Terminal QRS Complex Research Articles

CineECG for visualization of changes in ventricular electrical activity during ischemia

Abstract Background CineECG is a newly developed method which provides an anatomical visualization of ventricular de- and repolarization in a non-invasive manner. It combines the electrical information from the 12-lead electrocardiogram (ECG) with a 3D heart model. The location and direction of the average ventricular de- and repolarization over time is projected on the model. Until now, it has not been used for visualization of ventricular electrical activity during myocardial ischemia. Purpose We aimed to visualize changes in ventricular de- and repolarization during acute ischemia with CineECG and relate these to changes in the ECG. Methods CineECG was used to provide the location and direction of the average ventricular de- and repolarization over time, using a standardized 3D heart/torso model. Continuous ECG’s during percutaneous transluminal coronary angioplasty with prolonged balloon inflation from the STAFF III database were used as study sample. ECG’s at baseline and at every 10 seconds during the first 150 seconds of balloon inflation were analyzed with CineECG. For the terminal QRS-complex, ST-segment and terminal T-wave, the direction of the CineECG was determined. The changes in CineECG direction relative to the direction at baseline were quantified by calculating the Δangle between the CineECG direction at baseline and the direction after every 10 seconds of inflation. Additionally, the root mean square amplitude (rmsA) of the ST-segment of all ECG leads was computed for every ECG. Results 94 patients from the STAFF III database were included, 10 patients were excluded due to too much signal noise of the ECG. Within 10 seconds after start inflation, the median Δangle for the terminal QRS-complex, ST-segment and terminal T-wave were 21.8° [11.4 – 34.2] , 20.6° [8.0 – 43.9] and 23.5° [11.8 – 48.0], respectively. The median Δangle for the terminal QRS-complex reached its maximum after 130 seconds (41.0° [23.0 – 70.8]). The median Δangle of the ST-segment gradually increased to 26.1° [13.1 – 56.0] after 140 seconds of inflation. The Δangle of the terminal T-wave was greatest 30 seconds after start inflation (26.3° [12.6 – 49.2]), and changed only slightly during inflation. The rmsA of the ST-segment was 0.04 mV [0.03 – 0.08] during the first 10 seconds of inflation, and gradually increased until 0.08 mV [0.05 – 0.15] mV at 150 seconds. Conclusions CineECG proves to be very sensitive in detection of early changes in the ECG during prolonged balloon inflation, even before great changes occur in ST-amplitude. Therefore, CineECG might support the early detection of acute ischemia, even before clear ECG changes are visible.

P945What is the role of late-potentials determined by signal-averaged ECG in predicting flecainide provocative test in brugada pattern?

Abstract Introduction The sudden cardiac death risk in Brugada Syndrome (BrS) is higher in patients with spontaneous type 1 pattern. Brugada diagnosis is also established in patients with induced type 1 morphology after provocative test with intravenous administration with a sodium blocker channel. Nevertheless, this group of patients is known to be at a lower risk of SCD, and their risk stratification is still a matter of discussion. Late potentials (LP) detected on signal-averaged ECG (SAECG) on the RVOT have been previously proposed as a predictor factor for BrS, even though data is lacking on its value. Purpose To evaluate the association between positive LP (LMS40> 38ms) on SAECG with modified Brugada leads and a positive flecainide test in patients with non-type 1 BrS. Methods Retrospective single-center study of non-type 1 BrS patients referred for the performance of a flecainide provocative test. Patients presenting with spontaneous type 1 morphology were excluded from the study. Study of LP on SAECG with modified leads for Brugada were evaluated before administration of flecainide [2mg/kg (maximum150mg), for 10minutes] with determination of filtered QRS duration (fQRS), root mean square voltage of the last 40ms of the QRS complex (RMS40) and duration of low amplitude signals <40μV of the terminal QRS complex (LMS40). Results 126 patients (47.3 ± 14.1 years, 61.9% males) underwent study with LP SAECG and flecainide test. Among these patients, 7.9% were symptomatic and 16.7% had familiar history of BrS. Flecainide test was positive in 46.8% of patients. In patients with a positive flecainide test, 64.4% presented LMS40 > 38ms whereas LMS40 > 38ms was present in only 46% of those with a negative flecainide test (p = 0.031). The presence of positive LMS40 was a positive predictor for a positive flecainide test, associated with a two-fold increase likelihood in the induction of a Brugada pattern (OR: 2,12; IC95% 1,025-4,392; P = 0,043). There was no association between fQRS or RMS40 and a positive flecainide test (p = NS). fQRS > 114ms and RMS40 <20uV was present in 22% and 61% of patients with a positive flecainide test, respectively. Conclusion In patient with non-type 1 Brugada syndrome, LMS40 > 38ms in SAECG was a predictor for a positive flecainide test, suggesting that this finding could be helpful on the risk stratification of patients undergoing diagnostic study for Brugada syndrome. Abstract Figure. Effect of LMS 40 in flecainide test

Value of QRS distortion and ST-segment shift in acute coronary syndrome patients in relation to gensini score

Background: Terminal QRS complex distortion on admission electrocardiography (ECG) has been used to estimate the final infarct size and the prognosis after acute coronary syndrome (ACS); however, it is not sure whether the QRS distortion is more reliable for predicting the severity of coronary artery lesions or not. The Aim of the Work: The aim is to analyze the admission ECG in ACS based on abnormality observed in the terminal QRS complex distortion and ST-segment and its relation to coronary artery lesion severity. Patients and Methods: We included 150 patients presented with ACS. Patients were divided according to the presenting ECG in two major groups, 120 patients presented with ST-segment elevation myocardial infarction (STEMI) who were classified into two groups according the presence or absence of the QRS distortion: 42 patients with +ve QRS distortion (Group I) and 78 patients with −ve QRS distortion (Group II), and 30 patients presented with non-ST-segment elevation (NSTE)-ACS who were also further classified according the magnitude of ST shift by millimeter into three groups. All patients underwent primary percutaneous coronary intervention, and Gensini score defined the severity of coronary artery lesions. Results: In this study, in STEMI patients groups, we observed that QRS distortion on admission, ECG has a significant relationship with high Gensini score values, whereas in NSTE-ACS patients, we demonstrated no significant difference between the extents of ST-segment shift and Gensini score values. Conclusion: QRS distortion has a significant value in predicting severe coronary artery lesions in STEMI patients while the extent of ST-segment shift has no benefits in predicting the severity of coronary artery lesion in NSTE-ACS patients.

Prognostic significance of initial electrocardiogram in patients with ST elevation acute myocardial infarction (STEMI): A study of 52 cases

Context: In acute myocardial infarction (AMI), patient's surface electrocardiogram (ECG) allows risk management in individual patients by estimating the size of area at risk. This can be assessed from different waveforms of ECG. Settings and Design: In this prospective observational study we studied 52 consecutive patients of ST elevation AMI admitted into a teaching hospital. Materials and Methods: The electrocardiogram (ECG) of AMI patients which showed ST segment elevation of 1 mm in two or more limb leads or 2 mm in two or more chest leads with positive T waves in leads with ST segment elevation was analyzed in relation to ECG heart rate, number of leads showing ST segment deviation, ST segment deviation score, grades of ischemia as assessed by terminal portion of QRS complex. Out of 52 patients studied, mortality occurred in eight patients within 7 days of hospital stay. Thus we had two groups of patients, one who survived 7 days of hospital stay ( n = 44) and other who did not survive 7 days of hospital stay ( n = 8). The ECG parameters between these two groups were compared to determine significance of ECG in predicting short term mortality. Mean values with standard deviation (SD) were calculated for continuous variables. Chi-square tests were used to determine the significance of difference between proportions for discrete variables and P value of less than 0.05 was considered statistically significant. Results: Mean heart rate on admission was 84 beats per minute ranging from 32-136 beats per min. Tachycardia on admission was present in 17 patients who had high mortality than that in patients with normal heart rate ( 17.3 and 14.2% respectively). The mean ST segment deviation score was 22.69 ranging from 6-45. The high ST segment deviation score was associated with increased mortality at 7 days ( P = 0.0209). Similarly in patients with ECG showing more number of leads showing ST segment deviation mortality was high ( P = 0.009). Mortality in patients ( n = 27) with grade III ischemia (terminal QRS distortion) was significantly more than that in patients ( n = 25) with grade II ischemia (without distortion of terminal QRS complex, P = 0.0385). Conclusions: Tachycardia, high ST segment deviation score, more number of leads with ST segment deviation, distortion of terminal portion of QRS complexes on admission ECG denoted poor short-term prognosis.

Clinical Implication of Early Repolarization

Early repolarization described as J-point elevation with concaved ST segment, notch or slurred at terminal QRS complex on surface electrokardiography. This electrokardiography pattern that usually exists in young male population, for about 60 years has been concluded as benign normal variant electrokardiography. Klatsky in 2002, has strengthed this issues with his study with 1000 elecrokardiographies with early repolarization which were followed for 12 years. There was no significant case for hospitality or malignant ventricular arrhythmias among population with early repolarization comparared with normal elektrokardiography without early repolarization.But, recent studies with larger samples, show different thing, which is there was a correlation between early repolarization and malignat ventricular arrhythmias. So the issue is, whether we can still consider this early repolarization as a normal variant or not. And how about the management of asymptomatic population with early repolarization such as syncope or evidence of malignant ventricular arrhythmias.T-wave Alternans is a difference at amplitude or morphology of ST segment and T wave in every other heart beat. T-wave Alternans measurement is a non-invasive method to value cardiac cells hererogeneity. This examination has been proven to be useful as a risk stratification for malignant ventricular arrhythmias events in large studies. Higher T-wave Alternans value accompanied with higher risk for developing these arrythymias. T-wave Alternans measurement has been approved in the guideline for management of wide QRS complex tachyarrythmias for detection ventricular arrhythmias with I and IIa class of recommedantion. The more practical Modified Moving Average technicque which can be performed in healthy subjects with early repolarization is useful for risk stratification. Large studies have approved the use of Modified Moving Average for measure T-wave Alternans in these arrhythmias risk stratification.

High-resolution electrocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxer dogs

To evaluate the reliability of high-resolution electrocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxers, 20 dogs with no structural cardiac alterations at echocardiographic examination were grouped on the basis of frequency of ventricular arrhythmias, evaluated by 24-hour ambulatory ECG, and undergoing a high-resolution electrocardiography. High frequency QRS duration, duration of terminal QRS complex less than 40µV (LAS40) and root mean square voltage of the terminal 40 milliseconds of the QRS complex (RMS40) were measured. Differences in high-resolution ECG variables were not observed between groups. Therefore, the results of this investigation suggest that high-resolution electrocardiography is not a useful method for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxers without detectable myocardial alterations or systolic dysfunction.

Early Repolarization: A Rare Primary Arrhythmic Syndrome and Common Modifier of Arrhythmic Risk

Despite longstanding beliefs, early repolarization is not always a benign electrocardiographic observation. Its association with increased arrhythmic events has been observed in 2 strikingly different groups of individuals, retrospectively in young subjects with idiopathic ventricular fibrillation and in long-term cohort studies from the general population. This form of primary electrical disease is now referred to as the early repolarization syndrome and has mechanistically been demonstrated to occur secondary to a transmural gradient of early cellular repolarization, resulting in the presence of an ST-elevation pattern and J-waves merged within or offset from the terminal QRS complex. In addition to creating a milieu of increased arrhythmic risk in isolation, an increasing number of studies have highlighted that the presence of early repolarization and J-waves may provide a baseline electrical substrate that modifies the risk of malignant arrhythmias in other clinical settings, such as acute myocardial ischemia. The challenge ahead lies in discerning when early repolarization may represent an ominous ECG marker, as opposed to a benign entity.

Clinical Characteristics and Prevalence of Early Repolarization Associated With Ventricular Arrhythmias Following Acute ST-Elevation Myocardial Infarction

Early repolarization (ER) on a 12-lead electrocardiogram has recently been associated with ventricular tachyarrhythmias (VTAs) in patients without structural heart disease and in patients with healed myocardial infarction (MI). An association between ER and VTAs in the setting of acute ST-segment elevation MI (STEMI) has not been explored. In a single-center retrospective case-control design, 50 patients with STEMI complicated by VTAs (cases), defined as ventricular fibrillation, sustained ventricular tachycardia, or nonsustained ventricular tachycardia within 72 hours of the index hospitalization, were matched for age and gender with 50 subjects with STEMI without VTAs (controls). Electrocardiograms obtained an average of 1 year before STEMI were analyzed for ER pattern, defined as notching or slurring of the terminal QRS complex or J-point elevation >0.1 mV above baseline in ≥ 2 contiguous leads. A higher prevalence of ER was associated with VTAs overall in cases compared to controls (26% vs 4%, p = 0.01) and localized to anterior (16% vs 0%) and inferior (14% vs 2%, p = 0.07) leads but not lateral limb leads. Notching (10% vs 2%, p = 0.1) and J-point elevation (16% vs 0%) were more common in cases. Slurring was uncommon. ER was associated with VTAs (odds ratio [OR] 6.5, 95% confidence interval [CI] 1.5 to 28.8, p = 0.01), even after adjustment for creatine kinase-MB (OR 9.2, 95% CI 1.6 to 53.4, p = 0.01) and ejection fraction (OR 5.7, 95% CI 1.2 to 27.1, p = 0.03). In conclusion, ER is associated with VTAs in patients with STEMI even after adjustment for left ventricular ejection fraction or creatine kinas-MB levels. Larger prospective studies exploring potential associations and mechanisms of ventricular arrhythmogenesis with ER pattern are needed.

Definition of Early Repolarization

Early repolarization pattern (ERP) is a common ECG variant, characterized by J point elevation manifested either as terminal QRS slurring (the transition from the QRS segment to the ST segment) or notching (a positive deflection inscribed on terminal QRS complex) associated with concave upward ST-segment elevation and prominent T waves in at least two contiguous leads.1,2 The J point deflection occurring at the QRS-ST junction (also known as Osborn wave or J wave) was first described in 1938, and is seen in both extracardiac and cardiac disorders like hypothermia, hypercalcemia, brain injury, hypervagotonia, or spinal cord injury leading to loss of sympathetic tone, vasospastic angina. Besides recently described early repolarization syndrome,3–5 ERP has generally been considered a normal ECG variant with good long-term prognosis. However, this long-held concept has been challenged, and recently published population-based studies and reports of associations with ventricular fibrillation and sudden death continue to fuel more momentum.6–9 In the seminal article by Haissaguerre et al, cases of ERP associated with cardiac arrest had at least 0.1-mV J point elevation manifested as QRS slurring or notching in the 2 contiguous inferior or lateral leads.6 ERP has also emerged as a marker of increased long-term mortality (cardiac and arrhythmic) in the general population.10,11 Thus, ERP is probably not as benign as traditionally believed. Article see p 2208 The potential consequences of such an association are huge, especially as related to ECG screening and risk stratification in the general population. It is therefore extremely …

The delayed activation wave in non-ST-elevation myocardial infarction

BackgroundLittle is known about the relationship between the electrocardiographic characteristics and the infarct related artery (IRA) in non-ST-elevation myocardial infarction (NSTEMI). We found a curious phenomenon in electrocardiograms of patients with acute occlusion of left circumflex artery in NSTEM: A notch or deflection was often present in the terminal QRS complex in leads II,III and aVF or I,aVL . The objective of this study was to determine whether the previously unreported ECG phenomenon that we have found in NSTEMI could identify the culprit artery in non-ST-elevation myocardial infarction. Methods and ResultsOur study included 218 NSTEMI patients who presented to our institution and underwent coronary angiography within 24 hours of admission. For convenience, ‘N’ wave was defined as a notch or deflection in the terminal QRS complex of the surface ECG. The duration of QRS with N wave before PCI was more prolonged than the duration of QRS without N wave (121±12ms vs 106±11ms, P<0.01). In the LCX group, 66(77%) patients had N wave in leads II, III and aVF, whereas only 5(6%) patients in the LAD group and 9(18%) patients in the RCA group had such ECG feature (P<0.001). A greater proportion of patients in the LCX group also had N waves in leads I and aVL (P<0.001). N wave in leads II, III and aVF was associated with 77% sensitivity and 89% specificity, respectively. N wave in leads I and aVL was associated with 64% sensitivity and 96% specificity, respectively. ConclusionThe abnormal waveform in terminal QRS complex in NSTEMI ,which is described above, is the delayed activation wave of left ventricular basal region which the left circumflex artery supplies. It is associated with a higher specificity and higher sensitivity for culprit LCX in non-ST-elevation myocardial infarction. The delayed activation wave is a new pattern of ischemia in ECG.

Early Repolarization Associated With Ventricular Arrhythmias in Patients With Chronic Coronary Artery Disease

Early repolarization, indicated on the standard 12-lead ECG, has recently been associated with idiopathic ventricular fibrillation in patients without structural heart disease. It is unknown whether there is an association between early repolarization and ventricular arrhythmias in the coronary artery disease (CAD) population. Patients with CAD with implantable cardioverter-defibrillators in the healed phase of myocardial infarction were analyzed. In a case-control design, 60 patients who had ventricular arrhythmic events were matched for age and sex with 60 control subjects. ECGs were analyzed for early repolarization, defined as notching or slurring morphology of the terminal QRS complex or J-point elevation ≥0.1 mV above baseline in at least 2 lateral or inferior leads. Results were adjusted for left ventricular ejection fraction. Overall, early repolarization in 2 or more leads was more common in cases than control subjects (32% versus 8%, P=0.005). Early repolarization was noted more commonly in inferior leads (23% versus 8%, P=0.03), and a trend was noted in leads V(4) through V(6) (12% versus 3%, P=0.11). Early repolarization was uncommon in leads I and aVL in cases and control subjects (3% versus 0%). Notching was more common in cases than control subjects (28% versus 7%, P=0.008). Slurring and J-point elevation were not associated with ventricular arrhythmias. Early repolarization and, in particular, notching in the inferior leads is associated with increased risk of life-threatening ventricular arrhythmias in patients with CAD, even after adjustment for left ventricular ejection fraction. Our findings suggest early repolarization, and a notching morphology should be considered in a risk prediction model for arrhythmias in patients with CAD.

QRS complex abnormalities in subjects with idiopathic ventricular fibrillation

Recent data point to a high incidence of early repolarization abnormalities among patients with idiopathic ventricular fibrillation (IVF). ECG data from 11 patients with idiopathic IVF were evaluated for the presence of initial (slurring or notching of the ascending limb of the R-wave that resembles a "pseudo" delta-wave) and terminal (slurring or notching of the descending limb of the R-wave resembling the early repolarization pattern) QRS complex abnormalities in at least two contiguous leads. The control group comprised 101 age- and gender-matched healthy individuals without structural heart disease in whom the presence of an accessory pathway was excluded during electrophysiological study. Initial QRS complex abnormalities in the setting of a normal PR interval were more frequent in subjects with IVF than in control population (36.4% vs. 8.9%, p=0.023). Although not statistically significant, an early repolarization pattern was also more common among patients with IVF (27.3% vs. 12.9%, p=0.192). Among patients with IVF, there is an increased prevalence of initial and terminal QRS complex abnormalities.

Terminal QRS Complex Distortion on the Admission Electrocardiogram in Anterior Acute Myocardial Infarction and Association with Residual Flow and Infarct Size after Primary Angioplasty

BackgroundTerminal QRS complex distortion on admission is a simple and reliable predictor of infarct size in patients with acute myocardial infarction (AMI). It is uncertain, however, whether this reflects reduced myocardial perfusion of the infarct area and a larger area of the myocardium at risk. This study was conducted to investigate whether terminal QRS distortion complex on admission is a reliable predictor of reduced residual flow and a larger area of the myocardium at risk compared to patients who are admitted without a terminal QRS distortion.MethodsWe evaluated the relationship between terminal QRS complex distortion and residual flow to the infarct zone and risk area in 46 anterior AMI patients undergoing primary angioplasty. 99mTc-sestamibi imaging was performed at baseline and 5-9 days after angioplasty. The study population was divided into those with (Group I, n=16) and without (Group II, n=30) terminal QRS complex distortion.ResultsBaseline characteristics were similar between the two groups. The area of the myocardium at risk was higher in Group I (59.9±15.3%) than in Group II (48.6±13.7%, p<0.05; mean+SD) while the nadir measurement of the residual flow was lower in Group I (0.10±0.07) than in Group II (0.16±0.09, p<0.05). Although the final infarct size was significantly higher in Group I (40.8±17.2%) than in Group II (27.1±18.1%, p<0.05), the myocardial salvage index did not differ significantly between the two groups.ConclusionTerminal QRS complex distortion seems to be associated with less residual flow to the infarct zone, a larger risk area and greater infarct size in patients with anterior AMI.

High frequency intra-QRS signals in idiopathic dilated cardiomyopathy.

We extracted and quantified high frequency intra-QRS signals in idiopathic dilated cardiomyopathy (IDC). In IDC the analysis of late potentials in the terminal QRS complex often fails in predicting clinical events because of intraventricular conduction abnormalities and the absence of a circumscribed arrhythmogenic substrate. Therefore, new approaches are required to assess the electrical state of the myocardium. We investigated 21 patients suffering from IDC with (n = 14) and without (n = 7) bundle branch block. High resolution 31 lead magnetocardiograms were filtered with a 67 point 4th order Savitzky-Golay filter. The difference of the measured and filtered signals was calculated (67-200 Hz). The spatio-temporal properties and the areas under the curves of the resulting high frequency intra-QRS signals (IQCs) were studied. We detected IQCs in all patients. The patients had individual patterns regarding the temporal and spatial properties of the IQCs during depolarisation. The IQCs predominantly appeared in the initial portion of the QRS. The ratios of the areas under the curves of the IQCs and the measured signals were linearly correlated to the left ventricular enddiastolic diameter (r = 0.71, significance 0.0012). In IDC the ventricular depolarization is accompanied by individual spatial and temporal patterns of high frequency intra-QRS signals. They can be studied non-invasively from body surface mapping data with the algorithm used in this study. This provides access to the assessment of the electrical status in patients with IDC.

The Diagnosis

The Diagnosis

Determinants and prognostic implications of terminal QRS complex distortion in patients treated with primary angioplasty for acute myocardial infarction

Terminal QRS complex distortion on admission has an impact on a patient’s prognosis after primary angioplasty for acute myocardial infarction (AMI). We evaluated the determinants and prognostic significance of terminal QRS complex distortion in 153 consecutive patients with AMI after primary angioplasty. The study population was divided into 2 groups according to the presence (group I, n = 41) or absence (group II, n = 112) of terminal QRS complex distortion. The primary end points were the occurrence, within 6 weeks after AMI, of death, nonfatal reinfarction, or congestive heart failure. Baseline characteristics were similar between the 2 groups. However, patients in group I had higher peak levels of serum creatine kinase than those in group II (5,100 ± 3,100 vs 3,000 ± 1,800 U/L, respectively, p <0.01). The rate of angiographic no-reflow (Thrombolysis In Myocardial Infarction flow grade ≤2) was 31.7% in group I and 10.7% in group II (p <0.01). The predischarge left ventricular ejection fraction was 45.0 ± 12.0% in group I and 54.0 ± 8.0% in group II (p <0.01). Multivariate analysis identified the pressure-derived fractional collateral flow index and the culprit lesion in the left anterior descending coronary artery as independent determinants of the terminal QRS complex distortion. No patients died during 6 weeks of follow-up. The 2 groups were similar for life-threatening arrhythmia or reinfarction. However, there were more patients in group I than in group II with congestive heart failure (26.8% vs 5.4%, respectively, p <0.01) or who reached the primary end points (29.3% vs 5.4%, respectively, p <0.01). In conclusion, terminal QRS complex distortion on admission is associated with poor clinical outcome after primary angioplasty for AMI, and collateral flow may have a major influence on terminal QRS complex distortion during AMI.

Electrocardiographic manifestations: benign early repolarization

Early repolarization, also known as benign early repolarization (BER) or normal variant, is noted in approximately 1% of the population and in up to 48% of patients seen in the Emergency Department with chest pain. BER represents a benign variant of the normal electrocardiogram and is one of several syndromes producing electrocardiographic ST segment elevation (STE). The electrocardiogram (EKG) findings of BER include diffuse or widespread ST segment elevation, upward concavity of the initial portion of the ST segment, notching or slurring of the terminal QRS complex, and concordant T waves of large amplitude. This article focuses on BER and includes the electrocardiographic findings useful in making the diagnosis as well as distinguishing BER from other STE syndromes.

Benign early repolarization: Electrocardiographic manifestations and differentiation from other ST segment elevation syndromes

Early repolarization, also known as benign early repolarization (BER) or normal variant, is noted in approximately 1% of the population and in up to 48% of patients seen in the emergency department with chest pain. BER represents a benign variant of the normal electrocardiogram and is one of several syndromes producing electrocardiographic ST segment elevation. BER electrocardiographically includes diffuse or widespread ST segment elevation, upward concavity of the initial portion of the ST segment, notching or slurring of the terminal QRS complex, and concordant T waves of large amplitude. This article focuses on BER and includes a discussion of the electrocardiographic tools useful in making this diagnosis and in distinguishing BER from other ST segment elevation syndromes.

Signal-averaged electrocardiograms in normal Doberman pinschers.

Signal-averaged electrocardiograms (SAECGs) were performed on nonsedated normal dogs in left-lateral recumbency. Following signal averaging, both time-domain and 3-dimensional frequency-domain analyses were performed. For time-domain analysis, the high-frequency QRS (HFQRS) duration, duration of the terminal QRS complex less than 40 microV (LAS40), and root mean square (RMS) voltages (microV) of the terminal 40 milliseconds (RMS40) and 30 milliseconds of the QRS complex were calculated. For frequency-domain analysis, correlation ratios were calculated for 30-, 40-, 50-, and 60-millisecond segment lengths begun 10, 15, or 20 milliseconds before the end of the QRS complex. Spectro-temporal mapping was also performed. All of the parameters of the SAECGs analyzed in the time domain were associated with each other. LAS40 and RMS voltages regressed significantly (P < .0000) on the HFQRS duration. Ninety-five percent of the HFQRSs were 55-75 milliseconds, 95% of the LAS40s were 9-26 milliseconds, and 95% of the RMS40 voltages were 177-444 microV. None of the SAECGs contained evidence of ventricular late potentials. Spectro-temporal maps were similar in each dog when the same segment lengths and starting points were compared. No evidence of ventricular late potentials was observed. Correlation ratios were lower when windowed segments included 15 or 20 milliseconds (versus 10 milliseconds) of the terminal QRS complex. When only 10 milliseconds of the terminal QRS complex were included in windowed segments, the mean correlation ratios for 30- and 40-millisecond segment lengths were > 0.8 and > 0.61 in 67% of all analyses, respectively.

Possible late potentials in 4 dogs with sustained ventricular tachycardia.

Signal-averaged electrocardiograms (SAEKGs) were performed on 4 dogs with sustained ventricular tachycardia. Quantitative and qualitative analyses of SAEKGs were consistent with the presence of late potentials. Two of the 4 dogs subsequently died suddenly, and ventricular tachycardia and ventricular fibrillation were observed in 1 dog. High-frequency QRS durations (75-90 milliseconds), duration of low amplitude (less than 40 microV) signals during the terminal QRS complex (LAS40) (28-40 milliseconds), root mean square voltages of the terminal 40 milliseconds of the QRS complex (RMS40) (124-6.5 microV), and root mean square voltages of the terminal 30 milliseconds of the QRS complex (RMS30) (13-2.1 microV) differed from results obtained in 68 of 70 control dogs. Echocardiographic data suggested dilated cardiomyopathy in 2 dogs and the cause of the arrhythmia in 2 dogs was not determined. The SAEKG may be a useful adjunct in identifying a subset of dogs with ventricular tachyarrhythmias that are at high risk for sustained ventricular tachycardia and sudden death. The sensitivity, specificity, and predictive accuracies of the technique remain to be determined.