Índice de varianza versus duración del complejo QRS para el diagnóstico de dispersión mecánica del ventrículo izquierdo

Introducción. En el complejo universo de la falla cardíaca, el pronóstico y el tratamiento de la misma sumaron un aspecto de valor durante la última década del siglo pasado, a partir del reconocimiento de la disincronía mecánica durante la sístole y las consiguientes propuestas de resincronización cardíaca. Desde los inicios la predicción de disincronía mecánica se ha fundamentado en la duración del complejo QRS, las imágenes y más recientemente el análisis del índice de varianza del QRS. Objetivo. Tomando como estándar la dispersión mecánica ventricular izquierda medida por ecocardiografía, valorar la concordancia entre duración promedio del QRS del electrocardiograma (ECG) versus el índice de varianza, en cuanto a sensibilidad, especificidad y valor predictivo de dispersión anormal. Métodos. Población de pacientes consecutivos citados para ecocardiografía strain, sin escara ventricular, para medir dispersión mecánica, duración promedio del QRS del ECG e índice de varianza espacial. Resultados. Se evaluaron 54 pacientes y 57 escenarios distintos. Edad promedio: 66,3±14,2 años; duración promedio del QRS fue de 119,7±31,5 mseg. El índice de varianza promedio fue 0,52±0,35. Un índice de varianza >0,4 demostró sensibilidad y especificidad de 82,6% y 64,7% respectivamente, para diagnóstico de dispersión mecánica anormal (e"56 mseg); valor predictivo positivo: 61,3%, negativo: 84,6%. La duración promedio de QRS e"130 mseg logró sensibilidad y especificidad de 52,6% y 71%, con valores predictivos positivo y negativo de 54,5% y 68,6%, respectivamente. La duración promedio del QRS no guarda dependencia con la disincronía mecánica (p=0,1458); la disincronía mecánica (>56 mseg) y la electrocardiografía de varianza, por otra parte, sí guardan dependencia muy significativa (p=0,0012). Los métodos no son comparables para diagnosticar disincronía (kappa=0,376). Conclusión. El ECG de varianza tiene mejor sensibilidad y valor predictivo negativo para el diagnóstico de dispersión mecánica ventricular izquierda valorada por ecocardiografía.

Introduction. The prediction of mechanical dyssynchrony has generally been based on the duration of the QRS complex, although other resources are available, such as the QRS variance index; these methods have not been compared with each other. Objective. Taking as a standard the left ventricular mechanical dispersion measured by speckle-tracking strain echocardiography, to assess the concordance between the average QRS duration of the standard electrocardiogram versus the spatial variance index in terms of sensitivity, specificity and predictive value of abnormal mechanical dispersion. Methods. Population of consecutive patients cited for strain echocardiography and without ventricular scar tissue, to measure mechanical dispersion, average QRS duration of the standard electrocardiogram and the variance index. Results. Fifty-four patients and 57 different scenarios were evaluated; the average age was 66.3±14.2 years, the QRS average duration on standard electrocardiogram was 119.7±31.5 ms. Average ID was 0.52±0.35. A spatial variation index >0.4 showed sensitivity and specificity of 82.6% and 64.7% respectively, for the diagnosis of abnormal mechanical dispersion (e"56 ms); positive predictive value: 61.3%, negative: 84.6%. The average duration of QRS e"130 ms achieved sensitivity and specificity of 52.6% and 71%, and the positive and negative predictive values were 54.5 and 68.6%, respectively. The average QRS duration are not interdependent with mechanical dyssynchrony (p=0.1458); mechanical dyssynchrony (>56 ms) and spatial variance electrocardiography are, nevertheless, clearly interdependent (p=0.0012). The methods are not comparable between them (kappa=0.376). Conclusion. The QRS variation electrocardiogram has better sensitivity and negative predictive value respect to the average QRS duration for the diagnosis of left ventricular mechanical dispersion prevalence, measured by echocardiography.

Introdução. No complexo universo da insuficiência cardíaca, seu prognóstico e tratamento agregaram valor durante a última década do século passado, com base no reconhecimento da dissincronia mecânica durante a sístole e nas propostas subsequentes de ressincronização cardíaca. Desde o início, a previsão da dissincronia mecânica tem sido baseada na duração do complexo QRS, nas imagens e, mais recentemente, na análise do índice de variância QRS. Objetivo. Tomando como padrão a dispersão mecânica do ventrículo esquerdo medida pelo ecocardiograma, avalie a concordância entre a duração média do QRS do eletrocardiograma (ECG) versus o índice de variância, em termos de sensibilidade, especificidade e valor preditivo de dispersão anormal. Métodos População de pacientes consecutivos citados para ecocardiograma de deformação, sem escara ventricular, para medir dispersão mecânica, duração média do QRS do ECG e índice de variância espacial. Resultados. Foram avaliados 54 pacientes e 57 cenários diferentes. Idade média: 66,3±14,2 anos; a duração média do QRS foi de 119,7±31,5 mseg. O índice de variância médio foi de 0,52±0,35. Um índice de variância >0,4 mostrou sensibilidade e especificidade de 82,6% e 64,7%, respectivamente, para diagnóstico de dispersão mecânica anormal (e"56 mseg); valor preditivo positivo: 61,3%, negativo: 84,6%. A duração média do QRS e"130 mseg alcançou sensibilidade e especificidade de 52,6% e 71%, com valores preditivos positivos e negativos de 54,5% e 68,6%, respectivamente. A duração média do QRS não depende de dissincronia mecânica (p=0,1458); dissincronia mecânica (>56 mseg) e eletrocardiografia de variância, por outro lado, têm dependência muito significativa (p=0,0012). Os métodos não são comparáveis para diagnosticar dissincronia (kappa=0,376). Conclusão. A variância do ECG apresenta melhor sensibilidade e valor preditivo negativo para o diagnóstico de dispersão mecânica do ventrículo esquerdo avaliada pelo ecocardiograma.

Echocardiographic, Electrocardiographic Changes and Clinical Outcomes of Patients Who Respond to Cardiac Resynchronization Therapy after One Year

BACKGROUND: Response to cardiac resynchronization therapy (CRT) is commonly assessed after 6 or 12 months. We evaluated subsequent echocardiographic changes, serial QRS duration, and clinical outcomes in patients showing delayed responses to CRT after 12 months. METHODS: Among all patients who received CRT in Seoul St. Mary's Hospital, 36 one-year survivors were enrolled. Indicators of a positive CRT response were ≥ 15% reduction in left ventricular end-systolic volume (LVESV) or ≥ 10% increase in left ventricular ejection fraction (LVEF) on any follow up echocardiogram. We defined the early responders as patients responding before one year, the late responders as patients responding after one year, and the non-responders as patients who did not respond on any follow-up echocardiogram. RESULTS: We identified 17 early responders, 10 late responders, and 9 non-responders. The late responders showed modest improvement in LVESV and LVEF at two years after CRT. QRS duration was shortened the day after CRT in all three groups. Narrowed QRS was maintained for two years in early and late responders, whereas it was continuously prolonged over time in non-responders. Incidence of all-cause death or heart failure hospitalization was comparable between early and late responders, while non-responders showed worst prognosis. CONCLUSION: Patients responding to CRT after one year show modest echocardiographic improvement but clinical outcome is similar to early responders. Shorter baseline QRS duration and long-term maintenance of QRS duration shortening are important features of the late responders to CRT.

The normal variations in heart rate and QRS complex of healthy individuals in different age groups.

Background: Electrocardiography is the only practical method of recording the electrical behavior of the heart. It is often an independent marker of myocardial disease and occasionally the only indication of the pathologic process. Therefore the present study has been undertaken to find out the degree of normal variations in healthy individuals in different age groups. Methods: This study was conducted after the institutional ethical clearance and informed written consent from all the subjects belongs to age group of 18 to 40 years of either sex. All the ECG was taken in resting and supine position using BPL CARDIART 308 machine. The body weight, the QRS duration, QRS axis, P wave duration, P wave voltage, P wave axis in the frontal plane, QTc interval, T wave voltage and QRS-T angle was calculated. The values are expressed as mean and the percentile was calculated in each parameters. Results: The weight ranges from 56.37 ± 6.53 kg. QRS duration ranged from 0.04 to 0.12 seconds mean of 0.064 seconds. QRS voltage in V6 varied from 0.30 to 2.1 mv with a mean of 1.14 mv. The QTc interval was 0.31 to 0.47 seconds mean was 0.39 seconds. QRS-T angle varied from 0° to 70° with a mean of 30.9°. Conclusion: The study provides the frequency distribution and other statistical data when applied to all components of ECG which are commonly assessed during investigations of healthy young individuals. Having knowledge of these normal variants will be helpful in arriving at correct diagnosis.

Impact of paced QRS duration on heart function in patients with right ventricular apical pacing / 实用医学杂志

Objective To investigate the impact of paced QRS duration (pQRSd) on heart function in patients with right ventricular apical pacing. Methods Seventy-six patients with Ⅲ° atrioventricular block received pacemaker treatment were enrolled and randomized into group A (pQRSd 0.05). At 24 months after implanting, LAD、LVEDD、LVESD of group B increased significantly compared with those of group A [LAD,( 44.5 ± 6.2) mm vs (41.6 ± 5.1) mm, LVEDD, (52.7 ± 9.3) mm vs (48.2 ± 7.5) mm, LVESD, (37.5 ± 5.6) mm vs (33.8 ± 4.9)mm, each P 0.05)between two groups during 24-month follow-up. Conclusion The prolonged paced QRS duration has a detrimental effect on long-term cardiac function during RVA pacing in patients with Ⅲ°atrioventricular block.

QRS duration in evaluating ventricular dyssynchrony in patients with chronic systolic heart failure / 第二军医大学学报

Objective: To observe the types, prevalence of cardiac dyssynchrony in patients of chronic systolic heart failure (SHF) , and to investigate the value of QRS duration >135 ms in selecting patients for cardiac resynchronization therapy (CRT). Methods: Forty-five patients with SHF were randomly divided into two groups according to QRS width: Group 1 (QRS width 135 ms could finely predict the presence of interventricular dyssynchrony, with a sensitivity of 80% and a specificity of 87. 5% ; while the same cutoff value to predict intraventricular dyssynchrony only yielded a sensitivity of 44. 1 % and specificity of 73. 6%. Conclusion: Intraventricular dyssynchrony and(or) interventricular dyssynchrony has a high prevalence in patients with SHF. A QRS duration cutoff value higher 135 ms can well evaluate the cardiac mechanical dyssynchrony in clinical practice, which may be of value for optimizing selection of CRT candidates and reducing the nonresponders.

QRS dispersion in assessment of left ventricular systolic function and asynchronous left ventricular wall motion in patients with left buddle-branch block / 第二军医大学学报

Objective: To evaluate the role of QRS dispersion (QRSD) in evaluating left ventricular function and the asynchrony of ventricular motion in patients with left buddle-branch block(LBBB). Methods: Forty-two hospitalized patients with LBBB and 28 normal controls (group C) were included in the present study. The 42 LBBB patients were further divided into 2 groups: the isolated LBBB patients (group A, n = 7) and LBBB patients with other organic diseases (group B, n = 35). The indices of echocardiography and electrocardiogram were compared and analyzed among the three groups, including left ventricular ejection(LVEF) , left ventricular end-diastolid dimension(LVEDD), E/A ratio, interventricular mechanical delay (IVMD), left ventricular systolic asynchrony index (TS-SD), QRSD, and QRS duration(QRSd). Multivariate correlation analysis was used to analyze the correlation of QRSD and QRSd with the indices of electrocardiogram and echocardiography in the two LBBB groups. Results: All the indices were significantly different between group B and group C (P<0.05), except for LVEDD in group A (P = 0.145). All the indices were significantly different between group A and group B, except for QRSd (P = 0.175). The QRSd and QRSD were negatively correlated with LVEF in the two LBBB groups, with the correlation coefficients being -0.310 (P = 0.046) for QRSd and -0.341 (P = 0.027) for QRSD; QRSD and TS-SD were positively correlated, with the correlation coefficient being 0.318 (P = 0.040). The rest indices were not significantly correlated. Conclusion: QRSD of ECG can be used for evaluating left ventricular systolic dysfunction in patients with LBBB. However, further studies are needed in order to determine its role in estimating the asynchrony of ventricular motion.

The Effect of Taekwondo Training on Aerobic Capacity, MVO2, ST Slope and QRS Duration / 체질인류학회지

The purpose of this study was to investigate the effects of taekwondo training on VO2max, MVO2 and electrocardiogram ST slope, QRS duration in college woman. Subject were divided into two groups, one is taekwondo group (n=11) and the other is control group (n=10). They participated in graded exercise test (Balke protocol) and measured aerobic capacity and electrocardiogram. The aerobic capacity (VO2max and AT) was measured by autogas analyser. The resting and exercise rate-pressure product (RPP) could be measured with HR and systolic BP for MVO2 measurement. The electrocardiogram ST slope, QRS duration was calculated using automated software program (QMC). The measured data were analyzed by using paired t -test. The results of this study were as follows : There was a significant difference of VO2max and AT between taekwondo group and control group. VO2max of taekwondo group was 4~5 mL/kg/min higher than control group (p<0.01) and AT also taekwondo group was 3.4% higher than control group (p<0.05). There was no significant difference of maximal exercise MVO2 between taekwondo and control group. There was no significant difference of electrocardiogram ST slope between group but rest QRS duration in taekwondo group was longer than the control group (p<0.01). Conclusively, these data suggest that regular taekwondo training will strengthen on aerobic capacity and resting slow heart beats.

Comparison on QRS duration and cardiac function during Multi-site pacing in the right ventricular / 中国医师进修杂志

Objective To assess the effect of QRS duration (QRSd) and cardiac function during right ventricular apex(RVA) pacing,right ventricular outflow tract (RVOT) pacing and right ventricular bifocal (RV-Bi) pacing. Methods Eight patients underwent RVA pacing,RVOT pacing and RV-Bi pacing during pacemaker implantation operation.The ejection fraction (EF),stroke index (SV),cardiac output(CO),QRS QRSd,QRS axis (QRSa) were measured after each pacing at the same pacing frequency. Results Compared with RVA pacing,the EF,SV and CO increased during RVOT pacing and RV-Bi pacing.The cardiac function of RV-Bi pacing was significantly increased (P

The Effects of QRS Duration and Pacing Sites on the Acute Hemodynamic Changes during Right Ventricular Pacing

BACKGROUND: Has been reported that patients exhibiting prolonged paced QRS duration tend to have more serious heart disease, and the paced QRS duration can be an effective indicator of impaired left ventricular function. However, the acute and chronic hemodynamic effects of paced QRS duration and pacing sites during right ventricular (RV) pacing remain unknown. METHODS: A total of 14 patients who underwent electrophysiologic study for paroxysmal supraventricular tachycardia were examined. RV pacing was performed at 10 different sites with cycle lengths of 600 ms and 500 ms utilizing a 6-7F deflectable quadripolar electrode catheter. Systolic, diastolic, and mean blood pressures during pacing were measured once the blood pressure was stabilized. RESULTS: During RV pacing, blood pressures (systolic/diastolic/mean) decreased. The change of post-pacing QRS duration and pre-pacing the systolic blood pressure (SBP) were greater in the group with paced QRS duration. The differences overall were greater than 140 ms. The SBP decrease during pacing was larger in the group exhibiting paced QRS duration of greater than 140 ms. The SBP decrease during pacing showed relation to QRS duration during pacing (r=0.500, p=0.001), the change of QRS duration post-pacing (r=0.426, p=0.001), and SBP during sinus rhythm (r=0.342, p=0.001) on linear correlation analysis. The pacing site, on the other hand, did not affect acute hemodynamic changes during pacing. CONCLUSION: Ventricular pacing of less than 40 ms at the area of paced QRS duration is recommended.

The Usefulness of Surface Electrocardiogram as a Prognostic Predictor in Children with Idiopathic Dilated Cardiomyopathy

We investigated the interrelations between surface electrocardiographic changes and clinical outcomes in children with idiopathic dilated cardiomyopathy (DCMP). 33 patients (19 boys, 14 girls) were classified into two groups; group I (15) who were in poor clinical status or dead; and group II (18) who showed good clinical status. Group I had larger LV dimensions compared to group II (Gr I vs. Gr II; LVEDD, 52 +/-11 vs. 42+/-7 (mm); LVESD, 43+/-12 vs. 30+/-5 (mm); p<0.05). QRS duration was prolonged in Gr I compared to Gr II and normal (Gr I, 84+/-28; Gr II, 66+/-12; normal control, 67+/-9). The QRS duration was correlated with the dimensions of left ventricle (LV). Corrected QT and JT interval and dispersions of QT in the DCMP group showed a significant difference compared to the normal control, however there was no significant difference between Gr I and II. In conclusion, QRS duration was correlated with ventricular dimension and clinical outcome in children with idiopathic dilated cardiomyopathy. Irrespective of increased ventricular inhomogeneity, QT dispersion could not be used to predict long-term prognosis.

The effects of QRS duration and pacing sites on the acute hemodynamic change during right ventricular pacing / 대한내과학회지

BACKGROUND: Intraventricular conduction disturbances, as manifested by increased QRS duration, are common in patients with advanced left ventricular (LV) dysfunction and adversely affect LV systolic and diastolic function. It has been reported that the patients with prolonged paced QRS duration have more serious heart disease, and the paced QRS duration can be a useful indicator of impaired LV function. Hemodynamic effects of paced QRS duration and pacing site during right ventricular (RV) pacing are unknown. METHODS: A total of 14 patients who underwent electrophysiologic study for paroxysmal supraventricular tachycardia at Chonnam National University Hospital were examined. All the patients had no structural heart disease. RV pacing was performed at 10 different sites with cycle length of 600 ms and 500 ms using a 6-7F deflectable quadripolar electrode catheter (Livewire, St. Jude Medical, Minneapolis, MN, USA). Systolic, diastolic, and mean blood pressures were measured after stabilization of blood pressure during pacing. RESULTS: Blood pressures (systolic/diastolic/mean) decreased from 146 +/- 31/95 +/- 28/125 +/- 23 mmHg to 128 +/- 33/80 +/- 25/107 +/- 20 mmHg, respectively. The change of QRS duration during pacing and the systolic blood pressure (SBP) before pacing were higher in the group with paced QRS duration greater than 140 msec (59.1 +/- 13.6 msec vs 84.9 +/- 18.7 msec, 141 +/- 30 mmHg vs 152 +/- 38 mmHg, p<0.001, p=0.011, respectively). The decrease of SBP during pacing was higher in the group with paced QRS duration greater than 140 msec (13 +/- 11 mmHg vs 24 +/- 14 mmHg, p=0.009). The decrease of SBP during pacing was related with QRS duration during pacing (r=0.500, p=0.001), the change of QRS duration during pacing (r=0.426, p=0.001), and SBP during sinus rhythm (r=0.342, p=0.001) on linear correlation analysis. Pacing site, however, did not affect acute hemodynamic change during pacing. The independent factors associated with the decrease of SBP during pacing were SBP before pacing and QRS duration during pacing. CONCLUSION: We concluded that acute deleterious hemodynamic effects of RV pacing are related with paced QRS duration but not with pacing site. Ventricuar pacing at the area of paced QRS duration less than 140 msec is recommended particularly in high risk patients.

Value of QRS duration predicting response of cardiac resynchronization therapy / 中国实用内科杂志

QRS wave duration is a main method of deciding cardiac asynchrony in patients with Cardiac resynchronization therapy(CRT).But cardiac mechanical dyssynchrony was not always consistent with electrical dyssynchrony.A few patients with widened QRS wave duration had not the cardiac mechanical asynchrony,while some patients with normal QRS wave duration had cardiac mechanical asynchrony.If the cardiac mechanical dyssynchrony was determined,it would be possible to reduce the non-response of CRT.We review the role of QRS duration to predicting the prognosis of CRT and debate the effect of QRS duration to CRT.

QRS duration in evaluating ventricular dyssynchrony in patients with chronic systolic heart failure / 第二军医大学学报

135 ms in selecting patients for cardiac resynchronization therapy(CRT).Methods Forty-five patients with SHF were randomly divided into two groups according to QRS width: Group 1(QRS width 135 ms could finely predict the presence of interventricular dyssynchrony,with a sensitivity of 80% and a specificity of 87.5%;while the same cutoff value to predict intraventricular dyssynchrony only yielded a sensitivity of 44.1% and specificity of 73.6%.Conclusion Intraventricular dyssynchrony and(or) interventricular dyssynchrony has a high prevalence in patients with SHF.A QRS duration cutoff value higher 135 ms can well evaluate the cardiac mechanical dyssynchrony in clinical practice,which may be of value for optimizing selection of CRT candidates and reducing the nonresponders.