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BACKGROUND--Although heart rate variability has already been studied in survivors of sudden cardiac death secondary to coronary artery disease, an assessment of heart rate variability in survivors of sudden cardiac death not associated with coronary artery disease has not been made. METHODS--10 patients with aborted sudden cardiac death not associated with coronary artery disease (seven patients with primary ventricular fibrillation and three with unclassified mild cardiomyopathy) underwent two channel 24 hour Holter monitoring in a drug free state. All subjects were in sinus rhythm and had normal atrioventricular conduction and normal cardiac function. Spectral heart rate variability was analysed on a Holter analysis system and was expressed as total (0.01-1.00 Hz), low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency components for each hour. Heart rate variability index was calculated for the 24 hour periods. 10 age and sex matched healthy subjects were taken as a control group. RESULTS--The spectral heart rate variability over 24 hours was significantly lower in survivors of sudden cardiac death than in controls (total 38(15) v 48(14) ms; low, 25(11) v 32(13) ms; and high, 13(8) v 18(8) ms; p < 0.05 for all comparisons). The differences in the ratio of low/high (2.19(0.76) v 1.98(0.50), p = 0.132), mean heart rate (77(12) v 69(12) beats/min, p = 0.070), and heart rate variability index (38(12) v 44(16), p = 0.287) over 24 hours between survivors of sudden cardiac death and controls did not reach significance. Comparisons of the hourly heart rate variability over the 24 hour period between the two groups showed that the differences in all components of heart rate variability, low/high ratio and mean heart rate were highly significant. Furthermore, there was no significant difference in the maximum hourly heart rate variability over the 24 hour period. The minimum hourly heart rate variability was, however, significantly lower in survivors of sudden cardiac death than in controls (total, 20(8) v 28(4) ms; low, 12(6) v 17(3) ms; high, 6(2) v 8(2) ms; p < 0.05 for all comparisons). CONCLUSIONS--These findings suggest that there is abnormal autonomic influence on the heart in patients without coronary artery disease at risk of sudden cardiac death. Hourly analysis of heart rate variability throughout the 24 hour period may provide additional information important in the identification of high risk patients. [ABSTRACT FROM PUBLISHER]

OBJECTIVE--To develop a model to assess the cost-efficacy of the implantable cardioverter defibrillator to prevent sudden death. The model must be sufficiently flexible to allow the use of cost and survival figures derived from different sources. SETTING--The study was conducted in a teaching hospital department of cardiology with experience of 40 implantable cardioverter defibrillator implants and a large database of over 500 survivors of myocardial infarction. PROCEDURE--The basic costs of screening tests, stay in hospital, and purchase of implantable cardioverter defibrillators were derived from St George's Hospital during 1991. To assess the cost-efficacy of various strategies for the use of implantable cardioverter defibrillators, survival data taken from published studies or from our own database. Implications of the national cost of the various strategies were calculated by estimating the number of patients a year requiring implantation of a defibrillator if the strategy was adopted. RESULTS--Use of implantable cardioverter defibrillators in survivors of cardiac arrest costs between 22,400 pounds and 57,000 pounds for each year of life saved. Most of the strategies proposed by the current generation of implantable cardioverter defibrillator trials have cost efficacies in the same range, and adoption of any one of these strategies in the United Kingdom could cost between 2 million pounds and 100 million pounds a year. Future technical and medical developments mean that cost-efficacy may be improved by up to 80%. Due to the limitations of screening tests currently available restriction on the use of implantable cardioverter defibrillators to those groups where it seems highly cost-effective will result in a small impact on overall mortality from sudden cardiac death. CONCLUSION--Present and possible future applications of the implantable cardioverter defibrillator seem expensive when compared with currently accepted treatments. Technical and medical developments are, however, likely to result in a dramatic improvement in cost efficacy over the next few years. [ABSTRACT FROM PUBLISHER]

OBJECTIVE--Preliminary assessment of the efficacy and safety of the low speed rotational angioplasty catheter system (ROTACS). DESIGN--Open prospective trial. SETTING--Department of cardiology in a teaching hospital. PATIENTS--Eleven patients (10 with chronic stable angina and one with acute coronary occlusion after conventional angioplasty) in whom a coronary angiogram showed occlusion or critical stenosis of the coronary artery (right in seven patients, circumflex in two, and left anterior descending in two). The nature or severity of the lesion ruled out conventional coronary angioplasty. INTERVENTIONS--An attempt was made to cross the lesion with a rotating guide wire with a blunt swelling at its tip. Where necessary progress was assessed by simultaneous injection of contrast into both main coronary arteries. MAIN OUTCOME MEASURES--Progress of the ROTACS through the lesion that allowed a guide wire to pass into the distal vessel was regarded as a device specific success. When a guide wire crossed the lesion aided only by the support of the ROTACS without the use of rotation this was counted as a success that was not device specific. Failure to cross the lesion and any associated complications were noted. RESULTS--The ROTACS crossed only two of the 10 chronic lesions (20% device specific success rate); however, the support it provided enabled a guide wire to cross a further two lesions and allowed subsequent successful angioplasty in four of the 10 patients. One of these four patients presented after five months with recurrent angina requiring bypass grafting. The other three were symptom free at follow up seven months after the procedure. In the one patient with acute coronary occlusion the ROTACS was advanced over the guide wire to allow passage of an angioplasty balloon where this had previously proved impossible. An excellent final result was obtained and this patient remains symptom free. Three of the six patients in whom the ROTACS was unsuccessful had coronary artery dissection without sequelae. Three patients required subsequent elective coronary bypass grafting for control of symptoms while the other three remain well on medical treatment. CONCLUSIONS--The ROTACS may extend the range of patients with coronary artery occlusion or critical stenosis who can be treated non-surgically. The low device specific success rate (20%) achieved in this study indicates that it should be compared with other simpler mechanical devices that may be just as effective. [ABSTRACT FROM PUBLISHER]

Objective: To assess the accuracy of measurement of area of the lumen, and sensitivity, and specificity of detection of atheroma in coronary arteries in vitro with a commercially available 20 MHz intravascular ultrasound system., Setting: A teaching hospital department of cardiology with the support of the department of cardiovascular pathology., Procedure: 10 segments of coronary artery were removed from cadaver hearts. Intravascular ultrasound imaging was performed at fixed levels and the vessels were then sectioned and photographed before histological preparation. An independent blinded observer measured luminal area and assessed the presence of atheroma on the intravascular ultrasound images of 76 vessel sections (304 quadrants). The sensitivity and specificity of detection of atheroma was assessed in comparison with the histologically prepared sections. Luminal areas from intravascular ultrasound, photographs of cross sections of the vessels and histological sections were compared with the technique of limits of agreement., Results: Overall 36% of the 304 quadrants studied histologically had identifiable atheroma. Intravascular ultrasound sensitivity for atheroma was 0.593 and the specificity was 0.839. The positive predictive value was 0.674, and the relative risk 3.139. Values for area of the vessel lumen were on average 9.4 mm2 (confidence interval (CI) 8.6-10.2 mm2) larger than those measured from photographs and 10.7 (CI 9.8-11.6 mm2) larger than those measured from the histological sections., Conclusions: The intravascular ultrasound system assessed in this study significantly overestimated coronary vessel luminal area and had low sensitivity and specificity for detection of atheroma. Improvements in image resolution are required before this system can provide useful information on coronary artery size and morphology.