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Fourteen patients with supraventricular and/or ventricular ectopic beats selected by clinical, dynamic ECG and exercise test, underwent a basal continuous ECG recording (Holter) and then were given 400 mg of quinidine orally. The concentrations of the drug were determined in blood samples taken 30 minutes before, and 1, 2, 4, 6, 8, 12, and 24 hours after administration. On the same day patients were also monitored by continuous ECG recording (Holter). One week later, after a washout period, the same subjects were treated with 200 mg of quinidine orally 4 times a day for two weeks. On day 1, 2, 4, 7 and 14 quinidine was determined in plasma, and on day 7 and 14 a 24 hour ECG recording was also done. On the basis of pharmacokinetic parameters obtained from the acute test, the chronic levels of the drug were predicted. Predicted values were superimposable to those observed. Thus, the kinetics of single-dose quinidine is able to predict the steady-state levels after repeated dosing. During acute administration there was an increase in QTc interval and a decrease in ectopic beats. These effects correlated with a sigmoid pattern with acute quinidine levels. Concentrations producing 50% of the effect (EC50) could be calculated from these curves. In spite of similar steady-state blood levels of quinidine, some patients after chronic therapy did not respond to treatment (non responders). Non responders could be predicted by the acute test because they had greater EC50 values of QTc increase: patients with EC50 greater than 2 mg/L were all non responders.

The differences between diabetic and nondiabetic patients with silent myocardial ischemia were investigated. Based on the results of previous exercise testing, a total of 110 patients (15 diabetic and 95 nondiabetic) with exercise-induced myocardial ischemia were divided into the following 3 groups: 15 diabetics with silent myocardial ischemia, 49 nondiabetics with silent myocardial ischemia, and 46 nondiabetics with anginal symptoms. All patients underwent treadmill exercise testing and 24-hour ambulatory electrocardiographic recording. Before and during exercise, blood samples from the antecubital vein were obtained to determine the plasma beta-endorphin levels, and the pain threshold of each patient was measured with the electrical skin stimulation test. Furthermore, with regard to the ambulatory electrocardiographic recording, the mean of the SDs of all normal sinus RR intervals during successive 5-minute recording periods over 24 hours was analyzed and considered as an index of the autonomic function. The plasma beta-endorphin level during exercise was significantly greater in nondiabetic patients with silent ischemia than in diabetic ones. The SD mean was significantly less in the diabetic group than in the 2 nondiabetic ones. The findings suggest that the role of beta endorphin in diabetic patients with silent myocardial ischemia may be less significant than in nondiabetic ones; therefore, a diabetic neuropathy that affects the autonomic pain fibers that innervate the heart may be involved in the mechanism of silent myocardial ischemia in diabetics.

The prevalence and clinical significance of transient myocardial ischemia was evaluated prospectively in 43 patients with a clinical diagnosis of unstable angina. Continuous 2-channel Holter electrocardiographic monitoring was begun < 24 hours after admission. In 3,558 hours of recordings (mean 83 +/- 20 hours/patient), there were 1,671 episodes of transient ischemia; > 90% were asymptomatic. All patients but 1 had at least 1 episode of transient ischemia. Twenty-two patients (group 1) had a total ischemic duration of > or = 30 minutes/day, whereas 21 patients (group 2) had a total ischemic duration of < 30 minutes/day. A predischarge symptom-limited exercise test was performed in 40 of these patients after medical stabilization and 39 patients underwent exercise thallium-201 imaging, an average of 3 days after the exercise test. During a follow-up period of 39.9 +/- 9 months (range 28 to 49), 4 patients developed myocardial infarction and 22 required revascularization because of medically refractory angina. There were significantly more patients with total cardiac events (myocardial infarction or a need for revascularization) in group 1 than in group 2 (p < 0.05). Among patients undergoing an exercise test and exercise thallium-201 imaging, a positive exercise electrocardiogram and the presence of a reversible thallium-201 perfusion defect were also significant predictors of subsequent cardiac events (p < 0.05 and p < 0.001, respectively). The results of the Holter recordings did not add significantly more prognostic information.(ABSTRACT TRUNCATED AT 250 WORDS)

We performed a prospective study to evaluate the prognostic significance and the natural history of late ventricular potentials (LPs) in 209 patients (165 males and 44 females; mean age 59.8 +/- 10 years) who survived acute myocardial infarction. Signal-averaged electrocardiograms (SA-ECGs) were performed before hospital discharge (16 +/- 5 days) and after four years (mean follow-up 42 +/- 7 months). SA-ECGs were processed using a 40 Hz high-pass bidirectional filter. Duration of "filtered" QRS (normal value < 120 msec), duration of the low-amplitude signals (n.v. < 39 msec) and last 40 msec voltage of the QRS complex (n.v. > 20 microV) were measured. LPs were defined as the presence of two or more abnormal values. In addition, 24-hour Holter monitoring was performed in all patients, and left ventricular ejection fraction (LVEF) was determined by scintigraphy in 120 (57.4%). Sixty patients (28.7%) had LPs before hospital discharge (group 1), and 149 (71.3%) had normal SA-ECGs (group 2). During the follow-up period there were 10 arrhythmic events, 7 of which were sudden deaths, and three cases of sustained ventricular tachycardia. SA-ECG was repeated in 141 patients (68%). The mean values of SA-ECG's parameters did not change significantly between the two controls, and the correlation was good for all of them. Despite this, spontaneous normalization of SA-ECGs occurred in 21 patients (60%) and the subsequent appearance of LPs was seen in 13 (12%); in these latter, the SA-ECG's parameters measured before hospital discharge were "borderline" and significantly different from those who did not change. The sensitivity of SA-ECG as a predictor of arrhythmic events was 80% and the specificity 74%. Patients with arrhythmic events had a longer filtered QRS (126 +/- 33 vs 103 +/- 12 msec; p < 0.001), longer duration of the low-amplitude signals (57 +/- 23 vs 32 +/- 11 msec; p < 0.001), lower voltages (17 +/- 8 vs 36 +/- 24 microV; p < 0.001), and, moreover, higher peak CK values, lower LVEF and higher value of Lown modified class. In conclusion, SA-ECG confirms its value in identifying patients at risk of arrhythmic events after myocardial infarction. SA-ECG recordings taken before the discharge can be used to predict serial changes during follow-up.

Aim of this study was to evaluate the blood pressure (BP) measurement reliability of a light weight ambulatory BP and ECG recorder. Micro AM is a new 300 g portable apparatus that combines in one device both the ambulatory BP and solid state ECG recording. The dimensions of the Micro AM are 75 x 140 x 29 mm. The monitor measures BP using Korotkoff phase 1 for systolic and phase 5 for diastolic BP, and concurrently measures oscillometric BP, one method validating the other. In addition, the manual and programmed BP measurement modes can be supplemented by an "intelligent" mode in which the ECG triggers an ambulatory BP reading during an abnormal ST segment change. A standard mercury manometer was connected with the cuff of the Micro AM with a Y-shaped part, and 12 BP measurements were simultaneously taken at 5 min intervals by the automatic device in auscultatory mode and by a trained technician in 86 normotensive volunteers (aged from 18 to 44 years, 37 males and 49 females). The algebraic differences, the frequency distribution and the difference distribution of systolic and diastolic data between the 2 methods were calculated. The results show that the automatic method gives values for systolic BP that are lower than conventional ones (average differences -0.643 mmHg), whereas for diastolic BP, the values are higher (average differences +0.229 mmHg). Then, Student's paired t-test was used to evaluate statistically significant differences. The test relative to systolic BP was significant to the critical level of 0.1%, but the differences being 3 times smaller than the instrumental tolerance. On the contrary, diastolic BP differences were non significant. In conclusion, we found a good agreement between BP recorded automatically and by sphygmomanometer.

Twenty-four-hour ambulatory electrocardiographic examination was performed in 130 elderly patients (49 healthy, active subjects; 40 hypertensive without left ventricular hypertrophy; and 41 hypertensive with left ventricular hypertrophy). In the study group, mean age was 72.4 +/- 7.1 (sixty-five to eighty-eight) years. A significantly high prevalence of ventricular ectopic complexes was found both in hypertensive and in normotensive groups. According to the Lown grades, in grade 1, VPCs had very high prevalence in healthy subjects, in grade 2, VPCs had a high prevalence in hypertensives with left ventricular hypertrophy (73.5% and 48.8%, respectively). The results of this study demonstrate that ventricular premature complexes were common in hypertensive patients and healthy elderly but did not cause high complexity in either group. Ventricular premature complexes detected by ambulatory ECG monitoring in healthy, active subjects and in untreated hypertensive patients are not an independent risk factor in elderly patients.

The prevalence of chronotropic incompetence in patients with sinus node disease (SND) is not well defined. To assess this, we evaluated 18 patients (7 men, 11 women; mean age: 64 +/- 11) with SND and permanent pacemakers (AAI/DDD) with Holter monitoring and treadmill stress test. Only 2 patients received active cardiac drugs (1, L-dopa an 1 propafenone). The treadmill tests results were compared with a control group of 15 men and 18 women (mean age: 66 +/- 5, p = NS) without organic heart disease. During ambulatory activity all pacemaker patients increased their own cardiac rate to a value higher than the programmed basic pacemaker rate. In 8 patients the maximal rate attained was over 100/min (mean 95 +/- 19/min). The maximal rate during treadmill test in pacemaker patients was 131 +/- 25 (control group 138 +/- 14, p = NS). Exercise tolerance in METs was similar in pacemaker patients (5.2 +/- 2.6) and in controls (5.8 +/- 1.2) (p = NS). Two pacemaker patients (12%) didn't reach 100/min during stress test. Most patients with SND and permanent pacemakers (AAI/DDD) are able to increase cardiac rate during exercise. Rate responsive pacing (AAIR/DDDR) should be limited to a minority of patients with true chronotropic incompetence.

The effect of three-week standardized physical training on exercise-induced ischaemia was investigated in patients with silent ischaemia after myocardial infarction. 24-hour monitoring and exercise ECGs before and after the period of physical training, were undertaken in 32 men (mean age 53.6 +/- 8.1 years) with angiographically proven coronary heart disease. The protocol of the standardized exercise included bicycle ergometry, gymnastics, breathing and movement exercises, as well as nonstandardized walking or hiking. Following the training period the number of ischaemic episodes fell from 90 to 72 for the group as a whole and that of the asymptomatic episodes from 79 to 64. The number and severity of ventricular arrhythmias were similar during silent and symptomatic ischaemia. There was a significant increase in duration of exercise until reaching the ischaemia threshold (mean exercise duration 4.7 +/- 2.1 vs 5.9 +/- 2.5 min; P = 0.0007). There was no increased risk concerning ventricular arrhythmias.

Spectral methods for the assessment of heart rate variability (HRV) in 24-h electrocardiograms (ECG) are believed to require visual verification and manual editing of the computerised recognition of the ECG. This study investigated the effect of the recognition errors of computerised ECG recognition on two methods providing spectral HRV indices: (a) Fast Fourier Transformation (FFT); and (b) peak-to-trough analysis (PTA). Both methods were used to measure HRV spectra in 24-h ECGs recorded in 557 survivors of acute myocardial infarction. Each ECG was analysed using the Marquette 8000 Holter system and spectral HRV analyses were performed both prior to and after manual verification of the automatic ECG analysis. The FFT and PTA methods were used to calculate the low (0.04-0.15 Hz), medium (0.15-0.40 Hz) and high (0.40-1.00 Hz) HRV spectral components. For each method and for each spectral component, the rank correlations between the results obtained from unedited and edited ECG recognition were calculated. The correlations between the corresponding spectral components provided by the FFT and PTA methods applied to the edited recognitions were also calculated. Both methods were substantially affected by recognition errors. The FFT method was more sensitive to the misrecognition than the PTA method. The inter-method correlations were higher for the high and medium spectral components than for the low spectral component. The study suggests that spectral HRV analysis should be performed only on carefully verified and manually corrected recognitions of long-term electrocardiograms.

Left ventricular dysfunction has been identified as the strongest independent predictor of sudden death in patients with ventricular tachyarrhythmias. It has been suggested that some of these arrhythmias might be due to myocardial stretch which may alter cellular electrophysiological properties. In heart failure (HF) the abnormal mechanics of contraction may directly initiate an arrhythmia by mechano-electric feedback (MEF), defined as changes in mechanical state that precede and alter transmembrane potential. So far, the significance of MEF and its role in clinical arrhythmogenesis have received minimal attention. We report data of 3 patients, aged from 60 to 64 years (mean age 62 +/- 2), affected by HF from 28.3 +/- 3.5 months and ventricular arrhythmias recorded by Holter: premature contractions, couplets, nonsustained ventricular tachycardia (VT). Sinus rhythm was present in 2 patients, atrial fibrillation in the last one. Many VT episodes started after an abrupt spontaneous increase in ventricular cycle length or following an ectopic beat. A permanent VVI pacemaker (MEDTRONIC Legend) was implanted in each patient and programmed at different rate from 50 to 80 b/min. During the upper rates, 70 and 80 b/min, VT episodes decreased from 292 +/- 181 to 161 +/- 95 and 97 +/- 63 (p < 0.05), respectively. In fact, the permanent pacemaker could prevent the lengthening of ventricular cycle and the myocardial fibers stretch due to the increase in ventricular volume. In conclusion, in patients with HF and ventricular arrhythmias a pacemaker may be useful in preventing VT episodes and, probably, sudden death.

A Holter monitorization study was performed in 100 voluntary university students (64 men and 36 women). The mean age was 23.6 years and organic heart disease was ruled out in all cases. Data were analysed in different subgroups including the practice of physical activity and subjects smokers or alcohol consumers. The maximum heart rate (HR) achieved during the wake period was 138.3 +/- 20.43 beat/m. Minimum daytime heart rate was 61.42 +/- 10.32 beat/m and it was below 60 beat/m in 41 subjects. During the nighttime period, the maximum heart rate achieved by the group was 89.34 +/- 11.31 beat/m. Minimum nighttime heart rate was 45.82 +/- 6.35 beat/m. Maximum heart rate in men was 134.3 +/- 21.35 beat/m, while in women was 145.42 +/- 16.36 beat/m. Eighty students presented one or more arrhythmias, among them 28 women and 52 men (p = NS): 92% in sportsmen and women groups as compared with 79% in the non sports practicers, 90% of alcohol consumers and 82% between subjects who smoked and drank, compared with 63% in the non drinkers (p < 0.006). 48% of the subjects presented one or more supraventricular arrhythmias during the daytime or during the nighttime (p = NS). Ventricular rhythm disturbances were found in 20 subjects. There was only one case who had a non sustained ventricular tachycardia of 4 complexes. These disturbances were not increased by practising sport nor by toxic habits. In 15 cases we found sinoatrial block, with a male predominance. Five subjects presented some type of atrioventricular block, 4 of which were alcohol and tobacco consumers.(ABSTRACT TRUNCATED AT 250 WORDS)

This study examines the relation between signal-averaged electrocardiographic measurements and the occurrence of spontaneous ventricular arrhythmias in 86 patients with a postoperative right bundle branch block after repair of tetralogy of Fallot; special attention was given to the influence of age, body surface area and right ventricular systolic pressure on signal-averaged electrocardiograms. Twenty-eight of the 86 patients had significant ventricular arrhythmias on 24-hour ambulatory monitoring. A positive linear correlation was found between filtered QRS duration and age at evaluation or body surface area (r = 0.45, p = 0.00001; r = 0.54, p < 0.00001, respectively) and between amplitude of the last 40 ms of the filtered QRS and right ventricular systolic pressure (r = 0.48, p < 0.001). A negative linear correlation was found between amplitude of the last 40 ms of the filtered QRS and age at evaluation or body surface area (r = -0.27, p = 0.01; r = -0.34, p = 0.002, respectively). When the age of the patients or the body surface area was considered with an analysis of covariance, the presence of ventricular arrhythmias was associated with a higher amplitude of the last 40 ms of the filtered QRS. In addition, an amplitude of the last 40 ms of the filtered QRS > 170 microV had an excellent sensitivity (100%) and a good specificity (88%) for identifying patients with both right ventricular systolic hypertension and spontaneous ventricular arrhythmia. Thus, adjustment of signal-averaged parameters for age at evaluation and body size is mandatory when studying postoperative tetralogy of Fallot.

The authors made a retrospective analysis of case histories of 201 patients who had died of fatal cardiac arrhythmias. The predictors of their death were ventricular fibrillation in 133 (66.2%) patients, asystole in 68 (32.8%), electromechanical dissociation in 2 (1%). Terminal sinus tachycardia, atrial fibrillation and flutter, the second-third degree atrioventricular block, the third-fifth grade ventricular extrasystole were the most common clinical and electrocardiographic prodromes of ventricular fibrillation. In the development of the latter, various mixed disturbances of cardiac rhythm and conduction in combination with prolonged Q-T interval were of more unfavorable value. Asystole was more frequently preceded by the second-third degree atrioventricular block, complete bundle branch block, third-fifth grade ventricular extrasystole, atrial fibrillation and flutter, and various mixed disturbances of cardiac rhythm and conduction. Cardiac arrhythmias and conduction disturbance with prolonged Q-T interval were found to be precursors of asystole in 84.8%.

The choice of treatment of patients with unstable angina is one of the most important problems in cardiology. Establishment of its tactics is necessary both in hospital and in posthospital periods. 24-hour Holter monitoring is a safe and informative method which makes it possible to objectivize the state in such category of patients. In order to study the structure of ischemia and arrhythmias this approach was used in 50 patients with unstable angina at the first admission twice and also twice within the first year of follow-up. It was shown that stabilization which was achieved during the first hospitalization was retained in 58.2% during 1 year. In other cases increases of frequency, duration and significance of ischemia were observed. In the global structure of myocardial ischemia, silent ischemia composed 56-65%.

24-hour Holter monitoring was performed in 129 unselected subjects older than 80 years (69 women and 60 men) in order to evaluate arrhythmia incidence and to establish significance of symptoms; 56% patients had lipothymia and/or syncope, chest pain and palpitations, 44% were asymptomatic. All patients showed high incidence of hyperkinetic and hypokinetic arrhythmias; no significant differences between symptomatic and asymptomatic patients in arrhythmia incidence were seen. Moreover, no correlation could be seen of the symptoms reported by the patient to the incidence of any particular type of arrhythmia. In conclusion, these preliminary data suggest a criticism of the opportunity of indiscriminate and long term antiarrhythmic therapy. Nevertheless, Holter monitoring is useful in detecting hypokinetic arrhythmias of asymptomatic patients in whom pacemaker implantation is essential and curative.

The significance of ST segment elevation during ambulatory monitoring after acute myocardial infarction was examined in 203 patients. Ambulatory monitoring was performed both early (mean 6.4 days [range 3 to 15]; N = 201) and late (38 days [range 22 to 93]; N = 177), and 174 patients underwent exercise treadmill testing (38 days [range 22 to 93]). Cardiac events (death, reinfarction, and coronary revascularization) were documented during a 1-year follow-up period. ST elevation (all silent) occurred in 25 of 201 patients (12%) on early monitoring but in only 4 of 177 (2%) on late monitoring (p < 0.001). Compared with patients (N = 148) without any ST deviation, those with early ST elevation had more pericarditis (8/25 [32%] vs 23/148 [16%]; p = 0.089) but no more angina or exercise ischemia. The mortality rate tended to be higher in patients with early ST elevation (4/25 [16%] vs 10/148 [7%]; p = 0.24), but ST elevation was too infrequent to be a valuable prognostic indicator. ST elevation is not uncommon during ambulatory monitoring early after myocardial infarction but is rare during later monitoring. Such ST elevation is almost always silent, does not usually reflect myocardial ischemia, and is not a useful prognostic indicator.

The frequency of recording late potentials and their dynamics were studied in 25 patients with coronary heart disease before, during, and after transluminal angioplasty (TAP). Baseline late potentials were observed in 6 (20.7%) cases. During TAP, late potentials were recorded significantly more frequently (48.3%) than the baseline ones (p < 0.03), in 6 (20.7%) patients, late potentials appeared only in arterial dilatation and disappeared after TAP. There was a profound decrease in root-mean-square amplitude of late 40 msec in the QRS complex and an increase in the duration of low-amplitude (less than 40 microV) signals at the end of the QRS complex as compared to the baseline values. In ST-segment elevation, the parameters of the ECG signal-average become deteriorated to a greater degree than those in ST-segment depression.

Objectives: We performed Holter monitoring on days 4 and 7 after acute myocardial infarction in 109 patients to assess whether ST segment shift would identify those with more severe coronary artery disease, left ventricular dysfunction and unfavorable prognosis., Background: Silent myocardial ischemia is a frequent and prognostically significant event after acute myocardial infarction. However, the specific pathophysiologic mechanisms and the impact of thrombolytic therapy are uncertain., Methods: In addition to Holter monitoring, patients underwent exercise testing, radionuclide angiography on days 1 and 9 and quantitative coronary angiography on day 9., Results: Thirty-five patients (32%) had ST segment depression and had similar recombinant tissue-type plasminogen activator (rt-PA) treatment assignment and a reduced cross-sectional area of the infarct-related artery (0.59 +/- 0.57 vs. 1.04 +/- 1.26 mm2, p < 0.05). Global left ventricular function improved from day 1 to day 9 in patients without (4% +/- 11%, p < 0.001) but not in those with (0% +/- 7%) ST segment depression. In-hospital event rates were similar; however, follow-up 18 +/- 11 months after hospital discharge revealed a greater frequency of death and recurrent myocardial infarction in patients with compared with those without ST segment depression (27% vs. 6%, p = 0.03)., Conclusions: After acute myocardial infarction, approximately one third of patients have ST segment depression on Holter monitoring, independent of the use of thrombolytic therapy. The unfavorable prognosis observed in these patients may be related to greater lumen obstruction in the infarct-related artery and lack of improvement in left ventricular function.

Objective: To determine the effect of ventricular ectopy on subsequent sinus R-R intervals., Design: Comparative, repeated-measures design., Setting: University medical center., Subjects: Ten consecutive sinus R-R intervals and their standard deviations before and after ventricular ectopy from 24-hour ambulatory electrocardiogram recordings were obtained from 25 patients with heart failure (left ventricular ejection fraction 0.18 +/- 0.08; New York Heart Association Functional Class III-IV) and three healthy subjects., Results: The effects of 7564 single ventricular ectopic beats, 272 ventricular couplets, and 49 episodes of ventricular tachycardia in the patients with heart failure and 1369 single ventricular ectopic beats in the three healthy subjects were evaluated. Repeated-measures ANOVA indicated no significant differences in sinus R-R intervals immediately before or after ventricular ectopy. Standard deviation of sinus R-R intervals before and after ventricular ectopy did not differ significantly., Conclusions: Ventricular ectopy does not significantly alter subsequent sinus R-R intervals and is unlikely to affect measurement of heart rate variability, particularly by techniques that use standard deviation methods.

In this study we addressed the problem of the noninvasive evaluation of the overall gain of baroreceptor control of heart period. We studied a population of healthy controls (n = 49, age 30 +/- 2 years, systolic arterial pressure [by Finapres] 114 +/- 1 mmHg) and a group of mild hypertensive subjects (n = 14, age 51 +/- 2 years, systolic arterial pressure 151 +/- 5 mmHg). Subjects were studied at rest both in absence and in presence of chronic beta-adrenergic receptor blockade (atenolol: controls 50 mg po oid x 4 days; hypertensives 100 mg po oid x 2 weeks). Spectral analysis of RR interval and of systolic arterial pressure variabilities provided noninvasive markers of autonomic control of the SA node and of the vasculature. The index alpha, obtained from bivariate cross spectral and spectral analysis provided a quantitative assessment of the closed loop gain of baroreceptor control of the heart period. The index alpha resulted more elevated in the normotensive than in the hypertensive group. Additionally it appeared significantly increased at the end of the treatment with the beta-adrenergic blocking drug atenolol. Furthermore, alpha appeared significantly and negatively correlated with age, systolic arterial pressure and, although weakly, with low frequency; it was positively correlated with the average RR interval. In conclusion, this study suggested an important link between the average level of sympathetic activity and baroreceptor control of heart rate in normotensive and mild hypertensive subjects. The clinical importance of this sympathetic modulation of the gain of the heart period/arterial pressure relationship can now be assessed with this noninvasive approach.

Background: The recent development of an ambulatory radionuclide detector (VEST) to assess left ventricular (LV) function may enhance the detection of ischemia during routine daily activities in patients with coronary artery disease (CAD). The aim of this study was to evaluate the usefulness of VEST in monitoring LV ejection fraction (EF) responses to daily activities and sustained handgrip test (HG) in patients with CAD., Methods: 13 patients (12 men and 1 woman) with angiographically proven coronary artery disease were studied by VEST (mean 162 min, range 120 to 250 min). LV responses to different daily activities (walking and climbing stairs) and to HG were evaluated., Results: Walking on a level surface and climbing stairs did not induce significant change in mean LVEF. However, a transient decrease in EF was observed in 4 (31%) and in 5 (38%) of the 13 patients during walking and climbing stairs, respectively. HG induced a significant (p < 0.01) reduction in mean EF. In particular, during HG, EF decreased > or = 5% in 11 (85%) of the 13 patients. A transient spontaneous decrease in LVEF lasting > or = 1 min was observed on 18 occasions in 11 patients with CAD; 5 episodes were symptomatic and 13 asymptomatic. ECG ST segment depression was recorded in 4 of the 5 symptomatic and in 5 of the 13 asymptomatic episodes., Conclusions: These results suggest that simultaneous monitoring of LV function and ECG may permit a better understanding of the incidence and severity of ischemic symptomatic and asymptomatic episodes.

The prognosis of patients with heart disease and prediction of sudden cardiac death can be assessed through heart rate variability, an indirect measure of abnormal autonomic control. The authors have evaluated the heart rate variability by 24-hour ambulatory electrocardiographic monitoring in 25 diabetic patients, 19 ischemic heart disease patients, 18 congestive heart failure patients, and 10 normal subjects. Thirteen diabetic patients had autonomic neuropathy and 12 patients did not. Heart rate variability index (mean SD) in patients with diabetes mellitus, ischemic heart disease, and congestive heart failure was significantly lower (34.5 +/- 12.6 ms, 43.7 +/- 15.4 ms, and 34.6 +/- 15.8 ms vs 65.6 +/- 16.7 ms, p less than 0.05) than that of normal subjects. Mean SD was significantly lower in patients with autonomic neuropathy as compared to patients without autonomic neuropathy (26.4 +/- 6.5 ms vs 44.2 +/- 11.0 ms, p less than 0.05) mean SD as compared to survivors: 49 +/- 7 ms in patients with mild ischemic heart disease, 48 +/- 15 ms in patients with severe ischemic heart disease, and 23 +/- 7 ms in patients who died. Similarly, the mean SD in 4 congestive heart failure patients who died was lower significantly (p less than 0.05) than in those who survived (19.0 +/- 5.6 ms vs 40.0 +/- 14.5 ms). Among congestive heart failure patients, clinical improvement by therapy was associated with a significant increase in mean SD. When the mean SD of 30 ms was used as the cutoff point for detection of autonomic dysfunction or patient death, specificity exceeded 90% and sensitivity was 75%.(ABSTRACT TRUNCATED AT 250 WORDS)

Real-time ambulatory monitoring analyzes each heart beat, counts events, and stores ECG samples for later visual verification. Typically, a physician examines these to determine whether the computer algorithm accurately identified arrhythmias. Physician editing is performed using best clinical judgement. We developed a simple statistical editing procedure for adjusting false positive and false negative computer detections. In 20 subjects having 24-hr monitoring we compared statistically edited ventricular premature beat (VPB) counts and pair/run counts with the unedited monitor counts and with physician assessment using a visual counted gold standard. The agreement of the statistically edited count with the visual standard was 65% for total VPB, 85% for VPB pair/runs, and 90% for a risk score based on ventricular ectopy. Corresponding agreements for unedited monitor count were 15, 25, and 30%, respectively. Physician assessment was not sufficiently precise to allow quantitative count estimates. This study indicates a statistical editing procedure substantially increases the level of agreement between the visual standard and the monitor count of VPB frequency and complexity. Statistically edited data are suitable for quantitative counts of VPB and other arrhythmic events in research and in medical diagnosis and treatment. This editing procedure can be a useful adjunct to any ambulatory monitoring system.

Heart rate variability and heart period variability are important indicators of the functioning of the autonomic nervous system and are strong predictors of survival after myocardial infarction. The standard deviation of a patient's series of normal heart periods (consecutive normal RR intervals) is positively and, in some populations, strongly correlated with the mean period length. This phenomenon has led some investigators to use the coefficient of variation as their measure of variability, because it correlates less strongly with the mean period length. Using data from a multicentre post-infarction natural history study, we show that the standard deviation of the instantaneous heart rates has, like the coefficient of variation, only a modest correlation with the mean period length. Unlike the coefficient of variation, however, this standard deviation is derivable from established statistical principles. We show further that the coefficient of variation, the standard deviation of heart rates, and the standard deviation of heart periods are approximately equally strong predictors of survival after myocardial infarction.

To assess the impact of patient age on the use of diagnostic testing in the management of acute myocardial infarction, the authors reviewed the hospital charts of 4,109 patients hospitalized for validated acute myocardial infarction in the Worcester, Massachusetts, metropolitan area during selected years between 1975 and 1986. Older patients were more likely to be female and to have a prior history of angina, hypertension, and diabetes mellitus (p less than 0.001). Acute myocardial infarctions among older patients were more likely to be recurrent, anterior in location, non-Q wave, smaller as reflected by peak creatine kinase levels, and complicated by congestive heart failure, cardiogenic shock, and atrial fibrillation (p less than 0.001). In-hospital mortality was directly related to increasing patient age (p less than 0.001). Patterns of utilization of the following diagnostic tests were examined: Holter monitoring, radionuclide ventriculography, echocardiography, exercise testing, pulmonary artery catheterization, and coronary arteriography. After adjustment for differences in demographic and clinical characteristics and in-hospital mortality, patients aged 65 years and older were significantly less likely to undergo exercise testing than were patients less than age 55. Patients older than age 75 were significantly less likely to undergo radionuclide ventriculography, pulmonary artery catheterization, and coronary arteriography than were younger patients. Sex-specific analyses did not produce results substantially different from those for the overall study population. The results of this community-wide study suggest that among patients hospitalized for acute myocardial infarction, chronologic age may be an independent determinant of utilization patterns of diagnostic testing. These findings suggest the need for a prospective evaluation of this issue, with an additional emphasis placed on the contributions of functional status and noncardiovascular illness to decision-making in the clinical management of acute myocardial infarction patients.

Only simple methods have been used to assess antiarrhythmic and proarrhythmic effects when comparing baseline and on-therapy Holter recordings taken from the same patient. The paper suggests a new method for definition of these effects based upon comparisons of statistical distributions of ectopic beats. The method is based on multiple random sampling of the recordings and on application of the Smirnov test to compare the samplings. The results of these multiple comparisons are subsequently evaluated using the chi-squared test. An analysis is reported of Holter recordings made on seven patients suffering from ventricular arrhythmia but with anatomically normal heart. In each patient, one baseline recording and one recording on each of three different drugs were made. The results show that the definition of proarrhythmic effects can be partly addressed in a precise mathematical way. The method can also detect a significant change in the character of arrhythmia which can neither be classified as antiarrhythmic nor as proarrhythmic.

Access to ambulatory electrocardiography would enable general practitioners to investigate certain patients with cardiac symptoms without the need for hospital referral. An analysis has been made of the results in 200 consecutive patients referred to a pilot open-access service based at three health centres. Twenty-two GPs used the service, although there was a wide range (1-48) in the number of patients each referred. In 72 patients aged under 50 years, abnormalities other than extrasystoles were detected in only six; major significant arrhythmias were found in three patients, although treatment was required in only one case. Arrhythmias were frequent in patients aged over 50 years but were usually minor; 16/128 (13 per cent) showed major significant arrhythmias. Pacemakers were implanted in two patients. Palpitation and/or dizziness were reported during the period of monitoring by 39 per cent of patients (and were equally common in both age groups), but in neither age group did these symptoms correlate with the occurrence of a significant arrhythmia. In primary care, palpitation and dizziness are rarely due to significant arrhythmias. To increase the cost-effectiveness of the service, ambulatory monitoring could be restricted to patients over 50 years of age, except when there is other evidence of heart disease.

The use of spectral techniques to quantify short term heart rate fluctuations on the order of seconds to minutes has helped define the autonomic contributions to beat-to-beat control of heart rate. We used similar techniques to quantify the entire spectrum (0.00003-1.0 Hz) of heart rate variability during 24 hour ambulatory ECG monitoring. The ECG from standard Holter monitor recordings from normal subjects was sampled with the use of a phase locked loop, and a heart rate time series was constructed at 3 Hz. Frequency analysis of the heart rate signal was performed after a nonlinear filtering algorithm was used to eliminate artifacts. A power spectrum of the entire 24 hour record revealed power that was inversely proportional to frequency, 1/f, over 4 decades from 0.00003 to 0.1 Hz (period approximately 10 hours to 10 seconds). Displaying consecutive spectra calculated at 5 minute intervals revealed marked variability in the peaks at all frequencies throughout the 24 hours, probably accounting for the lack of distinct peaks in the spectra of the entire records.