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H A McCann

Publications and source records attributed to H A McCann.

34 records · Page 2Linked to original sources
PubMed1992

Automated St-segment trending: what does it mean?

This article is the first segment of what we hope will become a regular feature in the Journal of Clinical Monitoring. The Monitoring Dilemmas series is designed for clinicians who are struggling with the information presented by new monitoring. The past decade has seen an explosion in the number and type of clinical monitors in daily use. Health-care providers are increasingly faced with a plethora of monitoring data, often without guidance on how to interpret it. Each Monitoring Dilemma consists of a case report that describes a clinical dilemma brought on by information from a monitor--a dilemma that would not even have been considered had the monitor not been in place or existence. The case reports are sent to experts in the particular fields concerned. To prevent "Monday morning quarterbacking," each reviewer is sent several envelopes, each containing information that progressively reveals more and more about the case. The case is presented as it actually evolved, and the experts comment as the case unfolds. Thus, the reader can share the dilemma with the reviewers, as well as with the original clinicians. We welcome your comments on this new section. We also welcome your own Monitoring Dilemmas. Please contact the Section Editor, Dr Partridge, for more details.

Aged↗
PubMed1991

Reversibility of cardiac abnormalities in human immunodeficiency virus (HIV)-infected individuals: a serial echocardiographic study.

Seventy adults who tested positive for human immunodeficiency virus (HIV) were prospectively studied with serial echocardiography to better define the prevalence and progression of cardiac disease in such patients. Fifty outpatients (Group A), including 44 with acquired immunodeficiency syndrome (AIDS) and 6 with AIDS-related complex, and 20 additional patients (Group B) with asymptomatic HIV infection had baseline echocardiographic studies at a time when no patient had symptomatic heart disease. Follow-up studies were performed at 9 +/- 3 months in 52 patients (74%) and again at 15 +/- 3 months after baseline studies in 29 patients (41%). During the study, 22 patients (44%) in Group A and 1 patient (5%) in Group B died. Cardiac abnormalities were noted in 26 patients (52%) in Group A and 8 patients (40%) in Group B (p = NS) on initial or follow-up study. An abnormal left ventricular ejection fraction (less than 45%) or fractional shortening (less than 28%) was seen in seven patients in Group A; of these, three had normal left ventricular function on a later echocardiogram. One patient in Group B had persistent left ventricular dysfunction. All patients in Group A with left ventricular dysfunction on two serial studies died within 1 year after the initial echocardiogram. Ejection fraction did not change between baseline and two follow-up studies in either group (A: 52 +/- 9 vs. 56 +/- 9 vs. 55 +/- 5%, p = NS; B: 58 +/- 6 vs. 58 +/- 5 vs. 59 +/- 6%, p = NS). Right-sided cardiac enlargement resolved in 18 patients (44%), including 5 of 10 in Group A and 3 of 8 in Group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

International trials and national practice: a questionnaire survey of current physician practice in the treatment of acute myocardial infarction.

To establish current national clinical practice in the care of patients with acute myocardial infarction (AMI), a questionnaire survey of 50 consultant physicians currently working in the Republic of Ireland was carried out. There were 45 (90%) respondents. 32/45 (71%) give thrombolysis in CCU only; 13/45 (29%) give thrombolysis in casualty also. Streptokinase (Stk) is the first choice thrombolytic agent for the majority. 14/45 (31%) use tPA for anterior AMI in patients under 60 years. Angiotensin converting enzyme (ACE) inhibitors are given by 34/45 (76%) to patients with evidence of left ventricular dysfunction. ACE inhibitors are neither used routinely nor are they prescribed in the first three days after the AMI by the majority of the physicians surveyed. Serum magnesium is checked routinely by 5/45 (11%) and intravenous magnesium is given routinely by 5/45 (11%). The percentage of AMI patients considered for angiography varied from 10-50%. Despite reports from randomised, controlled trials showing reduced mortality in patients given tPA (versus Stk), routine early ACE inhibition and intravenous magnesium post-AMI, most clinicians in Ireland use streptokinase, selective late ACE inhibition and no magnesium. The reasons for the dichotomy between the favourable results of randomised clinical trials and routine practice are speculative.

Clinical Trials as Topic↗
PubMedDate not supplied

Thoracic aortic dissection or aneurysm: clinical presentation, diagnostic imaging and initial management in a tertiary referral centre.

Spontaneous thoracic aortic dissection carries a high mortality despite progress in diagnosis and treatment. Early and accurate diagnosis is paramount and dependent on clinical and diagnostic imaging skills. A retrospective review of 55 consecutive patients referred with suspected thoracic aortic dissection to a medical cardiology department was performed. Clinical follow up was complete to November 1995. Median age was 68 years (range 30-93), with 37 males, 18 females. Presenting complaints included interscapular chest pain in 23 (42 per cent), neurological deficit in 2 (4 per cent), and limb ischaemia in 8 (15 per cent). On examination 34 (62 per cent) patients had hypertension, 5 (9 per cent) a pulse deficit and 10 (18 per cent) aortic incompetence. Electrocardiography confirmed myocardial infarction in 1. Chest X-ray showed a widened mediastinum in 37 (67 per cent) patients. Dissection was confirmed in 35 (64 per cent) patients (13-DeBakey Type I, 6-Type II, 14-Type III); 10 had nondissecting aneurysm. Contrast aortography was equally sensitive (84 per cent) and more specific (100 per cent vs 80 per cent) than computed tomography for detection of dissection. Surgical repair was performed on 24 patients with concomitant coronary artery bypass grafting in 6. At follow up 33 patients were alive. Clinical diagnosis of thoracic aortic dissection or aneurysm may be difficult. Frequently more than one imaging modality may be required in order to provide all of the necessary information for optimal patient management.

Adult↗
PubMedDate not supplied

Emergency primary coronary angioplasty in patients with acute myocardial infarction who are unsuitable for intravenous thrombolysis.

Intravenous thrombolytic therapy is now accepted as the standard method of achieving coronary reperfusion in patients with acute myocardial infarction. There are several important limitations. Primary percutaneous transluminal coronary angioplasty is an attractive method for reopening occluded coronary arteries. Between 1986 and 1993, 14 patients in whom there was an absolute contraindication to thrombolysis underwent emergency coronary angioplasty as the primary treatment for acute myocardial infarction. Coronary artery patency was restored in 13/14 (93%). One patient died in hospital. The median follow-up was one year. One patient suffered a further myocardial infarction and one patient required coronary artery bypass surgery at follow-up. Emergency coronary angioplasty services should be developed to treat those patients in whom there is a contraindication to thromboloysis.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Diagnostic pitfalls in transesophageal echocardiography.

The technology of transesophageal echocardiography is now widely available and has proved extremely useful in evaluating cardiovascular anatomy and pathology. Unfortunately, the enhanced echocardiographic detail and multiple transesophageal imaging planes may sometimes be confusing and cause misinterpretations. The majority of these problems are simply the result of operator inexperience. To help prevent misdiagnoses, we have collected a series of the more common diagnostic and technical "pitfalls" of transesophageal echocardiography.

Aorta↗
PubMedDate not supplied

Influence of Doppler sample volume location on the assessment of changes in mitral inflow velocity profiles.

Previous studies that have validated Doppler indexes of mitral inflow have used pulsed wave sample volume locations either at the level of the mitral valve anulus or at the tips of the mitral valve leaflets. Although significant differences between absolute values for peak velocities and velocity time integrals at these sample volume locations have previously been reported, no information exists that has compared changes in inflow profiles after an intervention to improve left ventricular filling. To address this question, 13 patients with severe pulmonary hypertension (mean pulmonary artery pressure, 50 +/- 13 mm Hg) caused by chronic thromboembolic disease were studied with use of Doppler echocardiography immediately before and after surgical reduction of pulmonary hypertension (pulmonary vascular resistance decreased from 916 +/- 413 to 233 +/- 89 dynes.sec.cm5). This clinical model has been shown to have abnormal mitral inflow velocity profiles that improve markedly after surgery. Doppler measures of early and late peak velocities were significantly lower both before and after surgery when sampling at the mitral anulus compared with the leaflet tips, although late filling parameters and the deceleration of early flow velocity tended to differ little. With surgery, the significant increase in peak early velocity and the ratio of early to late velocity was present regardless of the sample volume location (peak E at leaflet tips, 47.1 +/- 16.0 to 68.9 +/- 15.4 [p less than 0.001], and at anulus, 40.7 +/- 11.3 to 56.2 +/- 14.6 cm/sec [p less than 0.001]; peak E/A at leaflet tips, 0.95 +/- 0.4 to 1.55 +/- 0.9, and at anulus, 0.78 +/- 0.3 to 1.32 +/- 0.7 [both p less than 0.02]).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMedDate not supplied

Evaluation of patients with diabetes mellitus for coronary artery disease using dobutamine stress echocardiography.

BACKGROUND: There is a high prevalence of coronary artery disease (CAD) in patients with diabetes mellitus. Detection of inducible ischaemia using treadmill exercise testing may be limited by the relatively poor inherent predictive accuracy of the test. The purpose of this study was to determine the value of dobutamine stress echocardiography (DSE) for the detection of CAD in patients with diabetes mellitus. METHODS: Patients with diabetes mellitus referred for cardiac assessment were considered eligible for study. DSE was performed in a standard fashion. Significant CAD was defined as a > 50% luminal diameter stenosis on coronary angiography. RESULTS: A total of 52 patients (mean age 59 years) with diabetes mellitus were studied prospectively using DSE. Risk factors for CAD included hypertension in 19, family history in 21, hypercholesterolaemia in 14, history of smoking in 38. The sensitivity, specificity, positive and negative predictive values of DSE for detection of CAD were 82, 54, 84 and 50% respectively. CONCLUSION: The specificity of DSE for CAD in patients with diabetes mellitus is low. Whether this reflects an underdetection of small vessel disease by contrast coronary angiography or whether it relates to test performance is unclear.

Cardiotonic Agents↗
PubMedDate not supplied

Safety of dobutamine stress echocardiography in 474 consecutive studies.

BACKGROUND: With expanding applications and increasingly aggressive stress protocols, concerns about the safety of dobutamine stress echocardiography (DSE) have arisen. The purpose of this study was to analyse prospectively the safety, adverse event profile and complication rate of DSE. METHODS: Prospective data were recorded in a consecutive series of 474 patients undergoing DSE. Dobutamine was administered intravenously in graded infusion, each stage over 3 min, at 10, 20, 40 and, if required, 50 micrograms/kg/min. Atropine (1 mg) was administered thereafter if the response remained suboptimal. RESULTS: The mean dose of dobutamine was 42 micrograms/kg/min, with 111 patients (23%) receiving 50 micrograms/kg/min. Atropine was required for 27 patients (6%). No patient died or suffered a myocardial infarction. Sustained ventricular tachycardia occurred in one patient, angina pectoris in 127 (27%), non-sustained ventricular tachycardia in eight (2%) and supraventricular tachycardia in 19 (4%). Profound bradycardia requiring cessation of the test occurred in one patient. Pulmonary oedema developed in one patient. A hypotensive response requiring cessation of the test was seen in one patient. Test termination because the patient complained of nausea, tremor or headache was not required. CONCLUSION: DSE is safe. Side effects are rare and when they occur, are usually minor. Ischaemic pain is effectively treated by termination of the test and sublingual administration of nitrates.

Adolescent↗
PubMedDate not supplied

Comparison of dobutamine stress echocardiography and treadmill exercise electrocardiography for detection of coronary artery disease.

BACKGROUND: Critical analysis of treadmill exercise testing (TMET) for the detection of coronary artery disease has revealed many shortcomings. Excellent diagnostic accuracy has been reported for dobutamine stress echocardiography (DSE). METHODS: A prospective comparison of DSE and TMET for the detection of coronary artery disease in routine clinical practice was performed using contrast cineangiography (significant stenosis > or = 50%) as a gold standard. RESULTS: A total of 116 patients (82 men, 34 women) were studied. Significant stenosis was detected by coronary angiography in 92 patients (79%). Single vessel disease occurred in 28, double-vessel disease in 32, and multivessel disease in 32 patients. Although sensitivity of DSE was better than that of TMET (82 versus 40%), specificity was worse (63 versus 79%). Positive predictive values for both DSE and TMET were good at 89 and 87%, respectively, whereas negative predictive values were poor for both (47% for DSE, 26% for TMET). CONCLUSIONS: Overall, DSE performs better than TMET in terms of sensitivity and positive and negative predictive value. Its lower specificity than that of TMET may lead to more patients being referred for diagnostic coronary angiography. The poor negative predictive value of DSE and TMET means that one should not be falsely reassured by normal results.

Adult↗
PubMedDate not supplied

Initial experience with percutaneous balloon mitral commissurotomy.

Percutaneous Transvenous Mitral Commissurotomy (PTMC) is an alternative to surgical mitral valvuloplasty for treatment of selected patients with rheumatic mitral stenosis. We report our initial experience with the technique in 10 patients. The procedure was successful in all patients. There were no major complications. Mitral valve area increased from a mean (+/- SD) of 0.95 +/- 0.2 to 2.18 +/- 0.8 cm2. Transmitral pressure gradient fell from 12 +/- 8 to 4 +/- 5 mmHg while New York Heart Association functional class improved by 1 grade or more in all patients. PTMC is a safe and cost effective alternative to surgical mitral valvotomy in appropriately selected cases.

Aged↗
PubMedDate not supplied

Emergency bail-out stenting for major coronary dissection complicating rotational atherectomy.

The problems of restenosis and abrupt occlusion following percutaneous transluminal coronary angioplasty (PTCA) remain a challenge. Restenosis occurs in 30-50% of lesions treated and substantially erodes the potential advantage of percutaneous treatment of obstructive coronary disease over alternative revascularisation strategies. Abrupt closure occurs in 5-7% of cases with significant associated morbidity and mortality. Up to 35% of patients require emergency bypass surgery for treatment of abrupt closure and more than half sustain a perioperative myocardial infarction. By debulking atherosclerotic lesions, atherectomy offers the potential to reduce restenosis. Coronary stenting, by acting as a scaffolding can sometimes solve the problem of abrupt closure due to intimal dissection. We report the use of emergency placement of multiple coronary stents for obstructive coronary dissection complicating rotational atherectomy.

Aortic Dissection↗
PubMedDate not supplied

Risks of long-term oral anticoagulation in a non-trial medical environment.

Randomised controlled trials have shown that anticoagulation with warfarin reduces the risk of stroke in patients with atrial fibrillation by two thirds. However there is concern as to whether the rate of anticoagulant-related haemorrhage seen in these trials would be reproduced in a non-trial setting. Four hundred and ten consecutive patients attending a special anticoagulation clinic over one year were asked to complete a questionnaire concerning their warfarin treatment. The total number of years on warfarin was 2870. Of the 410 patients, 59 (14%) admitted to 88 bleeding episodes while on warfarin. Of these bleeding problems, 36/88 (41%) required admission to hospital or to casualty for treatment and 52/88 (59%) required only a lowering or temporary cessation of warfarin therapy. The calculated annual non-fatal bleeding rate of 3% in this survey is identical to that reported from the Copenhagen AFASAK trial. Similarly the 1.3% annual rate of major bleeding requiring attendance at hospital is identical to that in the Stroke Prevention in Non-Rheumatic Atrial Fibrillation trial. The results of this study suggest that oral anticoagulation is as safe in an ordinary medical setting as in a closely supervised trial setting.

Anticoagulants↗