Vectorcardiogram Research Articles

Self-organizing visualization and pattern matching of vectorcardiographic QRS waveforms

QRS morphology is commonly used in the electrocardiographic diagnosis of ventricular depolarization such as left bundle branch block (LBBB) and ventricular septal infarction. We investigated whether pattern matching of QRS loops in the 3-dimensional vectorcardiogram (VCG) will improve the grouping of patients whose space-time electrical activity akin to each other, thereby assisting in clinical decision making. First, pattern dissimilarity of VCG QRS loops is qualitatively measured and characterized among patients, resulting in a 93×93 distance matrix of patient-to-patient dissimilarity. Each patient is then represented as a node in the network (or a star in the galaxy), but node locations are optimized to preserve the dissimilarity matrix. The optimization is achieved with a self-organizing algorithm that iteratively minimizes the network energy. Experimental results showed that patients’ locations converge as the representation error reaches a stable phase. The convergence is independent of initial locations of network nodes. Most importantly, 93 patients are automatically organized into 3 clusters of healthy control, LBBB, and infarction. Spatial coordinates of nodes (or patients) are evidently novel predictors that can be used in the computer-assisted detection of cardiac disorders. Self-organizing pattern matching is shown to have strong potentials for large-scale unsupervised learning of patient groups.

Detection of elevated pulmonary pressures by the ECG-derived ventricular gradient: A comparison of conversion matrices in patients with suspected pulmonary hypertension

BackgroundThe aim was to assess the diagnostic value of the Inverse Dower (INVD)-derived vectorcardiogram (VCG) and the Kors-derived VCG to detect elevated systolic pulmonary artery pressure (SPAP) in suspected pulmonary hypertension (PH). MethodsIn 132 patients, morphologic variables were evaluated by comparing the VCG parameters synthesized by INVD and Kors matrix. Comparison of the diagnostic accuracy of detecting SPAP ≥50mmHg between the matrices was performed by ROC curve analysis and logistic regression analysis. ResultsMost VCG parameters differed significantly between INVD and Kors. ROC analysis for detection of SPAP ≥50mmHg by VG projected on the X-axis demonstrated no difference (p=0.99) between INVD (AUC=0.80) and Kors (AUC=0.80). Both the INVD- and Kors-derived VCG provided significant diagnostic information on the presence of SPAP ≥50mmHg (INVD, OR 1.05, 95%CI 1.03–1.07; P<0.001; Kors, OR 1.05, 95%CI 1.03–1.08; P<0.001). ConclusionAlthough there were significant differences in measures of vector morphology, both INVD- and Kors-derived VCG demonstrated equal clinical performance in case of elevated SPAP.

89-02: Vectorcardiographic QRS area identifies delayed left ventricular lateral wall activation determined by electroanatomic mapping in candidates for cardiac resynchronization therapy

Introduction: Delayed left ventricular lateral wall (LVLW) activation is considered the electrical substrate underlying LV dysfunction amenable to cardiac resynchronization therapy (CRT). The purpose of this study was to assess LVLW activation in CRT candidates using coronary venous electroanatomic mapping (EAM) and to investigate whether the QRS area (QRSAREA) on the vectorcardiogram (VCG) can identify delayed LVLW activation. Methods: 51 consecutive CRT candidates (29 LBBB, 15 IVCD, 7 RBBB) underwent intraprocedural coronary venous EAM using EnSite NavX. VCGs were constructed from preprocedural digital 12-lead ECGs using the Kors method. QRSAREA was assessed and compared to QRS duration and 5 different LBBB definitions. Results: Delayed LVLW activation (activation time >75% of QRS duration, example in figure) occurred in 38 of 51 patients (29/29 LBBB, 8/15 IVCD, 1/7 RBBB). QRSAREA was larger in patients with than in patients without delayed LVLW activation (108 ± 42 µVs vs 51 ± 27 µVs, P < .001), and identified delayed LVLW activation better than QRS duration (area under the curve 0.89 [95% confidence interval 0.79–0.99] vs 0.49 [95% confidence interval 0.33-0.65] ). QRSAREA >69 µVs diagnosed delayed LVLW activation with a higher sum of sensitivity (87%) and specificity (92%) than any of the LBBB definitions. Of the different LBBB definitions, the European Society of Cardiology textbook definition performed best with sensitivity of 76% and specificity of 100%. Conclusion: Coronary venous EAM can be used during CRT implantation to determine the presence of delayed LVLW activation. QRSAREA is a noninvasive alternative for intracardiac measurements of electrical activation, which identifies delayed LVLW activation better than QRS duration and LBBB morphology.

Effects of Preexcitation Syndrome on Terminal QRS Vector Observed in Spatial Vector.

Preexcitation syndrome could affect terminal QRS vector, which is not emphasized in clinic. In this study, we made a comparison between vectorcardiogram (VCG) before and after ablation to observe the change of terminal QRS vector. Furthermore, the relationship between the change of terminal QRS vector and accessory pathway (AP) as well as the change of initial QRS vector (delta vector) was analyzed. Thirty patients who were proved to have a single AP by ablation were included. All patients were divided into seven groups based on the AP location. Comparison between VCG before and after ablation was made to observe the change of terminal and delta vector. The relationship between the change of terminal QRS vector and AP location as well as delta vector was analyzed. (1) All 30 patients had a change in terminal QRS vector (elevation and/or azimuth) in comparison to postablation VCG. (2) The change of terminal QRS vector was related to delta vector and AP location. The agreement and consistency between the change of terminal QRS vector and delta vector were 91.65% and 0.856 (P < 0.01), respectively. (1) Both initial and terminal QRS vector are affected by the antegrade conduction of AP. The change of terminal QRS vector is related to the AP location and delta vector. (2) The effect of preexcitation syndrome on QRS terminal vector is shown as more intuitive and easy in spatial vector by comparison with electrocardiogram, which is helpful for the diagnosis of atypical preexcitation and localization of AP.

Changes in P-wave morphology after pulmonary vein isolation: insights from computer simulations.

Apparently conflicting clinical measurements of P-wave duration (PWD) pre- vs. post-ablation have been reported. To assist the interpretation of these clinical data, we used a computer model of the atria and torso to simulate P waves before and after pulmonary vein (PV) isolation. Twenty ablation patterns were designed (segmental or ipsilateral ablation; five distances to PV sleeves; addition of a roof line or not). Possible PV reconnections were introduced as gaps in the ablation lines. PWD and area were measured during sinus rhythm in vectorcardiogram (VCG) magnitude signals and on the 16-lead ECG before and after ablation, and after PV reconnection. After PV isolation, biatrial activation time was prolonged by 0-5 ms without and by 48±5 ms with roof line. Yet PWD was shortened in lead V3 and V4 by up to 15 ms. The effect of ablation on P-wave morphology was stronger when larger PV areas were isolated. Segmental and ipsilateral PV isolation led to concordant results. P-wave area increased in V1 and decreased in V6. Changes in PWD and area on the VCG were sensitive to the threshold used for detecting the end of the P wave. The occurrence of PV reconnection was best identified on leads V3, V4, and V9. PV isolation and reconnection induced measurable changes on the 16-lead ECG that might be used to improve patient follow-up after ablation.

Continuous Rapid Quantification of Stroke Volume Using Magnetohydrodynamic Voltages in 3T Magnetic Resonance Imaging

To develop a technique to noninvasively estimate stroke volume in real time during magnetic resonance imaging (MRI)-guided procedures, based on induced magnetohydrodynamic voltages (VMHD) that occur in ECG recordings during MRI exams, leaving the MRI scanner free to perform other imaging tasks. Because of the relationship between blood flow (BF) and VMHD, we hypothesized that a method to obtain stroke volume could be derived from extracted VMHD vectors in the vectorcardiogram (VCG) frame of reference (VMHDVCG). To estimate a subject-specific BF-VMHD model, VMHDVCG was acquired during a 20-s breath-hold and calibrated versus aortic BF measured using phase-contrast magnetic resonance in 10 subjects (n=10) and 1 subject diagnosed with premature ventricular contractions. Beat-to-beat validation of VMHDVCG-derived BF was performed using real-time phase-contrast imaging in 7 healthy subjects (n=7) during 15-minute cardiac exercise stress tests and 30 minutes after stress relaxation in 3T MRIs. Subject-specific equations were derived to correlate VMHDVCG with BF at rest and validated using real-time phase-contrast. An average error of 7.22% and 3.69% in stroke volume estimation, respectively, was found during peak stress and after complete relaxation. Measured beat-to-beat BF time history derived from real-time phase-contrast and VMHD was highly correlated using a Spearman rank correlation coefficient during stress tests (0.89) and after stress relaxation (0.86). Accurate beat-to-beat stroke volume and BF were estimated using VMHDVCG extracted from intra-MRI 12-lead ECGs, providing a means to enhance patient monitoring during MR imaging and MR-guided interventions.

Automatic cardiac arrhythmia detection and classification using vectorcardiograms and complex networks.

This paper intends to bring new insights in the methods for extracting features for cardiac arrhythmia detection and classification systems. We explore the possibility for utilizing vectorcardiograms (VCG) along with electrocardiograms (ECG) to get relevant informations from the heartbeats on the MIT-BIH database. For this purpose, we apply complex networks to extract features from the VCG. We follow the ANSI/AAMI EC57:1998 standard, for classifying the beats into 5 classes (N, V, S, F and Q), and de Chazal's scheme for dataset division into training and test set, with 22 folds validation setup for each set. We used the Support Vector Machinhe (SVM) classifier and the best result we chose had a global accuracy of 84.1%, while still obtaining relatively high Sensitivities and Positive Predictive Value and low False Positive Rates, when compared to other papers that follows the same evaluation methodology that we do.

Vectorcardiographic QRS area identifies delayed left ventricular lateral wall activation determined by electroanatomic mapping in candidates for cardiac resynchronization therapy

Delayed left ventricular (LV) lateral wall (LVLW) activation is considered the electrical substrate underlying LV dysfunction amenable to cardiac resynchronization therapy (CRT). The purpose of this study was to assess LVLW activation in CRT candidates using coronary venous electroanatomic mapping (EAM) and to investigate whether the QRS area (QRSAREA) on the vectorcardiogram (VCG) can identify delayed LVLW activation. Fifty-one consecutive CRT candidates (29 left bundle branch block [LBBB], 15 intraventricular conduction delay [IVCD], 7 right bundle branch block [RBBB]) underwent intraprocedural coronary venous EAM using EnSite NavX. VCGs were constructed from preprocedural digital 12-lead ECGs using the Kors method. QRSAREA was assessed and compared to QRS duration and 5 different LBBB definitions. Delayed LVLW activation (activation time >75% of QRS duration) occurred in 38 of 51 patients (29/29 LBBB, 8/15 IVCD, 1/7 RBBB). QRSAREA was larger in patients with than in patients without delayed LVLW activation (108 ± 42 µVs vs 51 ± 27 µVs, P < .001), and identified delayed LVLW activation better than QRS duration (area under the curve 0.89 [95% confidence interval 0.79-0.99] vs 0.49 [95% confidence interval 0.33-0.65]). QRSAREA >69 µVs diagnosed delayed LVLW activation with a higher sum of sensitivity (87%) and specificity (92%) than any of the LBBB definitions. Of the different LBBB definitions, the European Society of Cardiology textbook definition performed best with sensitivity of 76% and specificity of 100%. Coronary venous EAM can be used during CRT implantation to determine the presence of delayed LVLW activation. QRSAREA is a noninvasive alternative for intracardiac measurements of electrical activation, which identifies delayed LVLW activation better than QRS duration and LBBB morphology.

T Vector and Loop Characteristics Improve Detection of Myocardial Injury After Infarction

Electrocardiography (ECG) is widely used to detect myocardial injury. ECG recordings after subendocardial, non-ST-elevation myocardial infarction (MI) may lack striking infarct patterns. A vectorcardiogram (VCG) of the T wave is a three-dimensional characterization of the ventricular repolarization and identifies abnormalities at an advanced level of analysis, which would normally be done manually from conventional ECG. Several parameters describing T vector loop morphology and T vector spatial orientation are examined with regard to their suitability for late MI detection. The discriminatory performance of VCG analysis is compared to that of conventional ECG analysis in identifying post-MI patients. T vector and T loop parameters as well as infarct indicators of the ECG recordings were calculated for 114 subjects: 59 patients (42 males; mean age: 54 years) 15 days after MI (11.9 ± 6.9 d) and 55 healthy controls (27 males; mean age: 49 years). ECG infarct indicators correctly identified 75.2 % of patients, while T vector and loop parameters correctly identified 83.2 % of patients. Discrimination analysis revealed a sensitivity of 66.7 % and a specificity of 77.4 % for conventional ECG, and a sensitivity of 71.7 % and a specificity of 88.7 % for the VCG parameters. T vector and loop characteristics were superior to conventional ECG in separating patients from controls. T vector ECG can improve the detection of myocardial injury and is applicable to the analysis of cardiac repolarization.

An in-silico analysis of the effect of heart position and orientation on the ECG morphology and vectorcardiogram parameters in patients with heart failure and intraventricular conduction defects

AimThe aim of this study was to investigate the influence of geometrical factors on the ECG morphology and vectorcardiogram (VCG) parameters. MethodsPatient-tailored models based on five heart-failure patients with intraventricular conduction defects (IVCDs) were created. The heart was shifted up to 6cm to the left, right, up, and down and rotated ±30° around the anteroposterior axis. Precordial electrodes were shifted 3cm down. ResultsGeometry modifications strongly altered ECG notching/slurring and intrinsicoid deflection time. Maximum VCG parameter changes were small for QRS duration (−6% to +10%) and QRS-T angle (−6% to +3%), but considerable for QRS amplitude (−36% to +59%), QRS area (−37% to +42%), T-wave amplitude (−41% to +36%), and T-wave area (−42% to +33%). ConclusionThe position of the heart with respect to the electrodes is an important factor determining notching/slurring and voltage-dependent parameters and therefore must be considered for accurate diagnosis of IVCDs.

Vectorcardiography for optimization of stimulation intervals in cardiac resynchronization therapy.

Current optimization of atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) is time consuming and subject to noise. We aimed to prove the principle that the best hemodynamic effect of CRT is achieved by cancelation of opposing electrical forces, detectable from the QRS morphology in the 3D vectorcardiogram (VCG). Different degrees of left (LV) and right ventricular (RV) pre-excitation were induced, using variation in AV intervals during LV pacing in 20 patients with left bundle branch block (LBBB) and variation in VV intervals during biventricular pacing in 18 patients with complete AV block or atrial fibrillation. The smallest QRS vector area identified stimulation intervals with minimal systolic stretch (median difference [IQR] 20 ms [−20, 20 ms] and maximal hemodynamic response (10 ms [−20, 40 ms]). Reliability of VCG measurements was superior to hemodynamic measurements. This study proves the principle that VCG analysis may allow easy and reliable optimization of stimulation intervals in CRT patients.

Abstract 11500: J-Point Syndromes From the Vectorcardiogram Point of View

Introduction: The potentially fatal outcome related to J-point syndromes raises heated debate about the pathophysiology of Brugada syndrome (BrS) and early repolarization (ER). It has not been established yet if they carry a depolarization, a repolarization or both electrical problems. Hypothesis: The objective of this study was to define BrS and ER characteristic and distinctive electrical patterns, using aspects of the QRS complex loops, ST-segments and T-waves obtained from the classical vectorcardiogram (VCG). Methods: VCG loops of 29 BrS patients and 30 individuals with ER were analyzed qualitatively and quantitatively. Non-paired t-test and ROC curve statistics were used (p≤ 0.05 significance level). Results: Mean age: 47±15 vs 38±14y.o. (p=0.02), 66% vs 90% male (p=0.03); QRS duration: 102±10 vs 95±13ms (p=0.03), BrS vs ER, respectively. All QRS loops showed an end-conduction delay located in right posterior-anterior quadrant (BrS) or left posterior-anterior quadrant (ER). A “break” in the QRS loop end, very much resembling a “nose”, is seen in BrS (100%), while in ER the QRS loop “break” was smoother with a “fish-hook” shape (100%). Normal T-wave loops with counterclockwise rotation were present in 86.2% of BrS and 73.3% of ER. End-conduction delay of 34±6ms vs 22±5ms (p&lt;0.0001); J-point amplitude of 0.14±0.07mV vs 0.22±0.08mV (p&lt;0.0001); SÂJ-point of 103±19° vs 55±16° (p&lt;0.0001), BrS vs ER, respectively. A 75o cutoff value (ROC analysis) could diagnose BrS (96.6% sensitivity, 93.3% specificity). Conclusions: The vectorcardiogram could clearly differentiate BrS from ER qualitatively as well as quantitatively: the transverse plane of VCG shows in BrS cases a longer end-conduction delay (&gt;30ms), with a right-sided and posterior-anteriorly oriented loop, with the aspect of a “nose”; in ER cases the end-conduction delay is shorter, located at the left posterior-anterior quadrant, with the aspect of a “fish-hook”. With a J-point angle above 75o we could diagnose BrS with 96.6% sensitivity and 93.3% specificity.

Abstract 11403: T-Wave Area as an Additional Predictor of Volumetric and Clinical Response to Cardiac Resynchronization Therapy

Purpose: Chronic heart failure (HF) patients with a left ventricular (LV) conduction delay, mostly due to left bundle branch block (LBBB), derive benefit from cardiac resynchronization therapy (CRT). However, approximately 30% of patients do not improve clinically after CRT. We investigated whether T-wave analysis can improve patient selection. Methods: The study population comprised 335 CRT recipients with baseline 12-lead electrocardiogram recordings. Echocardiographic response after 6-months CRT was defined as a ≥ 5% increase in LV ejection fraction (LVEF). Patients were assessed for HF hospitalization and death separately, as well as both combined with heart transplantation and LVAD implantation (HTLD) at 3 years follow-up. T-wave area was determined in vectorcardiograms (VCGs), constructed from digital 12-lead ECGs using an adapted Kors method. Results: Logistic regression models indicated repolarization variables as good predictors of CRT response. The VCG-derived T-wave area predicted CRT response (odds ratio (OR) per 10 μVs increase 1.172 (p &lt; 0.001)), even better than QRS-wave area (OR = 1.116 (p = 0.001)). T-wave area had especially predictive value in LBBB patients (OR = 2.77 in LBBB vs. 1.09 in non-LBBB). This predictive value persisted after adjustment for multiple covariates, such as gender, ischemia, age, hypertension, coronary artery bypass graft, and the usage of diuretics and beta-blockers. The table depicts that patients with large T-wave area showed a larger increase in LVEF and a lower occurrence of the end-points HF hospitalization, death and HTLD, as compared to those with a small T-wave area, the difference being significant for LBBB patients. Conclusions: In patients with LBBB morphology of the QRS complex, a larger baseline T-wave area is an important additional predictor of both volumetric and long-term clinical response following CRT.

Vectorcardiographic QRS area as a novel predictor of response to cardiac resynchronization therapy

BackgroundQRS duration and left bundle branch block (LBBB) morphology are used to select patients for cardiac resynchronization therapy (CRT). We investigated whether the area of the QRS complex (QRSAREA) on the 3-dimensional vectorcardiogram (VCG) can improve patient selection. MethodsVCG (Frank orthogonal lead system) was recorded prior to CRT device implantation in 81 consecutive patients. VCG parameters, including QRSAREA, were assessed, and compared to QRS duration and morphology. Three LBBB definitions were used, differing in requirement of mid-QRS notching. Responders to CRT (CRT-R) were defined as patients with ≥15% reduction in left ventricular end systolic volume after 6months of CRT. ResultsFifty-seven patients (70%) were CRT-R. QRSAREA was larger in CRT-R than in CRT non-responders (140±42 vs 100±40 μVs, p<0.001) and predicted CRT response better than QRS duration (AUC 0.78 vs 0.62, p=0.030). With a 98μVs cutoff value, QRSAREA identified CRT-R with an odds ratio (OR) of 10.2 and a 95% confidence interval (CI) of 3.4 to 31.1. This OR was higher than that for QRS duration >156ms (OR=2.5; 95% CI 0.9 to 6.6), conventional LBBB classification (OR=5.5; 95% CI 0.9 to 32.4) or LBBB classification according to American guidelines (OR=4.5; 95% CI 1.6 to 12.6) or Strauss (OR=10.0; 95% CI 3.2 to 31.1). ConclusionQRSAREA is an objective electrophysiological predictor of CRT response that performs at least as good as the most refined definition of LBBB. Condensed abstractIn 81 candidates for cardiac resynchronization therapy (CRT) we measured the area of the QRS complex (QRSAREA) using 3-dimensional vectorcardiography. QRSAREA was larger in echocardiographic responders than in non-responders and predicted CRT response better than QRS duration and than simple LBBB criteria. QRSAREA is a promising electrophysiological predictor of CRT response.

Abstract 417: Correlation Between The Mass Of The Left Ventricle By Echocardiogram And The Electrocardiographic And Vectorcardiographic Criteria In Left Ventricular Hypertrophy In Patients With Resistant Hypertension.

The difficult of most of patients in access the echocardiogram (ECHO) diagnosis services are common in small cities located far away from reference towns centers. Graphics methods (GM) , like electrocardiogram (ECG) and vectorcardiogram (VCG), have high sensibility but low specificity in detect LVH. The ECHO diagnosis criterion of LVH based on indexed left ventricular mass (LVMI), is usual and used now a days beside other methods like Nuclear Magnetic Ressonance. Objectives: Evaluate LVMI correlation with ECG and VCG criteria in patients with RHTN. Population: 120 RHTN patients were evaluated. Excluded patients with diseases: diabetes, valve heart, coronary, Chagas, renal, obese and excentric LVH. Study Protocol: After 06 months, between 2008&amp; 2011, measures BP monthly following the technique (JNC-VII) and receive directions, as well as pill counts (the method of Taylor) to assess compliance. Underwent echocardiography, following the recommendations of the ASE, then ECG and VCG. Formula to calculate LVMI : LVMI = 0,8 x{1.04x [(SIVD + DDVE + PPVED)3 - (DDVE)3]} + 0,6 g/(M-60) x 0,01 + H) ECG and VCG criteria to detect LVH: ECG Criterion: Sokolow-Lyon I(SL-I):SV1+RV5(6)≥3.5mV &amp; II(SL-II):RavL≥1.1mV; Gübner(G):SDI+RDIII≥2.5mV; Cornell(C):RavL+SV3≥2/2.8mV(woman/man); Romhilt-Estes(RE):Point Score≥5points; Perugia(P): RE or C(modify) or Strain. VCG Criterion: Mag Max QRS on Planes horizontal(HP) &amp; frontal(FP): vector≥2mV and right saggital(rSP): vector≥1.6 mV; Defl QRS HP &amp; rSP: angle≥ 330° &amp; ≥150°. Statistical Analysis: The correlations were obtained using the Pearson’s correlation formula and the is considered a good correlation values above 50%, and excellent correlation values above 70%. Values less than 50% are considered weak correlation. Results are expressed as mean and standard deviation, and relative values in percentage. Results: Criterion Correlation R SL- I 0.49 G 0.42 SL-II 0.50 C 0.49 RE 0.51 Mag Max QRS HP 0,59 Mag Max QRS rSP 0.60 Mag Max QRS FP 0.51 Defl QRS PH 0.33 Defl QRS rSP 0.56 Conclusion: The better correlation between LVMI and ECG criterion was Romhilt-Estes and the better for the VCG was Mag Max QRS HP. The VCG had the best correlation. Considered a good alternative to estimate the LVMI.

Abstract 217: Analysis Of Aspects Electrocardiographic, Vectorcardiographic And Echocardiographic Of Left Ventricular Hypertrophy In Resistant Hypertension

Introduction: Resistant hypertension (RHTN) defined as the failure to reach goal BP, with at least 3 drugs including a diuretic (JNC-VII). Affects 5-30% HTN, become high risk of developing target organ damage, like LVH rasing morbi-mortality (Framingham Study). Then is necessary a better treatment plan the early diagnosis. The electrocardiogram (ECG) and the vectorcardiogram (VCG), graphic methods (GM), alone, present, in spite of high specificity, have low sensitivity compared with echocardiography (ECHO). Objective: Analyze ECG/VCG for LVH diagnosed by ECHO in RHTN. Methods: Population: 120 RHTN. Excluded diabetic, valve heart, coronary, renal diseases and obese. Study Protocol: After 06 months, between 2008 and 2011, measures BP monthly (JNC-VII) receiving directions, as well as pill counts (Taylor Method) to assess compliance. Underwent ECHO (ASE) then GM. ECG&amp;VCG methods: ECG Criterion: Sokolow-Lyon I(SL-I):SV1+RV5(6)≥3.5mV &amp; II(SL-II):RavL≥1.1mV; Gübner(G):SDI+RDIII≥2.5mV;Cornell(C):RavL+SV3≥2/2.8mV(woman/man);Romhilt-Estes(RE):Point Score≥5points; Perugia(P): RE or C(modify) or Strain. VCG Criterion: Mag Max QRS on Planes horizontal(HP) &amp; frontal(FP): vector≥2mV and right saggital(rSP): vector≥1.6 mV; Defl QRS HP &amp; rSP: angle≥ 330° &amp; ≥150°. Statistical Analysis: Sensibility(SENS), accuracy(ACCU) and specificity(SPEC) to analyse GM. Results: Criterion Sens (%) Accu (%) Spec (%) SL-I 27 (16/60) 61 (73/120) 93 (56/60) G 18 (11/60) 58 (69/120) 97 (58/60) SL-II 18 (11/60) 58 (69/120) 97 (58/60) C 25 (15/60) 59 (71/120) 93 (56/60) RE 32 (19/60) 58 (77/120) 95 (58/60) P 50 (30/60) 68 (81/120) 85 (51/60) Mag Max QRS PH 28 (17/60) 61 (73/120) 93 (56/60) Mag Max QRS PSr 12 (07/60) 52 (62/120) 92 (55/60) Mag Max QRS PF 25 (15/60) 57 (68/120) 88 (53/60) Defl QRS PH 12 (07/60) 52 (62/120) 92 (55/60) Defl QRS PSr 13 (08/60) 50 (60/120) 87 (52/60) COMBINED* 70 (42/60) 76 (91/120) 82 (49/60) Conclusion: ECG: P had the best SENS &amp; ACCU, SL-II and G both showed the best SPEC. VCG: best criteria Mag Max QRS PH. Combined criteria* using best SENS and ACCU of each GM improved SENS &amp; ACCU demonstrated SPEC without injury to LVH in RHTN detection. Can be worn with method in a cost effectiveness ratio and in places where access is difficult to ECHO to be performed.

Electrocardiogram derived respiratory rate from QRS slopes and R-wave angle.

A method for estimating respiratory rate from electrocardiogram (ECG) signals is presented. It is based on QRS slopes and R-wave angle, which reflect respiration-induced beat morphology variations. The 12 standard leads, 3 leads from vectorcardiogram (VCG), and 2 additional non-standard leads derived from VCG loops were analyzed. The following series were studied as ECG derived respiration (EDR) signals: slope between the peak of Q and R waves, slope between the peak of R and S waves, and the R-wave angle. Information from several EDR signals was combined in order to increase the robustness of estimation. Evaluation is performed over two databases containing ECG and respiratory signals simultaneously recorded during two clinical tests with different characteristics: tilt test, representing abrupt cardiovascular changes, and stress test representing a highly non-stationary and noisy environment. A combination of QRS slopes and R-wave angle series derived from VCG leads obtained a respiratory rate estimation relative error of 0.50 ± 4.11% (measuring 99.84% of the time) for tilt test and 0.52 ± 8.99% (measuring 96.09% of the time) for stress test. These results outperform those obtained by other reported methods, both in tilt and stress testing.

Patient-specific modeling of ventricular activation pattern using surface ECG-derived vectorcardiogram in bundle branch block

Patient-specific computational models have promise to improve cardiac disease diagnosis and therapy planning. Here a new method is described to simulate left-bundle branch block (LBBB) and RV-paced ventricular activation patterns in three dimensions from non-invasive, routine clinical measurements. Activation patterns were estimated in three patients using vectorcardiograms (VCG) derived from standard 12-lead electrocardiograms (ECG). Parameters of a monodomain model of biventricular electrophysiology were optimized to minimize differences between the measured and computed VCG. Electroanatomic maps of local activation times measured on the LV and RV endocardial surfaces of the same patients were used to validate the simulated activation patterns. For all patients, the optimal estimated model parameters predicted a time-averaged mean activation dipole orientation within 6.7 ± 0.6° of the derived VCG. The predicted local activation times agreed within 11.5 ± 0.8 ms of the measured electroanatomic maps, on the order of the measurement accuracy.

Directionality and proportionality of the ST and ventricular gradient difference vectors during acute ischemia

BackgroundThe ECG is important in diagnosis and triage in the initial phase of the acute coronary syndrome (ACS). The primary goal of making an ECG at first medical contact should be the reliable detection of cardiac ischemia, thus facilitating a correct triage by corroborating the diagnosis of ACS. Ischemia detection by ST amplitude analysis is limited to situations in which there is an identifiable J point. The ventricular gradient (VG) is independent of conduction and might be an alternative ECG-based variable for ischemia detection. MethodsWe studied vectorcardiograms (VCGs) synthesized of the ECGs of 67 patients who underwent elective PTCA with prolonged balloon occlusions (mean±SD occlusion duration 214±77s), and computed, during occlusions, the changes of the ST and VG vectors with respect to baseline, ΔST and ΔVG, and the angle between these vectors, ∠(ΔST, ΔVG). We then analyzed directionality and proportionality of ΔST and ΔVG by performing linear regressions of ∠(ΔST, ΔVG) on time after occlusion, and of ΔVG on ΔST, respectively. ResultsLinear regression of ∠(ΔST, ΔVG) on time after occlusion yielded a slope of 1.55*10−3 °/s and an intercept of 11.96°; r2<0.001 (NS). Linear regression of ΔVG on ΔST on all data yielded a slope of 253mV and an intercept of 14.4mV•ms; r2=0.75 (P<0.001). Broken stick linear regression (breakpoint ΔST=0.255mV) yielded slopes of 330mV and 160mV, intercepts of 5.6mV•ms and 47.2mV•ms, and r2 values of 0.66 (P<0.001) and 0.63 (P<0.001) for the smaller and larger ΔST values, respectively. ConclusionOur study suggests that, because of the directionality and proportionality between ΔST and ΔVG, the change in the ventricular gradient, ΔVG, between a reference ECG and an ischemic ECG is a meaningful measure of ischemia.

3DQRS: A method to obtain reliable QRS complex detection within high field MRI using 12‐lead electrocardiogram traces

To develop a technique that accurately detects the QRS complex in 1.5 Tesla (T), 3T, and 7T MRI scanners. During early systole, blood is rapidly ejected into the aortic arch, traveling perpendicular to the MRI's main field, which produces a strong voltage (V(MHD)) that eclipses the QRS complex. Greater complexity arises in arrhythmia patients, since V(MHD) varies between sinus-rhythm and arrhythmic beats. The 3DQRS method uses a kernel consisting of 6 electrocardiogram (ECG) precordial leads (V1-V6), compiled from a 12-lead ECG performed outside the magnet. The kernel is cross-correlated with signals acquired inside the MRI to identify the QRS complex in real time. The 3DQRS method was evaluated against a vectorcardiogram (VCG)-based approach in two premature ventricular contraction (PVC) and two atrial fibrillation (AF) patients, a healthy exercising athlete, and eight healthy volunteers, within 1.5T and 3T MRIs, using a prototype MRI-conditional 12-lead ECG system. Two volunteers were recorded at 7T using a Holter recorder. For QRS complex detection, 3DQRS subject-averaged sensitivity levels, relative to VCG were: 1.5T (100% versus 96.7%), 3T (98.9% versus 92.2%), and 7T (96.2% versus 77.7%). The 3DQRS method was shown to be more effective in cardiac gating than a conventional VCG-based method.