Precordial Lead Research Articles

THE RESPONSE TO ANTITACHYCARDIA PACING DIFFERENTIATES VENTRICULAR FROM SUPRAVENTRICULAR TACHYCARDIA

High precordial lead ECGs were performed on 161 patients (60%) and SAECGs on 187 patients (70%). ST-segment elevation at baseline on standard or high-lead ECG was present in 120 patients (45%, Type 2 63%,Type 3 21%). 47 patients (18%) had a positive procainamide challenge. Of these patients, 35 patients had STelevation at baseline including Type 2 (n1⁄422) and Type 3 ECGs (n1⁄48), and 12 patients with no ST-elevation. Predictors for a positive challenge were: ethnicity, baseline ST-elevation, borderline or abnormal SAECG (Table). The combination of abnormal SAECG and any ST-elevation at baseline resulted in an even stronger association with positive procainamide challenge (OR 7.65; p<0.001). Therewere no associationswith age, sex, personal history ofUCA, or family history of Brugada ECG/Syndrome. CONCLUSION: The yield of procainamide infusion is markedly enhanced when the baseline ECG shows ST-elevation and in the presence of a concomitant borderline or abnormal SAECG. A baseline Type 2 or 3 ECG pattern is predictive for a positive procainamide challenge.

Common ECG Lead Placement Errors. Part II: Precordial Misplacements

Background: Electrocardiography is a very useful diagnostic tool. However, errors in placement of ECG leads can create artifacts, mimic pathologies, and hinder proper ECG interpretation. This is the second of a two-part series discussing how to recognize and avoid these errors. Methods: 12-lead ECGs were recorded in a single male healthy subject in his mid 20s. Various precordial lead misplacements were compared to ECG recordings from correct lead placement. Results: Precordial misplacements caused classical changes in ECG patterns. Techniques of differentiating these ECG patterns from true pathological findings were described. Conclusion: As in Part I of this series, recognition and interpretation of common ECG placement errors is critical in providing optimal patient care.

Can intensive exercise harm the heart? You can get too much of a good thing.

Can intensive exercise harm the heart? You can get too much of a good thing.

ST-segment elevation of right precordial lead (V4 R) is associated with multivessel disease and increased in-hospital mortality in acute anterior myocardial infarction patients.

ST segment elevation of chest lead V4 R is associated with worse prognosis in acute inferior ST-elevation myocardial infarction (STEMI). This study tried to determine the relationship between ST elevation in the right precordial lead V4 R and acute anterior STEMI. Prospective study of 144 consecutive anterior STEMI patients: all had 15-lead ECG recordings (12 conventional leads and V3 R-V5 R) obtained. Patients were classified into two groups on the basis of presence (Group I, 50 patients) or absence (Group II, 94 patients) of ST-segment elevation ≥0.5 mm in lead V4 R. Multivessel involvement was significantly higher in Group I compared with Group II (54% and 23% respectively, P < 0.001). Major adverse cardiac events and in-hospital mortality was also significantly higher for those in Group I (P < 0.02 for both). A significant correlation was found between in-hospital mortality and those in Group I (P = 0.03, OR: 6.27, CI: 1.22-32.3). There was an independent relationship between in-hospital mortality and V4 R-ST elevation (P = 0.03, OR: 11.64, CI: 1.3-27.4). ST segment elevation in chest lead V4 R is associated with multivessel disease and increased in-hospital mortality in patients with anterior STEMI that had undergone primary percutaneous coronary intervention to the left anterior descending artery.

Common ECG Lead Placement Errors. Part I: Limb lead Reversals

Background: Electrocardiography is a very useful diagnostic tool. However, errors in placement of ECG leads can create artifacts, mimic pathologies, and hinder proper ECG interpretation. This is the second of a two-part series discussing how to recognize and avoid these errors. Methods: 12-lead ECGs were recorded in a single male healthy subject in his mid 20s. Various precordial lead misplacements were compared to ECG recordings from correct lead placement. Results: Precordial misplacements caused classical changes in ECG patterns. Techniques of differentiating these ECG patterns from true pathological findings were described. Conclusion: As in Part I of this series, recognition and interpretation of common ECG placement errors is critical in providing optimal patient care.

Sensitivity of CIPS-computed PVC location to measurement errors in ECG electrode position: the need for the 3D Camera

BackgroundThe Cardiac Isochrone Positioning System (CIPS) is a non-invasive method able to localize the origins of PVCs, VT and WPW from the 12 lead ECG. The CIPS model integrates a standard 12-lead ECG with an MRI derived model of the heart, lungs, and torso in order to compute the precise electrical origin of a PVC from within the myocardium. To make these calculations, CIPS uses virtually represented ECG electrode positions. These virtual electrode positions, however, are currently assumed to represent the standard 12 lead positions in the model without taking into account the actual, anatomical locations on a patient. The degree of error introduced into the CIPS model by movement of the virtual electrodes is unknown. Therefore, we conducted a model-based study to determine the sensitivity of CIPS to changes in its virtually represented ECG electrode positions. MethodsPreviously, CIPS was tested on 9 patients undergoing PVC ablation, producing a precise myocardial PVC location for each patient. These initial results were used as controls in two different simulation experiments. The first moved all virtual precordial leads in CIPS simultaneously up and down to recalculate a PVC origin. The second moved each virtual precordial lead individually, using 8 points on multiple concentric circles of increasing radius to recalculate a PVC origin. The distance of the newly calculated PVC origin from the control origin was used as a metric. ResultsMoving either all electrodes simultaneously or each V1-6 precordial electrode independently resulted in non-linear and unpredictable shifts of the CIPS-computed PVC origin. Simultaneously moving all V1-6 precordial electrodes by 10mm increments produced a shift in CIPS-computed PVC origin between 0 and 62mm. Independently moving an electrode, a shift of more than 10mm resulted in an unpredictable CIPS-computed PVC origin relocation between 0 and 40mm. The effect of moving the virtual electrodes on CIPS modeling more pronounced the closer the virtual electrode was positioned to the actual PVC origin. ConclusionsSlight changes in the virtual positions of the V1-6 precordial electrodes produce marked, non-linear and unpredictable shifts in the CIPS-computed PVC origin. Thus, any variation in the physical ECG electrode placement on a patient can result in significant error within the CIPS model. These large errors would make CIPS useless and underscore the need for accurate, patient specific measurement of electrode position relative to the patient specific torso geometries. A potential solution to this problem could be the introduction of a 3D camera to incorporate accurate measurement of physical electrode placement into the CIPS model.Since the 3D camera software integrates the 3D imaged position of the electrode with the MRI derived torso model, it is conveniently incorporated in the next generation CIPS software to decrease the errors in modeled location of the electrodes. Thus, the 3D camera will be the IIIrd component of the CIPS to increase its accuracy in PVC, VT, and WPW localization.

Prevalence and Prognostic Significance of Low QRS Voltage Among the Three Main Types of Cardiac Amyloidosis

Low voltage is classically reported as an electrocardiographic (ECG) finding in cardiac amyloidosis (CA). We evaluated electrocardiograms to determine the prevalence of low voltage and its association with outcomes. Electrocardiograms in 200 patients with CA were reviewed. The presence of low voltage was assessed by all limb leads≤0.5 mV, all precordial leads≤1.0 mV, or Sokolow index≤.5 mV, and the association with time to adverse outcomes, including hospitalization, orthotopic heart transplant, and death, was assessed by the Cox proportional hazards model. Low voltage prevalence was 60% when using Sokolow index≤.5 mV, 34% by QRS amplitude≤0.5 mV in each limb lead, and 13% when ≤1.0 mV in each precordial lead with no differences in prevalence noted by the type of amyloid. Apart from atrial fibrillation and second-degree atrioventricular block being more common in wild type transthryretin cardiac amyloid (ATTRwt), the prevalence of ECG findings was similar among the 3 types of amyloid. Sokolow≤1.5 mV (HR 1.690; 95% CI of 1.069 to 2.672; p=0.0246) was independently associated with adverse outcomes. In conclusion, among the 3 main types of CA, the prevalence of low voltage is dependent on the method used for defining low voltage. Sokolow index≤1.5 mV indicated the highest prevalence and was associated with adverse outcomes in CA. Our data suggest that low voltage is a relatively late finding in CA and may not be useful for early identification.

Precordial electrode placement accuracy by nurses in a large midwestern tertiary care hospital.

A quality improvement project to increase the knowledge of nurses and the accuracy of electrocardiogram precordial lead placement among intensive care unit and progressive care unit staff was conducted using a single-group, pretest-posttest preexperimental design. Educational interventions based on the theory of planned behavior were developed from focus group data. A tip card, poster, and video were sequentially presented to more than 1,600 nurses. This resulted in statistically significant gains in both knowledge and accuracy (p < 0.02). This project supports the use of focus groups and the theory of planned behavior to guide education related to quality improvement.

Relationship between Echocardiographic LV Mass and ECG Based Left Ventricular Voltages in an Adolescent Population: Related or Random?

In attempts to detect diseases that may place adolescents at risk for sudden death, some have advocated for population-based screening. Controversy exists over electrocardiography (ECG) screening due to the lack of specificity, cost, and detrimental effects of false positive or extraneous outcomes. Analyze the relationship between precordial lead voltage on ECG and left ventricle (LV) mass by echocardiogram in adolescent athletes. Retrospective cohort analysis of a prospectively obtained population of self-identified adolescent athletes during sports screening with ECG and echocardiogram. Correlation between ECG LV voltages (R wave in V6 [RV6] and S wave in lead V1 [SV1]) was compared to echocardiogram-based measurements of left ventricular mass. Potential effects on ECG voltages by body anthropometrics, including weight, body mass index (BMI), and body surface area were analyzed, and ECG voltages indexed to BMI were compared to LV mass indices to analyze for improved correlation. A total of 659 adolescents enrolled in this study (64% male). The mean age was 15.4 years (14-18). The correlations between LV mass and RV6, SV1, and RV6 + SV1 were all less than 0.20. The false positive rate for abnormal voltages was relatively high (5.5%) but improved if abnormal voltages in both RV6 and SV1 were mandated simultaneously (0%). Indexing ECG voltages to BMI significantly improved correlation to LV mass, though false positive findings were increased (12.9%). There is poor correlation between ECG precordial voltages and echocardiographic LV mass. This relationship is modified by BMI. This finding may contribute to the poor ECG screening characteristics.

Interpretation of the Low-Voltage ECG

Interpretation of the Low-Voltage ECG

Differences in Negative T Waves Between Acute Pulmonary Embolism and Acute Coronary Syndrome

Patients with acute pulmonary embolism (APE) often have negative T waves (Neg T) in precordial leads at presentation, but this is also found in acute coronary syndrome (ACS) caused by left anterior descending coronary artery (LAD) disease. Differences in Neg T on admission electrocardiograms were studied between 107 patients with APE and 248 patients with ACS caused by LAD disease. All patients had Neg T in leads V1-4 and were admitted within 7 days from symptom onset. The number of leads with Neg T (4.8±1.8 vs. 5.5±1.7, P<0.001) and maximum magnitude of Neg T (3.4±2.0 vs. 4.7±3.3mm, P<0.001) were lower in APE. The frequency of occurrence of Neg T in each of the 12 leads, and the precordial lead with the greatest Neg T (peak Neg T) differed between APE and ACS (all P<0.05, respectively). APE was strongly associated with the presence of Neg T in both leads III and V1 and peak Neg T in leads V1-2. The combination of these 2 findings identified APE with 98% sensitivity, 92% specificity, and 94% predictive accuracy, which represented the highest diagnostic accuracy. Among patients with APE and ACS who have precordial Neg T, the presence of Neg T in leads III and V1 and/or peak Neg T in leads V1-2 simply but accurately differentiates APE from ACS.

A case of noncompaction at all segments of both right and left ventricles.

Background. Noncompaction/hypertrabeculation left ventricle (NCM/HVM) is most commonly reported in one or more segments of left ventricle and sometimes both ventricles. In this case, we present noncompaction of all segments of right and left ventricle, in a young man with mental retardation. Case Presentation. A 19-year-old male was referred to us with sudden dyspnea at rest and chest discomfort. He was a known case of mental retardation. He was born full term with birth weight = 1250 grams. On physical examination. A systolic murmur (II/VI) at left sternal border was heard. ECG showed increased voltage in precordial lead and deep ST segment depression. Chest X-ray (CXR) was within normal limits. Transthoracic echocardiography showed situs solitus, D loop, normal connection of great vessels, noncompaction LV at all segments (noncompaction/compaction = 2.5/0.5) with moderate systolic dysfunction (LVEF = 40%), diastolic dysfunction grade II, normal RV size with mild systolic dysfunction and hypertrabeculation, mild tricuspid regurgitation (TR), and normal pulmonary artery systolic pressure. After injection of agitated saline some bubbles were passed from right to left through patent foramen oval (PFO). Conclusions. Extensive sinusoid formation and trabeculation of RV and nearby all LV segments and its association with mental retardation suggest presence of strong genetic background.

Is there a role of MMA T wave alternans test for risk assessment in Brugada syndrome?

We read with interest the scientific letter by Drs. Yalin et al. (1) in The Anatolian Journal of Cardiology on the null outcome of their T-wave alternans (TWA) analysis by the Modified Moving Average method in patients with the Brugada syndrome. To date, TWA has been found in only two studies (2, 3) to predict lethal arrhythmias in Brugada syndrome patients, despite the fact that it is a prominent feature in their ambulatory ECG (AECG) recordings (4). Tada and colleagues (2) reported in a case series of 77 Brugada syndrome patients that overt TWA provoked by pilsicainide predicted spontaneous ventricular fibrillation with odds of 22.2 (95% CI: 3.3-149.9, p<0.001) after multivariate analysis. Most recently, Uchimura-Makita and coworkers (3) used MMA-based TWA in a case series of 42 Brugada syndrome patients and reported that the incidence of VF events was significantly higher among those with TWA ≥60μV than in those with lower TWA levels in lead V2 (p=0.0026). Dr. Yalin et al. (1) indicated that TWA testing was performed at the time of diagnosis of Brugada syndrome but did not state whether the patients were undergoing an exercise stress test or were at rest. While no studies have been undertaken to examine the optimum recording conditions for TWA analysis, it is reasonable to expect that TWA testing should be performed in conjunction with a diagnostic stressor such as the sodium channel blocking agents ajmaline, flecainide, procainamide, pilsicainide (2, 5), which unmask the Brugada syndrome (6), or during spontaneous appearance of the diagnostic Brugada ECG during daily activity at more normal heart rates (7), as is captured on AECG recordings. Indeed, the presence of TWA is considered to support the diagnosis of Brugada syndrome in asymptomatic patients with ST-segment elevation in at least one right precordial lead (6). Nighttime may be a particularly suitable period for AECG recording for TWA analysis, as the majority of ventricular fibrillation episodes in Brugada syndrome patients occur during sleep (8). The finding that TWA level is greatly reduced when heart rate is increased to 80-110 beats/min (7), such as is reached during exercise, may be the key to the failure of TWA testing by the spectral method (9, 10). If TWA had been analyzed from AECGs recorded during daily activity or sleep, it is likely that many if not all of the Brugada syndrome patients enrolled in this study may have shown significant levels of TWA. Determining the most appropriate setting for TWA testing in Brugada Syndrome patients will be an important contribution to stratification of their risk for lethal arrhythmias and ICD discharge. We compliment Dr. Yalin and colleagues on the valuable contributions of their study. With best regards,

The effect of precordial lead displacement on ECG morphology

Inaccurate electrode placement and differences in inter-individual human anatomies can lead to misinterpretation of ECG examination. The aim of the study was to investigate the effect of precordial electrodes displacement on morphology of the ECG signal in a group of 60 patients with diagnosed cardiac disease. Shapes of ECG signals recorded from precordial leads were compared with signals interpolated at the points located at a distance up to 5 cm from lead location. Shape differences of the QRS and ST-T-U complexes were quantified using the distribution function method, correlation coefficient, root-mean-square error (RMSE), and normalized RMSE. The relative variability (RV) index was calculated to quantify inter-individual variability. ECG morphology changes were prominent in all shape parameters beyond 2 cm distance to precordial leads. Lead V2 was the most sensitive to displacement errors, followed by leads V3, V1, and V4, for which the direction of electrodes displacement plays a key role. No visible changes in ECG morphology were observed in leads V5 and V6, only scaling effect of signal amplitude. The RV ranged from 0.639 to 0.989. Distortions in ECG tracings increase with the distance from precordial lead, which are specific to chosen electrode, direction of displacement, and for ECG segment selected for calculations.

Brugada-type patterns are easily observed in high precordial lead ECGs in collegiate athletes

BackgroundDisplacement of ECG leads can result in unwarranted findings. We assessed the frequency of Brugada-type patterns in athletes when precordial leads were purposely placed upward. MethodsFour hundred ninety-one collegiate athletes underwent two ECGs: one with standard leads, one with V1 and V2 along the 2nd intercostal space. A positive Brugada-type pattern was defined as ST elevation in V1 or V2 consistent with a Type 1, 2, or 3 pattern in the high-lead ECG. A control group was comprised of 181 outpatients. ResultsNo Type 1 patterns were seen. In 58 athletes (11.8%), a Brugada-type 2 or 3 pattern was observed. Those with Brugada-type 2 or 3 patterns were more likely male, taller, and heavier. In the control group, 18 (9.9%) had Brugada-type 2 or 3 patterns and were more likely male. ConclusionsProper lead positioning is essential to avoid unwarranted diagnosis of a Brugada-type ECG, especially in taller, heavier male athletes.

A new algorithm differentiate the septum originated ventricular arrhythmias from the free wall in the right ventricular outflow tract

Background: Until now, no ventricular arrhythmias QRS axis dominated ECG algorithms was used to differentiate VT/PVCs originating from the free wall or septum in the RVOT. In this study, we described new ECG criteria and investigated the sensitivity and specificity of them in practice. Method: Consecutive 121 patients with LBBB morphology and precordial transition lead ≥ V4 were successfully underwent mapping and ablation by contact or non-contact mapping. They were rerolled into the septum group (group A, n=95) and the free wall group (group B, n=26) according to VT/PVCs origin. We analyzed the ECG pattern with following criteria: 1) QRS axis >89°; 2) R wave amplitude III > II, and 3) A2III score including QRS axis 154.5ms (score = 1) and AVL QRS >156.5ms (score = 1). Results: Retrospective analysis that VT/PVC axis > 89° and R wave amplitude III > II predict the septum PVCs origin with 100.00% sensitivity, 93.94% specificity, and 97.78% positive prediction value. VT/PVCs A2III score ≥ 2 predicts VT/PVCs originating from the free wall in the RVOT with 80.00% sensitivity, 87.50% specificity and 84.09% positive predictor value. The new algorithm predicted VT/PVCs originating from the RVOT septum with the overall sensitivity, specificity, and positive predictor value were 91.30%, 81.48% and 97.78%. Prospective analysis in 23 patients showed that the new algorithm predicted VT/PVCs originating from the RVOT septum and free wall with overall sensitivity, specificity and positive predict value were 95.23%, 100% and 100%; 100.00%, 95.23%, and 66.67, respectively. Conclusion: VT/PVC axis > 89°, R wave amplitude III > II and A2III score ≤1 with very high sensitivity, specificity and positive prediction value for prediction VT/PVCs originating from septum origin in the RVOT.

GW24-e1760 Localisation of the origin site of outflow tract ventricular arrhythmias by surface electrocardiogram

ObjectivesIt has been reported that the origin site of idiopathic ventricular arrhythmias from left or right outflow tract (L/RVOT) can be judged from the transition of R/S on precordial lead...

GW24-e3925 The R-wave deflection interval in lead V3 combining with R-wave amplitude index in lead V1: A new surface ECG algorithm for distinguishing left from right ventricular outflow tract tachycardia origin in patients with transitional lead at V3

ObjectivesTo distinguish left ventricular outflow tract (LVOT) from right ventricular outflow tract (RVOT) origin in idiopathic premature ventricular contractions or ventricular tachycardia (PVCs/VT) patients with transitional lead at V3 is...

GW24-e2282 A new algorithm differentiate the septum originated ventricular arrhythmias from the free wall in the right ventricular outflow tract

ObjectivesUntil now, no ventricular arrhythmias QRS axis dominated ECG algorithms was used to differentiate ventricular tachycardia or premature ventricular complexes (VT/PVCs) originating from the free wall or septum in the...

Fragmented QRS Complex Predicts the Arrhythmic Events in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Fragmented QRS (frQRS) complex, with various morphology, has been recently described as a diagnostic criterion of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). However, there are little data regarding the prognostic role of frQRS in these patients. Therefore, we aimed to investigate the association of frQRS with arrhythmic events in patients with ARVC/D. Seventy-eight patients (51 men, 65.4%; mean age: 31.25 ± 11.5 years) with the diagnosis of ARVC/D according to 2010 modified Task Force Criteria were analyzed retrospectively. Baseline ECG evaluation revealed frQRS complex in 46 patients (59%). Eleven patients with complete/incomplete right bundle branch block were excluded from the study. The phenomenon of frQRS was defined as deflections at the beginning of the QRS complex, on top of the R-wave, or in the nadir of the S-wave similar to the definition in CAD in either one right precordial lead or in more than one lead including all standard ECG leads. During 38 ± 14 months follow-up period, 3 patients (3.8%) died suddenly, 36 patients (46.1%) experienced arrhythmic events (32 ventricular tachycardias [VTs] and 4 ventricular fibrillation [VF], 30 in the ICD group). The frQRS was significantly associated with arrhythmic events (P < 0.001). Also, the number of ECG leads with frQRS complex was higher in patients with arrhythmic events (5.08 ± 2.5 vs 1.14 ± 1.7, P < 0.001, respectively). The frQRS complex on standard 12-lead ECG predicts fatal and nonfatal arrhythmic events in patients with ARVC/D. Therefore, large scale and prospective studies are needed to confirm those findings.