Electrocardiographic abnormalities in patients receiving hemodialysis.

We assessed standard 12-lead and Holter electrocardiographic (ECG) abnormalities in maintenance hemodialysis (HD) patients. Of 221 outpatients receiving HD, 143 (65%) had ECG abnormalities. Rates were higher in male, elderly, hypertensive, and diabetic patients than in female, younger, normotensive, and nondiabetic patients. The prevalence of ECG changes correlated inversely with HD duration. Serial ECGs were compared in 87 patients whose average HD duration was 7.5 +/- 2.5 years. Thirty-four patients (39%) showed normal ECGs throughout, 27 (31%) relatively stable abnormalities, 22 (25%) worsening, and 4 (5%) reversion to normal. Age, hypertension, and diabetes are factors related to abnormal ECG findings. Among the 142 Holter recordings from 72 patients, 70 (97%) were basically in sinus rhythm, and 2 (3%) were in atrial fibrillation. The average frequency of supraventricular premature contractions (SVPCs) was 1597 +/- 9725 per 24 hours, and that of ventricular premature contractions (VPCs), 556 +/- 1415. VPCs were multifocal in 9%, in runs in 25%, and early in 1%. In 29 (40%) of recordings, VPCs appeared mainly during and for several hours after HD. ST-T changes were seen in 43 (60%). In 11, ST depression occurred during and a few hours after HD. Patients receiving HD showed diverse ECG abnormalities. Holter ECGs revealed a high incidence of arrhythmias and ST-T changes, which frequently appeared in relation to HD timing.

Angiotensin-converting enzyme inhibition, the sympathetic nervous system, and congestive heart failure. The Australian Zestril (Lisinopril) Study Group.

Catecholamines have been found to be powerful indicators of prognosis in patients with congestive heart failure. However, it is uncertain whether catecholamines are a marker for decreased cardiac performance or part of the pathologic process. Catecholamines, exogenously derived beta-adrenergic stimulants, and drugs that amplify sympathetic responsiveness produce early hemodynamic benefits, but do not appear to provide long-term improvement in terms of symptoms or exercise tolerance, whereas blockade of the beta-adrenoceptor appears to have little early benefit but may improve long-term prognosis. This suggests that in the long term, increased catecholamine levels may be deleterious. Angiotensin-converting enzyme (ACE) inhibitors can modulate circulating catecholamines, and the persistence and degree of ACE inhibition may be important not only in reducing catecholamines, but possibly also in reducing mortality in heart failure. It appears that ACE inhibitors definitely reduce mortality in congestive heart failure. It remains to be documented whether the persistence and degree of ACE inhibition is a factor in this effect, and, thus, comparison of short- with long-acting ACE inhibitors and study of the dosage of ACE inhibitors are of importance. The extent to which modulation of the sympathetic nervous system by ACE inhibitors is an important mechanism in their effect in reducing mortality remains to be established.

Blood pressure changes with age in two ethnic groups in Fiji.

Blood pressure was studied in urban and rural samples of the Melanesian and Indian populations of Fiji during a National Cardiovascular Disease and Diabetes Survey in 1980. Mean blood pressures rose with age and tended to be higher in urban than in rural populations, particularly in the middle age range. There was no clear or significant difference between the ethnic groups. When the prevalence of hypertension was studied (using WHO criteria) similar age, geographic and ethnic differences were found. Comparisons with data from 1960 revealed no significant change in mean blood pressures during the 20-year interval. Rural populations were leaner and appeared to consume less salt than did urban groups. There were positive and significant correlations between blood pressure and triceps skinfold thickness in most subgroups.

Cardiac surgery in a private hospital. With special reference to coronary artery surgery.

In a four-year period in a private hospital there were 1396 open heart operations of which 1275 were for isolated coronary artery disease. The various techniques that were used for coronary artery reconstruction were saphenous vein grafts and internal mammary artery grafts, both singly and sequentially, and endarterectomy. The operative mortality for isolated coronary artery surgery was 1.1% and the perioperative infarction rate was 2.1%. When combined with an endarterectomy of the right coronary artery, the mortality was 3% and the infarction rate was 4% (not significant); when combined with endarterectomy of the left anterior descending coronary artery, the mortality was 11.7% (not significant), and the infarction rate was 11.7% (not significant). The operative risk was no higher in patients with poor ventricular function.

Prevalence of diabetes and impaired glucose tolerance in the biracial (Melanesian and Indian) population of Fiji: a rural-urban comparison.

Rural-urban and ethnic comparisons of impaired glucose tolerance and diabetes mellitus were made in the biracial population of Fiji in 1980. No statistically significant differences existed in age-standardized impaired glucose tolerance prevalence between rural and urban groups or between Melanesians and Indians. The age-standardized prevalence of diabetes in the rural Melanesian male population was one-third that of the urban male population (1.1 vs. 3.5%). In females, there was a sixfold rural-urban difference (1.2 vs. 7.1%). By contrast, rural and urban Indians had similar rates (12.1 vs. 12.9% for males; 11.3 vs. 11.0% for females). Standardization of two-hour plasma glucose for age and obesity did not eliminate the rural-urban difference in plasma glucose concentration for Melanesian males and females. The results in Melanesians confirm previously reported rural-urban diabetes prevalence differences, and suggest that factors other than obesity, such as differences in physical activity, diet, stress, or other, as yet undetermined, factors contribute to this difference. The absence of a rural-urban difference in diabetes prevalence in Indians may suggest that genetic factors are more important for producing diabetes in this ethnic group, or that causative environmental factors such as diet operate similarly upon both the rural and the urban populations.

Comparison of lead complications with polyurethane tined, silicone rubber tined, and wedge tip leads: clinical experience with 822 ventricular endocardial lads.

Lead-related complications have been prospectively studied for 602 unipolar tined endocardial ventricular pacemaker leads implanted over a five-year period. No differences were noted in overall complication rates between 238 polyurethane insulated leads (4.2%) and 364 silicone rubber insulated leads (3.6%). Comparing the total series of 602 tined leads to a retrospective survey of 220 wedge tip leads, a marked reduction in dislodgements (0.3% vs. 7.7%, P less than 0.001) and reoperations (2.0% vs 15.0%, P less than 0.001) was found using tined leads. We conclude that tined ventricular leads are far superior to wedge tip leads with respect to lead complications.

Electrophysiologic studies in survivors of late cardiac arrest after myocardial infarction.

Nine patients resuscitated from life-threatening ventricular arrhythmias (VA) within 3 months of an acute myocardial infarction (AMI) underwent electrophysiologic studies (EPS) with clinical follow-up for at least 12 months. Neither reinfarction, drug therapy, nor electrolyte imbalance was a precipitating factor. VA was induced by ventricular pacing in six of nine patients. Five patients were prescribed empiric drug therapy, while the four other patients had repeated EPS to select optimal drug therapy. One patient remained unstable and died of VA in the hospital. No patient was discharged and successfully maintained on a drug known to prevent induction of VA, yet only two patients (25%) had a further recurrence of VA, one fatal. Our findings suggested that either drug therapy that is determined empirically or found not to suppress the induction of VA during EPS can be associated with a successful outcome in some of these patients, or the natural history of VA after myocardial infarction is that they are self-limiting in the absence of a new ischemic event.

High density lipoprotein apoprotein variability in a biracial population.

High density lipoprotein (HDL) cholesterol is a sensitive index for coronary disease in affluent societies. We have measured plasma apoprotein A-I levels (the major HDL protein) in randomly selected groups of urban and rural Fijian Melanesians and Indians. Despite higher prevalence rates of coronary disease and diabetes mellitus in Indians, Indian men and women had significantly higher A-I levels than Melanesian men and women. Multivariate analysis was carried out separately in all men and women of both races and also in younger men and women (less than 45 years old) to determine the predictive values of seven variables that might influence A-I levels. These variables accounted for about 16% of the A-I variation and of this more than one-half was due to ethnic origin. The remainder was largely due to three environmental factors: urbanization, alcohol consumption, and physical activity. Men and women aged 20 to 44 years had significantly higher A-I levels in the town than in villages; alcohol drinkers had significantly higher A-I levels than nondrinkers, and in women physical inactivity resulted in significantly lower A-I levels. Age, smoking cigarettes, and body mass index did not contribute to the differences in A-I levels between the two races, despite less smoking and overweight among Indians. This study of a biracial population, that shares a similar environment but differs in cultural habits, has demonstrated the operation of genetic and environmental factors that explain a minor proportion of apoprotein A-I variability.

Prediction of sudden death by electrophysiologic studies in high risk patients surviving acute myocardial infarction.

Seventy patients surviving a myocardial infarction complicated by heart failure or arrhythmias, or both, were studied 7 to 20 days after the infarction. Twenty-four hour electrocardiographic ambulatory monitoring and intracardiac electrophysiologic studies were performed in each patient. Electrophysiologic studies included introduction of single right ventricular premature stimuli during sinus rhythm (70 patients), atrial pacing (35 patients) and ventricular pacing (70 patients) at a stimulating voltage of 2 V, with the use of higher stimulating voltages (up to 10 V), and double right ventricular premature stimuli in 33 patients and pacing at a second right ventricular site in 50 patients. A repetitive response was defined as two or more spontaneous ventricular depolarizations in response to the premature stimuli, with His bundle reentry and aberrant conduction of supraventricular impulses excluded by a His bundle recording. Repetitive responses were initiated in 20 patients, and 12 patients had responses that were either sustained ventricular tachycardia or self-terminating ventricular tachycardia of more than five complexes in duration. The finding of a repetitive response was not related to the occurrence of complex ventricular arrhythmias during ambulatory monitoring or in the coronary care unit. Five of the 12 patients with sustained or self-terminating responses of more than five complexes died during the 12 month follow-up period, 4 suddenly, and these responses were significantly associated with late sudden death (p less than 0.05), because only 1 of 25 patients with responses of fewer than five complexes or no response to maximal provocation died suddenly. It is concluded that induced responses of more than five complexes in duration may be an important indicator of a potentially reversible risk of sudden death after myocardial infarction.

The St Jude medical valve - the Australian experience.

Since October, 1978, 181 St Jude medical cardiac valves have been implanted in 166 patients throughout Australia. There were 152 single implants, 13 combined mitral and aortic valve implants, and one triple valve implant. Hospital mortality rates were similar to those for all types of prosthetic cardiac valves. Thromboembolic complications occurred less frequently in the patients with St Jude valves than in reports of similar patients with other prostheses, provided that anticoagulation was maintained.

Results of coronary artery surgery.

Four hundred and two patients undergoing coronary artery surgery from 1972 to 1978 inclusive have been followed up; 343 patients had coronary artery surgery without associated surgical procedures. In the over-all experience, the operative mortality rate was 5% falling to 1.5% in recent years. The seven-year survival rate was 90% compared with a 92% for an age-sex matched population. Late survival figures have improved with further surgical experience and the 30-month survival is now 98%. Seven per cent of patients sustained a perioperative infarction, but the over-all mortality rate was similar in patients with or without infarction. There has been a recurrence rate of angina of approximately 5% per annum; however, in our more recent experience, 82% of our patients were alive and free of angina two years after surgery.

Use of lignocaine and atropine autoinjectors for patients at high risk of sudden death and reinfarction after myocardial infarction.

Twenty-five patients entered a prospective study to assess the usefulness of atropine and lignocaine autoinjectors for coronary events after discharge from hospital after a definite, complicated myocardial infarction. They were selected on the basis of being at high risk of sudden death and reinfarction, being less than 70 years of age and being able to maintain a close liaison with the hospital. One or both autoinjectors were used for five reported events (four of collapse, one of chest pain) in four patients, with possible benefit in two instances. Six patients collapsed and died, despite the use of autoinjectors in three of their fatal collapses. In our experience, the use of autoinjectors has been of little observable benefit, perhaps due to the lack of specific warning symptoms preceding the onset of lethal arrhythmias, so that the injectors were often used for unobserved collapses when the chances of survival were remote.

Patient initiated implantable pacemakers for paroxysmal supraventricular tachycardia.

Seven patients with recurrent paroxysmal supraventricular tachycardia (PSVT) resistant to standard drug therapy were treated with patient initiated implantable pacemakers. All patients had required frequent hospital admissions and cardioversions prior to pacemaker implantation. Two patients had Wolff-Parkinson-White (WPW) syndrome on their surface ECGs and five patients had no ECG evidence of preexcitation. All patients had detailed electrophysiological studies. Three patients had junctional tachycardia, one patients had reciprocating atrial tachycardia and in three, including one with normal surface ECG, retrogradely conducting accessory atrio-ventricular connections (AAVC) formed a part of the tachycardia circuit. Initiation and termination of tachycardia were re-checked at subsequent studies. On the basis of these studies, two patients with WPW syndrome had right ventricular endocardial leads and custom-built, magnet actuated pacemakers capable of delivering right ventricular coupled stimuli at fixed, present intervals of 200 and 400 ms. Both these pacemakers provided inconsistent reversions and proved unsatisfactory. In the remaining five patients, a unipolar tined J-shaped right atrial (RA) lead (Medtronic 6991) and a radiofrequency (RF) receiver (Medtronic 5998T) were implanted and enabled patients to overdrive ranged from 14 to 20 months. Several episodes of PSVT have been consistently reverted and none have required hospitalisation or cardio-version. Two patients had transient atrial fibrillation following the application of RF pacemaker. Three have required no antiarrhythmic drugs and in two the drug therapy has been greatly reduced and simplified. The Medtronic 6991 lead provided satisfactory RA stimulation without dislodgement. In carefully selected patients with PSVT, RF pacemakers provide a useful mode of treatment.

Effects of quinidine and disopyramide on serum digoxin concentrations.

Although quinidine and digoxin are frequently given together, it has only recently become apparent that serum digoxin concentration may rise during quinidine treatment. A prospective study was performed to compare the effects of quinidine and disopyramide in patients receiving maintenance digoxin therapy. During quinidine administration serum digoxin concentration rose by more than 50% in seven of nine patients (the mean concentration rising from 1.43 +/- 0.20 to 2.61 +/- 0.43 nmol/l, P < 0.005). During the disopyramide treatment a small rise in serum digoxin was noted (mean 1.3 +/- 0.16 to 1.5 +/- 0.19 nmol/l, P < 0.05). We suggest that digoxin doses should be reduced immediately prior to commencing quinidine therapy in patients already receiving adequate maintenance digoxin, and patients should be followed carefully for evidence of digoxin toxicity. Disopyramide appears a suitable alternative anti-arrhythmic drug to quinidine in patients on maintenance digoxin.

Prospective angiographic assessment of factors affecting early patency of saphenous vein-coronary artery bypass grafts.

Between November 1977 and September 1978, early post-operative angiography was performed in 50 of 53 consecutive patients undergoing coronary artery bypass surgery. An average of 2.4 grafts per patient were applied. The overall patency rate was 82% and was not affected by the degree of proximal native vessel stenosis. Grafts to circumflex marginal vessels had a significantly lower (P < 0.05) patency rate (72%) than grafts to the left anterior descending (84%) and its diagonal branches (85%), or to the right coronary artery (90%). Ten single grafts were applied and all were patent. Forty-nine of the 50 patients had at least one patent graft. Fifty-three per cent of the grafts were considered of excellent quality and 25% patent but of fair quality only. There was a 100% patency rate for vessels of 2 mm diameter or more, which is significantly better (P < 0.01) than for vessels of 1-2 mm diameter (78%) or for vessels of less than 1 mm diameter (50%). There was a suggestion of a lower patency rate (74%) for vessels with evidence of distal disease, compared with vessels without such disease (85%). An assessment of the overall quality of the recipient vessel was made, taking both diameter and disease into account. This showed improved results for better quality vessels in terms of graft patency (P < 0.1) and graft quality (P < 0.05).

The refurbished pulse generator.

With the advent of long-life lithium pulse generators, normally functioning pulse generators with a potential life of more than five years have been removed from patients and become available for re-implantation. Although pulse generator refurbishing is widely employed, the practice has not been accepted in the United States. At The Royal Melbourne Hospital, all lithium pulse generators removed because of patient death or other causes were washed in a quaternary ammonium compound and soaked in formaldehyde. Pulse generators were than electronically tested and, if within specification, were made available for re-implantation. Pulse generators were then washed under sterile conditions in distilled water and gas-sterilized with ethylene oxide. Between 1975 and 1978 (48 months), 600 pulse generators were implanted and 93 pulse generators removed. There were 56 deaths, 22 cases of pre-erosion, erosion, or infection and 15 elective removals either due to lead problems or impending power source depletion. Eight-three (89%) pulse generators were refurbished (14% of total implants). This included 12 pulse generators refurbished on two occasions. Ten pulse generators were returned to manufacturers, seven because of impending power source depletion, two with suspected electronic faults, and one with a damaged case. Two complications occurred in patients with refurbished pulse generators. An infective process present with the previous pulse generator spread to a new pocket. The other pulse generator was removed 35 months post second implantation because of impending power source depletion. Primary infection or unusual tissue reactions did not occur. Pulse generator refurbishing as described was found to be a safe and economic procedure.