Dispersion of ventricular repolarisation: a marker of ventricular arrhythmias in patients with previous myocardial infarction

Objective—To examine whether, in coronary patients after myocardial infarction, the dispersion of ventricular repolarisation measured through QT and JT intervals from a surface electrocardiogram could allow separation of those with ventricular tachyarrhythmias (VT) complicating their myocardial infarct from those without.
Design—A retrospective comparative study.
Setting—University hospital.
Patients—39 patients with myocardial infarction complicated by VT, 300 patients after myocardial infarction without arrhythmic events, and 1000 normal subjects. The myocardial infarction groups were divided into anterior, inferior, and mixed locations.
Interventions—A computer algorithm examined an averaged cycle from a 10 second record of 15 simultaneous leads (12 lead ECG + Frank XYZ leads). After interactive editing, four intervals were computed: QTapex, JTapex, QTend, and JTend. For each interval, the dispersion was defined as the difference between the maximum and minimum values across the 15 leads.
Results—The mean values of all four dispersion indices were higher in patients with myocardial infarction than in normal subjects (p < 0.01). In the infarct groups, patients with VT had significantly greater mean and centile dispersion values than those without VT. For instance, the 97.5th centile value of QTend was 65 ms in normal individuals, 90 ms in infarct patients without arrhythmia, and 128 ms in those with VT; 70% of the infarct patients who developed serious ventricular arrhythmias had values exceeding the 97.5th centile of the normal group, while only 18% of the infarct patients without arrhythmia had dispersion values above this normal upper limit. Among the infarct patients, nearly half of those (18 of 39) with tachyarrhythmias had dispersion values that exceeded the 97.5th centile of those without arrhythmia.
Conclusions—Dispersion of ventricular repolarisation may be a good non-invasive tool for discriminating coronary patients susceptible to VT from those who are at low risk.

Keywords: QT dispersion;  myocardial infarction;  computer analysis;  arrhythmias     

Bradykinin induced dilatation of human epicardial and resistance coronary arteries in vivo: effect of inhibition of nitric oxide synthesis

Objective—To clarify whether endothelium derived nitric oxide contributes to exogenous bradykinin induced dilatation of human epicardial and resistance coronary arteries in vivo.
Design—Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthesis inhibitor, N^G-monomethyl-L-arginine (L-NMMA), on bradykinin induced dilatation of the epicardial and resistance coronary arteries.
Setting—Hiroshima University Hospital.
Patients—20 patients (16 men and four women, mean (SD) age 56 (9) years) with angiographically normal smooth epicardial coronary arteries.
Interventions—Serial infusions of bradykinin (0.5, 1.5, and 2.5 µg/min) were given into the left coronary ostium before and after L-NMMA infusion (60 µmol/min).
Main outcome measures—Epicardial coronary diameter, coronary blood flow, and coronary vascular resistance.
Results—Bradykinin-induced epicardial coronary vasodilatation after L-NMMA (dilatation by 2.5 µg/min, 3.8(1.4)% in the proximal and 5.9(1.8)% in the distal segments, mean (SEM)) was less (p < 0.001, respectively) than before L-NMMA (11.7(2.5)% and 15.1(2.0)%, respectively). In contrast, L-NMMA did not affect the bradykinin induced increase in coronary blood flow and decrease in coronary vascular resistance.
Conclusions—Endothelium derived nitric oxide contributes to bradykinin induced dilatation of epicardial coronary arteries, but may be less important in coronary resistance vasodilatation.

Keywords: bradykinin;  nitric oxide;  coronary artery;  coronary blood flow     

Angiographic and electrophysiological substrates for ventricular tachycardia mapping through the coronary veins

Objective—To study the value of epicardial mapping through the coronary venous system in patients with sustained ventricular tachycardia.
Design—20 consecutive patients with sustained ventricular tachycardia who were candidates for radiofrequency ablation.
Setting—Electrophysiological laboratory.
Interventions—Coronary venous angiography was performed with a catheter, which provided coronary sinus occlusion during injection of contrast media. Multipolar microelectrode catheters were then manoeuvred into the tributaries of coronary sinus, using an over-wire system or an on-wire system. An endocardial ablation catheter was positioned in the left ventricle. Conventional programmed ventricular stimulation was performed for sustained ventricular tachycardia induction. Endocardial radiofrequency ablation was performed using impedance or temperature monitoring.
Results—Coronary veins were catheterised in all patients; 20 had induction of sustained ventricular tachycardia, 14 were stable. Presystolic epicardial electrograms were recorded in six patients and concealed entrainment in two, helping as a landmark for endocardial ablation. After simultaneous epicardial and endocardial mapping, successful endocardial radiofrequency ablation was achieved in nine of 14 patients with stable ventricular tachycardia (64%).
Conclusions—Epicardial mapping through the coronary veins in patients with ventricular tachycardia is feasible, safe, and can be a useful landmark for endocardial catheter mapping and ablation.

Keywords: ventricular tachycardia; coronary angiography; cardiac mapping; radiofrequency ablation     

Dispersion of QT and QTc interval in healthy children, and effects of sinus arrhythmia on QT dispersion

Objective—To determine the normal values of QT and QTc dispersion and the effects of sinus arrhythmia on QT dispersion in healthy children.
Patients and setting—The study was carried out in a university hospital on 372 local schoolchildren (200 male, 172 female), aged seven to 18 years.
Methods—The QT and preceding RR intervals of at least one sinus beat were measured manually in a range of nine to 12 leads on standard 12 lead surface ECGs. The corrected QT interval was computed by the method of Bazett. Dispersion of QT and QTc were defined as (1) the difference between the maximum and minimum QT and QTc intervals occurring in any of the 12 leads (QTD and QTcD), (2) the standard deviation of the QT and QTc interval in the measurable leads (QT-SD and QTc-SD).
Results—There was no significant difference in QT, QTc, and RR dispersion between girls and boys. Overall 53% of children had sinus arrhythmia. Although QTD and QT-SD were not affected by sinus arrhythmia, both QTcD and QTc-SD were significantly greater in children with sinus arrhythmia than in those without (QTcD: 52.9 (17.4) v 40.9 (13.1); QTc-SD: 17.5 (5.9) v 13.2 (4.0); p < 0.001).
Conclusions—As calculation of QTc dispersion is affected by sinus arrhythmia, which is common in childhood, we suggest that QT dispersion should not be corrected for heart rate in children.

Keywords: QT dispersion;  heart rate;  children;  sinus arrhythmia     

Nitrate induced coronary vasodilatation: differential effects of sublingual application by capsule or spray

Background—Sublingual nitroglycerin (glyceryltrinitrate, GTN) capsules or isosorbide dinitrate (ISDN) spray are routinely used to treat anginal attacks and to vasodilate maximally the epicardial coronary arteries during coronary angiography.
Objective—To compare the coronary vasodilatory effects of GTN capsules and ISDN spray with those induced by intracoronary GTN using quantitative coronary angiography.
Design—96 patients (79 men and 17 women; median age 59 years) were randomised to four groups to receive either a sublingual capsule containing 0.8 mg GTN or two puffs of spray delivering 0.8 mg ISDN, followed or preceded by an intracoronary bolus of 0.2 mg GTN used as reference for maximal vasodilatation.
Results—There was a significant increase in the mean diameter of coronary arteries in angiographically normal segments in patients who received either intracoronary GTN (groups 1 and 2) or ISDN spray (group 4) as a first application (group 1, 0.46 mm, +17%, (baseline vessel diameter 100%), p < 0.001; group 2, 0.45 mm, +13%, p < 0.001; group 4, 0.47 mm, +13%, p < 0.05). Patients who received a sublingual GTN capsule as the first application mode (group 3) had no significant change in epicardial vessel diameter (0.10 mm, +5%, p = 0.3).
Conclusions—Sublingual ISDN spray may be more efficacious than sublingual GTN capsules in certain patients with anginal attacks. ISDN spray should be preferred over capsules in coronary angiographic procedures.

Keywords: angiography;  isosorbide dinitrate;  nitroglycerin;  vasodilatation;  angina     

Prediction of the onset of atrial fibrillation after cardiac surgery using the monophasic action potential

Objective—To show that the monophasic action potential (MAP) recorded continuously from human epicardium may be used to predict the imminent onset of atrial fibrillation or flutter (AF) following surgery, thus allowing prophylactic treatment to be started.
Patients—22 patients (14 male, 8 female; mean (SD) age 64 (12) years) undergoing aortic valve replacement.
Setting—Tertiary referral centre.
Methods—Over a mean observation period of 8 (2.7) days (range 4 to 14), nine episodes of AF were seen in six patients. Before AF, specific and significant alterations of the MAP morphology were observed. In seven of nine episodes the MAP shortened (25 (4)% 60 minutes before AF), developed a triangular shape, and the plateau amplitude decreased from 5.3 (1.2) to 2 (0.2) mV. In the two remaining episodes the beat to beat variability of cycle length and MAP duration at 90% repolarisation (MAPd₉₀) increased significantly from 24 (7) ms and 12 (8) ms (24 hours before AF) to 137 (27) ms and 56 (11) ms (30 minutes before AF) respectively. AF was successfully treated by the administration of sotalol in three cases and by a combination of verapamil and digoxin in a further four. Previously observed changes of MAPd₉₀ and MAP morphology regressed after conversion to sinus rhythm.
Conclusions—The continuous and intermediate term recording of the MAP from atrial epicardium appears to be a valid tool for detecting imminent AF after cardiac surgery with a high sensitivity (99%) and specificity (88%). Optimised antiarrhythmic treatment may thus be given selectively for prophylaxis.

Keywords: postoperative atrial fibrillation;  monophasic action potential;  postoperative management;  prophylactic antiarrhythmic treatment;  arrhythmias     

Intravascular stents: a new technique for tissue processing for histology, immunohistochemistry, and transmission electron microscopy

Background—Study of the vascular response to stent implantation has been hampered by difficulties in sectioning metal and tissue without distortion of the tissue stent interface. The metal is often removed before histochemical processing, causing a loss of arterial architecture. Histological and immunohistochemical sections should be 5 µm with an intact tissue stent interface.
Objectives—To identify the most suitable cutting and grinding equipment, embedding resin, and slides for producing thin sections of stented arteries with the stent wires in situ for histological, immunohistochemical, and transmission electron microscopic (TEM) analyses.
Methods—20 balloon stainless steel stents were implanted in the coronary arteries of 10 pigs. Twenty eight days later the stented arterial segments were excised, formalin fixed, embedded in five different resins (Epon 812, LR white, T9100, T8100, and JB4), and sectioned with two different high speed saws and a grinder for histological, immunohistochemical, and TEM analyses. Five stented human arteries were obtained at necropsy and processed using the best of the reported methods.
Results—The Isomet precision saw and grinder/polisher unit reliably produced 5 µm sections with most embedding resins; minimum section thickness with the horizontal saw was 400 µm. Resin T8100, a glycol methacrylate, enabled satisfactory sectioning, grinding, and histological (toluidine blue, haematoxylin and eosin, and trichromatic and polychromatic stains) and immunohistochemical analyses (α smooth muscle actin, von Willebrand factor, vimentin, proliferating cell nuclear antigen, and CD68 (mac 387)). T9100 and T8100 embedded stented sections were suitable for ultrastructural examination with TEM. Stented human arterial sections showed preserved arterial architecture with the struts in situ.
Conclusion—This study identified the optimal methods for embedding, sawing, grinding, and slide mounting of stented arteries to achieve 5 µm sections with an intact tissue metal interface, excellent surface qualities, histological and immunohistochemical staining properties, and suitability for TEM examination. The technique is applicable to experimental and clinical specimens.

Keywords: stents; resin; histology; immunohistochemistry; transmission electron microscopy     

Physiological cardiac reserve: development of a non-invasive method and first estimates in man

Objective—To investigate whether physiological cardiac reserve can be measured in man without invasive procedures and whether it is a major determinant of exercise capacity.
Design—Development of method of measurement and an observational study.
Setting—A regional cardiothoracic centre.
Subjects—70 subjects with a wide range of cardiac function, from heart failure patients to athletes.
Methods—Subjects underwent treadmill, symptom limited cardiopulmonary exercise tests to measure aerobic exercise capacity (represented by O₂max) and cardiac reserve. Cardiac output was measured non-invasively using the CO₂ rebreathing technique.
Results—Cardiac power output (CPO_max) at peak exercise was found to be significantly related to aerobic capacity: CPO_max (W) = 0.35 + 1.5O₂max (l/min), r = 0.87, p < 0.001. It also correlated well with exercise duration (r = 0.62, p < 0.001), suggesting that cardiac reserve is a major determinant of exercise capacity. In the study, cardiac reserve ranged from 0.27 to 5.65 W, indicating a 20-fold difference between the most impaired cardiac function and that of the fittest subject.
Conclusions—A non-invasive method of estimating physiological cardiac reserve was developed. The reserve was found to be a major determinant of exercise capacity in a population of normal subjects and patients with heart disease. This method may thus be used to provide a clearer definition of the extent of cardiac impairment in patients with heart failure.

Keywords: cardiac reserve;  cardiac power output;  oxygen consumption;  congestive heart failure     

S-Nitrosoglutathione inhibits platelet activation and deposition in coronary artery saphenous vein grafts in vitro and in vivo

Objective—To investigate platelet activation and deposition in human saphenous vein and internal mammary artery grafts following coronary artery bypass in vitro and in vivo, as well as inhibition of activation by the platelet selective nitric oxide donor S-nitrosoglutathione (GSNO).
Design—Controlled in vitro and in vivo studies.
Setting—Tertiary cardiac centre.
Patients—24 patients undergoing coronary artery bypass surgery requiring vein and artery grafts.
Interventions—In vitro: human platelet rich plasma was perfused through segments of vein and artery, with or without GSNO 10^-6 M, and the platelet count was measured in the effluent. In vivo: indium-111 labelled antibody against the platelet α granule protein GMP-140 was injected at the end of coronary bypass grafting and γ counts were compared between vein and artery grafts with or without systemic infusion of GSNO (40 nmol/min).
Results—In vitro: platelet count in perfused vein (< 70% of baseline) decreased more than in artery segments (89-94% of baseline) (p < 0.001). The platelet count was unchanged with GSNO in vein and artery segments. In vivo: γ counts were greater at all time points over vein than artery grafts (p < 0.05), and were reduced by infusion of GSNO (p < 0.05).
Conclusions—Platelet activation is greater in vein than in artery grafts in vitro and in vivo. Activation, which contributes to early vein graft failure, was inhibited by GSNO.

Keywords: coronary artery bypass surgery;  platelet activation;  S-nitrosoglutathione;  ischaemic heart disease     

Reduction in treatment delay by paramedic ECG diagnosis of myocardial infarction with direct CCU admission

Objectives—To establish the feasibility of training paramedics to diagnose acute myocardial infarction by ECG before hospital admission and whether direct paramedic coronary care admission, arranged by very high frequency (VHF) radio communication with the coronary care unit (CCU), would reduce delay of thrombolysis treatment.
Design—Prospective controlled study.
Setting—District general hospital CCU and a local district ambulance paramedic service.
Patients—124 patients with ECG evidence of myocardial infarction or ischaemia admitted directly to the CCU by the paramedic service were compared with 123 patients admitted by the emergency department and subsequently transferred to the CCU.
Main outcome measures—ECG diagnostic accuracy by paramedics, and interval durations for CCU admission and thrombolysis.
Results—ECG diagnostic accuracy by the paramedics was 87.5% in the training phase and 92% in admission. The total call to thrombolysis interval was reduced from 154 to 93 minutes and the "door to needle" interval was reduced from 97 to 37 minutes.
Conclusions—Trained paramedics can reliably diagnose myocardial infarction by ECG. The use of a direct admission procedure, by a VHF radio link to the CCU, substantially reduces the time interval for thrombolytic treatment after acute myocardial infarction.

Keywords: myocardial infarction;  electrocardiogram;  thrombolysis;  paramedic     

Residual and recurrent shunts after implantation of Cook detachable duct occlusion coils

Objective—To assess the presence and outcome of Doppler detectable shunts following implantation of the Cook detachable PDA coil.
Design—Prospective study.
Setting—Tertiary paediatric cardiac centre.
Patients—76 consecutive patients undergoing coil implantation (80 procedures).
Main outcome measures—Detection and colour Doppler echocardiographic appearance of residual or recurrent shunts, the timing of the appearance of recurrent shunts, and the time taken for spontaneous resolution of these shunts.
Results—Immediate occlusion was achieved in 52 patients. At one month 63 patients had complete occlusion and after three months the duct was completely occluded in 67 patients. In 27 cases small residual shunts were detected on echocardiography 10 minutes after the completion of the implantation procedure; 15 of these had resolved by 24 hours and 20 had resolved by three months. Recurrent shunts were detected after apparent initial complete occlusion in 11 cases 24 hours after coil implantation and in two cases one month after the procedure. Six recurrent shunts resolved on later follow up. Residual shunts appeared as single jets after implantation of a single coil, but up to three separate jets were detected after implantation of multiple coils.
Conclusions—Spontaneous resolution of small residual shunts occurs in most patients. The recurrence of small shunts after apparent complete occlusion suggests that recanalisation of the duct may occur in a small percentage of patients up to one month after occlusion. Residual shunts may take the form of multiple residual jets that may require implantation of further coils to achieve complete duct occlusion.

Keywords: coil occlusion;  arterial duct;  congenital heart disease     

Dipyridamole thallium-201 scintigraphy for early risk stratification of patients after uncomplicated myocardial infarction

Objective—To determine the safety and prognostic value of dipyridamole thallium-201 scintigraphy performed in patients within three to five days of acute myocardial infarction, including those receiving thrombolytic treatment.
Design—A prospective study of dipyridamole thallium-201 scintigraphy in patients early after acute myocardial infarction.
Setting—University hospital.
Patients—200 patients who were clinically uncomplicated at day 3 after infarction, 92 (46%) of whom had received thrombolysis.
Main outcome measures—Incidence of cardiac death, non-fatal reinfarction, readmission to hospital for unstable angina, or non-elective revascularisation procedure within six months' follow up.
Results—No patient had a serious complication from the dipyridamole study. At six month follow up, 55 patients (28%) had suffered a defined cardiac event. Patients who received thrombolysis had the same extent of thallium-201 redistribution and the same occurrence of subsequent cardiac events as those not receiving thrombolysis. Patients who subsequently had an event had more myocardial segments showing thallium-201 redistribution than event free patients: 2.7 (SD 1.9) v 1.2 (1.4), respectively (p < 0.001). Among all clinical and scintigraphic variables, multivariate analysis identified the extent of thallium-201 redistribution as the only independent predictor of outcome (p < 0.001). Among 63 patients (32%) of the study cohort who showed more than two myocardial segments with thallium-201 redistribution, the adjusted risk ratio for a cardiac event was 7.5 (95% confidence interval 2.9 to 19.1) compared with patients without any redistribution.
Conclusions—Dipyridamole thallium-201 scintigraphy can be performed safely within a few days of the event in patients with uncomplicated myocardial infarction, including those who received thrombolysis, and can identify a subgroup of patients at high risk of future ischaemic events.

Keywords: dipyridamole; thallium; myocardial infarction; prognosis     

Electrocardiographic changes after alcohol septal ablation in hypertrophic obstructive cardiomyopathy

Objective—To report acute and mid-term electrocardiographic changes in patients with hypertrophic obstructive cardiomyopathy (HOCM) after alcohol ablation of the first large septal branch of the left anterior descending coronary artery; and to relate electrocardiographic data with the left ventricular outflow tract pressure gradients.
Patients—Nine consecutive symptomatic patients with HOCM (mean (SD) age 45 (12) years).
Methods—Analysis of baseline and postprocedure ECGs and 24 hour ambulatory monitoring (up to six months). ECG data were related to left ventricular outflow tract pressure gradients.
Results—One patient developed complete atrioventricular block requiring permanent pacing. The PR interval was significantly prolonged up to third month after ablation. Immediately after the procedure all patients developed right bundle branch block. At the sixth month of follow up, right bundle branch block was present in four patients. New anterior ST elevation developed immediately after ablation in five of the nine patients, and new Q waves in four. The QRS duration was significantly prolonged immediately after ablation and during follow up. There was significant but transient prolongation of QT-mean and QTc-mean intervals. QT dispersion, QTc dispersion, and JTc-mean interval were not affected. JT and JTc dispersions were transiently prolonged. No serious ventricular arrhythmias were recorded during Holter monitoring, either before or after the procedure. There were no significant correlations between the left ventricular outflow tract pressure gradient and QTc, QT-d, QTc-d, JTc, JT-d, JTc-d, or QRS duration before and after ablation.
Conclusions—Alcohol septal ablation for HOCM induces significant changes in the resting ECG in most patients, despite the occlusion of a relatively small artery. The changes include new Q waves, new bundle branch block, transient anterior ST segment elevation, atrioventricular block, and transient prolongation of QT interval.

Keywords: hypertrophic obstructive cardiomyopathy;  alcohol septal ablation;  electrocardiography;  QT interval     

Subpectoral implantation of a cardioverter defibrillator under local anaesthesia

Objective—To evaluate patient acceptability of submuscular implantation of a cardioverter defibrillator (ICD) under local anaesthesia with conscious sedation.
Design—Retrospective review. Patient acceptability in the second half of the study was routinely assessed within 24 hours.
Setting—Regional cardiac centre.
Patients—45 consecutive patients with either aborted sudden death or haemodynamically unstable ventricular tachycardia were referred for ICD im- plantation.
Interventions—A subpectoral implantation technique was employed. Twelve procedures were performed under general anaesthesia. Thirty three patients were sedated with midazolam and diamorphine, and local anaesthesia was achieved with bupivicaine. Ventricular fibrillation for defibrillation threshold testing was induced by alternating current, T wave shock, or ultrarapid burst pacing. Patients were contacted after the procedure to assess acceptability.
Results—32 patients having implantation under local anaesthesia did not recall the surgical procedure. One patient described an awareness of "pushing" as the generator was positioned in the pocket. Seven patients said that the procedure was painless but recalled a test shock, four describing it as mildly uncomfortable. All 33 patients stated that they would be willing to have a second implant under local anaesthesia. Twelve patients who had the implant performed under general anaesthesia had no recollection of the procedure. Mean (SD) total procedure duration was significantly longer in those who had general anaesthesia (93 (16) v 67 (17) minutes; p = 0.0009).
Conclusions—Subpectoral implantation of ICDs may be performed safely with patient acceptability under local anaesthesia with conscious sedation.

Keywords: cardioverter defibrillator;  subpectoral implantation;  local anaesthesia;  pacing     

Ten year follow up of patients referred for coronary artery bypass grafting from a single district general hospital

Objective—To determine the status of patients 10 years after referral for coronary artery bypass graft (CABG) surgery.
Design—Retrospective analysis of case notes from all patients referred between 1 April 1981 and 31 March 1985. Full information gathered from hospital notes, GP records, and Registrar General for Scotland.
Setting—District General Hospital, West Lothian, Scotland.
Patients—102 patients referred for CABG during study period. Cardiac surgery was undertaken in Brompton Hospital, London, Royal Infirmary, Edinburgh, and Western Infirmary, Glasgow.
Results—At 10 years after operation 32 patients had died (27 cardiac, five non-cardiac causes). Full data were not available for five patients. Of the 65 remaining patients 24 had no angina, 13 had had a repeat procedure (CABG or angioplasty), and 28 had angina.
Conclusions—Long term benefits of CABG surgery is disappointing. Further steps are required to reduce progression of disease in this population.

Keywords: coronary artery bypass surgery;  repeat procedure;  survival;  audit     

Fibrinolytic potential is significantly increased by oestrogen treatment in postmenopausal women with mild dyslipidaemia

Objective—To study the effects of oestrogen replacement treatment on fibrinolytic potential in postmenopausal women.
Design—Randomised, double blind, placebo controlled trial of oral 17β-oestradiol.
Setting—Subjects were evaluated in the outpatient setting.
Patients—Nineteen postmenopausal women with mild dyslipidaemia, aged 44 to 69 years (mean (SD) 55.7 (6.7)).
Main outcome measures—Fibrinolytic activity (fibrin plate assay) and tissue plasminogen activator (t-PA) antigen were measured at baseline and after three, six, and nine weeks of each treatment.
Results—After nine weeks of 2 mg oestradiol treatment, there was a significant increase in fibrinolytic potential compared with placebo, as indicated by an increase in fibrinolytic activity (mean (SEM), 80 (9) v 54 (5) mm² of lysis in the fibrin plate, 2 mg v placebo, p = 0.002) and a decrease in t-PA antigen (5.8 (0.9) v 8.4 (1.2) ng/ml, 2 mg v placebo, p < 0.001). There was a similar trend with the 1 mg dose but the changes were less noticeable.
Conclusions—Hormone replacement treatment with 17β-oestradiol for nine weeks significantly increased fibrinolytic potential in postmenopausal women with mild dyslipidaemia. This suggests that the cardioprotective effect of oestrogen may be mediated, in part, by an increase in fibrinolytic potential.

Keywords: oestrogen;  fibrinolysis;  randomised controlled trial;  dyslipidaemia     

Five minute recordings of heart rate variability for population studies: repeatability and age-sex characteristics

Objective—To evaluate the stability of short recordings of heart rate variability (HRV) with time, and the association of HRV with age and sex.
Design—Five minute Holter recordings were made twice over a two month interval (tracking study). In addition, HRV was measured in a cross sectional study.
Setting—Residents of 11 Israeli kibbutzim were examined in their settlements.
Subjects—32 men and 38 women (aged 31-67) participated in the tracking study and 294 (aged 35-65) were involved in the cross sectional study.
Main outcome measures—Time and frequency domain analyses on Holter recordings were undertaken in two breathing conditions: spontaneous and controlled breathing (15 respirations per minute). Regression was used to assess the relations of sex, age, heart rate, and logarithmically transformed HRV indices.
Results—HRV measures were highly consistent with time with correlations of 0.76-0.80 for high frequency and total power. Geometric mean total power declined with age by 45% in men and 32% in women, and was lower by 24% among women than among men (all p 0.005). Men had a 34% higher very low and low frequency power and a higher ratio of low to high frequency power (p < 0.001). Conversely, high frequency power in women represents a greater proportion of total power than in men.
Conclusion—Short recordings of HRV in a non-laboratory setting are stable over months and therefore characteristic of an individual. Strong age and sex effects were evident. HRV derived from short recordings can be informative in population based studies.

Keywords: heart rate variability; parasympathetic activity; reliability; sex differences     

Cost effective management programme for heart failure reduces hospitalisation

Objective—To study the effects of a management programme on hospitalisation and health care costs one year after admission for heart failure.
Design—Prospective, randomised trial.
Setting—University hospital with a primary catchment area of 250 000 inhabitants.
Patients—190 patients (aged 65-84 years, 52.3% men) hospitalised because of heart failure.
Intervention—Two types of patient management were compared. The intervention group received education on heart failure and self management, with follow up at an easy access, nurse directed outpatient clinic for one year after discharge. The control group was managed according to routine clinical practice.
Main outcome measures—Time to readmission, days in hospital, and health care costs during one year.
Results—The one year survival rate was 71.8% (n = 79) in the control group and 70.0% (n = 56) in the intervention group (NS). The mean time to readmission was longer in the intervention group than in the control group (141 (87) v 106 (101); p < 0.05) and number of days in hospital tended to be fewer (4.2 (7.8) v 8.2 (14.3); p = 0.07). There was a trend towards a mean annual reduction in health care costs per patient of US$1300 (US$1 = SEK 7.76) in the intervention group compared with costs in the controls (US$3594 v 2294; p = 0.07).
Conclusions—A management programme for patients with heart failure discharged after hospitalisation reduces health care costs and the need for readmission.

Keywords: heart failure;  hospitalisation;  management;  health care costs;  nurse led clinics     

Heartstart Scotland: the use of paramedic skills in out of hospital resuscitation

Objective—To assess the frequency with which paramedic skills were used in out of hospital cardiac arrest and the effect of tracheal intubation on outcome.
Design—Retrospective analysis of ambulance service reports and hospital records.
Setting—Scottish Ambulance Service and hospitals admitting acute patients throughout Scotland.
Results—A total of 8651 out of hospital resuscitation attempts were recorded and tracheal intubation was attempted in 3427 (39.6%) arrests. One hundred and thirty six patients (3.7%) were intubated and 476 (9.1%) of the patients who were not intubated survived to hospital discharge (p < 0.001). Among the patients who were defibrillated the proportion intubated was highest in the patients who received the greatest number of shocks (p < 0.01). Among subjects receiving similar numbers of shocks survival rates were lower for intubated patients (p < 0.01). Patients with unwitnessed arrests were most frequently intubated and survival rates were lowest in this group.
Conclusions—Patients who are intubated seem to have lower survival rates. This may however reflect the difficulty of the resuscitation attempt rather than the effects of intubation. The use of basic life support skills rapidly after cardiac arrest is associated with the best survival rates.

Keywords: paramedics;  resuscitation;  myocardial infarction;  tracheal intubation;  prehospital care     

von Willebrand factor, tissue plasminogen activator, and dehydroepiandrosterone sulphate predict cardiovascular death in a 10 year follow up of survivors of acute myocardial infarction

Background—Haemostasis plays a major part in the process initiating a myocardial infarction. The impact of haemostatic variables on long term prognosis is unknown.
Objective—To evaluate von Willebrand factor (vWF), tissue plasminogen activator antigen (t-PA) and its activity before and after venous occlusion, plasminogen activator inhibitor (PAI-1), dehydroepiandrosterone sulphate (DHEAS), and established clinical risk factors as long term predictors for reinfarction and mortality.
Patients—123 consecutive survivors of myocardial infarction followed up for 10 years.
Design—Study entry took place between 1982 and 1983. Fifty seven patients died (54 of cardiovascular disease) during the mean observation time of 10 years.
Results—Cox's univariate regression analysis showed that cardiovascular mortality was significantly associated with age, hypertension, previous history of angina pectoris, DHEAS, mass concentration of t-PA, and vWF. These associations were significant for vWF and mass concentration of t-PA after adjusting for age and hypertension.
Conclusions—A low concentration of DHEAS and high levels of the endothelially derived haemostatic variables vWF and mass concentration of t-PA are predictors of cardiovascular mortality in survivors of myocardial infarction. This association is independent of established clinical risk factors for mass concentration of t-PA and vWF.

Keywords: myocardial infarction;  risk factors;  fibrinolysis;  tissue plasminogen activator;  plasminogen activator inhibitor;  von Willebrand factor;  dehydroepiandrosterone sulphate