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PubMed2000

Effects of spinal manipulative therapy on autonomic activity and the cardiovascular system: a case study using the electrocardiogram and arterial tonometry.

OBJECTIVE: To determine if there is alteration in the autonomic nervous and cardiovascular systems after chiropractic manipulative therapy (CMT). A novel approach was used to quantitatively probe for changes in the activity of the autonomic nervous system, in blood pressure, and in pressure pulse transmission time. This approach uses the electrocardiogram and arterial tonometry equipment. DESIGN: This case study involves 1 subject treated over a 6-week period (2 visits/week). Respiration, electrocardiogram, and left and right radial artery blood pressures were measured during the baseline (2 visits) and treatment (10 visits) phases. Measurements were obtained before (n = 3) and after (n = 3) a break period (baseline) or before and after CMT. High-velocity, low-amplitude CMT that produced joint cavitation was used. SETTING: The study was performed at the Parker College Research Institute in a temperature-controlled laboratory. MAIN OUTCOME MEASURES: Fourier analysis was performed on the electrocardiogram-determined rest-redistribution intervals. The low frequency power between 0.04 to 0.15 Hz and the high frequency power between 0.15 to 0.40 Hz represent the activity of the sympathetic and parasympathetic nervous systems, respectively. The main outcome measure was the sympathovagal index, which is determined from the ratio of low frequency to high frequency. The arterial pressure and the time for pressure pulses to travel from the heart to the radial artery recording sites (pressure pulse transmission time) were studied. Differences (average of 3 measurements after treatment minus measurements before treatment) for each variable were calculated. RESULTS: After the 1st CMT treatment, the difference between treatment and baseline decreased for both the low frequency/high frequency (-2.804 +/- 1.273) and low frequency power (-0.135 +/- 0.056). These findings indicated that the parasympathetic nervous system predominated the sympathetic nervous system. After the 3rd, 4th, 6th, and 9th treatment, the difference between treatment and baseline increased for low frequency/high frequency (0.908 +/- 0.338, 2.313 +/- 0.300, 2.776 +/- 1.102, and 0. 988 +/- 0.269, respectively) and indicated that the sympathetic nervous system predominated the parasympathetic nervous system. In addition, the difference between treatment and baseline for the pressure pulse transmission time decreased bilaterally after the 4th treatment (left, -13.52 +/- 3.70 ms; right, -9.75 +/- 3.76 ms) and 6th treatment (left, -9.53 +/- 3.60 ms; right, -9.24 +/- 3.50 ms), which indicated that arterial compliance had decreased. Furthermore, after the 6th treatment, the difference between treatment and baseline for the rest-redistribution interval time decreased (-0.084 +/- 0.014 s). The difference between treatment and baseline for the systolic, diastolic, and mean arterial pressure for the above-mentioned treatments was not considered significant. CONCLUSION: This case study is the first to attempt to use electrocardiogram and arterial tonometry data to study the effects of CMT on the autonomic nervous and cardiovascular systems over an extended period of time. These devices allowed a more in-depth study of the cardiovascular and autonomic changes associated with CMT. Although changes in the autonomic nervous and cardiovascular systems can be detected, further development of a reliable and reproducible experimental protocol is required before validating the effects of CMT on these systems.

Adult↗

PubMed2003

Short-term inhalation of particulate transition metals has little effect on the electrocardiograms of dogs having preexisting cardiac abnormalities.

There is growing epidemiological evidence for statistical associations between increases in air pollution, especially particulate matter, and increases in cardiovascular morbidity and mortality. Laboratory studies have shown that transition metals contribute strongly to the effects of high lung doses of model particles on changes in the electrocardiograms of animals. The present study evaluated the effects of short-term inhalation exposure to respirable particles of specific oxide and sulfate forms of transition metals on heart rate and the electrocardiogram of old dogs having preexisting cardiac abnormalities. Conscious beagle dogs were exposed by oral inhalation for 3 h on each of 3 successive days to aerosols of manganese, nickel, vanadium, iron, and copper oxides, and nickel and vanadium sulfates as single compounds at concentrations of 0.05 mg/m(3). Electrocardiograms were recorded and evaluated for exposure-related changes in heart rate, heart rate variability, and abnormalities of waveforms. Although the electrocardiograms of this population of dogs having potential age and cardiovascular susceptibility factors reflected their underlying clinical abnormalities, no significant effect of exposure to the transition metal aerosols was observed.

Administration, Inhalation↗

PubMed1990

Effects of tilt and exercise on signal-averaged electrocardiogram after acute myocardial infarction.

To determine whether enhanced sympathetic activity could alter a non-invasive index of cardiac instability, we analysed the effects of 90 degrees head-up tilt and submaximal exercise stress test on high amplification signal-averaged electrocardiogram in 64 patients after acute myocardial infarction. At rest, ventricular late potentials were detected in 25% of patients, characterized by a significant prolongation of filtered QRS complex (137 +/- 3 vs 115 +/- 2 ms) and of its components smaller than 40 microV (38 +/- 2 vs 16 +/- 1 ms), as well as by a reduced root mean square voltage calculated for the terminal 40 ms of QRS complex (RMS40 voltage) (19 +/- 1 vs 75 +/- 9 microV) in comparison to patients without micropotentials. Sympathetic activation induced by tilt caused a significant increase in heart rate (from 67 +/- 3 to 79 +/- 3 beats min-1) but did not modify either the incidence of ventricular late potentials or the values of any of the signal-averaged electrocardiogram parameters considered. In 19 patients, recordings were also obtained during a submaximal bicycle exercise stress test at a heart rate of 114 +/- 4 beats min-1 and with systolic arterial blood pressure at 153 +/- 6 mmHg. No effect on signal-averaged electrocardiogram parameters was detectable during this experimental intervention. These data indicate that after myocardial infarction, sympathetic activation does not seem to modify signal-averaged electrocardiogram parameters.

Electrocardiography↗

PubMed1994

Microalbumin excretion in patients with positive exercise electrocardiogram tests.

Thirty-three subjects underwent exercise electrocardiogram testing, 20 had a history of myocardial infarction and 13 were age-matched volunteers. Exercise electrocardiograms were positive in 15 subjects, negative in 12 and anomalous in six. Urinary microalbumin excretion was measured at rest, 30 and 60 min after exercise. Urinary microalbumin excretion was expressed as the albumin-creatinine ratio in mg.mmol-1. In the positive exercise electrocardiogram group median albumin-creatinine ratio increased from 1.0 mg.mmol-1 (95% CI 0.94-1.49) at rest to 2.0 mg.mmol-1 (95% CI 1.51-3.94) 30 min after exercise, whilst in the negative electrocardiogram group median resting and 30 min post exercise albumin-creatinine ratio values of 0.85 (95% CI 0.53-1.32) and 1.80 (95% CI 0.63-2.32) mg.mmol-1 respectively were not significantly different. These results suggest that exercise-induced myocardial ischaemia is associated with increased urinary microalbumin excretion.

Albuminuria↗

PubMed2005

An electrocardiogram-based technique to assess cardiopulmonary coupling during sleep.

STUDY OBJECTIVES: To evaluate a new automated measure of cardiopulmonary coupling during sleep using a single-lead electrocardiographic signal. DESIGN: Using training and test datasets of 35 polysomnograms each, we assessed the correlations of an electrocardiogram-based measure of cardiopulmonary interactions with respect to standard sleep staging, as well as to the cyclic alternating pattern classification. The pattern of coupling in 15 healthy individuals was also assessed. SETTING: American Academy of Sleep Medicine Accredited Sleep Disorders Center. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: From a continuous, single-lead electrocardiogram, we extracted both the normal-to-normal sinus interbeat interval series and a corresponding electrocardiogram-derived respiration signal. Employing Fourier-based techniques, the product of the coherence and cross-power of these 2 simultaneous signals was used to generate a spectrographic representation of cardiopulmonary coupling dynamics during sleep. This technique shows that non-rapid eye movement sleep in adults demonstrates spontaneous abrupt transitions between high- and low-frequency cardiopulmonary coupling regimes, which have characteristic electroencephalogram, respiratory, and heart-rate variability signatures in both health and disease. Using the kappa statistic, agreement with standard sleep staging was poor (training set 62.7%, test set 43.9%) but higher with cyclic alternating pattern scoring (training set 74%, test set 77.3%). CONCLUSIONS: A sleep spectrogram derived from information in a single-lead electrocardiogram can be used to dynamically track cardiopulmonary interactions. The 2 distinct (bimodal) regimes demonstrate a closer relationship with visual cyclic alternating pattern and non-cyclic alternating pattern states than with standard sleep stages. This technique may provide a complementary approach to the conventional characterization of graded non-rapid eye movement sleep stages.

Electroencephalography↗

PubMed1991

Inability of the signal-averaged electrocardiogram to determine risk of arrhythmia recurrence in patients with implantable cardioverter defibrillators.

Signal-averaged electrocardiography has been used to identify patients at risk for arrhythmic death after myocardial infarction. Since patients with implantable cardioverter defibrillators (ICDs) are at high risk for arrhythmic events, they should also be expected to have a high incidence of abnormal signal-averaged electrocardiograms (SAECGs). However, whether the SAECG can discriminate patients who will have arrhythmia recurrence and receive appropriate ICD shocks from those who will have no recurrence and no shocks is unknown. This study examines the usefulness of the SAECG to separate appropriate users from non-users of the ICD. Fifty patients with ICDs participated in this study. Those who received a shock preceded by symptoms, a shock without preceding symptoms but with electrocardiographic documentation of ventricular fibrillation or ventricular tachycardia, or a shock while asleep were classified as ICD users. All other patients were classified as nonusers. The SAECG was classified as normal if the QRS duration on the standard electrocardiogram was less than or equal to 110 msec and if the total filtered QRS duration was less than 120 msec, the root-mean square voltage of the terminal 40 msec was greater than 25 muV, and the terminal low amplitude signal duration measured less than 38 msec. The SAECG was classified as abnormal if the QRS duration on the standard electrocardiogram was less than or equal to 110 msec and any one of these three criteria were outside the "normal range." The SAECG was classified as indeterminate if the QRS duration on the standard 12-lead electrocardiogram was greater than 110 msec. For the entire group of 50 patients, 8 (16%), 12 (24%), and 30 (60%) had normal, abnormal, and indeterminate SAECGs, respectively. Of the 22 ICD users, 1 (5%), 5 (23%), and 16 (73%) patients had normal, abnormal, and indeterminate SAECGs, respectively. Of the 28 ICD nonusers, 7 (25%), 7 (25%), and 14 (50%) patients had normal, abnormal, and indeterminate SAECGs, respectively. ICD users had lower left ventricular ejection fractions (P = 0.0002), a higher incidence of ventricular tachycardia (P = 0.04), prior exposure to a greater number of antiarrhythmic drugs (P = 0.04), and a lower likelihood for survival (P = 0.02) compared to the ICD nonusers. There was no statistically significant difference between the ICD users and nonusers as stratified by SAECG classification regardless of whether or not the interminate studies were included or excluded from the analysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Arrhythmias, Cardiac↗

PubMed1979

Thallium-201 myocardial imaging in evaluation of asymptomatic individuals with ischaemic ST segment depression on exercise electrocardiogram.

Asymptomatic adults with normal physical examination, normal resting electrocardiogram, and normal routine laboratory evaluation who have a positive exercise electrocardiogram and abnormal exercise thallium-201 myocardial image have a very high probability of angiographically significant coronary artery disease. If, on the other hand, the exercise electrocardiogram is positive for "ischaemic" ST segment changes, but the exercise thallium image is normal, the probability for coronary disease is low. The exercise electrocardiogram combined with thallium-201 myocardial image are safe non-invasive methods which can be performed on an out-patient basis.

Adult↗

PubMed1994

New sex dependent normal limits of the signal averaged electrocardiogram.

BACKGROUND: An earlier study of 1555 normal 12 lead electrocardiograms has shown that the mean QRS duration in men is 8 ms longer than in women. OBJECTIVE: To establish the sex related normal limits of the signal averaged electrocardiogram. PEOPLE: 195 people (160 men and 35 women aged 40 to 69) with normal clinical history, physical examination, 12 lead electrocardiogram, and echocardiogram were recruited for this study. METHODS: Signal averaged electrocardiograms were recorded by the Arrhythmia Research Technology 1200 EPX machine and analysed twice with bidirectional Butterworth filters with frequency ranges of 25-250 Hz and 40-250 Hz. Three time domain parameters of the QRS vector magnitude, namely filtered total QRS duration, duration of low amplitude signals under 40 microV (LAS40), and root mean square voltage of the last 40 ms (RMS40), were evaluated. RESULTS: There were significant differences between the two sexes in QRS duration (mean (95% confidence interval (95% CI) (8.0 (3.1 to 13.0) ms, t = 3.29, degrees of freedom = 41, p = 0.0021 with the 25-250Hz filter; mean (95% CI) 10.2 (6.9 to 13.5) ms, t = 6.26, degrees of freedom = 53, p < 0.0001 with the 40-250Hz filter)) and in body surface area (mean (95% CI) 0.26 (0.21 to 0.31) m2, t = 10.63, degrees of freedom = 57). There was no significant correlation between age and QRS duration, LAS40, or RMS40, but there was a highly significant correlation between body surface area and QRS duration (correlation coefficient = 0.396, p < 0.0005) and RMS40 (correlation coefficient = -0.159, p < 0.025). Current sex independent criteria defining ventricular late potentials as the presence of any two of QRS duration > 114 ms, LAS40 > 38 ms, RMS40 < 20 microV, give a specificity of 85% for men and 91% for women in this normal population. RECOMMENDATIONS: Ventricular late potentials should be regarded as present when (a) QRS duration exceeds 114 ms in men or 104 ms in women and (b) either LAS40 > 38 ms or RMS40 < 20 microV. This gives a specificity of 97% in men and 100% in women in the population studied.

Adult↗

PubMed1998

A normal electrocardiogram precludes the need for left ventriculography in the assessment of coronary artery disease.

OBJECTIVE: To assess whether a normal electrocardiogram can identify good left ventricular function and obviate the need for routine left ventriculography in patients undergoing cardiac catheterization for suspected coronary artery disease. DESIGN: A prospective study of patients undergoing cardiac catheterisation. SETTING: A regional cardiac centre. PATIENTS: The electrocardiograms, coronary angiograms, and left ventriculograms of 391 consecutive patients undergoing investigations for suspected coronary artery disease were entered into the study. Patients with arrhythmias and cardiac pathologies other than coronary artery disease were excluded. MAIN OUTCOME MEASURES: The electrocardiogram was assessed using a 29 point QRS scoring system, and classified by two cardiologists and a trainee cardiologist as normal or abnormal. Left ventricular function was assessed by digital ventriculography. RESULTS: The sensitivity, specificity, and negative predictive value of a QRS score of 0 (normal QRS complexes) for discriminating good left ventricular function (ejection fraction > or = 50%) were 92.6%, 41.5%, and 97.2%, respectively. The figures for a normal electrocardiogram as assessed by a doctor were 96.3%, 40.4%, and 98.6% for cardiologist A; 96.3%, 37.4%, and 98.4% for cardiologist B; and 94.4%, 49.6%, and 98.2% for the cardiology trainee. CONCLUSIONS: If a cardiologist judges the ECG to be normal, left ventriculography is unnecessary and a formal QRS score does not improve reliability of this clinical judgment. Adopting this strategy would save 30-40,000 Pounds in consumables and 65-87 hours of catheter laboratory and staff time for a department catheterising 3000 patients with suspected coronary artery disease annually.

Adult↗

PubMed1991

How reliable is the electrocardiogram in detecting left ventricular hypertrophy in hypertension?

This paper assesses the sensitivity and specificity of the electrocardiogram in detecting left ventricular hypertrophy in 75 hypertensive patients. Each patient underwent a 12 lead electrocardiogram and echocardiogram. Left ventricular mass index, using echocardiogram, was calculated according to the Penn convention and left ventricular hypertrophy was assessed by standard electrocardiographic criteria. The electrocardiogram was found to be very specific but insensitive in the detection of left ventricular hypertrophy as compared with the echocardiogram. Other non-voltage dependent markers appeared to have similar reliability. We conclude that the electrocardiogram may be unreliable in the detection of left ventricular hypertrophy in hypertensive patients. Accurate assessment of left ventricular hypertrophy, in these patients should be by echocardiography.

Adult↗

PubMed1991

Predictive value of a negative exercise electrocardiogram.

Conventionally, if an exercise electrocardiogram does not show evidence of ischemia, the patient must have achieved at least 85% of the predicted maximum heart rate for that test to be considered negative. However, no documentation of the validity of this practice exists. Thus, we evaluated the exercise electrocardiograms of 164 patients who had also undergone coronary angiography within 6 months of the exercise test. The predictive value of a negative exercise electrocardiogram was determined for each percentage point between 50 and 90% of the age-predicted maximum heart rate achieved or exceeded. The predictive value was found to increase modestly between 65 and 80% of the predicted maximum heart rate with no major changes above or below this range. Thus, it appears reasonable (in the setting of a hospital-based exercise laboratory) to either consider a negative exercise electrocardiogram as a valid finding if at least 80% of the predicted maximum heart rate is achieved, or preferably to simply report the negative finding with the percent maximum heart rate attained and the proviso that the predictive value of the test is progressively improved as higher heart rates are attained.

Adult↗

PubMed1977

Serial electrocardiograms in hypertensive cardiovascular disease.

A graphic method for depicting serial changes in electrocardiograms is described and demonstrated for patients being treated in an antihypertension clinic. For these patients, the diagnostic categories, normal, left ventricular hypertrophy, and biventricular hypertrophy, are of primary interest. For each electrocardiogram, 14 measurements are used to compute posterior probabilities for each of the three categories. A triangular grid is used to plot each set of probabilities for an electrocardiogram as one point, which by its position in the triangle can be related to the three categories simultaneously. Points representing successive electrocardiograms can be plotted in the same triangle, giving a pattern of change with time. This pattern of change has been corroborated with associated clinical information on a number of patients. This display, which can be produced quickly and efficiently on a computer graphics terminal, should be considered as a possible tool in evaluating the status of individual hypertensive patients in terms of increase or decrease of ventricular hypertrophy and the efficacy of therapeutic measures.

Aged↗

PubMed1985

Abnormal signal-averaged electrocardiograms in patients with nonischemic congestive cardiomyopathy: relationship to sustained ventricular tachyarrhythmias.

We assessed whether signal-averaged electrocardiography could identify patients with sustained ventricular arrhythmias in 41 patients with non-ischemic cardiomyopathy. Twelve of these patients presented with sustained ventricular arrhythmia and 29 patients had no history of sustained ventricular arrhythmias. The mean ejection fractions in the groups were 30 +/- 9% and 24 +/- 9%, respectively. Results were compared with signal-averaged electrocardiograms in 55 normal individuals. The filtered QRS duration was longest in patients with sustained ventricular arrhythmias (130.2 +/- 19.5 vs 105.0 +/- 13.1 msec in the group without sustained ventricular arrhythmia, p less than .001 and 95.9 +/- 9.1 in the normal group, p less than .001). The voltage in the last 40 msec of the filtered QRS was lower in the sustained ventricular arrhythmia group (11.3 +/- 9.3 microV) than the group without sustained ventricular arrhythmia (53.5 +/- 28.3 microV; p less than .001) or the normal group (53.7 +/- 25.2 microV; p less than .001). Eighty-three percent of patients in the sustained ventricular arrhythmia group had an abnormal signal-averaged electrocardiogram characterized by both a long filtered QRS duration and a late potential of low voltage level; only 2% of normal subjects and 14% of patients without sustained ventricular arrhythmias had an abnormal signal-averaged electrocardiogram. The signal-averaged electrocardiogram can identify patients with nonischemic congestive cardiomyopathy and sustained ventricular arrhythmias.

Adult↗

PubMed1987

Detection and localization of coronary artery disease with body surface mapping in patients with normal electrocardiograms.

Patients with clinically significant coronary artery disease often have normal resting electrocardiograms. Clinical and experimental studies have shown that body surface potential maps provide improved recognition of some disease states and more regionally selective information than standard electrocardiograms. Body surface maps were recorded at rest from 41 symptomatic patients with angiographically documented coronary artery disease and normal electrocardiograms. Patient maps were statistically compared with maps recorded from 644 normal subjects with the use of previously reported data representation technique. By this technique, maps from patients with symptomatic coronary artery disease and normal electrocardiograms were separated from maps of normal subjects with a sensitivity and specificity greater than 94%. The majority of discriminating information was present in the QRS interval. Fifteen of the 41 symptomatic patients had documented single-vessel coronary disease and their maps were separately compared with normal maps. Average maps from each of three patient groups with single-vessel disease contained abnormal patterns during the QRS interval that were unique to the vessel affected. In comparison with a average map from normal subjects, the average map from the group with left anterior descending coronary disease showed lower potentials over the anterior and inferolateral thorax during the early to mid QRS interval, the average map from the circumflex disease group showed decreased potentials around the entire inferior thorax in the mid to late QRS interval, and the average map from the right coronary disease group showed decreased potentials over the right anterior thorax during the mid to late QRS interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

A markup language for electrocardiogram data acquisition and analysis (ecgML).

BACKGROUND: The storage and distribution of electrocardiogram data is based on different formats. There is a need to promote the development of standards for their exchange and analysis. Such models should be platform-/ system- and application-independent, flexible and open to every member of the scientific community. METHODS: A minimum set of information for the representation and storage of electrocardiogram signals has been synthesised from existing recommendations. This specification is encoded into an XML-vocabulary. The model may aid in a flexible exchange and analysis of electrocardiogram information. RESULTS: Based on advantages of XML technologies, ecgML has the ability to present a system-, application- and format-independent solution for representation and exchange of electrocardiogram data. The distinction between the proposal developed by the U.S Food and Drug Administration and ecgML model is given. A series of tools, which aim to facilitate ecgML-based applications, are presented. CONCLUSIONS: The models proposed here can facilitate the generation of a data format, which opens ways for better and clearer interpretation by both humans and machines. Its structured and transparent organisation will allow researchers to expand and test its capabilities in different application domains. The specification and programs for this protocol are publicly available.

Decision Support Techniques↗

PubMed1993

Functional limitation of recruitable collaterals in human subjects--ST segment deviation on intracoronary electrocardiogram during transient coronary occlusion induced by balloon inflation.

Three patients showed ST elevation on precordial electrocardiogram and ST depression on intracoronary electrocardiogram during angioplasty of the left anterior descending coronary arteries (LAD). While none of the patients had spontaneously visible collaterals, all showed transient recruitable collaterals to the LAD. No evident collaterals into the diagonal branches were observed. Possibly, if the intracoronary electrocardiogram represents the potential changes of the epicardial surface in the vicinity of the guidewire tip, then endocardial ischemia may have developed even though epicardial ischemia was not observed, due to relatively sufficient blood flow through the recruitable collaterals to the LAD. ST elevation on the precordial electrocardiogram may have represented epicardial and endocardial ischemia of the diagonal branches, where the recruitable collaterals could not protect against transmural ischemia. These phenomena suggests that the recruitable collaterals are functionally limited during acute coronary occlusion, even though the collaterals are well developed.

Aged↗

PubMed2006

Time domain analysis of the signal averaged electrocardiogram to detect late potentials in heart failure patients with different etiologies.

OBJECTIVE: To evaluate the frequency, clinical correlations and prognosis influence of late potentials on the of heart failure patients with different etiologies using the signal averaged electrocardiogram. METHODS: A 42 month study of the signal averaged electrocardiograms of 288 heart failure patients with different etiologies was conducted. The group of patients included 215 males (74.65%) and 73 females (25.35%) between the ages of 16 and 70 (mean 51.5, standard deviation 11.24). The heart failure etiologies were: hypertensive heart disease (78 patients, 27.1%); idiopathic dilated cardiomyopathy (73 patients, 25.4%); ischemic cardiomyopathy (65 patients, 22.6%); Chagas disease (42 patients, 14.6%); alcoholic cardiomyopathy (9 patients, 3.1%); peripartum cardiomyopathy (6 patients, 2.1%); valvular heart disease (2 patients, 4.2%) and viral myocarditis (3 patients, 1.04%). The variables included the duration of the standard QRS complex, duration of the filtered QRS complex, duration of the signal below 40 microV and the root mean square of the last 40 ms which were analyzed in regard to age, gender, etiology and mortality as well as the findings of the 12-lead electrocardiogram at rest, echocardiogram and ambulatory electrocardiogram. The statistical analysis tests used were: the Fisher exact probability test, Students t-test, Mann Whitney test, variance analysis, Log-Hank and the Kaplan-Meyer method. RESULTS: Late potentials were diagnosed in 90 patients (31.3%) and there was no association with the etiologies. The presence of this condition is associated with: a lower maximum oxygen uptake during the ergospirometry (p=0.001); sustained and non-sustained ventricular tachycardia during Holter monitoring (p=0.001), sudden death and mortality (p<0.05). Patients that did not present late potentials had a higher overlife rate. CONCLUSION: The presence of late potentials was not associated with the etiologies and proved to be an indication of a worse prognosis.

Adolescent↗

PubMed2003

[A comparison of three electrocardiogram coding systems for chronic Chagas' disease].

OBJECTIVE: To compare three electrocardiogram coding systems (Buenos Aires, New York Heart Association, and modified Minnesota) for use with Chagas' disease. METHODS: Between January 1976 and December 1978 persons older than 2 years of age living in the town of Agua Comprida, Minas Gerais, Brazil, underwent a patient history, physical examination, conventional electrocardiography, and serology for Chagas' disease. Those records were archived, and in 1999 from this sample, 100 seropositive individuals were matched by sex and age with 100 seronegative controls. The electrocardiograms of these 200 patients were read using the three coding systems. Each system was assessed in terms of its gradient, that is, the difference between the number of abnormalities found in the electrocardiograms of individuals with and without Chagas' disease. RESULTS: The gradient was 7% for the New York Heart Association coding system, 15% for the modified Minnesota system, and 17% for the Buenos Aires one. The ability of the Buenos Aires method to detect electrocardiographic abnormalities was significantly greater in the group with Chagas' disease than in controls (P = 0.012), followed by the modified Minnesota system (P = 0.028) and the New York Heart Association system (P = 0.31). The Buenos Aires method was also easier to use, in terms of both the analysis of electrocardiograms and queries to a database. CONCLUSIONS: Although the Buenos Aires method had advantages over the two other systems, some changes are still needed in it to make it more useful. It would be worth carrying out further studies to evaluate this method with the changes that we have suggested in this study.

Adolescent↗