those patients with anterior descending disease, 67% (4/6) of those with circumflex disease and 58% 14/24) of patients with right coronary disease. Thirty-four patients (68%) following successful angioplasty were rendered asymptomatic. Five (10%) underwent emergency coronary bypass grafting and one of these patients died. Percutaneous transluminal coronary angioplasty is a useful alternative to coronary artery bypass surgery and may be performed in a majority of patients with symptomatic single vessel coronary artery disease and in selected individuals with multiple vessel coronary disease.
Exercise electrocardiography in women with chest pain is associated with a high incidence of false positive ST segment depression. The recent observation that changes in R wave amplitude during exercise can also be used diagnostically may improve the value of stress testing in women. The results of 12 lead treadmill exercise and coronary angiography were reviewed in 62 women, mean age 51 years, presenting with "angina" without previous myocardial infarction. These were compared with exercise results in 14 healthy asymptomatic volunteers with a mean age of 26 years. In addition to conventional ST analysis, R wave amplitude changes during exercise, measured in leads II, III, a VF, and V4 to 6, were examined. While the sensitivity and specificity of ST and R wave changes were similar at about 67%, their combined interpretation was helpful. If both ST and R wave criteria were negative the predictive accuracy for normal coronary angiography was 94% (17/18). Alternatively, in tests showing both ST depression and an abnormal R wave response, coronary angiography was always abnormal (13/13). None of the normal volunteers developed ST segment depression and 93% (13/14) had a normal R wave response. If both were positive, however, coronary angiography was always abnormal (13/13). Although stress test interpretation in women is difficult, R wave analysis is a useful adjunct to ST change and can improve the predictive accuracy of the test in a significant number of patients.
Between 10 and 20% of coronary arteriograms in patients with chest pain show normal vessels, often in association with a history of "atypical" angina. Conventional non-invasive tests are inaccurate in this group of patients compared with those with classical angina. This study prospectively evaluates combined 12 lead exercise electrocardiography and thallium-201 scintigraphy as a screening test in patients with atypical angina in order to determine whether normal arteriograms are avoidable in this important subgroup of patients presenting with chest pain. Sixty seven consecutive patients with atypical angina underwent both maximal exercise testing and thallium scintigraphy before coronary arteriography. Chest pain during exercise was a poor predictor of coronary disease in this group. Eleven (16%) had abnormal arteriography, with the sensitivity of exercise and thallium tests being 45% and 73%, respectively. When both tests were applied the predictive accuracy for normal coronary arteries was 96% (54/56) and that for the presence of coronary disease was 82% (9/11). If coronary arteriography was withheld in patients in whom both the exercise test and thallium scintigraphy were negative, the number of normal coronary arteriograms could be reduced with only a very small risk of failing to detect individuals with coronary disease.
The relationship between R-wave amplitude and left ventricular volume was examined using two groups of patients, undergoing diagnostic cardiac catheterisation for investigation of chest pain, who had simultaneous R-wave recording and left ventricular angiography. R-wave amplitude was measured in leads 1, 2, 3 and V4-6. Left ventricular volume was altered by nitroglycerine (n = 18) and atrial pacing (n = 13). In both groups, increase or decrease in left ventricular volume was associated with a concomitant change of R-wave amplitude. We conclude that left ventricular volume is an important determinant of surface-recorded R waves with increased amplitude reflecting increased left ventricular volume and vice versa.
Change in R wave amplitude (mean delta R) was measured sequentially during and after 12 lead maximal treadmill exercise tests in 14 subjects with normal coronary arteries and 62 patients with coronary artery disease. In normal subjects mean delta R decreased maximally one minute after exercise and returned to control levels within three minutes. In contrast, mean delta R increased in patients with coronary artery disease, the greatest change occurring in patients with either triple vessel or left main disease or those with an akinetic region on the left ventriculogram. R wave amplitude returned to resting levels in five minutes. Increase in R wave amplitude was not directly related to changes in the ST segment. Changes in R wave amplitude during maximal treadmill exercise may improve the discrimination between patients with and without coronary artery disease and may help to identify those patients with abnormal left ventricular function.
Trichoplusia ni cells infected with a low passage (LP) strain of Autographa californica nuclear polyhedrosis virus (NPV) produce large numbers of polyhedral inclusion bodies (PIBs). Interference with PIB production occurs when T. ni cells are first inoculated with a high passage (HP) strain and then challenged with the LP strain. PIB production is reduced 100 fold to the level seen with HP virus infection only.
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The effect of preoperative left ventricular function on eraly and late prognosis was assessed in 69 patients with aortic regurgitation who underwent homograft replacement of the aortic valve. Patients were divided into two groups: Group A (38 patients) had an ejection fraction of 0.46 or more and Group B (31 patients) had an ejection fraction of 0.45 or less. Clinical data, hemodynamic data, and operative results were compared in the two groups. In Group A there was one early death (2.6%) and there were two late deaths (5.3%) compared to two early deaths (6.5%) and seven late deaths (22.6%) in Group B during a follow-up period of 13 to 98 months (mean, 49 months). Actuarial analysis showed a 94% survival at 6 years in Group A compared to 80% in Group B. Twenty-four patients were reinvestigated by repeat cardiac catheterization and coronary angiography at a mean time of 38 months following valve replacement. Left ventricular function was assessed by computerized quantitative radial analysis of segmental wall motion. Improvement in left ventricular function occurred in eight of the 14 patients reinvestigated in Group B, and appeared to be closely related to the etiology of the initial valve lesion. Despite the higher mortality rate in patients with poor left ventricular function, most derived considerable benefit from operation.