The use of 188Re to treat in-stent re-stenosis of coronary arteries.

A pilot study has been conducted in which coronary arteries subject to re-stenosis after angioplasty and stenting have been irradiated following further angioplasty. The method of irradiation has been to use radioactive 188Re in an angioplasty balloon. This paper considers all aspects of the procedure including elution of the rhenium from a tungsten/rhenium generator, its concentration, dispensing and safe delivery to the patient using specially designed equipment to reduce staff doses and radioactive spills. In the pilot study of 28 lesions in 26 patients only 1 was recorded as having angiographic re-stenosis in the treated region at 6 months although 4 other patients had edge re-stenosis. This represents less than 18% re-stenosis in a population that would have been expected to exhibit at least 50% re-stenosis at 6 months. A total of 72 patients have been treated either in the pilot study or a subsequent trial. In only one case has a minor spill of radioactivity occurred and in no case has the balloon burst. Radiation doses to staff are approximately 20 microSv per procedure and are therefore not of serious consequence. It is concluded that this procedure is safe, feasible and effective in reducing in-stent re-stenosis.

Short and long-term results of coronary angioplasty in patients over 75 years.

AIMS: This report reviews the outcome of percutaneous transluminal coronary angioplasty (PTCA) on patients aged 75 years or over at this institution, in order to provide statistics that may be useful in managing elderly patients. METHODS: All elderly patients undergoing PTCA between January 1984 and December 1990 were included. Data concerning the PTCA procedure and short term (hospital stay) outcome were compared to those of all patients less than 75 years who underwent PTCA during the same period. Long term outcome was obtained for all surviving elderly patients. RESULTS: One hundred and eleven procedures were performed on patients over 75 years, compared to 3183 procedures on patients under 75. The incidence of PTCA in the elderly increased to 6.7% of all procedures in 1990. Elderly patients were more symptomatic (97% vs 79% in patients under 75 years had Canadian Cardiovascular Society grade 3 or 4 angina), more frequently had the procedure performed urgently (39% vs 14%) and often (67%) had risk factors for PTCA (3 vessel disease, significant left ventricular dysfunction, or a complicating medical illness). Primary success rates (86% vs 90% in patients under 75 years), urgent coronary artery bypass grafting (1.8% vs 1.9%) and Q wave infarction (1.8% vs 1.0%) were similar in the two age groups. In the elderly, procedural difficulties requiring non standard equipment were common (61%), and in-hospital mortality was increased (4.5% vs 0.7%). Additionally, three patients died after discharge resulting in a 30 day mortality of 7.2%. A favourable long term outcome was obtained in 50% of patients at a mean follow up of 20 months. Unfavourable or neutral outcome was due to one or more of the following; death (16%), coronary artery bypass grafting (19%), acute myocardial infarction (7.5%) or significant residual angina (17%). CONCLUSIONS: Highly symptomatic patients over 75 years constitute a high risk group for PTCA, with approximately half obtaining a favourable long term outcome.

Use of twenty-four hour infusions of intracoronary tissue plasminogen activator to increase the application of coronary angioplasty.

Coronary arteries occluded by long lengths of thrombus are usually considered unattractive for angioplasty. Nine patients (8 male, mean age 50.1 years) undergoing angiography for unstable angina were found to have single vessel disease considered unsuitable for angioplasty as the vessel was occluded by a long length of thrombus. These patients were treated with 24 hr intracoronary infusions of 100 mg tPA in an attempt to make angioplasty feasible. Marked thrombolysis occurred in 7 patients who received uncomplicated infusions. One case was unsuccessful due to catheter displacement, while another had the infusion ceased due to an intracerebral bleed from a previously silent A-V malformation. This was the only major complication. Angioplasty was attempted in 6 of 7 cases where lysis had been achieved, with success in all lesions attempted. This reports shows that intracoronary tPA infused over prolonged periods produces excellent thrombolysis, making angioplasty feasible in some patients who were previously unsuitable.

Effects of low-dose aspirin on restenosis after coronary angioplasty.

After angioplasty of a previously untreated native coronary artery and after 2 weeks of aspirin therapy, 216 subjects (aged less than 70 years without acute infarction) were randomized to treatment with soluble aspirin, 100 mg/day, or placebo to study the effect on restenosis. Follow-up, defined as angiography at 6 months, earlier angiographic restenosis or coronary bypass surgery was completed by 108 aspirin- and 104 placebo-treated patients. Restenosis (stenosis greater than or equal to 50% plus loss of greater than or equal to 50% of gain, or surgery) occurred in 38 (35%) aspirin- and 45 (43%) placebo-treated subjects (p = not significant). No patient died. Restenosis occurred in 42 of 168 (25%) aspirin- and 51 of 135 (38%) placebo-treated lesions (p less than 0.025). Aspirin-treated lesions (n = 163) had lost 16 +/- 22% (mean +/- standard deviation) of lumen and placebo-treated lesions 22 +/- 25% of lumen (n = 134) at angiography (p less than 0.01). There were more left anterior descending lesions in the placebo group and these had a higher recurrence rate than other lesions. The beneficial effect of aspirin was not dependent on this, although significance was reduced in subgroup analysis. Loss of lumen in left anterior descending lesions was 20 +/- 24% (n = 57) in the aspirin-treated and 27 +/- 25% (n = 70) in the placebo-treated lesions (p less than 0.1). It is concluded that there is a small beneficial effect of low-dose aspirin on restenosis after coronary angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Update on percutaneous transluminal coronary angioplasty and CABG.

Over the past decade percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) have undergone substantial changes. The growth of PTCA has been phenomenal and it now accounts for about 50 per cent of revascularisation procedures at Royal Perth Hospital. Coronary surgery has undergone less growth, but it is now being successfully used in a much more elderly and high risk group of patients without an increase in mortality.

Long term efficacy of transvenous catheter ablation of the atrioventricular junction for refractory supraventricular tachycardia.

Twenty-four patients who underwent transvenous catheter ablation of the atrioventricular (A-V) junction between November 1982 and February 1987 were followed from 18-72 months (mean 47.9) to assess the long term efficacy and safety of the procedure. All had severely symptomatic supraventricular tachyarrhythmias refractory to standard treatment. Atrioventricular conduction was abolished in 23 patients, 22 having permanent pacemakers implanted. Conduction has recovered, though it is modified, in one patient who is asymptomatic on digoxin. Four patients have died; one suddenly 20 months following the procedure, one of progressive heart and liver failure due to hemochromatosis, and two of a stroke. Four patients have had complications related to permanent pacing; one patient has required generator replacement and one patient ventricular lead replacement, one patient had asystole and one patient had a pacemaker-related tachycardia. Two patients remain symptomatic but improved by the procedure. Seventeen patients are free of their original symptoms, 11 having no intervening morbid events. These results demonstrate that patients with severely symptomatic supraventricular tachyarrhythmias may gain long term symptomatic relief from the procedure, but permanent pacing is a cause of significant morbidity and there is a small incidence of late sudden cardiac death.

Echocardiographic characterization of dilatation cardiomyopathy in the English cocker spaniel.

The echocardiographic characterization of a dilatation cardiomyopathy in small-breed dogs is reported. Twelve clinically healthy adult English Cocker Spaniel dogs (between 2 and 9 years old and weighing 11.5 to 15.4 kg [mean 12.9 +/- 1.00 kg]) from a kennel population with a history of cardiomyopathy were assessed, using M-mode echocardiography. The dogs were selected on ECG and/or radiographic evidence of ventricular enlargement. Nine dogs had R-wave amplitude in lead 11 of greater than 3.0 mV. Two dogs had an unusual right-axis deviation, the result of deep Q waves in the limb leads and deep S waves in chest leads CV6LL and CV6LU, indicating that there was right ventricular enlargement. All dogs had increased end-systolic dimensions (mean 3.0 +/- 0.6 cm). End-diastolic dimensions were increased in 9 dogs (mean 4.0 +/- 0.5 cm), and there was a decrease of left ventricular (LV) function as measured by fractional shortening in 8 dogs. Mean fractional shortening for the 12 dogs was 25.4 +/- 5.7%. There was significant correlation between LV dimensions and age at echocardiographic assessment, indicating that LV dilatation was progressive. Three of the oldest dogs had severe dilatation of the LV, and in 2 of these, LV function was severely decreased. Left ventricular function in the 3rd dog, however, was within the acceptable range. Fractional shortening and thickness of the LV caudal wall and interventricular septum were significantly correlated (P less than 0.01 for interventricular system and P less than 0.05 for LV caudal wall).(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic assessment of left ventricular dimensions in clinically normal English cocker spaniels.

Seventeen clinically normal adult English Cocker Spaniels from a kennel population with a history of cardiomyopathy were assessed, using M-mode echocardiography, to establish reference values for left ventricular (LV) dimensions for this breed of dog. Echocardiographic measurements were compared with postmortem measurements in 10 of 17 dogs. The LV weight calculated from the echocardiographic measurements correlated significantly with LV weight at postmortem (P less than 0.05). Echocardiographic measurements of end diastolic and end systolic diameters for the 17 dogs correlated significantly with body surface area (P less than 0.01). Measurements of the interventricular septum were in close agreement with values in clinically normal dogs and were significantly correlated with postmortem measurements (r = 0.94, P less than 0.01). However, 76% of the measurements for LV caudal wall thickness in this group of dogs were above the normal range. Calculation of fractional shortening values identified a group of 5 dogs with reduced fractional shortening (mean +/- SD, 20.97 +/- 3.66%), which indicates that a depression in contractility may be present in some apparently healthy dogs of this kennel population. The remaining 12 dogs had fractional shortening values of mean +/- SD, 34.26 +/- 4.54%.

Initial experience with physiological pacing.

Fifty patients, aged 23 to 88 years, with permanent rate-responsive dual chamber pacemakers were studied prospectively for 14.1 +/- 11.4 (S.D.) months after implantation to assess the benefits and complications associated with this technique. In 12 patients the device replaced a ventricular demand pacemaker. Minor complications associated with implantation occurred in one case. Atrial leads required repositioning because of increase in threshold and/or problems of sensing in five cases and ventricular leads in five. There were two patients with symptomatic pacemaker-related arrhythmias necessitating reprogramming; one patient with pacemaker-mediated tachycardia and one with pacemaker autoinhibition. Seven patients have died; one suddenly and possibly related to a pacemaker-triggered arrhythmia. Of 43 living patients, five are now programmed to the ventricular demand mode; two with atrial fibrillation, one with failed atrial lead repositioning, one with persistent sinus tachycardia, and one because of angina pectoris. Thirty-six of the 43 living patients are asymptomatic and a further six are symptomatically improved. All 12 patients changed from ventricular demand pacing have less symptoms. Rate-responsive dual chamber pacing is safe and appears to improve symptoms in most cases. Complications are infrequent and usually easily overcome. This mode of pacing should be considered in all patients with normal sinoatrial function in whom a permanent pacemaker is indicated.

A comparison of intravenous and intracoronary streptokinase in acute myocardial infarction.

A randomised study of intravenous and intracoronary streptokinase therapy was carried out in 20 subjects with acute myocardial infarction and angiographically confirmed complete obstruction of the associated coronary artery. Two dose levels of therapy were used. Although more recanalisations occurred with intracoronary than intravenous therapy at the low dose levels, overall there was not a significant difference between the two groups; one million IU intravenously over 20 minutes recanalised four of five arteries. While seven of nine recanalisations with intracoronary therapy occurred within an hour, only two of five with intravenous therapy did so. Hence prolonged angiographic observation is necessary to document recanalisation with intravenous therapy adequately. Nevertheless, the time disadvantage of large dose intravenous therapy is not great and it may yet prove as effective as, and more practical than, intracoronary therapy.

Transvenous ablation of atrioventricular conduction for refractory or malignant supraventricular arrhythmias.

In nine patients with recurrent disabling supraventricular arrhythmia refractory to, or intolerant of, multiple drug combinations, and two patients with Wolff-Parkinson-White (WPW) syndrome and documented malignant atrial fibrillation, transvenous ablation of atrioventricular (AV) conduction, utilising synchronised unipolar DC shocks delivered by catheter to the AV node-His bundle or to the accessory AV pathway, was attempted. One to two 200-300 J discharges produced complete heart block in all of the nine patients, with markedly improved symptomatic status at one to ten month follow-up including the one patient with recovery of modified AV conduction. Single 100-150 J shocks ablated pre-excitation for five to fifteen minutes in the two WPW patients without subsequent modification of accessory pathway conduction. There were no complications. This simple technique has great potential and may supplant some open-heart procedures. With refinement it may be possible to slow rather than to ablate AV-His conduction, to ablate conduction via accessory AV pathways permanently and to interrupt ventricular re-entrant circuits.

Exercise testing and thallium-201 myocardial imaging in relation to coronary artery disease in patients with severe aortic valve disease.

Thirty-three patients with aortic valve disease, fifteen with regurgitation, eleven with stenosis and seven with mixed disease, undergoing assessment for valve replacement which included adequate coronary angiography, were studied. A symptom limited graded treadmill exercise test was undertaken with administration of 40-70 MBq of 201Tl. Myocardial imaging was started within 15 minutes and repeated after four hours using a 37 PM tube Searle gamma camera. Myocardial images were read independently by three observed. Of the 33 sets of images, 21 were -ve, 5 +ve, 2 I (Indeterminate) and 5 D (Difference of opinion). Eight of the 33 patients had significant coronary artery disease (CAD) and of these three were scored +ve (all triple vessel). Two patients without CAD were scored +ve. Eight subjects developed angina during exercise testing, of whom four had CAD, and four with CAD did no develop angina. Historically, 13 of the 33 subjects had typical angina, six having CAD; an additional eight had other significant chest pain, two having CAD. In these subjects with severe aortic valve disease, exercise testing and myocardial imaging with 201 TI was of little value in detecting CAD. All patients with CAD gave a history of significant chest pain.