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PubMed2003

Quantitative improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

Abnormal signal-averaged electrocardiography (SAECG) reflects slow and heterogeneous myocardial conduction, predicting ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease. The purpose of this study was to investigate the quantitative effect of coronary artery bypass grafting (CABG) on SAECG, which is still controversial, and to identify the factors that are related to it. Pre- and postoperative SAECGs were recorded in 100 patients who underwent CABG. Compared parameters included filtered QRS duration (dQRS), root mean square voltage in the terminal 40 ms of the QRS complex (RMS40), and duration of the terminal low-amplitude signal less than 40 microV (LAS40). All 3 parameters in SAECG improved significantly after CABG (dQRS: 105+/-21 ms-->99+/-18 ms, RMS40: 55+/-45 microV-->65+/-41 microV, LAS40: 29+/-19 ms-->25+/-12 ms). The improvements in SAECG were greater in patients who underwent complete revascularization and in those without prior myocardial infarction. In conclusion, CABG improved SAECG quantitatively, even in patients with normal SAECG. However, this improving effect was variable and closely related to the presence of prior myocardial infarction and the completeness of revascularization.

Aged↗

PubMed2004

Clinical significance of electrocardiography recordings from a higher intercostal space for detection of the brugada sign.

BACKGROUND: The significance of higher intercostal space electrocardiography (HICS ECG) for the detection of the Brugada sign was investigated. METHODS AND RESULTS: The subjects consisted of 113 cases (108 males, 5 females; mean age, 57+/-17 years) with incomplete right bundle branch block type QRS morphology and ST-segment elevation (>0.10 mV) in the right precordial leads. Obvious structural heart disease was not observed in any of the subjects. The V(1-3) leads of the standard 12-lead ECG and the HICS ECG were recorded in the supine position, and the amplitude of the terminal portion of the QRS (J-point) and ST-segment (80 ms from the J-point) were measured. In the HICS ECG, there was an increase in the area in which the Brugada sign was detectable (47 leads to 66 leads), and in cases with the Brugada sign, the amplitude of the J-point increased. CONCLUSIONS: The HICS ECG may be helpful for the detection of the Brugada sign.

Adult↗

PubMed2004

Impact of diabetes mellitus on the improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

BACKGROUND: Although it has been reported that coronary artery bypass grafting (CABG) for multivessel disease markedly improves several parameters of signal-averaged electrocardiography (SAECG), its beneficial effect on SAECG is variable. The hypothesis of the present study was that the presence of diabetes mellitus (DM) affects the improvement in SAECG after CABG. METHODS AND RESULTS: Pre- and post-operative SAECGs were recorded in 100 consecutive patients who underwent complete surgical revascularization. Changes in the following parameters were compared between the diabetic (n=43) and non-diabetic (n=57) patients: filtered QRS duration (dQRS), root mean square voltage in the terminal 40 s of the QRS complex (RMS40), and duration of the terminal low-amplitude signal lower than 40 microV (LAS40). Although baseline characteristics and the occurrence of late potentials were similar in both groups, quantitative improvements in the SAECG parameters after CABG were significantly greater in non-diabetic than in diabetic patients (dQRS: 109 +/- 22 ms vs 102 +/- 19 ms in diabetics and 106 +/- 21 ms vs 88 +/- 11 ms in non-diabetics; p=0.028, RMS40: 55 +/- 46 microV vs 65 +/- 38 microV in diabetics and 50 +/- 37 microV vs 76 +/- 37 microV in non-diabetics; p=0.037, LAS40: 31 +/- 20 ms vs 26 +/- 17 ms in diabetics and 32 +/- 12 ms vs 17 +/- 8 ms in non-diabetics; p=0.007, respectively). CONCLUSIONS: The presence of DM limits the CABG-induced improvement in SAECG. In diabetic patients, therefore, perioperative changes of the SAECG must be interpreted with caution.

Aged↗

PubMed2005

Portable type signal-averaged electrocardiography with dipyridamole: a new and convenient method to detect patients with coronary artery disease and ischemia.

BACKGROUND: Whether or not patients with coronary artery disease (CAD) could be easily detected at the bedside using dipyridamole stress was investigated using a portable type signal-averaged electrocardiography (portable SAECG). METHODS AND RESULTS: The standard 12-lead QRS wave SAECG was performed at the bedside before and after dipyridamole stress in 30 patients with angiographically significant stenotic lesions, who had positive myocardial ischemia in the dipyridamole-thallium myocardial perfusion imaging (CAD group), and 33 patients with no significant stenotic lesions, who had negative imaging (control group). The filtered QRS duration (fQRSd) before and after dipyridamole stress was determined by the vector magnitude method and the difference (DeltafQRSd) was obtained. Furthermore, the DeltafQRSd was obtained using the multiphasic oscillation method, as well at the same standard 12-lead, and the maximal value of changes in fQRSd (MAX DeltafQRSd) between the 12 leads was determined. The DeltafQRSd was similar between 2 groups (p = 0.11). The MAX DeltafQRSd associated was significantly greater in the CAD group (p < 0.0001). When a cut-off value of MAX DeltafQRSd > or = 5 ms was used for the detection of CAD, the sensitivity and specificity were 97 and 94%, respectively. CONCLUSION: The portable dipyridamole-stress SAECG easily detect CAD and myocardial ischemia at the bedside.

Aged↗

PubMed2006

Portable-type signal-averaged electrocardiography with dipyridamole to detect patients with coronary artery disease.

BACKGROUND: In a retrospective study portable-type signal-averaged electrocardiography (SAECG) with dipyridamole stress was found to identify patients with coronary artery disease (CAD) at their bedside with high sensitivity and specificity, so the utility of this method was prospectively investigated in the present study. METHODS AND RESULTS: Standard 12-lead QRS wave SAECG was performed before and after dipyridamole stress at the bedside in 71 patients with chest pain (43 males, mean age 63 +/-9 years). The filtered QRS duration (fQRSd) before and after dipyridamole stress was determined by multiphasic oscillation method for each of the standard 12 leads, and the maximal value of changes in fQRSd (MAX DeltafQRSd) among the 12 leads was determined. The positive test was defined as MAX DeltafQRSd >or=5 ms, and negative as MAX DeltafQRSd <5 ms based on the previous study. Selective coronary arteriography was performed next. In the positive group (n=31), 25 patients had significant stenosis of the coronary artery and 6 did not. In the negative group (n=40), 5 patients had significant stenosis and 35 did not. The sensitivity, specificity, positive predictive accuracy and negative predictive accuracy for CAD detection by SAECG was 83%, 85%, 81% and 88%, respectively. CONCLUSIONS: Dipyridamole-stress portable SAECG is useful for detecting CAD at the patient's bedside with high sensitivity and specificity.

Adult↗

PubMed1988

The total heart beats per 24 hours by ambulatory electrocardiography and the changes of heart rate by treadmill exercise test in sick sinus syndrome.

To study the clinical implications of the total number of heart beats per 24 hours (THB), 24 hour ambulatory electrocardiography and treadmill test were performed by sixty patients with sick sinus syndrome (SSS, 58 +/- 12 years old) who underwent overdrive suppression test. Results were compared with thirty control subjects (58 +/- 12 years old). The THB was 74 +/- 11 thousand beats in the SSS group and 99 +/- 10 thousand beats in the control group. The THB and the maximal heart rate (MHR) achieved during the treadmill test were significantly lower in the SSS group than in the control group. However, the exercise duration in patients with SSS was similar to that of the control subjects. The exercise duration and the MHR were correlated to age, but not to the THB in the patients with SSS. There was no significant relationship between the total heart beats per 24 hours and the maximal sinus node recovery time (max. SNRT). We conclude that the THB, independent of the max. SNRT, can be a useful index in diagnosing and assessing the quantity of bradycardia in patients with SSS. The tolerance of exercise and the MHR were not correlated with the THB, in patients with SSS.

Adult↗

PubMed1995

Diagnosis of occlusion site in the left anterior descending coronary artery in patients with anterior myocardial infarction--comparison of thallium-201 myocardial scintigraphy and 12-lead electrocardiography.

To evaluate whether the site of occlusion/stenosis in the left anterior descending coronary artery (LAD) could be diagnosed by noninvasive techniques, thallium-201 myocardial scintigraphy (TMS), 12-lead electrocardiography (ECG), and coronary arteriography were performed in 33 patients with anterior acute myocardial infarction (AMI). The subjects were divided into two groups according to the location of stenosis: ie, either proximal to the first diagonal branch (PRO, n = 18), or beyond the first diagonal branch (NON-PRO, n = 15). The location of the anterior interventricular groove was defined as 0 degrees. The extent of persistent perfusion defect was greater in the PRO group than in the NON-PRO group (0.43 +/- 0.12 vs 0.31 +/- 0.14, p < 0.01). The left margin of the defect in the basal short-axis layer was at 75 +/- 30 degrees in the PRO group and at -19 +/- 43 degrees in the NON-PRO group (p < 0.001). A defect with a left margin at > 30 degrees in the basal layer was found in 94% (17/18) of the patients in the PRO group and in 6% (1/15) of the patients in the NON-PRO group (p < 0.001). An abnormal Q wave in leads a VL/I was found in 78% (14/18) of the patients in the PRO group and in 20% (3/15) of the patients in the NON-PRO group (p < 0.001). The sensitivity, specificity and total predictive accuracy of detection of proximal lesions of the LAD were 94%, 93% and 94% by TMS, and 78%, 80% and 79% by ECG, respectively. A significant difference in accuracy existed between TMS and ECG (p < 0.05). These data suggest that it is possible to diagnose the site of occlusion/stenosis of the LAD as either proximal or non-proximal in patients with anterior AMI by TMS and ECG.

Coronary Angiography↗

PubMed1999

Detection of a biphasic response of hibernating myocardium by dobutamine-stress electrocardiography-gated technetium-99m-tetrofosmin single photon emission computed tomography--a case report.

A woman with coronary artery disease underwent a new imaging technique: dobutamine-stress electrocardiography (ECG)-gated tetrofosmin-single photon emission computed tomography (SPECT). Dobutamine-stress ECG-gated tetrofosmin-SPECT with automatic left ventricular function analysis software programs detected improvement and a biphasic response of dysfunctional myocardium during dobutamine infusion, which suggested viable but hibernating myocardium. Dobutamine-stress ECG-gated tetrofosmin-SPECT with automatic left ventricular function analysis software programs has the potential to detect viable but dysfunctional myocardium with contractile reserve.

Aged↗

PubMed1997

A home electrocardiography and blood pressure telemonitoring system.

A home electrocardiography (ECG) and blood pressure telemonitoring system for cardiac patients was installed in the Macau region. The monitoring centre was established in the emergency unit at the Government Hospital of Macau. The first users were 10 cardiovascular patients selected by a physician. The average age of these users was 61 years (range 30-78). The results of a three-month trial showed that the system was easy to operate and technically reliable. It was found to be helpful for cardiac patients. The most significant problem during the trial was electrical noise from the ECG electrodes.

Adult↗

PubMed1989

[Application of Holter electrocardiography to exercise testing for the group examination of school children: comparison between obese and normal children].

Application of Holter electrocardiography to an exercise test for heart function is useful in the group examination of school children. The circulatory responses to a step test among obese boys and girls and control were as follows: 1. Four cases of arrhythmia were detected, of whom 2 cases were discovered during exercise. ST-segment depression of 0.1 mV or more during and after exercise was recognized in 29 cases, 27 of the junctional- and 2 of the sagging slope, with a higher percentage in obese girls than in normal girls. 2. Serial ECG records during the procedure, performed for all children with the same single-step test, showed differences in the circulatory responses among the test groups. The load was estimated to be 76-86% of the maximal heart rate predicted by Cummings, with obese and girl groups being higher than other groups. The comparison revealed that the heart rate (HR) responses to exercise done by the boys increased faster than those by the girls at 1 minute after exercise. There were differences between obese and control and between boys and girls in HR at recovery, and also in HR before and 4 minutes after exercise between two sexes, which findings agree with other reports. 3. Concerning anthropometric factors, either the skinfold thickness or the obesity index was related to the HR at the peak of the exercise as well as immediately after it and to the half time. By contrast, the arm muscle diameter was found unrelated to the HR. Using this method, applied these combination of Holter ECG and step test to a group examination, we got ECG data for 254 subjects, 97.5% of which were suitable for analysis. We found this method to be effective for detecting ECG changes and for determining HR responses to exercise. This method is safe, simple, and inexpensive and is applicable to examination not only for school children but also for different population groups, for the estimation of circulatory responses.

Age Factors↗

PubMed1992

[Spatial and quantitative analysis of the QRS and T waves by Frank-lead orthogonal electrocardiography in normal children. Comparative study in an early and late cord-clamping groups in newborns].

We studied a spatial and quantitative analysis of QRS and T waves by Frank-lead orthogonal electrocardiography (afterwards; ECG) in 50 cases of normal newborns, 30 cases of infants, 50 cases of adults, and also the variation in age was investigated. In the newborns, the comparative study was made serially, longitudinally in 21 infants with an early clamping of the cord and 29 infants with a late clamping of the cord. The results are mainly as follows. 1) The parameters reflecting the cardiac electromotive force of the right ventricle such as Sx, Qz and Sx+Qz decreased with aging. 2) Rx, i.e., the maximum leftward projection of QRS vector increased until the children, probably because the left ventricle was dominant in their growth and development and in the increased amount of work. A subsequent reduced value in the adults was considered to be mainly due to an increase of the distance between the heart and electrode by the increase in the thorax, particularly the transverse diameter and due to the growth in subcutaneous fat and muscle. 3) The values of Rx/Sx increased with aging. Rx and Sx in the adults were less than those in the children, but Rx/Sx was larger than that of Rx because Sx was less than Rx. 4) Age-related changes of Tz was most characteristic and was negative up to several days after birth. T vector was in forward direction and then turned positive (in backward). This was greatest at the period of the infants. Subsequently, it turned negative in the childhood, and extent was maximum in the adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2002

Electrocardiography to define clinical status in primary pulmonary hypertension and pulmonary arterial hypertension secondary to collagen vascular disease.

STUDY OBJECTIVES: To determine the utility of the ECG for predicting clinical status in adults with primary pulmonary hypertension (PPH) or pulmonary arterial hypertension (PAH) secondary to collagen vascular disease. DESIGN: Retrospective study. SETTING: Outpatient clinic in a tertiary referral center. PATIENTS: Adult outpatients with PPH or PAH secondary to collagen vascular disease who underwent electrocardiography within 30 days of undergoing right-heart catheterization, echocardiography, and 6-min walk testing. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The following measurements were recorded from each ECG: P-wave amplitude in lead II; mean frontal QRS axis; QRS duration; R-wave and S-wave deflections in leads I and V6; and the T-wave configurations in the precordial leads. These ECG variables were correlated with hemodynamic variables, RV size, and exercise capacity. Of the 61 patients included in this study, 56 (92%) were women. Eight of 61 patients (13%) had normal findings on ECGs. There was no significant difference in the demographics or hemodynamics when comparing groups with normal vs abnormal ECGs. All ECG parameters had no more than moderate correlation with hemodynamic variables, ventricular size measured by echocardiogram, and exercise capacity as measured by a 6-min walk. The best correlation was between mean the frontal QRS axis and cardiac index (r = -0.46). CONCLUSIONS: The ECG is an inadequate screening tool to rule out the presence of clinically relevant pulmonary hypertension, either primary or secondary to collagen vascular disease. The mean frontal QRS axis correlated best with the severity of hemodynamic impairment.

Cardiac Catheterization↗

PubMed1982

Antepartal analysis of fetal heart rate variability by abdominal electrocardiography.

The success rate of some methodological factors influencing the antepartal analysis of fetal heart rate variability (FHRV) by abdominal electrocardiography (aFECG) were studied in 80 normal and 554 high risk pregnancies. The success rate of FHRV analysis was found to be dependent on the gestational age with virtually 100% success at 22 to 25 weeks and at 40 to 41 weeks of gestation. The lowest rate of success, 50% was found around the 30th week of gestation (Fig. 1). The fifteen-degree lateral tilt and the supine position of the mother were found to be equal respecting the success rate and the test results, while the 90-degree lateral tilt was found to be less favorable for the analysis. FHRV analysis succeeded more often with electrode paste than it did with tap water moistening or with dry electrodes. The rejection limit of maximum interval differences in FHRV analysis was found to be an important factor influencing the test results. The variability indices should be compared only if they have been measured with the same rejection logic. Differential index, of short-term variability, can be measured from short samples of aFECG, having a good correlation between DIs measured using 1-minute, 5-minute and 20-minute samples (Figs. 3, 4). On the other hand, interval index measuring the long-term variability should be measured using longer samples of aFECG.

Electrocardiography↗

PubMed1988

Effect of a new calcium antagonist, nilvadipine, on variant angina pectoris evaluated by 24-hour Holter electrocardiography.

The clinical effect of nilvadipine, a new calcium antagonist, was investigated in a single blind trial in 19 patients with variant angina pectoris. The efficacy of the drug was evaluated on the basis of frequency of anginal attacks and Holter electrocardiographic findings during observation periods and during two treatment periods when the drug was given in doses of 4 mg twice a day or 4 mg 3 times a day. The frequency of anginal attacks and the consumption of sublingual nitroglycerin tablets decreased significantly in both treatment periods in comparison with those in the observation period before treatment, but in the observation period after treatment tended to increase in comparison with those during the second treatment period. The frequency and duration of ST-segment elevation and the maximum ST-segment elevation confirmed by Holter electrocardiography also improved significantly in both treatment periods, compared with those in the observation period before treatment. Our findings show that nilvadipine is effective for variant angina pectoris at doses of 4 mg twice a day.

Angina Pectoris, Variant↗

PubMed2001

Evaluation of myocardial involvement in systemic lupus erythematosus by signal-averaged electrocardiography and echocardiography.

OBJECTIVE: The myocardial involvement in systemic lupus erythematosus (SLE) patients, frequently found at autopsy or at endomyocardial biopsy, is less easily detected clinically. The myocardial lesions are characterized by an increase in interstitial connective tissue and myocardial scarring. Signal-averaged electrocardiography (ECG-SA) is currently used for recording ventricular late potentials which are the expression of slowed and disorganized conduction through zones of myocardial scarring. M-mode, two-dimensional and Doppler echocardiography (ECHO) represent relatively simple methods for evaluating the left ventricular function. This study was aimed to evaluate by ECG-SA and ECHO the myocardial involvement of SLE patients without clinical and electrocardiographic evidence of cardiac disease. METHODS AND RESULTS: Twenty outpatients with SLE were studied and compared with 18 normal controls. Late potentials were recorded in 20% of SLE patients and in 5.5% of controls. A significant increase of abnormal left ventricular diastolic filling was found in the SLE patients, characterized by reduced E/A (p = 0.018), a lower deceleration rate of early diastolic flow velocity (p = 0.048) and a prolonged isovolumic relaxation time (p = 0.001). SLE patients had diastolic dysfunction of various degrees although the depolarization abnormalities detected by ECG-SA were found only in a few subjects. CONCLUSIONS: The depolarization abnormalities, revealed by ECG-SA, probably reflect a longer extent of myocardial fibrosis in SLE patients with ECHO evidence of abnormal left ventricular filling. The simultaneous occurrence of ECHO and ECG-SA alterations could be a marker of subclinical myocardial involvement.

Adult↗

PubMed1995

Limitations of electrocardiography in the diagnosis of acute myocardial infarction--comparison with two-dimensional echocardiography.

In order to assess the sensitivity of the initial electrocardiogram (ECG) in diagnosing the first attack of acute myocardial infarction (AMI), we compared the findings on ECG and two-dimensional echocardiogram (2-D echo) in 74 patients with single vessel coronary artery disease. Group A consisted of 41 patients with infero-posterior AMI while group B consisted of 33 patients with antero-septal AMI. In group A, 12 patients showed normal ECGs, while 2-D echo failed to reveal abnormal left ventricular wall motion in only 2 patients. In those two patients, the quality of the echocardiogram was poor. In group B, only one patient showed a normal ECG, and all patients showed abnormal left ventricular wall motion on 2-D echo. We conclude that electrocardiography has limitations in diagnosing infero-posterior myocardial infarction especially during the acute phase, but 2-D echo is an additional useful diagnostic procedure.

Echocardiography↗

PubMedDate not supplied

Asymptomatic myocardial ischemia in diabetes and its relationship to diabetic neuropathy: an exercise electrocardiography study in middle-aged diabetic men.

The incidence of painless ischemic heart disease is increased in diabetic patients, and it has been suggested that this may be partly due to diabetic neuropathy involving cardiac afferent nerves. We have performed exercise electrocardiography in middle-aged diabetic men without cardiac symptoms to see if silent myocardial ischemia is more common in patients with neuropathy. Thirty patients had diabetic neuropathy (group 1), and 30 did not (group 2). The groups were matched for age and duration of diabetes. The exercise test was abnormal in 14 patients. A positive test was no more common in patients with diabetic neuropathy. During a mean follow-up period of 50 mo, five patients developed clinical heart disease, four of whom had a positive exercise test. An abnormal exercise ECG is common in diabetic men without cardiac symptoms, but our study does not suggest that the high incidence of silent myocardial ischemia in diabetic patients is related to the presence of diabetic neuropathy. In patients with diabetes a positive exercise test is associated with a high risk of developing clinical heart disease in subsequent years.

Adult↗

PubMedDate not supplied

Developments in ambulatory electrocardiography.

Cardiovascular disease (CVD) is the leading cause of death in many developed countries. There is a need for cardiovascular monitoring devices that can supplement traditional medical and clinical care by enabling the diagnosis of conditions with infrequent symptoms, the timely detection of critical signs that are precursors to sudden cardiac death, and the long-term management of chronic conditions through monitoring of symptoms, risk factors, and the effects of therapy. This paper provides an overview of ambulatory electrocardiogram (ECG) monitors, which are one of the most widely prescribed diagnostic procedures for cardiovascular disease. The engineering challenges associated with ambulatory electrocardiography are discussed, and technological improvement areas that are the focus of current research effort are reviewed.

Algorithms↗