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Biomedical subjects

B C Morton

Publications and source records attributed to B C Morton.

At least 19 recordsLinked to original sources
PubMed2001

Prospective multicenter study of pregnancy outcomes in women with heart disease.

BACKGROUND: The maternal and neonatal risks associated with pregnancy in women with heart disease receiving comprehensive prenatal care have not been well defined. METHODS AND RESULTS: We prospectively enrolled 562 consecutive pregnant women with heart disease and determined the outcomes of 599 pregnancies not ending in miscarriage. Pulmonary edema, arrhythmia, stroke, or cardiac death complicated 13% of pregnancies. Prior cardiac events or arrhythmia, poor functional class or cyanosis, left heart obstruction, and left ventricular systolic dysfunction independently predicted maternal cardiac complications; the cardiac event rate can be predicted using a risk index incorporating these predictors. Neonatal complications (20% of pregnancies) were associated with poor functional class or cyanosis, left heart obstruction, anticoagulation, smoking, and multiple gestations. CONCLUSIONS: Pregnancy in women with heart disease is associated with significant cardiac and neonatal complications, despite state-of-the-art obstetric and cardiac care. Maternal cardiac risk can be predicted with the use of a risk index.

Adolescent↗
PubMed1998

Safety and criteria for selective use of low-osmolality contrast for cardiac angiography.

OBJECTIVES: Recommendations to restrict low-osmolality contrast to high-risk patients having cardiac angiography have been challenged because of safety and uncertainty about selection criteria. The authors document frequency and severity of adverse events with diagnostic cardiac angiography under the influence of guidelines for selective use of low-osmolality contrast in high-risk patients and refine high-risk criteria. METHODS: Subjects of this prospective cohort study were 7,448 unselected patients having diagnostic cardiac angiography in St. John's, Newfoundland or Ottawa, Ontario. Measures included prespecified risk factors, procedure, contrast, and adverse events such as death within 24 hours, myocardial infarction, stroke, arrhythmias, hypotension, and anaphylactoid reactions. RESULTS: Patients were similar at both sites. Fourteen point two percent received low-osmolality nonionic agents in St. John's. Thirty-four point one percent received low-osmolality (mostly ionic) media in Ottawa. Overall adverse event rates were similar at both sites: death, 0.07%; myocardial infarction or stroke, 0.03%; moderate events, 2%; and mild events, 16.8%. Event rates were low in those given high-osmolality media: death, 0.02%; myocardial infarction or stroke, 0.24%; moderate events, 1.6%; and mild events, 18%. The risk with cardiogenic shock and prior severe reaction to contrast could not be examined, but otherwise only current heart failure and markers of recent ischemia were associated with events after high-osmolality media. CONCLUSIONS: Clinicians, using guidelines, can identify high-risk patients and should be able to safely limit use of low-osmolality media to them.

Adverse Drug Reaction Reporting Systems↗
PubMed1997

Torsade de pointes with amiodarone in a patient with previous torsade during beta-receptor blockade.

Torsade de pointes is a potentially lethal ventricular arrhythmia that is associated with prolonged QT intervals and is often caused by drugs that prolong repolarization. Among the most common drugs that may cause torsade de pointes are antiarrhythmic drugs including quinidine, procainamide, sotalol and newer class III antiarrhythmic agents. The incidence of torsade de pointes associated with amiodarone, however, is reported to be much lower. A case is reported of amiodarone-induced torsade de pointes following the development of the same arrhythmia during beta-blocker use. This case illustrates that although the reported incidence of torsade de pointes during amiodarone therapy is low, patients with bradycardia-induced torsade de pointes may be a subgroup of patients who are at increased risk of this arrhythmia with amiodarone.

Adrenergic beta-Antagonists↗
PubMed1996

Improvement of ventricular function after atrioventricular junction ablation in a patient with atrial flutter after Mustard's operation.

Arrhythmias are common problems following Mustard's operation for D-transposition of the great arteries. A 19-year-old male is presented who was diagnosed at birth with D-transposition of the great arteries and a right aortic arch and underwent a Mustard procedure at 12 months of age. He developed sinus node dysfunction and atrial flutter unresponsive to antiarrhythmic drugs and dual chamber pacing. Following complete heart block with radiofrequency catheter ablation of the atrioventricular junction, the patient's heart was paced in VVIR mode. Ventricular function improved after the ablation and persisted in two years' follow-up.

Adult↗
PubMed1996

Primary repair of Fallot's tetralogy in an older adult: a 20-year follow-up.

A patient with tetralogy of Fallot who presented at 58 years of age is described. Following surgical intracardiac repair he had 20 years of improved functional capacity. Though such surgery is now usually performed in infancy, the literature indicates that surgical correction of tetralogy of Fallot in appropriate adults is associated with low mortality and good long-term results.

Age Factors↗
PubMed1995

Does it matter how coronary projections are combined to assess restenosis following PTCA?

Three methods were used to combine measurements from biplane coronary views to assess restenosis following PTCA. The first 153 patients from the EMPAR trial with 118 measurable coronary stenoses were chosen for this study. The mean difference between the RAO and LAO projections used was 88 +/- 22 degrees (S.D.). There was no systematic difference in coronary dimensions between RAO and LAO views for the group. Coronary restenosis was primarily defined as loss of 50% or more of the luminal diameter gain from the procedure. The ratio of luminal loss to gain was calculated for each stenosis using (Method 1) only the lesser diameter of the two views, (Method 2) an average of the two views and, (Method 3) a calculated cross-sectional coronary lumen area. Rates of restenosis calculated in this way ranged between 36 and 44% amongst the three methods, which was not significantly different. However, individual coronary lesions might be classified as either restenosed or not by this formula, depending on which method was used to integrate the biplane coronary measurements.

Angioplasty, Balloon, Coronary↗
PubMed1993

Death in a catheterization laboratory.

OBJECTIVE: To assess current rates of death from diagnostic and therapeutic cardiac catheterization as well as changes in the rates, if any, from 1977 to 1991. DESIGN: A prospective descriptive study. SETTING: Catheterization laboratory, University of Ottawa Heart Institute. PATIENTS: Consecutive patients undergoing diagnostic and therapeutic procedures from 1977 to 1991. Those undergoing endomyocardial biopsy or electrophysiologic study were excluded. INTERVENTIONS: Cardiac catheterization with angiography, percutaneous transluminal coronary angioplasty (PTCA) or valvuloplasty. MAIN OUTCOME MEASURES: Rates of death within 24 hours after the procedure or later if causally related to the procedure. RESULTS: There were 32 deaths attributed to 30,838 diagnostic catheterization procedures, for a rate of 0.10%. The rate did not change significantly during the study period. Most (24 [75%]) of the 32 deaths were related to coronary angiography; all but one of these patients had left main-stem artery or triple-vessel disease. None of the cases of anaphylactoid reaction to the contrast medium resulted in death. Death from PTCA was largely confined to patients with unstable coronary syndromes, including postinfarction shock. The rate of death from elective PTCA was approximately 0.1%. CONCLUSIONS: The death rate in our catheterization laboratory has remained the same since 1977, despite changes in the patient population. Patients at highest risk of death from angiography are those with unstable and global myocardial ischemia. The universal use of low-osmolar contrast medium is not justified given the absence of fatal anaphylactoid reactions. The risk of death from elective PTCA is low, and patients at highest risk have unstable coronary artery syndromes.

Aged↗
PubMed1993

Complementary role of transoesophageal echocardiography to coronary angiography in the assessment of coronary artery anomalies.

OBJECTIVE: To examine the role of transoesophageal echocardiography in the assessment of patients with coronary artery anomalies. BACKGROUND: Coronary artery anomalies are difficult to detect clinically. Most are benign but some may produce symptoms that can be life threatening. Until recently the non-invasive assessment of coronary artery anomalies has been limited. METHODS: The data base of transoesophageal echocardiographic studies performed between September 1988 and April 1991 were reviewed to identify all cases of coronary artery anomalies. There were six patients with such anomalies who had also had coronary angiography. The findings of these two imaging techniques were analysed to determine whether transoesophageal echocardiography added useful data in these cases. RESULTS: Of the six patients, the coronary anomaly was discovered during angiography in four patients, during a transthoracic echocardiographic study in one patient, and as an incidental finding in the other patient. Aberrant origins of the left coronary artery were detected in two patients, and coronary artery fistulae were present in the other four. Transoesophageal echocardiography provided unique information on the course of an aberrant left coronary artery in one patient and the precise location of drainage sites of coronary artery fistulas in three patients. CONCLUSION: Transoesophageal echocardiography was complementary to angiography in the assessment of coronary artery anomalies. It can locate and delineate the course of an ectopic coronary artery and the drainage site of a coronary fistula. These anatomical data can be crucial to the management of these patients.

Adult↗
PubMed1989

Intravenous dipyridamole-induced myocardial ischemia during percutaneous transluminal coronary angioplasty in humans.

Percutaneous transluminal coronary angioplasty was used as a model of controlled myocardial ischemia to study the effect of intravenous dipyridamole on myocardial ischemia and coronary hemodynamics in 10 patients. All patients had 1-vessel coronary artery disease with visualized collaterals. Intravenous dipyridamole increased myocardial ischemia during inflations. ST elevation, as measured by intracoronary electrogram, increased significantly from the control inflation to the second inflation after dipyridamole injection (0.05 +/- 0.23 vs 0.44 +/- 0.43 mV, p less than 0.03). Of the 10 patients, 8 developed new or more severe angina with subsequent inflations after dipyridamole. The pulmonary artery wedge pressure increased significantly from the control inflation to the fourth inflation (15 +/- 8 vs 20 +/- 9 mm Hg, p less than 0.05). The coronary wedge pressure showed a decreasing trend with subsequent inflations after dipyridamole but did not reach statistical significance. The double product (heart rate X blood pressure) was not significantly altered by dipyridamole. The findings indicate that intravenous dipyridamole increases myocardial ischemia during balloon occlusion. The constancy of the double product and the trend toward a decrease in coronary wedge pressure suggest that dipyridamole may induce ischemia by reducing the amount of collateral flow through a coronary steal phenomenon.

Adult↗
PubMed1989

Late reassessment of percutaneous transluminal coronary angioplasty results: clinical, exercise and angiographic follow-up.

One hundred and forty-five patients underwent percutaneous transluminal coronary angioplasty (PTCA) in the authors' hospital between 1981 and 1983. Four have since died and all but one of the remainder were accounted for at follow-up 41 +/- 12 months later. Recurrence of angina was present in 28% of patients having successful PTCA versus 33% of patients with surgery for failed PTCA. Use of antianginal drugs and return to work was similar in the two groups. Mean treadmill time, peak heart rate, incidence of treadmill angina and exercise thallium-201 defects were not different in the two groups. Late follow-up coronary angiography in 60 patients who had successful PTCA showed a significant decrease in mean stenosis of the dilated segment from 31 to 23%. Of 25 patients who had late angiography after failed PTCA, three had satisfactory patency of the dilated segment. New significant coronary stenosis was seen in only 17% of patients not having coronary bypass surgery.

Angioplasty, Balloon, Coronary↗
PubMed1988

Comparison of ioxaglate with diatrizoate in angiography of the internal mammary artery.

To compare ioxaglate with the traditional agent diatrizoate, 44 patients scheduled to undergo coronary angiography that included internal mammary artery (IMA) visualization were entered into a randomized double blind-parallel design protocol. Complete data were collected on 32 out of 44. Four patients were withdrawn because of angiographically normal coronary arteries; seven, because of unsuccessful IMA cannulation; and one, because of an anaphylaxis-like reaction to ioxaglate. No other serious adverse effects were seen with either agent. The major endpoints were patient and physician assessments of discomfort, rated independently on a 4-point scale. Ioxaglate caused significantly less discomfort (n = 17, median rating of "mild discomfort") than did diatrizoate (n = 15, median rating of "severe discomfort"; P less than 0.01); this effect was independent of patient sex, the number of injections, and the volume of dye injected. Radiographic quality was good with both agents. We conclude that ioxaglate is much better tolerated than diatrizoate during angiography of the IMA.

Diatrizoate↗
PubMed1987

Do symptoms reflect a change in left ventricular function after aortocoronary bypass grafting in patients with depressed left ventricular function?

Seventy-nine patients with moderate to severe left ventricular dysfunction who underwent aortocoronary bypass grafting between 1971 and 1977 had follow-up heart catheterization at a mean interval of 3 years. Thirty-three patients (42%) had angiographic improvement in left ventricular function at follow-up and 18 (25%) had a decrease in left ventricular end-diastolic pressure. Fifty-eight patients (73%) had improvement in angina of at least one New York Heart Association class at follow-up. There was no correlation between late improvement in left ventricular function and improvement in angina. Improvement in left ventricular function did not correlate with preoperative indices of severity of coronary disease or with indices of completeness of surgical repair.

Adult↗
PubMed1984

Complications of cardiac catheterization: one centre's experience.

Data on complication rates in a cardiac catheterization laboratory were prospectively gathered over a 6-year period. During this time 7960 catheterizations were performed. Death occurred in seven (0.1%) of the cases. The difference between the mortality rates for procedures performed with and without systemically administered heparin (0.04% and 0.2% respectively) was barely statistically significant (p less than 0.05). A significant complication occurred in 1.5% of the cases; however, most did not have long-term sequelae. No significant change in the annual rate of such complications was seen during the study period. Such a tabulation permits audit of quality of care, points out changing trends in morbidity and offers meaningful information on the safety of cardiac catheterization to referring physicians and their patients.

Arrhythmias, Cardiac↗
PubMed1984

Magnesium therapy in acute myocardial infarction--a double-blind study.

Various methods have been proposed and tried to limit the extent of myocardial damage at the time of infarction. We chose to assess the usefulness of intravenous magnesium in this regard because of its important role in myocardial metabolism and function and the suggestion of its deficiency in ischemic hearts. A double-blind randomized trial was carried out and results analyzed in 76 patients. At the end of the infusion period the mean serum Mg++ level for the treated group was 3.6 versus 1.9 mg/dl for the control group. The estimated size of infarction (as measured by MB-CK release) was not significantly smaller overall in the treated group (37.4 +/- 4.3 vs. 45.6 +/- 4.6 MB-CK g/Eq), but was significantly smaller in the treated subgroup without heart failure (31.6 +/- 5.8 vs. 44.7 +/- 4.8 MB-CK g/Eq). A trend toward less ventricular ectopy was seen in the group treated with magnesium. There was significantly less lidocaine used for the treatment of ventricular dysrhythmias in this group. Magnesium supplementation in patients undergoing acute coronary events is promising and deserves further study.

Clinical Enzyme Tests↗
PubMed1983

A computer graphic-based angiographic model for normal left ventricular contraction in man and its application to the detection of abnormalities in regional wall motion.

Analyzing the digitized left ventricular cineangiograms of 70 patients with no demonstrable heart disease (NDHD), we derived an angiographic model for normal contraction in the intact heart as viewed in the 30 degree right anterior oblique projection. This model was verified statistically by comparing the predicted regional stroke volumes with the measured volumes for the NDHD group. A wall motion system based on this model was compared with four other systems by examining the ventriculograms of 141 patients, all suffering from coronary artery disease but with normal volumes and ejection fractions (greater than 0.61). Of these, 60 had normally contracting ventricles and 81 exhibited mild regional abnormalities according to two experienced angiographers. Using Cochrane's Q test, we found significant differences among the five methods (Q = 29.5;p less than .001). The new approach showed significantly better agreement with the subjective assessment than the next best method (Q = 5.3;p less than .05). On a regional basis, overall sensitivity was 87.5% and specificity was 97.9%.

Adult↗
PubMed1982

Natural history and management of chronic aortic valve disease.

Chronic aortic valve disease involving stenosis, regurgitation or both is insidious and progressive. Severe valvular dysfunction may be present for years without symptoms, but functional deterioration is often rapid once congestive heart failure, angina or syncope with effort is present. As the severity of aortic stenosis may not be easy to assess clinically, the relative usefulness of various tests is considered in this paper. The difficulty with chronic aortic regurgitation lies not in diagnosing the problem but in detecting early left ventricular dysfunction in time to perform the surgery that can prevent further functional deterioration. Patients with significant aortic valve disease should undergo surgery when the important symptoms of dyspnea, angina or syncope with effort first appear. Surgery should also be considered in selected patients with aortic regurgitation in whom left ventricular function has diminished even without symptoms.

Aortic Valve Insufficiency↗
PubMed1981

Serum CK-MB activity during and after aortocoronary bypass surgery.

Frequent serum sampling of CK-MB and total CK levels was carried out in 100 patients during and up to 48 hours following aortocoronary bypass surgery. Using an ion exchange chromatography method for CK-MB determination, significantly higher serum CK-MB levels (peak 46.1 +/- 5.2 cf. 31.3 +/- 2.2 u/L), but not total CK levels were present 6 to 16 hours postoperatively in those with new Q waves in the ECG. Serum levels of CK-MB in those patients with uncomplicated surgery were defined. New post-operative Q waves were seen in only one half of cases with frankly abnormal CK-MB curves and seriously underestimated the incidence of perioperative infarction. Peak levels of CK-MB in patients with new Q waves occurred within 16 hours of surgery suggesting that infarction is usually an intraoperative or early post-operative event.

Chromatography, Ion Exchange↗