Biomedical subjects
Publications and source records attributed to M G Baird.
Cardiac explantation and autotransplantation is a procedure by which the heart is removed from the chest and replaced. Explantation of the heart for tumor removal has been documented six times in the literature; however, with this aggressive approach, the median patient survival rate is only eight months. This article presents a case study in which this procedure was used to treat a patient with malignant fibrous histiocytoma.
BACKGROUND: The aim of this study was to examine the acute hemodynamic and neurohormonal effects of the angiotensin II antagonist telmisartan relative to placebo in patients with chronic symptomatic (New York Heart Association class II to III) congestive heart failure and to explore the dose-response relation for these effects. METHODS AND RESULTS: After baseline hemodynamic and neurohormonal measurements made with the use of a pulmonary artery and radial arterial catheter, 82 patients were randomly assigned to placebo or 10, 20, 40, or 80 mg of telmisartan in a double-blind fashion. Hemodynamic and neurohormonal measurements were carried out over 24 hours. Telmisartan caused significant decreases in systemic arterial, pulmonary arterial, and pulmonary capillary wedge pressures with evidence of a dose-response relation for each of these parameters. The drug had no significant effects on heart rate, cardiac index, or systemic vascular resistance. Telmisartan did not have consistent effects on either plasma norepinephrine or plasma atrial natriuretic peptide levels, although it did cause significant increases in both plasma renin activity and angiotensin II levels at higher doses. CONCLUSIONS: The acute administration of the angiotensin II antagonist telmisartan was associated with significant dose-dependent reductions in systemic arterial blood pressure and pulmonary pressures. Long-term follow-up studies are required to translate changes in hemodynamic parameters into a clinical benefit.
Nifedipine gastrointestinal therapeutic system (GITS) is a once-daily formulation of nifedipine that provides stable plasma concentrations over the entire 24 h dosing interval. Two-hundred and one patients with Canadian Cardiovascular Society class II to III angina who were on 50 mg of atenolol yet still experiencing angina symptoms were randomized to receive either placebo or nifedipine GITS 30, 60 or 90 mg/day. After four weeks of treatment, the changes in time from baseline to onset of 1 mm ST segment depression in the 183 eligible patients were 26.7+/-10.2 s, 40.9+/-11.3 s, 63.2+/-12.9 s and 70.3+/-12.6 for the placebo, and 30, 60 and 90 mg/day groups, respectively. These differences were significant (P<0.05) for the 60 and 90 mg/day groups compared with placebo and for the 60 mg/day group compared with the 30 mg/day group. The times to onset of pain and termination of exercise showed similar prolongation but did not achieve statistical significance. During the one-year open label phase of the study, patients exhibited statistically significant improvements in the time to onset of ST segment depression, time to anginal pain and time to termination of exercise at a mean dose of 52.3 mg/day of nifedipine GITS. Adverse events were primarily vasodilatory in nature. This study supports the use of nifedipine GITS in patients with chronic stable angina inadequately controlled on beta-blocker alone.
Technological advances in safety and the performance of electrosurgical units (ESUs) have made the ESU the most common piece of electrical equipment in the OR. The constant presence of the ESU in the OR increases the potential for patient injury that is associated with the use of any piece of electrical equipment. To prevent injuries related to the use of an ESU, the perioperative nurse must understand the types of current used, types of ESUs available, and potential complications and have a working knowledge of safe practices for using this equipment in the perioperative setting.
OBJECTIVE: To analyze and compare the incidence of procedural complications and failure of intubation with various sizes of probes used in transesophageal echocardiography. DESIGN: Retrospective chart review. SETTING: A Canadian, tertiary care hospital. PATIENTS: A total of 2947 consecutive transesophageal echocardiographic patient examinations between January 1992 and March 1996 at the University of Ottawa Heart Institute, Ottawa, Ontario. RESULTS: The multiplane probe (MP) was used in 1274 studies, biplane (BP) in 1642 and single plane (SP) in 31. Data for BP and SP were combined because of their similar size. Complications or failed intubation occurred in 86 studies (2.9%). There were 53 complications (1.8%) and 40 failed intubations (1.4%). Seven patients (0.3%) had both. Complications were death in one, tracheal intubation or bronchospasm in nine, bleeding in nine, angina in two, pulmonary edema in two, superficial thrombophlebitis in two, supraventricular tachycardia in one and minor adverse events in 27. Complications were unrelated to the choice of probe (MP 2%, BP and SP 1.7%, not significant). Failure of intubation (40 cases) was more common with MP than with BP and SP (2.3% versus 0.7%, P = 0.0003, OR 3.5, 95% CI 1.7 to 7.5). The main reasons for failure were cervical spondylosis in 16 patients and hypersensitive pharynx despite topical anesthesia and sedation in 13 patients. Of 21 cases of failed MP intubation, 16 (76%) were subsequently successful with BP. CONCLUSIONS: Serious complications with transesophageal echocardiography, although infrequent, do occur. The MP carries a 3.5-fold increased risk of failed intubation. In the majority of failures, successful intubation can be achieved with a smaller probe.
OBJECTIVE: To assess the anti-anginal efficacy of eccentric dosing with a sustained-release formulation of isosorbide dinitrate (ISDN) administered twice daily in an eccentric fashion (08:00 and 14:00). DESIGN: A placebo controlled crossover study of 16 patients with chronic stable angina who received, in random order, either placebo or sustained-release ISDN 40 mg twice daily for a period of seven to 10 days. Patients were entered who had reproducible exercise test to the development of moderate angina. All anti-anginal drugs with the exception of beta-blockers were withheld during the study period. The primary end-point was the treadmill walking time to the development of moderate angina. RESULTS: Patients receiving active therapy showed a significant increase in treadmill walking time to moderate angina over that seen with placebo at 3 and 6 h after the morning dose and 3 and 8 h after the afternoon dose. Similar trends occurred for the time to onset of angina and the time to development of 1 mm of ST segment depression on the electrocardiogram. CONCLUSIONS: Eccentric dosing with sustained-release ISDN, 40 mg given 6 h apart, provided significant improvement in exercise performance for up to 14 h during sustained therapy.
OBJECTIVES: This study was performed to assess the efficacy, safety and clinical consequences of abrupt cessation of quinapril therapy in a placebo-controlled, randomized, double-blind withdrawal trial. BACKGROUND: Angiotensin-converting enzyme inhibitor therapy has assumed a pivotal role in the treatment of chronic heart failure. Quinapril hydrochloride, a nonsulfydryl angiotensin-converting enzyme inhibitor, has shown beneficial clinical effects in previous studies. METHODS: After > or = 10 weeks of single-blind quinapril therapy, 224 patients with New York Heart Association class II or III heart failure were randomized in double-blind fashion to continue quinapril (n = 114) or to receive placebo (n = 110) for 16 weeks. Changes in treadmill exercise time, New York Heart Association functional class, quality of life and symptoms of heart failure were assessed. RESULTS: Patients withdrawn to placebo had a significant deterioration in exercise tolerance (median change -16 s with placebo vs. +3 s with quinapril, p = 0.015). New York Heart Association functional class (p = 0.004) and quality of life were improved and signs and symptoms of congestive heart failure were lessened in those remaining on quinapril therapy compared with those receiving placebo. During double-blind treatment, 18 patients were withdrawn from the placebo group because of worsening heart failure compared with 5 patients withdrawn from quinapril treatment (p < 0.001). Rather than a precipitous deterioration of clinical status or early incidence of adverse events, withdrawal from quinapril was associated with steady worsening of heart failure, beginning 4 to 6 weeks after randomization to placebo. CONCLUSIONS: Quinapril is effective and safe for maintaining clinical stability in patients with moderate congestive heart failure. Withdrawal of quinapril from patients with heart failure results in a slow progressive decline in clinical status.
One hundred and seven patients with chronic heart failure (NYHA class II to IV) stabilized on digitalis and/or diuretics, recruited from 11 centres were randomized into a double-blind, placebo-controlled study to assess the effect of 12 weeks of cilazapril therapy on exercise tolerance and clinical status. Thirty-five patients were randomized to placebo and 72 to cilazapril at a starting dose of 1 mg daily; titration to cilazapril 2.5 mg at week 4 and 5 mg at week 8 (or matching placebo) was carried out in patients who did not improve clinically. Demographic characteristics, including exercise test duration increased from 402 s (+/- 17 SEM) at baseline to 462 s (+/- 19 SEM) at week 12 for the cilazapril group (+15%) and from 405 s (+/- 23 SEM) at baseline to 408 s (+/- 30 SEM) at week 12 in patients on placebo (+1%) (P < 0.001). In the placebo group, patients able to exercise for more than 6 min at baseline showed an increase in exercise duration at week 12 while those able to exercise for up to 6 min at baseline showed a decrease (P = ns). In contrast, cilazapril-treated patients showed an increase in exercise tolerance regardless of baseline exercise test duration; patients with the most impaired exercise tolerance at baseline showed a greater improvement than patients with mildly impaired baseline exercise tolerance (P < 0.05 vs placebo). NYHA class improved by at least one grade in 51% of the cilazapril group vs 32% in the placebo group (P = ns). At the end of the trial, 15% of the patients were non-responders on cilazapril vs 41% on placebo (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
The prognostic value of information derived from clinical characteristics and exercise treadmill tests performed before discharge and repeated at three months was evaluated in 205 consecutive patients followed for five years. Recurrent myocardial infarction, unstable angina and mortality were tabulated. Survival was analyzed by the Kaplan-Meier life-table method and the Cox regression model. The major difference between the predischarge and three month intervals was the failure of exercise-induced ST depression to predict mortality from the predischarge test. However, it was predictive of mortality at three months when 76% survived five years with a positive ischemic response compared to 94% with a negative response (P less than 0.0005). In contrast, resting ST depression of at least 1 mm was associated with a very poor five year survival rate of 58.3% and 50% when assessed at both predischarge and three months (P less than 0.0005 and P less than 0.004, respectively). Selected univariately at the predischarge interval, the following characteristics were ranked in descending order of predictive power for five year mortality by discriminant analysis: history of previous infarction; exercise capacity; and ST depression on resting ECG greater than 1 mm. At three months, the same characteristics were selected. However, recurrent infarction and unstable angina were not predictable at either interval by any clinical or treadmill variable. Characteristics tending to reflect poor exercise capacity are stronger predictors of five year outcome than exercise-induced ischemia. While predischarge exercise testing for ST segment response failed to predict survival, this variable showed improved predictive power with repeat testing at three months.(ABSTRACT TRUNCATED AT 250 WORDS)
To assess the relative prognostic merits of 15 clinical and 10 predischarge exercise test variables, 226 patients who had sustained an acute myocardial infarction were studied. A submaximal treadmill test was performed on 205 patients to a mean work load of 5.7 +/- 2.9 METS. Testing was performed an average of 11.7 (range 6 to 33) days after myocardial infarction. During the first year of observation, major cardiac events were noted in 33 patients (16%), unstable angina in 7 (3.4%), recurrent myocardial infarction in 14 (6.8%) and death in 12 patients (5.9%). Cardiac mortality correlated with mean peak serum creatine kinase (CK) (p less than 0.05), history of previous myocardial infarction (p less than 0.01) and ST segment depression at rest (p less than 0.01). The only exercise variable that correlated with cardiac mortality was poor exercise endurance (p less than 0.05). Multivariate risk stratification of clinical and treadmill variables from these 205 patients using linear discriminant analysis produced a function that correctly classified 95% of those who were event-free and 80% of those who died. The first four discriminant variables that contributed independent information for the prediction of cardiac mortality were: 1) ST segment depression at rest; 2) CK greater than 1,280 IU/liter; 3) exercise duration less than 3 minutes; and 4) a history of previous myocardial infarction. ST segment depression on the predischarge treadmill test did not predict any event, nor did it improve the predictive accuracy of the clinical variables. It is concluded that a history of previous myocardial infarction and ST segment depression on the rest electrocardiogram indicate a poor prognosis after acute myocardial infarction. Poor endurance is the only exercise variable that suggests a future cardiac event. Prognosis after acute myocardial infarction is more accurately predicted by these clinical data than by variables derived from the predischarge treadmill test.
The effects of metoprolol (Betaloc tablets) in a group of 193 hypertensives were compared with the effects of a slow-release formulation (Betaloc Durules) in a further group of 196 patients. Patients were selected at random for treatment. There were no differences between the groups in terms of age, weight, sex, blood pressure, concurrent illness or concomitant therapy. Blood pressure control and apparent adverse effects were similar for both groups; the overall withdrawal rate from each group was similar. Compliance, assessed by tablet counts, was significantly improved in the group receiving once-daily therapy. Simplification of the dosage regimen to once-daily therapy appears to improve the patient's willingness to comply with the physician's instructions.
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Combined forms of left ventricular outflow obstruction are being recognized with increasing frequency. A patient who had coarctation of the aorta, valvular aortic stenosis, and fixed and dynamic subvalvular obstruction is described. The importance of recognizing multiple levels of obstruction in such patients is emphasized.
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Recent studies have suggested a similar prognosis for patients with transmural myocardial infarction and nontransmural myocardial infarction despite a smaller infarct size in the latter patients estimated by creatine phosphokinase (CPK). Thirty-one patients with transmural myocardial infarction and 17 patients with nontransmural myocardial infarction as defined by electrocardiographic criteria underwent coronary angiography and left ventriculography from 10 to 24 days after they had an acute myocardial infarction. Forty-three of these 48 patients were asymptomatic following their myocardial infarction. When compared to patients with nontransmural myocardial infarction, those with transmural myocardial infarction had greater peak CPK levels, 1,090 +/- 210 versus 290 +/- 60 IU (p less than 0.01). There was no difference in prevalence of single, double or triple vessel coronary artery disease, mean number of coronary arteries 50 per cent narrowed (2.0 +/- 0.2 versus 2.0 +/- 0.2), near total or total occlusions, coronary score (Friesinger) (7.9 +/- 0.6 versus 8.2 +/- 0.7), left ventricular ejection fraction (48 +/- 2 versus 53 +/- 4), or per cent of akinetic-dyskinetic myocardial segments (66 of 242 [27 per cent] versus 32 of 132 [24 per cent]) between two groups. The similar extent of coronary artery narrowing and degree of left ventricular dysfunction may explain the similar prognosis for patients with transmural myocardial infarction and those with nontransmural myocardial infarction despite differences in enzymatically estimated acute infarct size.
Late hospital phase ventricular arrhythmias in acute myocardial infarction (MI) have been associated with a high incidence of sudden death following hospital discharge. Thirty-eight patients were studied 10-24 days following onset of symptoms of MI. Each patient had a 24-hour ambulatory ECG tape recording and left ventricular and coronary angiography performed. Patients with complicated ventricular arrhythmias (multiform, coupled, R on T VPCs or ventricular tachycardia), when compared to those with uncomplicated ventricular arrhythmias (unifocal or no VPCs), had a greater number of proximally narrowed major coronary arteries (P less than 0.001), a higher coronary "score" (P less than 0.001), a greater incidence of previous myocardial infarction (P less than 0.005), a greater percentage of abnormal left ventricular segments 86% vs 69% (P less than 0.001) and lower ejection fractions. These data suggest that late hospital phase survivors of MI with complicated ventricular arrhythmias have more extensive coronary artery disease with greater left ventricular dysfunction than survivors with uncomplicated ventricular arrhythmias. This more extensive disease may result in increased areas of ischemic myocardium and may help explain the refractoriness of these arrhythmias to pharmacologic therapy.
The echocardiographic measurements of cardiac chamber dimension, ejection phase indices of left ventricular function and the systolic time intervals of 23 adult patients with sickle cell anemia were compared to those of normal control subjects. Patients with sickle cell anemia had a significantly greater mean left ventricular systolic dimension index, left ventricular diastolic dimension index, left ventricular mass, stroke volume index, interventricular septal width, aortic root index and left atrial index. No significant differences were noted between the mean velocity of circumferential fiber shortening, ejection fraction or systolic time intervals. The anemic population was divided into two groups; one consisting of patients less than 30 years old and the other of patients over 30 years old. There was no significant differences between the ventricular dimensions, velocity of circumferential fiber shortening, ejection fraction and systolic time intervals of the two groups. These data indicate that the chronic volume overload of sickle cell anemia is well tolerated without development of left ventricular dysfunction.