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Biomedical subjects

D Mulcahy

Publications and source records attributed to D Mulcahy.

At least 73 records · Page 4Linked to original sources
PubMed1992

Can we really justify the treatment of silent ischemia in 1992? No!

Since the advent of ambulatory ST-segment monitoring, it has been established that silent ischemia is common in patients with various coronary artery disease syndromes, and such silent episodes represent up to 80% of all ischemic episodes. It appears to be associated with an adverse prognosis when compared with similarly characterized patients without silent ischemia during daily life. Silent ischemia does not, however, bother the patients, by virtue of the fact that it is silent, and therefore treatment of such ischemia must be justified by an improved outlook for the patient, rather than symptom relief. There is no direct evidence to date that silent ischemia is associated with acute myocardial infarction or sudden cardiac death in a cause-and-effect relationship, or that reduction or eradication of silent ischemia will lead to an improved prognosis for the patient; indeed, we have been unable to demonstrate any significant improvement in outlook when using the various antianginal/antiischemic agents at our disposal. Until we can demonstrate a benefit to the patient by detecting and treating silent ischemia, we should not waste large resources attempting to eradicate something whose significance we do not understand.

Coronary Disease↗
PubMed1992

Effects of coronary artery bypass surgery and angioplasty on the total ischemic burden: a study of exercise testing and ambulatory ST segment monitoring.

To assess the effects of standard therapeutic interventions on the total ischemic burden, 86 patients with stable angina underwent 48 hours of ambulatory ST segment monitoring and treadmill exercise testing before and at a mean of 10 weeks after coronary artery bypass surgery (CABG) (group 1, N = 46) or percutaneous transluminal coronary angioplasty (PTCA) (group 2, N = 40). There were 72 male and 14 female patients with a mean age of 56.4 years. All patients had documented coronary artery disease (24, single-vessel; 28, two-vessel; 34, three-vessel disease). Both groups were characteristically similar apart from more severe coronary artery disease (p less than 0.001) and more previous myocardial infarctions (p less than 0.05) in group 1. Groups with CABG and PTCA had significant prolongation of exercise time after intervention (group 1: 7.6 to 9.8 minutes, p less than 0.0001; group 2: 8.1 to 10.0 minutes, p less than 0.001), and both interventions led to a significant reduction in ischemic responses (group 1: 33 to 4, p less than 0.001; group 2: 20 to 13, p less than 0.05) to exercise. During a total of 7643 hours of ST segment monitoring, 253 episodes of ischemia were recorded in 3768 hours before and 44 ischemic episodes in 3875 hours after intervention (group 1, 113 episodes in 24 patients and 21 episodes in 10 patients; group 2, 140 episodes in 13 patients and 23 episodes in six patients). Both interventions reduced the mean frequency of ischemia per 24 hours (group 1: 1.24 to 0.22 episodes per 24 hours; p less than 0.01; group 2: 1.9 to 0.3 episodes per 24 hours; p less than 0.05). Almost 28% (N = 24) of resting electrocardiographic findings were altered as a result of intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1992

Value of ambulatory ST segment monitoring in patients with chronic stable angina: does measurement of the "total ischaemic burden" assist with management?

OBJECTIVE: To assess the prognostic significance of transient ischaemic episodes during daily activities in patients with stable angina. PATIENTS AND METHODS: 172 patients with stable angina attending the cardiac outpatients departments of Hillingdon Hospital (n = 155) and the National Heart Hospital (n = 17) were prospectively studied by exercise testing and 48 hours of ambulatory ST segment monitoring, and followed for prognostic purposes for up to 39 months (mean 24.5 months). Patient inclusion depended on a clinical diagnosis of stable coronary artery disease which necessitated outpatient review (and antianginal treatment in 94% of patients). It was not dependent on objective evidence of reversible ischaemia. Events recorded during the follow up period included death, non-fatal myocardial infarction, unstable angina, and the requirement for revascularisation. RESULTS: 72 patients (42%) had transient ischaemic episodes during daily activities, and 104 patients (60.5%) had an ischaemic response to exercise. 63 patients (36%) had evidence of ischaemia on both investigations; with 59 (34%) having no documented ischaemia on either investigation. There were 27 patient events (15.7%) recorded over a mean 24.5 month follow up, including five deaths (2.9%) (three cardiac related (1.7%)), six non-fatal myocardial infarctions (3.5%), six admissions with unstable angina (3.5%), and 10 revascularisation procedures (5.8%). Of the nine "hard" or objective end points (cardiac death and non-fatal myocardial infarction), only two had evidence of transient ischaemia on ambulatory ST segment monitoring at initial investigation, with 10 of the 25 patients (38.5%) with any cardiac event having such episodes. CONCLUSIONS: The outcome in patients with chronic stable angina receiving standard medical treatment was good over a mean two year follow up period. For the purpose of assessing prognosis over this time scale, there was no advantage to performing ambulatory ST segment monitoring in such patients.

Adult↗
PubMed1991

Clinical validation of four solid state ambulatory monitoring devices in detecting shift of the ST segment.

Continuous monitoring for detection of changes in the ST segment during daily life in patients with stable angina has received increasing attention in recent years. Various reports testify to its role in the detection of silent ischaemia, and its potential usefulness in stratification of risk. Frequency modulated recorders, using magnetic tape for recording with subsequent visual analysis, have been previously validated for the detection of such changes. Analysis, however, is time consuming, and is subject to technical faults due to the presence of moving parts. Several new solid state devices have become available in recent years which provide real-time automated analysis, and have theoretically ideal recording capabilities with frequency response down to 0.05 Hz and linear phase integrity which may be as good, or better than, tape based recorders. We compared each of four solid state devices with a previously validated frequency modulated recording device in patients with angina in order to assess whether such devices correlate well in detecting changes in the ST segment.

Angina Pectoris↗
PubMed1991

Therapeutic implications of dynamic coronary stenosis in patients with single vessel coronary artery disease.

Ten patients with proven single-vessel coronary artery disease and a positive exercise test for ischaemia were investigated to establish the importance and therapeutic implications of dynamic coronary stenosis in such patients. All patients interrupted their anti-anginal therapy and under took serial exercise testing in an attempt to identify variability in the ischaemic threshold. Ergonovine testing was performed in nine patients and all underwent 48 h of ambulatory ST segment monitoring while treatment was discontinued. Patients then entered a randomized double-blind study of atenolol and nifedipine; treadmill exercise testing and 48 h of ambulatory ST segment monitoring were performed at the end of each treatment phase. Six (60%) patients showed evidence of variability in coronary vasomotor tone four of whom developed significant ST segment changes during administration of ergonovine; a further two had greater than 30% variability in time to onset of ischaemia during serial treadmill exercise testing. Atenolol significantly increased the time to ischaemia on exercise testing, both in the group as a whole and in the subgroup with evidence of altered vasomotor tone when compared with no therapy, and led to a non-significant reduction in the frequency and duration of ischaemia during the patients' daily lives. Nifedipine, conversely, did not significantly increase time to ischaemia on exercise testing or reduce the frequency or duration of ambulatory ischaemia in either the whole group or the subgroup. With evidence of altered vasomotor tone when compared to no therapy however it was beneficial in terms of reduction in chest pain and requirement for glyceryl trinitrate during daily life.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Successful stenting of a life threatening pulmonary arterial stenosis.

A 35 year old woman with multiple pulmonary arterial stenoses and occlusions was admitted with increasingly severe breathlessness. Balloon angioplasty of a life threatening stenosis in a remaining pulmonary artery branch was attempted on two occasions but without success. When a self-expanding stainless steel stent was inserted at the site of stenosis after a further angioplasty acute localised pulmonary oedema developed as blood flow distal to the lesion increased considerably. This was followed by a slow and dramatic improvement in the patient's condition. She no longer required an urgent transplant and resumed an active life.

Adult↗
PubMed1991

Circadian patterns of myocardial ischaemia and the effects of antianginal drugs.

Chronopathology of cardiovascular disease is now well documented. Silent myocardial ischaemia involves the same pathophysiological changes as conventional ischaemia. Early morning peaks in angina and myocardial ischaemia call for adequate timing of medication. beta-blockers abolish the morning peak, and aspirin reduces morning infarctions. The effects of other antianginals on these phenomena are presently unknown.

Angina Pectoris↗
PubMed1990

Characteristics of silent and painful ischaemia during ambulatory monitoring in patients with coronary arterial disease.

We compared the characteristics of silent and painful ischaemia during ambulatory ST segment monitoring in 288 patients with documented coronary arterial disease and stable angina. During 12,436 hours of monitoring, 890 ischaemic episodes were recorded, of which 652 (73%) were silent. Silent and painful ischaemic episodes were similar in terms of heart rate at onset of ischaemia, increase in heart rate prior to ischaemia, duration of ischaemia, and percentage of episodes not preceded by an increase in heart rate. Change in the mean maximal ST segment was greater during painful ischaemic episodes (P less than 0.01). Silent ischaemia is characteristically painful ischaemia without the pain.

Adult↗
PubMed1990

Circadian variation of heart rate is affected by environment: a study of continuous electrocardiographic monitoring in members of a symphony orchestra.

Twenty four hour ambulatory ST segment monitoring was performed on 48 members (43 players and five members of the management/technical team) of the British Broadcasting Corporation (BBC) symphony orchestra without a history of cardiac disease. This period included final rehearsals and live performances (for audience and radio) of music by Richard Strauss and Mozart at the Royal Festival Hall (n = 36) and Rachmaninov and Tchaikovsky at the Barbican Arts Centre (n = 21). During the period of monitoring one person (2%) had transient ST segment changes. Mean heart rates were significantly higher during the live performances than during the rehearsals. Mean heart rates during the live performance of Rachmaninov and Tchaikovsky were significantly higher than during Strauss and Mozart in those (n = 6) who were monitored on both occasions. Mean heart rates in the management and technical team were higher than those of the players. The recognised circadian pattern of heart rate, with a peak in the morning waking hours, was altered similarly during both concert days, with a primary peak occurring in the evening hours and a lesser peak in the morning for both musicians and management/technical staff. This study showed that environmental factors are of primary importance in defining the circadian pattern of heart rate. This has important implications when identifying peak periods of cardiovascular stress and tailoring drug treatment for patients with angina pectoris.

Adult↗
PubMed1990

The cytobrush for evaluating routine cervicovaginal-endocervical smears.

While the conventional wooden spatula/cotton-tipped applicator has remained the method of obtaining Papanicolaou smears for most clinicians at the University of California at Los Angeles, the Student Health Service (SHS) adopted the Zelsmyr cytobrush as its sole method of obtaining cervical samples in late 1986. A study was done to define changes in both the adequacy of sampling and the detection rate for both squamous and glandular epithelial abnormalities with the cytobrush. To accomplish this goal, 1,000 cytobrush and 244 conventionally obtained smears were analyzed prospectively, and 3,864 SHS samples obtained in 1986 prior to the change in method were reviewed retrospectively. As compared to cervical samples obtained by conventional methods, the cytobrush smears contained significantly more endocervical cells and had fewer drying artifacts. Both methods obtained equivalent squamous samples and had similar final class distributions. No case of endocervical adenocarcinoma carcinoma in situ or invasive adenocarcinoma was detected. SHS patients who had initial "no endocervical cells" samples but whose repeat sample did contain endocervical cells retained the same class in more than 75% of cases. This study confirmed that the cytobrush technique produces Papanicolaou smears with improved sampling of the squamocolumnar junction but questioned whether that results in an increased detection rate for cervical pathology.

Adolescent↗
PubMed1989

Ischemia in the ambulatory setting--the total ischemic burden: relation to exercise testing and investigative and therapeutic implications.

To establish the relation between treadmill exercise testing and ambulatory St segment monitoring in the detection of ischemia in patients with coronary artery disease, and to assess whether standard medical therapy affects any such relation, 277 patients with stable angina and angiographically documented coronary artery disease were studied with treadmill exercise testing and 48 h ambulatory ST segment monitoring. One hundred forty-six patients (52%) were studied while receiving no routine antianginal therapy, and 131 (48%) while receiving standard medical therapy. In 187 patients (67%) the exercise test was positive for ischemia. During 11,964 h of ambulatory monitoring, 881 episodes of ischemia (645 [73%] silent) were recorded, of which 809 (92%) occurred in patients with a positive exercise test. The mean heart rate at the onset of ischemic episodes during ambulatory monitoring was significantly less than that at the onset of 1 mm ST segment depression during exercise testing (94.5 versus 105.9 beats/min, p less than 0.0001). However, the frequency of ambulatory ischemic episodes was strongly related to a positive exercise test (p less than 0.001), and this relation was similar for both silent and painful ischemia (p less than 0.0001 for both) and in patients who were and were not receiving therapy (p less than 0.0001 for both). The total duration of ischemia was similarly related to a positive exercise test (p less than 0.0001). Only one patient with a negative exercise test had frequent (greater than 5/day) episodes of ischemia on ambulatory monitoring and had documented coronary artery spasm. Thus, exercise testing identifies the majority of patients likely to have significant ischemia during their daily activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Circadian patterns of myocardial ischemia.

In this overview we studied evidence for the occurrence of silent myocardial ischemia, its pathophysiologic mechanisms, and the circadian distribution of ischemic episodes. The correlation between many hemodynamic parameters and their potential as drug targets was assessed. ECG evidence of myocardial ischemia (ST segment), a parameter often used in exercise tests, also occurs during ambulatory monitoring. Use of the isotope rubidium-82 and positron emission tomography helped confirm the significance of these changes in the ST segment, both painful and silent. Ischemia was detected by a reduction in the uptake of the isotope in a region of the heart reflecting a decrease in myocardial blood flow. Also it was shown that both painful and silent ischemia are caused by similar pathophysiologic mechanisms; such mechanisms include alterations in coronary blood flow and increases in myocardial oxygen demand. Episodes of ST segment depression show a circadian rhythm similar to that seen for heart rate and catecholamine release. The basic pattern shows a low incidence of ischemia at night, followed by a primary peak on rising, a decrease at midday, and then a secondary peak in the evening, with a final decrease again at night. Similar circadian rhythms have been described for acute cardiovascular events, and this may be important for treatment.

Angina Pectoris↗
PubMed1989

Ambulatory ST segment monitoring in the assessment of patients following PTCA.

In this article we discuss the place of ambulatory ST-segment monitoring in the investigation of the patient following coronary angioplasty. Particular attention is focused on the relationship between the results of exercise testing (the standard technique in the evaluation of the post-angioplasty patient) and ambulatory ST-segment monitoring, in order to assess whether ST-segment monitoring might contribute further information in the identification of residual or recurrent ischaemia.

Angioplasty, Balloon, Coronary↗
PubMed1989

Silent myocardial ischaemia in patients referred for coronary bypass surgery because of angina: a comparison with patients whose symptoms were well controlled on medical treatment.

The frequency and characteristics of silent ischaemia were prospectively studied in 114 patients with confirmed coronary artery disease and angina. Fifty seven patients who had angina that was not adequately controlled by standard medications were referred for elective coronary artery bypass surgery (group 1). Fifty seven other patients had symptoms that were well controlled on medical treatment (group 2). Patients underwent treadmill exercise testing (n = 109) and 48 hours of ambulatory ST segment monitoring (total 5125 hours). Patients in group 1 had more severe coronary artery disease and a shorter time to 1 mm ST segment depression and maximal exercise. Twenty two patients in group 1 (38%) and 16 in group 2 (28%) had greater than or equal to 1 episode of silent ischaemia during 48 hours of ST monitoring. There was no significant difference in the mean frequency of silent ischaemic episodes in 24 hours between the two groups (group 1 0.72 v group 2 0.64); however, the mean frequency of painful ischaemic episodes in 24 hours was greater in group 1 patients (0.51) than in group 2 (0.11). In both groups the frequency of silent ischaemia was significantly related to a positive exercise test, as was the total duration of silent ischaemia. The circadian variation of silent ischaemia showed a peak of episodes in the evening in both groups. The frequency of silent ischaemia in patients with coronary artery disease and angina receiving standard antianginal medications was not related to the severity of symptoms, but was significantly related to a positive exercise test. Thirty three percent of the patients studied had evidence of silent ischaemia during 48 hours of ambulatory ST segment monitoring; however, only four patients (3.5%) had frequent (>/=5) daily episodes of silent ischaemia.

Adult↗
PubMed1988

Circadian variation of total ischaemic burden and its alteration with anti-anginal agents.

6264 hours of ambulatory ST segment monitoring of 150 unselected patients with proven coronary artery disease, who were off all routine anti-anginal treatments, showed 598 ischaemic episodes, of which 446 (75%) were silent (symptom-free). Most (68%) ischaemic episodes occurred between 0730 and 1930, with a peak in the morning and a lesser peak in the evening. Two subgroups were studied further in double-blind controlled trials: 33 patients had a total of 1313 hours of ST segment monitoring while treated with nifedipine; and 41 patients a total of 1581 hours while treated with atenolol. Nifedipine did not alter the circadian pattern of ischaemic episodes; atenolol abolished the morning peak, and the peak incidence of ischaemia then occurred in the evening. Circadian patterns for total duration of ischaemic episodes corresponded closely to those of episodes of ischaemia, and were similarly altered by treatment. The circadian pattern of silent ischaemic episodes and their total duration were very similar to those of total ischaemia for the group as a whole and the different subgroups. This circadian distribution of ischaemic episodes and the observed changes with treatment resemble the reported circadian variation of acute myocardial infarction and sudden death.

Adult↗
PubMed1988

Cardiac transplantation in severely ill patients requiring intensive support in hospital.

Sixty four patients were referred for cardiac transplantation from a single cardiac team at this hospital between October 1984 and December 1986. Of these patients, 33 were referred for urgent transplantation, all of whom required intensive treatment in hospital with intravenous infusions of cardiac drugs, intra-aortic balloon counterpulsation, peritoneal dialysis, ventilation, or any combination of these to sustain life. Of these 33 patients, six died while awaiting transplantation, one was removed from the waiting list for a transplant, and 26 received cardiac transplants. There were five deaths within 24 hours of operation and one death 10 days after the operation. Twenty of those who had surgery had a successful outcome of transplantation, but there was one late death 10 weeks postoperatively and a further death 31 months after surgery. Eighteen patients were alive and well 10 to 33 months (mean 19.4 months) after transplantation, with an overall survival rate after surgery of 69%. Provided that surgery can be performed before renal failure has progressed such that renal dialysis [corrected] is necessary, the results are excellent (surgical survival 85.5%) and, we believe, justify the expenditure and staffing requirements necessary to treat these terminally ill patients.

Adolescent↗