The Canadian journal of cardiology

Published by Elsevier
Print ISSN: 0828-282X
The authors have previously reported on Canada-wide outcomes of coronary artery bypass graft (CABG) surgery for 1992/93 through 1995/96. To provide an updated Canada-wide CABG surgery outcome report with outcome data organized by province and by year for 1992/93 through 2000/01. Hospital discharge abstract data were obtained from the Canadian Institute for Health Information and were used to identify all patients who underwent isolated CABG surgery in eight provinces from fiscal year 1992/93 through 2000/01. Crude data from Quebec hospitals were available for calendar years 1998 and 1999. Logistic regression modelling was used to calculate risk-adjusted in-hospital mortality rates by year and province. Patients undergoing CABG surgery in the later years studied were on average older and had more comorbidities than did patients undergoing this surgery in earlier years. Despite increasing case complexity, risk-adjusted mortality rates decreased significantly from 3.5% (95% CI 3.2% to 3.8%) to 2.0% (95% CI 1.8% to 2.3%). Risk-adjusted mortality rates varied between provinces. Provincial risk-adjusted mortality rates ranged from 2.0% to 3.3%. However, all provinces studied had either persistently low mortality rates (Nova Scotia) or declining mortality rates across years studied, such that all provinces achieved risk-adjusted mortality rates of 2.7% or lower in 2000/01. This evaluation of Canadian CABG surgery outcomes demonstrates a pattern of either steadily improving or persistently favourable provincial in-hospital mortality rates after isolated CABG surgery. These favourable provincial outcome trends have been achieved despite an accompanying increase in the average case complexity of patients undergoing CABG in Canada.
Despite existing research on outcomes of cardiac care in Canada, little is known about Canada-wide trends and interprovincial differences in outcomes after percutaneous coronary intervention (PCI). To examine Canadian trends in rates of in-hospital mortality and same-admission coronary artery bypass grafting (CABG) after PCI and to compare provincial risk-adjusted in-hospital death and same-admission CABG rates. Hospital discharge abstract data were obtained from the Canadian Institute for Health Information and were used to identify cohorts of patients who underwent PCI in eight provinces in fiscal years 1992/93 through 2000/01. Crude data from Quebec hospitals were available for calendar years 1998 and 1999. Logistic regression modelling was used to calculate risk-adjusted in-hospital death and same-admission CABG rates by year and province. A total of 127,103 PCI cases performed in 23 hospitals across eight provinces were examined, with an overall unadjusted death rate of 1.4% and an overall unadjusted CABG rate of 1.6%. A national trend of stable in-hospital mortality rates was observed with a risk-adjusted death rate of 1.4% in 1992/93 versus 1.4% in 2000/01. An overall decline was seen in rates of same-admission CABG with a risk-adjusted rate of 2.7% in 1992/93 versus 0.9% in 2000/01 (relative decrease 67%, P<0.01). New Brunswick, Manitoba and British Columbia achieved overall declines in risk-adjusted death rates over the study period, while the other provinces experienced a slight increase (Newfoundland, Nova Scotia, Ontario, Alberta and Saskatchewan). All provinces displayed a similar decline in risk-adjusted same-admission CABG rates post-PCI. Risk-adjusted rates of in-hospital death after PCI in Canada have remained stable over nine years, while risk-adjusted rates of same-admission CABG have decreased. The presence of interprovincial differences in risk-adjusted outcomes raises the possibility of variable quality of care for patients undergoing PCI across the Canadian provinces.
The Fick and indicator-dilution techniques for measurement of cardiac output (CO) were compared at rest in 1,022 patients and in 786 during exercise. Duplicate measurements of dye CO at rest revealed that 92.7% fell within 10% of the line of identity and 99% within 20%. For the resting Fick and dye comparisons, 44.6% were within 10% of the identity line and 74.7% within 20%. When mean CO was less than 4.4 L/min, dye CO was higher than Fick. This relationship persisted for CO between 4.4 and 7.4 whereas for above 7.4 L/min, Fick was higher than dye. During exercise, 50.2% of the Fick and dye comparisons fell within 10% and 77.1% within 20% of the line of identity. There was a systematic difference between the two methods during exercise with dye CO higher than Fick CO. This study agrees with Fick and dye comparison studies with 74.7% and 77.1% of values within 20% of the identity line during rest and exercise, respectively. However, these results differ from others in that dye CO was higher than Fick CO for low and normal values whereas Fick was greater for the higher CO values. The overall agreement between the two methods in a large group of patients with diverse cardiac diseases over a broad spectrum of CO values supports use of either method for clinical studies.
1,2-Diacylglycerol (DAG) is an intracellular signal mediator that may initiate protein synthesis and cardiac hypertrophy via activation of protein kinase C. The amounts of 1,2-DAG and its fatty acid components in the myocardium was assessed and compared with the concentrations of RNA and DNA in cardiac hypertrophy induced by administering triiodothyronine (T3) with and without cycloheximide, an inhibitor of protein synthesis. After the first injection of T3 no cardiac hypertrophy was observed, and there were no differences in myocardial 1,2-DAG content or in RNA and DNA concentrations. Cardiac hypertrophy was present on days 3 and 7 after a daily injection of T3. Myocardial RNA concentration was increased by 26% on day 3 and by 34% on day 7, whereas the myocardial 1,2-DAG content was decreased by 8% on day 3 and by 24% on day 7. Pretreatment with cycloheximide of T3-treated rats prevented the development of cardiac hypertrophy, but elevated the RNA concentration and lowered the 1,2-DAG content compared with the findings in T3-treated rats. Analysis of the fatty acid components of 1,2-DAG revealed that the amounts of 16:0, 18:1 and 18:2 were decreased, accompanied by an elevation of RNA concentration and a decrease in 1,2-DAG content. It seems that RNA synthesis preceded the alteration in 1,2-DAG. These findings suggest that 1,2-DAG is not involved in the initiation of cardiac hypertrophy induced by T3, but is affected by the enhanced concentration of RNA resulting from the introduction of thyroid hormones into the myocardium.
Brugada syndrome (BS) and long QT syndrome (LQTS) are electrical disorders with a genetic background. They are revealed on surface electrocardiograms as either right bundle branch block and ST segment elevation in the right pericardial leads (V1, V2 and V3) in BS or as a long QTc interval on all 12 leads of the electrocardiogram in LQTS. Both BS and LQTS can lead to syncope and even sudden death. The R1193Q SCN5A variant was recently associated with LQTS, BS and cardiac conductance disease. The aim of the present study was to screen the SCN5A gene from two patients -- one with BS and the other showing signs of a BS/LQTS phenotype -- for mutations, and to characterize the effect of the mutations on channel function using the patch clamp technique. A heterozygous mutation (R1193Q) was identified on the SCN5A gene in both patients. The R1193Q polymorphism was absent in 100 unrelated control alleles, suggesting that it has a low frequency in the French Canadian population. Mutant R1193Q expressed in tsA201 cells, which was studied using the patch clamp technique, had a persistent sodium current that could account for the QTc prolongation. A shift of steady-state inactivation toward more hyperpolarized voltages was observed that could explain the BS phenotype. The R1193Q polymorphism is definitively associated with cardiac electrical abnormalities.
The diagnosis of cardiac allograft rejection is based on routine endomyocardial biopsy. To study an alternative method the authors evaluated the migration and scintigraphic imaging of 111Indium-labelled lymphocytes in a model of acute heart allograft rejection. Cervical heterotopic heart transplantation was performed in 10 dogs. Blood samples were harvested at 24 and 48 h after surgery for labelling of 36 +/- 6 x 10(6) lymphocytes with 6.62 +/- 0.56 MBq of 111Indium. Daily blood samples and heart biopsies were obtained for nuclear counting on the next three days; animals were sacrificed and both donor and native hearts were studied. Between 20 and 31% of autologous labelled lymphocytes remained in circulation until 72 h after injection. Maximal plasma 111Indium activity was 315 +/- 90 compared with 5513 +/- 1483 cpm/mL in whole blood (P less than 0.05). An average of 10,176 +/- 3444 labelled lymphocytes per gram of tissue were present in allograft biopsies while histological evaluation showed mild to moderate acute rejection. The ratio of tissue biopsy to blood 111Indium counts varied from 0.7 +/- 0.2, 6 h after autologous injection to 8.5 +/- 3.8 48 h later (P less than 0.05). At autopsy, 298 +/- 66 labelled cells per gram of tissue were present in native hearts compared with 2686 +/- 711 in allografts (P less than 0.05). Scintigraphic imaging using holospectral acquisition was performed; six lateral projections showed an indium activity ratio (transplanted heart to background tissue) of 2.8, 24 to 72 h after autologous injection of labelled cells. Labelling of a small number of lymphocytes with 111Indium gave a stable population of circulatory lymphocytes for studying migration of labelled cells into allografts and a noninvasive scintigraphic approach to diagnose cardiac allograft rejection.
The role of antithrombotic therapy has been studied in patients with acute coronary ischemia without ST segment elevation. Unfractionated heparin (UFH) has been found to decrease the rate of myocardial infarction (MI), and to reduce overall mortality and recurrent MI in a series of trials in patients with unstable angina and non-Q wave MI. UFH is limited due to its unpredictable antithrombotic effect, poor bioavailability when given subcutaneously, requirement for hospitalization and need for frequent laboratory monitoring. Conversely, low molecular weight heparins (LMWHS) offer a number of advantages over UFH. LMWHs have a predictable antithrombotic response, good bioavailability following subcutaneous administration and longer half-life than UFH, require less frequent monitoring than UFH and can be administered in fixed or weight-adjusted subcutaneous dosages once or twice daily. The safety and efficacy of the LMWH enoxaparin are evaluated in the Thrombolysis in Myocardial Infarction (TIMI) 11 program. TIMI 11 A was designed to compare the safety and tolerability of two dosage regimens of enoxaparin in patients with unstable angina or non-Q wave MI, whereas TIMI 11B was designed as a phase III trial, comparing the efficacy and safety of enoxaparin with those of UFH in the acute phase, and the efficacy and safety of extended administration of LMWH with those of placebo for 45 days. TIMI 11A found that the rate of major hemorrhage was significantly lower for the lower enoxaparin dose (1.0 mg/kg). The results of the published studies indicate that LMWHs are effective in reducing major ischemic outcomes in patients with unstable angina and non-Q wave MI. The results of the TIMI 11B trial will be available in late 1998.
The application of 11C acetate kinetics determined by positron emission tomography (PET) imaging has been proposed as a noninvasive means to measure myocardial oxygen consumption in order to determine myocardial efficiency. Such an approach considers the balance of the effect of ventricular performance and myocardial oxygen consumption (MVO2), which may be important in the assessment of heart failure but is not usually evaluated by current methods. In this paper, the authors review their previously published series of studies, in which the aim was to: first, apply the 11C acetate PET approach in patients with dilated cardiomyopathy in order to determine myocardial oxidative metabolism and estimate myocardial efficiency; second, verify a correlation between 11C acetate kinetics and directly measured MVO2; and third, evaluate the effects of dobutamine and nitroprusside on MVO2 and efficiency in dilated cardiomyopathy. In these previous studies, 13 patients with severe dilated cardiomyopathy were studied, via echocardiography, hemodynamic and PET studies, at baseline and during drug infusion. Seven patients were given dobutamine and six were given nitroprusside. A two-compartment kinetic model approach was applied to 11C time activity curves obtained from dynamic 11C acetate PET imaging to determine the clearance rate constant, k2. Myocardial efficiency was estimated from a work metabolic index, defined as (stroke work index multiplied by heart rate) divided by k2. The k2 significantly increased with dobutamine (P < or = 0.05), consistent with increased MVO2, and tended to decrease with nitroprusside. The work metabolic index derived from hemodynamic parameters increased significantly with both drug regimens (P < or = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
To assess the procedural success and complication rates of the first 120 directional coronary atherectomy cases performed at two Toronto hospitals. Case series in tertiary referral centres. One hundred and thirteen patients in whom 120 atherectomy procedures were attempted between July 1990 and April 1992. Directional coronary atherectomy. Angiographic success was obtained in 115 of 120 procedures (96%) involving 117 of 123 lesions (95%). Procedural success (angiographic success without death, myocardial infarction or coronary bypass surgery) was obtained in 110 of 120 procedures (92%). Adjunctive balloon angioplasty was required in 20 procedures (17%). There was one death at 36 h in an elderly patient who underwent an emergency procedure while in cardiogenic shock. Periprocedural non-Q wave myocardial infarction occurred in five patients. There were no Q wave myocardial infarctions. Three patients required coronary bypass surgery prior to discharge and vascular complications occurred in five patients. Directional coronary atherectomy can be performed with procedural success and complication rates comparable to conventional balloon angioplasty. Randomized trials are underway to determine if atherectomy results in a lower restenosis rate.
A muscle slice technique was used to compare the development changes in binding of the beta-adrenergic antagonist, [3H]CGP-12177 (CGP), in right ventricles of male Canadian Hybrid Farms CHF 147 cardiomyopathic hamsters and two strains of control healthy animals, golden Syrian (GH) and CHF 148 albino noncardiomyopathic (AH) hamsters. CGP binding to myocardial slices was saturable, reversible, stereospecific, proportional to slice number and of high affinity. Bmax in GH and AH myocardium was not altered with age although there was a tendency to decrease between 16 and 30 days of age in both strains. In the cardiomyopathic ventricles, receptor number decreased between 30 (7.07 +/- 0.74 fmol/mg wet weight) and 60 days of age (4.58 +/- 0.52) (P less than 0.05) and remained at the lower level thereafter. Bmax in cardiomyopathics was slightly higher than that of either GH (5.01 +/- 0.88) or AH (5.05 +/- 0.82) at 30 days of age (P less than 0.05) but was not different at the other ages tested. Kd was decreased in GH at 30 days of age but was unaltered during postnatal development in either the AH or cardiomyopathic hearts. The elevated level of cell surface beta-adrenergic receptors in the cardiomyopathic ventricle at a time when necrotic lesions are developing may be important with respect to the pathogenesis of cardiomyopathy in these animals.
The purpose of this investigation was to examine the ability of beta-methyl-15-P-[123I]-iodophenyl-pentadecanoic acid (beta 123IPPA) and thallium-201 to assess the ischemic risk zone associated with myocardial infarction. The hearts of mongrel dogs were infarcted by ligating the left anterior descending coronary artery and at 6 h post infarction injected with thallium-201 (2 mCi; scanning time 30 mins) followed by beta 123IPPA (3 to 5 mCi; scanning time 30 mins). Scintigraphic assessment of the perfusion defect yielded perfusion defect size (percentage of whole slice), which was then compared to the defect when assessed by tetrazolium staining. Myocardial ratios were calculated to assess differences in localization between tracers. Any differences noted may affect identification of the area at risk following acute myocardial infarction. A slice-by-slice comparison of perfusion defect size for scintigraphic methods and histochemical method showed no significant difference between beta 123IPPA and thallium-201. The mean ratio for myocardial defect size expressed as beta 123IPPA/thallium-201 was 1.03 +/- 1.29. Enzymatic analysis demonstrated significant increases in creatine kinase (160.33 +/- 46.44 to 5030.6 +/- 2238 U) and creatine kinase-MB% (31.85 +/- 15.11 to 82.99 +/- 8.14%) post infarction (P less than 0.05 in both cases). Elevated ST segments were also seen in all dogs post infarction. It can be concluded that the combined use of beta 123IPPA and thallium-201 does not allow the identification of the ischemic risk zone (percentage area at risk) often associated with myocardial perfusion defects. Problems continue to exist with image resolution and border demarcation.
After a brief historical account of the methods for pressure measurements in the cardiovascular system, the basic structural elements of a new generation of miniaturized catheter pressure transducers are described. These catheters have an outside diameter at the tip of 0.9 mm (3 French) and have been routinely applied in left and right heart catheterization in intact, anesthetized rats. Together with cardiac output measured by the thermodilution technique, a complete set of basal functional parameters can be obtained in vivo. The method of cardiac catheterization in rats is accurate, reliable and easy to perform. As to left heart function, changes occurring in several models of cardiac hypertrophy and heart failure have been recorded and correlated with morphological and metabolic alterations. In addition, the functional effects of catecholamines and thyroid hormones have been evaluated. In addition to the routine catheterization procedure, a double catheter method has been introduced recently, which allows measurement of left ventricular isovolumetric pressure in intact rats. Catheterization of the right ventricle requires a more refined catheter with a characteristic bend at the tip so that it can be comfortably slid from the right atrium into the right ventricle. With this method it was found that right ventricular systolic pressure was elevated markedly in rats with chronic myocardial infarction induced by ligation of the left anterior descending coronary artery, by pulmonary artery banding, by intermittent chronic hypoxia and by noradrenaline administration. The ultraminiature catheter pressure transducer has also been successfully applied in an isolated working rat heart preparation. Recent modifications of this kind of catheters also enabled the catheterization of the left ventricle in mice. Future applications of ultraminiature catheter pressure transducers may be directed to catheterization of the pulmonary artery in rats and to the in vivo and in vitro assessment of heart function of transgenic mice.
To characterize the pathological features of right ventricular dysplasia (RVD). Retrospective morphological case study. Three referral-based university medical centres. Thirteen subjects (one female) aged 16 to 55 years including 10 necropsy hearts from sudden deaths out of hospital, one explant heart and two partial right ventricular resections from patients with intractable ventricular tachycardia. Most hearts showed hypertrophy and localized or generalized dilatation of the right ventricle. Transillumination revealed myocardial thinning of variable configuration usually conforming to regions of dilatation. Common sites of involvement were apex, infundibular region and posterobasal wall. Histologically, focal or extensive segments of right ventricular myocardium were absent or replaced. Three patterns were found: right ventricle markedly thinned, epicardium and endocardium contiguous, virtually no intervening tissue; wall normal thickness or thinned, myocardium almost totally replaced by fat; and wall normal or thin, myocardium largely replaced by fat with scattered residual myocardial cells and fibrous tissue (the predominant pattern). Endocardial fibrosis was present in eight cases and focal mononuclear cell infiltrates in 10. Electron microscopy in two cases showed nonspecific findings. RVD has gross and microscopic features which permit its recognition. While a majority of cases are likely congenital (genetic or acquired in utero), the possibility of postnatally acquired conditions (inflammatory, toxic, ischemic) inducing RVD must be explored. The incidence and importance of RVD as a cause of sudden death can only be assessed by continued systematic and detailed studies of patients with recurrent ventricular tachycardia and of hearts, especially from sudden death victims. Although uncommon, RVD should be considered in the differential diagnosis of arrhythmia and sudden death by both clinicians and pathologists.
Catheter ablation is a curative treatment with excellent success and minimal complication rates for patients with supraventricular or ventricular arrhythmias. The acute outcomes and complications of all catheter ablation procedures for supraventricular and ventricular arrhythmias performed at the Quebec Heart Institute (Sainte-Foy, Quebec) during a 14-year period from January 1, 1993, to December 31, 2006, were prospectively assessed. The ablation procedures were classified according to the arrhythmias induced using standard electrophysiological techniques and definitions. Immediate success and complication rates were prospectively included in the database. A total of 5330 patients had catheter ablation performed at the Institute during the period assessed. The mean (+/- SD) age of patients was 50 +/- 18 years (range four to 97 years), and 2340 patients (44%) were men. Most of the patients were younger than 75 years (group 1), and 487 (9%) were 75 years of age and older (group 2). Indications for ablations were as follows: atrioventricular nodal re-entry tachycardia (AVNRT) in 2263 patients, accessory pathways in 1147 patients, atrioventricular node ablation in 803 patients, typical atrial flutter in 377 patients and atrial tachycardia in 160 patients; 580 patients had other ablation procedures. The overall success rates were 81% for atrial tachycardia, 92% for accessory pathways or flutter, and 99% for AVNRT or atrioventricular node ablation. There was no difference in the success rates of the younger (group 1) and older (group 2) patients. Seventy-seven patients (1.4%) had complications, including 11 major events (myocardial infarction in one patient, pulmonary embolism in three patients and permanent pacemaker in seven patients). In patients undergoing AVNRT ablation, two had a permanent pacemaker implanted immediately after the procedure and three had a permanent pacemaker implanted at follow-up. The results confirm that radiofrequency ablation is safe and effective, supporting ablation therapy as a first-line therapy for the majority of patients with cardiac arrhythmias.
To determine prevalence of diastolic arterial hypertension (DAH) in young individuals using different criteria. Secondly, to test the possible different blood pressure reactions to mental stress and hand grip in two groups: group A, a 'low blood pressure group', and group B, diastolic blood pressure 90 mmHg or greater in one interview and below these values in a second interview. A total of 1423 volunteer medical students was recruited at La Plata School of Medicine, average age 21 +/- 3 years. Systolic and diastolic blood pressure were measured three times on two different occasions separated by one week. With the values obtained, prevalence of arterial hypertension was determined according to the criteria suggested by The Joint National Committee 4 (JNC-4) and the World Health Organization (WHO), and to statistical bases. Mental stress and hand grip tests were performed by groups A and B. The prevalence of DAH when only the first determination of the first interview was considered was 14.7%, 6.7% (considering the WHO criterion) or 5% (using the statistical criterion). These values are reduced if repeated measurements are averaged. The greatest reduction was obtained when the JNC-4 criterion was used (1.6%). The reactivity of stressors did not show any relationship with the initial blood pressure of the subjects. In epidemiological studies, the differences among the criteria should be considered when analyzing blood pressure of populations. Stress tests (mental stress and hand grip) do not help in identifying differences between the groups studied.
To assess the effect of the angiotensin II type 1 receptor (AT1-R) antagonist L-158,809 on acute infarct expansion and left ventricular (LV) function during acute anterior myocardial infarction. Dogs were randomized to receive intravenous L-158,809 (0.1 mg/kg bolus and 0.6 microgram/kg/min infusion) or vehicle beginning 1 h after permanent left anterior descending coronary artery ligation and continued for 48 h. In vivo LV remodelling and function (quantitative echocardiography) and hemodynamics over 48 h, and postmortem remodelling after 48 h were measured. L-158,809 produced 90% to 100% inhibition of the angiotensin II pressor response during the infusions. With respect to percentage changes over the 48 h in vivo, compared with vehicle controls, L-158,809 decreased mean arterial pressure (-20 +/- 4 versus -9 +/- 2%, P = 0.03) and left atrial pressure (-38 +/- 5 versus 25 +/- 6%, P < 0.0001) but did not change heart rate. These unloading effects were associated with a smaller percentage increase in infarct expansion index (-5 +/- 7% versus 27 +/- 2%, P = 0.001) and LV diastolic volume (11 +/- 11% versus 52 +/- 6%, P = 0.008), less shape deformation, fewer apical aneurysms (0 versus 100%, P = 0.0003), better global ejection fraction (49 +/- 2% versus 39 +/- 2%, P = 0.005), less ST segment elevation and fewer Q waves. Also compared with vehicle controls, with L-158,809 postmortem infarct size (19.8 +/- 2.4% versus 50.4 +/- 4.7% of risk region, P = 0.0002) and expansion index (2.06 +/- 0.09 versus 2.76 +/- 0.18, P = 0.006) were less and thinning ratio greater (0.92 +/- 0.02 versus 0.60 +/- 0.05, P = 0.0001). The novel AT1-R antagonist L-158,809 produces significant AT1-R blockade, reduces LV loading, and effectively limits acute infarct expansion and early LV remodelling during canine myocardial infarction.
Myocardial involvement in Behçet's disease has been reported to be relatively rare. To evaluate myocardial involvement noninvasively in patients with Behçet's disease by measuring signal-averaged electrocardiography (SAECG), QT dispersion and heart rate variability (HRV). The study group comprised 28 eligible patients (16 male, mean age 37+/-13 years) of 33 patients with Behçet's disease, and 25 age- and sex-matched control subjects. The echocardiographic left ventricular measurements were within normal limits and similar in both groups except the E/A ratio, which was significantly lower in patients with the disease than in control patients. Minimal pericardial effusion was detected in four patients. Considering the SAECG recordings, values of root mean square voltage in the last 40 ms were 30+/-18 microV and 38+/-18 microV in patients with Behçet's disease and in the control group, respectively. The number of cases with a value less than 20 microV was seven (25%) and one (4%) in the same groups, respectively. Both QT dispersion and the corrected QT interval dispersion were significantly increased in patients with Behçet's disease compared with the control patients (50.2+/-16.6 versus 20.4+/-18.8, P<0.01). Although all HRV measures appeared to be decreased in the Behçet's group, only the standard deviation of all filtered RR intervals in the entire 24 h ECG recordings and the percentage of differences between adjacent filtered RR intervals that are greater than 50 ms for the whole analysis values differed significantly between the groups (P<0.05). No significant difference was observed in frequency domain parameters. In the Holter ECG recording, grade 2 or greater premature ventricular complexes were observed in seven patients from the Behçet's group (25%) but in only one subject from the control group (4%) (P<0.05). Patients with Behçet's disease appeared to have significantly increased QT dispersion, a left ventricular diastolic dysfunction pattern in echocardiography, a high incidence of positive late potentials and more complex ventricular arrhythmias, suggesting myocardial involvement and the existence of an arrhythmogenic substrate, whereas the HRV measures do not suggest a clear autonomic abnormality in Behçet's disease.
The predominant role of the endothelium in vascular healing after balloon injury and stent implantation is better recognized. The endothelium regulates vascular tone, thrombosis, inflammation and cell proliferation. It may be important to favour endothelial recovery after percutaneous coronary intervention (PCI) to reduce restenosis and improve clinical outcome. The present article reviews the scientific rationale, experimental data and early clinical results of 17-beta-estradiol and its role in the acceleration of endothelial recovery in vivo after PCI.
Epidemiological information on patients with acute coronary syndromes managed in specialized cardiac centres is limited. To report the evolution of demographics, treatment and outcome of patients admitted to a tertiary coronary care unit (CCU) over a 17-year period. A prospective database of 18,719 patients admitted from April 1986 to March 2003 in a 21-bed CCU was analyzed. From 1986 to 2003, the number of admissions increased from 937 to 1577 per year, while the length of stay declined from 7.5 to 3.5 days. The mean age increased from 58.4 to 63.4 years, and the proportion of men remained stable at approximately 70%. The use of coronary angiograms increased from 49.8% to 81.1% in all patients, while fibrinolysis dropped to 0.4%. In-hospital mortality decreased from 9% to 1.5%. The percentage of overall instrumentation (arterial line, central venous catheter, temporary pacemaker, Swan-Ganz catheter and intra-aortic balloon pump) decreased from 38% to 8.1%. From 1995 to 2003, the proportion of stenting during percutaneous transluminal coronary angioplasty increased dramatically from 0% to 86%. In the past five years, surgical revascularization has remained stable at approximately 20% of all admissions. The proportion of patients discharged with a noncoronary chest pain diagnosis has remained constant at approximately 4%. There has been a tremendous increase in efficiency, with an approximate doubling of the admissions turnover rate in a tertiary CCU. Patients with acute coronary syndromes are stratified faster and treated more invasively. Therapeutic advances are reflected by an almost linear 0.5% per year decrease in in-hospital mortality.
Blalock-Taussig shunts (subclavian to pulmonary anastomoses) have remained the most effective palliation in cyanotic heart disease. Late complications are rare but can be devastating. The case of a 26-year-old female with tetralogy and an original Blalock shunt constructed at age four years is reported. Despite subsequent primary repair of the tetralogy and presumed ligation of the Blalock shunt, the patient succumbed to a fatal hemorrhage due to esophageal-arterial fistula involving the Blalock shunt. The circumstances leading to this dramatic outcome are outlined and discussed. It is important for cardiologists caring for congenital heart disease patients to be aware of the late complications of congenital heart surgery, and carry out the proper follow-up investigations.
To examine patient characteristics affecting the utility of transthoracic echocardiography in determining aortic valve morphology, particularly for the diagnosis of congenital bicuspid aortic valve (BAV). A retrospective comparison of preoperative echocardiographic determination of aortic valve morphology with pathological findings of the explanted valves. A tertiary referral centre. Consecutive patients who had aortic valve replacement between July 1994 and April 1996, and had preoperative echocardiograms. Of 313 patients, 181 (58%) had preoperative echocardiography. Three of the valves were excluded because they were too fragmented for pathological determination of valvular morphology. In the remaining 178 patients, aortic valvular morphology was determined by echocardiography in 104 (58%). Multivariate analysis showed that echocardiography was successful less often in women (odds ratio 0.44, P = 0.03) and in patients with densely calcified valves (odds ratio 0.69, P = 0.02), whereas age had no effect (odd ratio 0.99, P = 0.42). In those with adequate echocardiographic images, echocardiography had both a high sensitivity (0.92) and a high specificity (0.96) for the diagnosis of BAV. Echocardiography is a useful tool for the diagnosis of BAV, although suboptimal images may pose a problem in many patients, particularly women and patients with heavily calcified valves. When adequate images are obtained, transthoracic echocardiography can reliably identify aortic valvular morphology in most patients.
To study the acute results and long-term clinical course after percutaneous transluminal septal myocardial ablation (PTSMA) in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). In 18 patients (seven women, 11 men; average age 53+/-15 years) with symptomatic and medically refractory HOCM, 1.3+/-0.4 septal branches were occluded with an injection of 3.6+/-1.2 mL of 95% alcohol to ablate the hypertrophied interventricular septum. After three years, noninvasive follow-up results of clinical course, echocardiographic and electrocardiographic findings were determined. The invasively measured left ventricular outflow tract (LVOT) gradients were reduced in all patients, with a mean decrease from 79+/-21 mmHg to 11+/-8 mmHg at rest (P<0.01) and from 136+/-41 mmHg to 49+/-21 mmHg after extrasystole. All patients had angina pectoris for 8 h to 24 h. Eleven patients (61.1%) developed a trifascicular block for 3 min to four days requiring temporary (n=10 [56%]) or permanent dual chamber pacemaker implantation (n=1 [6%]). All patients were discharged after 5.9+/-2.3 days. Clinical, electrocardiographic and echocardiographic follow-up was achieved in all patients after three years (3.1+/-0.5 years). No cardiac complications occurred. Thirteen patients (72%) showed clinical improvement, with a New York Heart Association functional class of 1.5+/-0.8. A further reduction in LVOT gradient was shown in eight patients (44%). The LVOT gradient was greatly reduced in patients with HOCM undergoing a PTSMA procedure and their symptoms were greatly improved without cardiac complications during three-year follow-up. Possible complications include different degrees of heart block, such as trifascicular blocks, requiring temporary pacemaker implantation. PTSMA is a promising nonsurgical method for the treatment of symptomatic patients with HOCM. Clinical long-term follow-up of a larger series of patients is required to determine the therapeutic significance conclusively.
To determine whether pulsatile perfusion is clinically beneficial for adult cardiac operations. Data concerning consecutive patients undergoing isolated coronary bypass surgery (n=1820) from January 1, 1997 to July 31, 1999 were reviewed. Nine hundred fifteen patients received pulsatile perfusion (PP) while perfusion in the remaining 905 patients was nonpulsatile (NP). Patients in the PP group were older (64.0 +/- 9.2 years versus 63.1 +/- 9.9 years) and experienced more of the following: urgent operations (42.4% versus 38.0%), preoperative intra-aortic balloon pump (4.8% versus 1.8%), preoperative cerebrovascular accidents (CVA; 3.1% versus 1.3%) and renal insufficiency (10.5% versus 7.0%). The PP group had higher incidence of early postoperative mortality (2.6% versus 1.5%), CVA (3.1% versus 1.3%), need for dialysis (3.2% versus 2.2%) and longer hospital stay (9.2 +/- 8.3 days versus 8.5 +/- 5.8 days). The incidence of postoperative myocardial infarction and renal dysfunction was similar in both groups (2.0% versus 2.2% and 3.3% versus 3.9% respectively; not significant). Because of the significant difference in preoperative parameters for the PP and NP groups, the following three statistical techniques were used to isolate the effect of perfusion characteristics on operative outcome: multiple regression, propensity score and risk stratification. Multivariate analysis did not find PP to be protective against mortality, morbidity and mortality, and CVA or for the development of postoperative renal dysfunction. When propensity score analysis was applied, the incidence of cardiac morbidity and mortality was strongly associated with the quintile (first quintile 6.7%, fifth quintile 27.0%, P<0.001). Multivariate analysis including quintiles did not find PP to be an independent predictor for mortality or for morbidity and mortality. Risk stratification was performed for age and for preoperative creatinine clearance levels. In all groups, PP did not seem to reduce the incidence of morbidity, morbidity and mortality, or the development of postoperative renal dysfunction. In patients with preoperative renal dysfunction, mean postoperative creatinine levels and the need for dialysis following surgery were similar in the PP and NP groups. Pulsatile flow does not appear to offer any clinical benefit over nonpulsatile flow for cardiac surgery patients.
During the past two decades epidemiological, clinical and laboratory studies have confirmed the existence of the diabetic heart in some patients with diabetes mellitus. The diagnosis was made in patients in whom other known etiological factors, such as coronary artery disease, alcoholism or hypertensive cardiovascular disease, were ruled out. The newer concept of the diabetic hypertensive heart is clinically based on a higher incidence of congestive heart failure caused by extensive myocardial involvement. In patients with hypertension and hypertension associated with diabetes, the intramyocardial arterioles present medial hypertrophy and a diminished lumen, increased periarteriolar fibrosis, accumulation of fibrillar collagen and patent extramural coronary arteries. Such confirmatory findings have been previously seen in experimental animals and in patients with diabetes and no hypertension. In the genetically diabetic rat, diabetes may be prevented by neonatal thymectomy, suggesting the existence of an autoimmune deficiency syndrome. Furthermore, conversion of Ala 776 into Thr 776 on the polyprotein by a point mutation results in loss of diabetogenicity. Abnormalities in systole and diastole related to lowering of CK-M and CK-B mRNA levels are normalized following insulin therapy. Identification of the genetic factors in the diabetic heart may lead to the identification of its pathogenic mechanisms.
Origin of a pulmonary artery from the aorta is a rare congenital defect which usually is fatal if not surgically corrected in infancy. Medical treatment often is unsatisfactory because of progressive heart failure. Described is a 19-year follow-up of a patient who underwent surgery at age three weeks to correct a right pulmonary artery from the aorta.
Mitral valve disease (MVD) is a significant clinical problem that is becoming more common in the 21st century. The pathogenesis of MVD seems to be changing and is not well understood. The present study details the morphological findings in 192 native mitral valves excised over a one-year period at the Toronto General Hospital, Toronto, Ontario. The mean patient age was 59.7+/-12.3 years at operation. There were 106 men (55.2%) and 86 women (44.8%) in the present study. The most frequent changes in the surgically excised valvular leaflets were fibrosis (78.6%) and thickening (66.2%). Fusion (32.3%) and calcification (25.2%) were common changes at the commissures. Chordae tendineae most often showed evidence of thickening (47.9%) and fibrosis (37.0%). In total, 110 valves showed mitral incompetence (57.3%), 72 showed mitral stenosis (37.5%), and 10 showed a combination of stenosis and incompetence (5.2%). In the present series, MVD was most frequently caused by postinflammatory (rheumatic) valve disease (RVD) (35.9%), followed by myxomatous degeneration (33.3%). Patients with RVD were usually female (66.7%), while those with myxomatous degeneration were more likely to be male (76.6%). RVD remains a significant problem even though the incidence of acute rheumatic fever with cardiac involvement has declined in Canada. This most likely reflects the current sociodemographic composition of the referral population.
To determine the incidence, risk factors and prognosis of regular narrow QRS complex tachycardia (NQT), which develops in the absence of pre-excitation in subjects free from ischemic heart disease in the Manitoba Follow-up Study. The Manitoba Follow-up Study is a longitudinal cardiovascular study of 3983 initially healthy men (primarily living in Canada) followed prospectively for 40 years. Risk factors and prognosis were assessed in a nested case-control study. Twenty-two individuals were diagnosed with NQT before clinical and/or electrocardiographic manifestation of ischemic heart disease (145,408 person-years of observation). Between the ages of 30 and 80, the incidence of NQT was one per 6000 person-years and increased with age. History of childhood diseases, valvular disease, smoking, elevated blood pressure and body mass index did not increase the likelihood for NQT development. NQT was diagnosed concurrently with a serious noncardiac condition in seven cases; excess mortality resulted as six of these subjects died within one year of NQT diagnosis while only two subjects without concurrent disease at NQT diagnosis died during follow-up. In comparison with 2% of control subjects, 27% of subjects with NQT subsequently developed electrocardiographical evidence of atrial fibrillation (relative risk was 12 with lower 95% confidence limit of 1.8). NQT in an otherwise healthy individual is a benign condition and increases the likelihood of atrial fibrillation development.
The Manitoba Follow-up Study is one of the few large prospective studies of cardiovascular disease and is the only study of this dimension in Canada. The young age of the cohort at entry to this study provides an opportunity to identify characteristics in young men that relate to clinical development in later life. The main ECG findings over 35 years of 3983 Royal Canadian Air Force aircrew are reviewed.
As the first and only manifestation of ischemic heart disease, sudden unexpected cardiac death (SUCD) is a serious clinical and epidemiological concern. Prospective population studies permit the identification of risk factors for SUCD. Knowledge of the short-and long-term risks for SUCD are key to understanding the basis of any intervention. The present paper explores the effect of time since the detection of factors on the risk for SUCD. The Manitoba Follow-Up Study is a longitudinal, prospective study of 3983 originally healthy young men who have been followed with routine medical examinations since 1948. During 56 years of follow-up, SUCD occurred in 171 men. This analysis examined 21 possible risk factors for SUCD, including clinical findings, social variables and electrocardiographic abnormalities. Time-dependent covariate Cox proportional hazard models were used to estimate age-adjusted relative risks for SUCD. In multivariate models, the relative risk of SUCD was estimated as a function of time since the documentation of each risk factor. Excess alcohol consumption and T wave changes were associated with a high short-term risk for SUCD. Arterial hypertension and ST/T changes had sustained excess risk over both the short and long term. Newly developed left bundle branch block was a highly significant short-term risk that diminished with time. These findings add new information for the clinical management of risk factors. The identification of time since the detection of these risk factors is an important consideration to reduce SUCD.
A diagnosis of endocarditis was made in 37 patients (three days to 21 years old) on the basis of the following: histology in 11; at least two positive blood cultures in patients with underlying cardiac disease in 22; less than two positive blood cultures, vegetations seen at echocardiography and a suggestive clinical syndrome in four. Twenty-six patients had primary endocarditis (17 with pre-existing cardiopathy, nine with normal hearts). The 11 others developed secondary endocarditis following heart surgery (early onset in six, late onset in five). The mean delay before diagnosis was prolonged 35.8 days. The clinical and laboratory findings included weakness in 36 patients, fever in 35, new or modified heart murmur in 14, positive blood cultures in 30, anemia in 12, high white blood cell count in 15, increased sedimentation rate in 14, and positive echocardiogram in 11. Etiologic agents isolated were: streptococci in 17, staphylococci in seven, miscellaneous germs in eight, and aspergillus in two. Mortality was greater in patients less than one year old, infected with aspergillus or without underlying heart disease. The present study suggests that childhood endocarditis remains uncommon but presents a poor prognosis with a mortality of 27% and a morbidity of 85.7%.
To review the changing clinical profile of isolated coronary artery bypass graft (CABG) surgery patients at the University of Alberta Hospitals during the past two decades. Data were obtained retrospectively by review of patients' hospital charts and cardiologists' charts. The three patient cohorts consisted of the first 411 consecutive patients who underwent isolated CABG surgery between 1970 and 1974, 302 consecutive patients who had CABG surgery in 1984 and 346 consecutive patients who had the operation in 1989. Patients who underwent CABG surgery in 1984 and 1989 were older than patients undergoing the same operation in the 1970s. Emergency and/or urgent operations and the number of patients with prior myocardial infarct were increased significantly in 1984 and 1989. The incidence of patients with multiple vessel disease and left main stem stenosis increased significantly over the two decades. The number of bypass grafts per patient and the use of internal mammary grafts have increased since 1970. The endarterectomy procedure was performed less frequently in 1984 and 1989. The use of radial artery grafts has been discontinued. Perioperative mortality remained stable throughout the study period despite an increasing incidence of high risk patients. The major cause of death was pump failure. The incidence of peripostoperative myocardial infarct was higher in the 1970s. A multivariate analysis of the 1984 and 1989 cohorts was performed to identify temporal trends in risk factors. Emergency surgery, preoperative heart failure, age (older than 65 years), prior CABG surgery and preoperative renal failure are significant predictors of operative motility. The clinical profile of patients for isolated CABG surgery has changed over the years. The mortality rate has been stable over two decades despite the advancement of medical and surgical practices, representing a balance of increasingly high risk patients presenting for CABG surgery.
To assess mortality rates from congestive heart failure in Canada from 1970 to 1989. Observational, retrospective design using national population and mortality data. There is a definite age gradient for deaths from congestive heart failure which, combined with a general ageing of the Canadian population, has lead to an increase in the absolute number of deaths. However, Standardized Mortality Ratios, which account for shifting population distributions, have shown steadily decreasing values for both men and women since 1980. Recent improvements in cardiology care demonstrated in controlled clinical trials appear also to be present in epidemiological studies.
The relationships of systolic and diastolic blood pressure (BP) to ischemic heart disease (IHD), intermittent claudication (IC) and stroke were evaluated in 4385 men (aged 35 to 64 years in 1973) clinically free from these vascular diseases at entry and followed for 16 years. The mean of two readings measured in 1973-74 was used as the baseline BP. The cut-of for quintile 5 was systolic BP greater than 152 mmHg and diastolic BP greater than 92 mmHg. Relative risks (RR) were adjusted for main risk factors and calculated separately for systolic and diastolic BP. From 1974-90, 1120 first ischemic vascular events were documented: 792 IHD, 216 IC and 112 strokes. The incidences of each ischemic vascular disease increased, starting at quintile 4, for either systolic or diastolic BP. For systolic BP, the adjusted RR of quintile 5 compared with quintile 1 were 1.8 for IHD (95% confidence interval 1.4 to 2.2), 2.7 for IC (1.8 to 4.2) and 3.8 for stroke (2.1 to 7.0); for diastolic BP, the RR were 1.8 for IHD (1.5 to 2.3), 1.5 for IC (1.0 to 2.1) and 3.5 for stroke (2.0 to 6.4). For IHD, the RR of BP were similar for angina and myocardial infarction, and more pronounced for coronary death. In this population, elevated BP constitutes an important risk factor not only for stroke, but also for the main manifestations of IHD and IC. The impact of systolic BP was at least as significant as that of diastolic BP on these ischemic vascular events.
To present national trends in mortality rates for myocardial infarction and cardiovascular disease. Observational study using mortality statistics and hospital separation data from Statistics Canada for the period 1976 to 1991. Despite ageing of the population, there has been a substantial decrease in the number of deaths attributed to ischemic heart disease, from 51,000 in 1976 to 44,000 in 1991, with most of the decrease due to fewer deaths from myocardial infarction. Although age-adjusted death rates remain higher for men, the observed mortality decline has been more pronounced in men than in women. Age-adjusted separation rates have also decreased, suggesting a decrease in the incidence of myocardial infarction, particularly in the 45 to 64 year age group. The duration of hospital stay has shortened dramatically. From 1976 to 1991, mortality rates for ischemic heart disease in Canada decreased sharply, suggesting that advancements observed in clinical trials are being translated to the population level. The decrease appears to be due to both preventive measures and improved hospital care, but further studies are necessary to define better the relative contribution of each factor. The extent of this progress over the past 15 years is similar to the American experience.
The total number of cardiac patients requiring valve surgery in Canada has remained relatively constant over the years 1978-86, at about 2900 cases per year. However, the type of valve used has changed with most centres now using bioprosthetic valves as compared to mechanical valves which were popular until 1978. Unfortunately, there is a lack of uniform follow-up data on cardiac valve replacement patients and a countrywide registry is needed in order to monitor morbidity, mortality and long term results.
Top-cited authors
Sheldon W Tobe
  • Northern Ontario School of Medicine
Simon Rabkin
  • University of British Columbia - Vancouver
Ellen D Burgess
  • Alberta Health Services
Lawrence Leiter
  • University of Toronto
Padwal Raj
  • University of Alberta