Total QRS Research Articles

PM035 Remodelling defined by multipolar lead activation sequence

O ST E R A B ST R A C T S Introduction:Multiple analyses have demonstrated that targeting left ventricular (LV) leads to sites of increasing electromechanical delay can improve echocardiographic parameters and clinical outcomes in patients undergoing cardiac resynchronization therapy. Most studies have included a wide spectrum of electrical delay. Computer modelling of resynchronization would argue that a threshold of electromechanical delay should exist and beyond a certain level increasing delays will not improve and may even worsen resynchronization parameters. Objectives: We sought to quantify the effect of increasing electromechanical delays on echocardiographic parameters of resynchronization in patients with multipolar leads positioned only in areas of significant electrical delay. Methods: Patients undergoing cardiac resynchronization therapy using multipolar leads were evaluated between 2011 and 2012. A 12 lead ECG was performed and the longest QRS duration recorded. %QLV was defined as the time from first surface ECG deflection to LV electrogram peak during sinus rhythm as a % of total QRS duration. %QLV was measured to each of the 4 LV electrodes. Significant electrical delay was defined as a %QLV> 85% which represents the upper tertile or quartile of previously published analysis. Only patients with four electrodes recording of %QLV > 85% were enrolled. Echo measures including dyssynchrony index (DI), were recorded during pacing from each of the LV electrodes. Results: Fifteen patients had %QLV > 85%. There was no correlation in the group as a whole betweenmeasures of electrical delay and the optimal DI. Using interquartile analysis % QLV 85 -90 gave optimal DI in 6 patients, %QLV 90-95 gave optimal DI in 5 patients, %QLV 95-100 gave optimal DI in 2 patients and %QLV > 100 gave optimal DI in 1 patient. In this group of most delayed LV leads the optimal DI was seen with a mean %QLV of 91+-4%. Conclusion: In the areas of most delayed electrical activation, increasing delays correlate poorly with improved echocardiographic parameters of resynchronization. Targeting extreme %QLVs beyond 85% may result in suboptimal resynchronization. Disclosure of Interest: M. Flannery Grant/research support from: Medtronic, A. Teh: None Declared, H. Sugumar: None Declared, T. Lin Grant/research support from: Medtronic, M. Swale Grant/research support from: Medtronic and St Jude Medical, Consultancy for: Medtronic and St Jude Medical, D. O’Donnell Grant/research support from: Medtronic and St Jude Medical, Consultancy for: Medtronic and St Jude Medical

ELECTROCARDIOGRAMS OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) OUT OF WATER: HABITUATED COLLECTION VERSUS WILD POSTCAPTURE ANIMALS

Electrocardiography (ECG) was performed on captured free-ranging bottlenose dolphins (Tursiops truncatus) during a health assessment exercise and compared with that of a Navy collection of dolphins habituated to handling out of water in order to assess possible cardiovascular impacts of capture and handling. Six-lead recordings (I, II, III, aVr, aVl, and aVf) in the frontal plane and direct thorax leads were collected from both groups, with a modified base-apex lead additionally employed with the Navy collection dolphins. Measured and calculated parameters included amplitudes of P, R, S, and T waves and total QRS complex; T:S and T:QRS ratios; heart rate; durations of P wave; QRS complex, PR, QT, and RR intervals; maximum minus minimum RR interval; ST segment elevation-depression; and mean electrical axis (MEA). Physiologically minor but statistically significant differences were detected in S wave amplitude, PR interval, QRS duration, and MEA. The PR interval, QRS duration, and S wave amplitude were slightly greater and the MEA oriented slightly rightward in wild postcapture dolphins compared to Navy collection dolphins. There were no differences in heart rate or maximum minus minimum RR interval, which serves as a proxy for the expected sinus arrhythmia of dolphins. The base-apex lead resulted in greater QRS amplitude than lead II, as expected for the category B ventricular activation of dolphins. The left-side direct thorax lead was more consistent than that of the right side. Clinically, ECG was a useful adjunct to auscultation and thoracic palpation for monitoring heart rate and rhythm and generated a record for archiving. Safe capture and handling protocols in place, under which dolphins are immediately returned to the water at progressive signs of distress, may make cardiovascular decompensation less likely to be detected by ECG. It appears that the dolphin cardiovascular system compensates suitably well to capture, as measured by ECG under the conditions of this study.

Right‐Ventricular Enlargement in Arrhythmogenic Right‐Ventricular Cardiomyopathy Is Associated with Decreased QRS Amplitudes and T‐Wave Negativity

Arrhythmogenic right-ventricular cardiomyopathy (ARVC) can lead to RV dilatation. We hypothesized that electrocardiographic characteristics including QRS amplitudes in the extremity- and precordial leads, the S amplitude in lead V1 , and extent of T-wave negativity over the precordial leads are related to RV dilatation in this condition. In 42 ARVC patients and 42 controls, we correlated total QRS amplitude in the extremity leads (∑QRSext ), precordial leads (∑QRSprec ) and in all leads (∑QRStot : summation of ∑QRSext and ∑QRSprec ), S amplitude in lead V1 and the extent of T-wave inversion in the precordial leads (V1 vs. beyond V1 ) with RV end diastolic diameter (RVEDD) by echocardiography. In the ARVC group, the mean age was 46 ± 14 years, 31 patients were male, 28 had an implantable cardioverter defibrillator (ICD), and 7 had a LV ejection fraction (EF) < 55%. The control group was age- and gender matched to the ARVC cohort. In contrast to controls, the ∑QRSext (regression coefficient (RC), -0.29; P = 0.020), ∑QRSprec (RC, -0.20; P = 0.015), and ∑QRStot (RC, -0.14; P = 0.009) were lower with RV dilatation in ARVC. S amplitude in lead V1 was not related to RV diameter (RC, -0.98; P = 0.088). Precordial T-wave inversion beyond lead V1 (V2 -V6 ) was associated with a larger RV diameter (RC, 8.58; P = 0.012). Summed QRS amplitudes in the extremity and precordial leads, and T-wave inversion beyond lead V1 are associated with RV dilatation in patients with ARVC.

Electrophysiological characteristic and ablation of epicardial idiopathic ventricular arrhythmias arising around left fibrous triangle

Background: The success rate of radiofrequency catheter ablation of ventricular arrhythmias originating from Left Fibrous Triangle (LFT) is not high. This article was to discuss the characteristics of surface electrocardiogram and the strategy of ablation of ventricular arrhythmias originating from LFT. Methods: From February 2002 to March 2012, total 323 patients with outflow ventricular arrhythmias were ablated in our hospital, including 46 patients whose ventricular arrhythmias originated from the LFT. The mean age of the 46 patients was 44±13 years (16-87 years), and 24 of them (52.2%) were male. Thirty patients had frequent premature ventricular contractions (PVCs) and 16 patients had both PVCs and nonsustained or sustained ventricular tachycardia (VT). All the patients were examined with ECG, electrophysiology, active mapping and pace mapping. The computer tomography angiogram (CTA) 3D reconstruction of coronary artery, venous was completed in 20 patients. Results: Successful ablation was achieved in 41 of the 46 patients (89.1%, 41/46) targeting left coronary cusp (LCC, 30 patients), infra aortic valve (infra AV, 6 patients) and great cardiac vein (GCV, 5 patients). The surface ECG in all the three groups presented with inferior axis and R/S-transition in lead V1 and V2. There were no differences in the total QRS duration in the three groups. Most of the patients presented with right bundle branch block (RBBB) morphology in infra AV group and GCV group compared with LCC group (67%,80% vs 15%, P=0.002). Regarding to the classification of the LFT according to CTA, the patterns of distribution were as follows: closed in 10 (50%, 10/20) hearts; completely opened in 2 (10%, 2/20); inferiorly opened in 5 (25%, 5/20) hearts and superiorly opened in 1 (5%, 1/20) hearts. In the remaining 2 (10%, 2/20), there were not any distances between GCV and left coronary artery. The closest distance between the corner of the GCV and LCC is 17.6±4.2 mm (9.1mm∼26.3mm). Conclusions: Ventricular arrhythmias originating from the LFT can be ablated in the nadir of the LCC, infra AV and the GCV. The success rate may be impacted by the distance from the GCV and the LCC.

GW24-e1769 Electrophysiological characteristic and ablation of epicardial idiopathic ventricular arrhythmias arising around left fibrous triangle

ObjectivesThe success rate of radiofrequency catheter ablation of ventricular arrhythmias originating from left fibrous triangle (LFT) is not high. This article was to discuss the characteristics of sueface electrocardiogram and...

A novel electrocardiographic predictor of clinical response to cardiac resynchronization therapy

A wide QRS with left bundle branch block pattern is usually required for cardiac resynchronization therapy (CRT) in patients with dilated cardiomyopathy. However, ∼30% of patients do not benefit from CRT. We evaluated whether a detailed analysis of QRS complex can improve prediction of CRT success. We studied 51 patients (67.3 + 9.5 years, 36 males) with classical indication to CRT. Twelve-lead electrocardiogram (ECG) (50 mm/s, 0.05 mV/mm) was obtained before and 3 months after CRT. The following ECG intervals were measured in leads V1 and V6: (i) total QRS duration; (ii) QRS onset-R wave peak; (iii) R wave peak-S wave peak (RS-V1 and RS-V6); (iv) S wave peak-QRS end; and (v) difference between QR in V6 and in V1. Patients were considered as responder when left ventricular ejection fraction (LVEF) increased by ≥5% and New York Heart Association class by ≥1 after 3 months of CRT. Of ECG intervals, only basal RS-V1 was longer in responders (n = 36) compared with non-responders (52.9 ± 11.8 vs. 44.0 ± 12.6 ms, P = 0.021). Among patients with RS-V1 ≥45 ms 83% responded to CRT vs. 33% of those with RS-V1 < 45 ms (P < 0.001). RS-V1 ≥ 45 ms was independently associated with response to CRT in multivariable analysis (odds ratio 9.8; P = 0.002). A reduction of RS-V1 ≥ 10 ms by CRT also significantly predicted clinical response. RS-V1 shortening correlated with improvement in LVEF (r = -0.45; P < 0.001) and in MS (r = 0.46; P < 0.001). Our data point out that RS-V1 interval and its changes with CRT may help to identify patients who are most likely to benefit from CRT.

ASSA13-02-4 Electrophysiological Characteristic and Ablation of Epicardial Idiopathic Ventricular Arrhythmias Arising Around Left Fibrous Triangle

Background The success rate of radiofrequency catheter ablation of ventricular arrhythmias originating from left fibrous triangle (LFT) is not high. This article was to discuss the characteristics of sueface electrocardiogram and the strategy of ablation of ventricular arrhythmias originating from LFT. Methods From February 2002 to March 2012, total 323 patients with outflow ventricular arrhythmias were ablated in our hospital, incluing 46 patients whose ventricular arrhythmias originated from the LFT. The mean age of the 46 patients was 44 ± 13 years (16–87 years), and 24 of them (52.2%) were male. Thirty patients had frequent premature ventricular contractions (PVCs) and 16 patients had both PVCs and nonsustained or sustained ventricular tachycardia (VT). All the patients were examined with ECG, electrophysiology, active mapping and pace mapping. The computer tomography angiogram (CTA) 3D reconstruction of coronary artery, venouswas completed in 20 patients. Results Successful ablation was achieved in 41 of the 46 patients (89.1%, 41/46) targeting left coronary cusp (LCC, 30 patients), infra aortic valve (infra AV, 6 patients) and great cardiac vein (GCV, 5 patients). The surface ECG in all the three groups presented with inferior axis and R/S-transition in lead V1 and V2. There were no differentces in the total QRS duration in the three groups. Most of the patients presented with right bundle branch block (RBBB) morphology in infra AV group and GCV group compared with LCC group (67%, 80% vs 15%, P = 0.002). Regarding to the classification of the LFT according to CTA, the patterns of distribution were as follows: “closed” in 10 (50%, 10/20) hearts; “completely opened” in 2 (10%, 2/20); “inferiorly opened” in 5 (25%, 5/20) hearts and “superiorly opened” in 1 (5%, 1/20) hearts. In the remaining 2 (10%, 2/20), there were not any distances between cardiac vein and artery. The closest distance between the corner of the GCV and LCC is 17.6 ± 4.2 mm (9.1mm ∼ 26.3mm). Conclusions Ventricular arrhythmias originating from the LFT can be ablated in the nadir of the LCC, infra AV and the GCV. The success rate may be impacted by the distance from the GCV and the LCC.

Comparison of electrocardiogram aVR QRS metrics, as indices of the sums of leads I and II, and all 6 limb leads

Electrocardiogram (ECG) peak-to peak amplitude (Pk-pk) of the limb leads, in the form of sums of leads I and II (I+II), or all 6 limb leads (Σ6Lblds), and lead aVR have been employed for the monitoring of patients with edematous states (ES), including heart failure (HF), or those undergoing hemodialysis (HD). The aim of this study was to compare aVR metrics (net QRS area [NQRSA], total QRS area [TQRSA], Pk-pk, and QRS root mean square [QRSRMS]) as indices of the corresponding metrics of I+II and Σ6Lblds. Automated measurements of the above metrics deriving from a set of randomly selected 1784 ECGs were compared and inter-correlated. NQRSA of aVR showed the best correlation with I+II (r=−0.99) and Σ6Lblds (r=−0.78), while Pk-pk the worst (r=0.68) and (r=0.62), correspondingly. NQRSA of aVR has advantages over Pk-pk, reflecting I+II or Σ6Lblds, and thus it might be employed in serial ECGs for the monitoring of patients with ES, including HF, and HD. However the present paper constitutes a methodological work, and thus the performance of NQRSA of aVR in monitoring patients with ES needs to be substantiated by a future study. Automated measurements of NQRSA of aVR are provided by many contemporary electrocardiographs upon recording of the ECG and could be put to use at the “point of care”.

Refinement of total 12-lead QRS voltage criteria for diagnosing left ventricular hypertrophy

Objective: We sought to test the hypothesis that the total QRS voltage without either set of the limb leads (I, II, III) or (R, L, F) may be a better indicator of LVH as compared to the total QRS voltage. Background: The total 12 lead QRS voltage has been a validated electrocardiographic criterion for left ventricular hypertrophy (LVH), with an upper limit of175 mm. However, there is some redundancy in this measurement as the output of the limb leads is repeated because leads I, II, III, and R, L, F use the same three electrodes. Methods: 43 unselected, consecutive echocardiograms were examined for evidence of LVH by wall thickness. Electrocardiogram (ECG) of these patients within a week of the echocardiogram were then examined for the total 12 leads QRS voltage, minus I, II, III and total minus R, L, F voltages. ECG findings were then compared with corresponding echocardiographic dimensions. Results: A total QRS voltage of123 mmon ECG yielded a sensitivity of 73% and specificity of 67% for diagnosing LVH with 95% CI = 0.59 - 0.89, p = 0.007. Total minus (R, L and F) value of110 mmon ECG appears to give the best sensitivity (73%), specificity (72%), and accuracy (64% negative predictive value and 82% positive predictive value) for LVH. Conclusion: It appears that total QRS voltage minus either set of the limb leads, especially the total minus R, L and F is a better criterion, with110 mmbeing the best specific, sensitive and accurate index for diagnosing LVH.

Electrocardiogram as prognostic and diagnostic parameter in follow up of patients with heart failure

IntroductionMost patients with HF due to systolic dysfunction have a significant abnormality on ECG. It is a widely available tool relatively inexpensive, simple to perform, and yields an instant result. AimTo determine whether heart failure (ECG) conveys prognostic and diagnostic information in patients with HF. MethodsThe study was carried out on 100 heart failure patients. All patients were subjected to history taking, clinical examination, standard 12 lead ECG (at admission, discharge, and 3month follow up) for assessment of the following: (QRS voltage amplitude: in limb leads and in chest leads, total QRS voltage and transthoracic echocardiography were done for all patients (at discharge and at 3month follow up (FU). ResultsThere were 75 males and 25 females, aged between 21 and 86years (mean=59.14±13.41years). Total QRS voltage, limb leads voltage and chest leads voltage; all significantly increased from admission values (98.54±20.64, 37.87±11.06, and 60.67±15.26mm) to (110.72±21.28, 43.01±11.92, and 67.71±15.22) at discharge (p<0.001 for all). Also there was a significant increase in voltage at FU (111.72±21.28, 43.30±11.96, and 68.61±16.61mm) (p<0.001 for all). There was a negative correlation found between left ventricular end diastolic and systolic dimensions (LVEDD and LVESD) with total QRS voltage, chest leads voltage and limb leads voltage, both at discharge and at FU. The total QRS Voltage was significantly higher in patients having no lower limb (LL) edema than those with edema on admission, at discharge and on FU (p<0.001). ConclusionVoltages of ECG are considered one of the most important parameters in diagnosis and FU of patients with heart failure. Voltage of chest leads well correlated with LVEDD and LVESD. Voltage of limb leads has important inverse correlation with LL edema.

Goldberger's Electrocardiographic Triad in Patients With Echocardiographic Severe Left Ventricular Dysfunction

In 1982, Goldberger described an electrocardiographic triad (SV1 or SV2 + RV5 or RV6 ≥ 3.5 mV, total QRS amplitude in each of the limb leads ≤ 0.8 mV, and R/S ratio < 1 in lead V4) that was 70% sensitive and > 90% specific for detecting severe left ventricular (LV) dysfunction. To confirm his sensitivity results, in 51 consecutive patients (36 men) aged 28 to 84 years (mean 56) with LV ejection fractions ≤ 20%, the electrocardiographic triad was sought in the electrocardiogram (ECG) recorded closest in time to the echocardiographic study. All 51 patients had systemic arterial hypertension. Evidence of ischemia was present in 7 and absent in 38, and in 6 patients, ischemic status was unknown. In 49 patients, New York Heart Association functional class was available: class II in 8, class III in 32, and class IV in 9. LV ejection fractions ranged from 4% to 20% (mean 14%), and LV internal end-diastolic diameters ranged from 5.7 to 8.6 cm (mean 6.6). Left atrial anteroposterior diameters ranged from 2.9 to 6.1 cm (mean 4.7) and were ≥ 4.0 cm in 47 of the 51 patients. The right ventricular cavity was enlarged in 22 patients. SV1 or SV2 + RV5 or RV6 was ≥ 3.5 mV in 29 of the 51 ECGs; total QRS amplitude was ≤ 0.8 mV in each of leads I, II, and III in 10; and the R/S ratio was < 1 in lead V4 in 37. Only 1 of the 51 ECGs met all 3 criteria. In contrast to Goldberger's finding of the triad to be 70% sensitive for severe LV dysfunction, in this study, the triad was found to be only 2% sensitive. The difference is likely due to his patients' having idiopathic dilated cardiomyopathy, whereas those in this study had hypertensive cardiomyopathy with or without ischemia. Also, in this study, 1 specific ECG was used for each patient, whereas Goldberger reviewed all of the patients' ECGs looking for the triad. In conclusion, Goldberger's triad is a sensitive or insensitive marker for severe LV dysfunction depending on the patient population and the number of ECGs reviewed.

Left ventricular function-conduction impairment as reflected by the ECG in chronic aortic regurgitation

The study was conducted to ascertain that the ECG assists in the assessment of systolic dysfunction in chronic aortic regurgitation. Five variables were reviewed in 146 adults without bundle branch block who underwent angiocardiography: total 12-lead QRS amplitude, QRS duration, maximum R peak time in I, V5 or V6, maximum R peak time relative to S peak time of the maximum S in V1, V2 or V3, and maximum T wave amplitude and polarity in I, V6 or aVF. In order to define which of them could differentiate left ventricular ejection fraction (EF) ≥50% (n = 101) from EF <50% (n = 45) they were subjected to stepwise linear discriminant analysis. The maximum R peak time relative to S peak time emerged as the most promising variable. In predicting EF <50%, R peak time prolongation exceeding S peak time, i.e. R peak delay, yields reliable results, with specificity, positive and negative predictive value being 89.1%, 70.3% and 82.6%, respectively, and sensitivity being 57.8%. As given by the sample odds-ratio, R peak delay indicates an 11-fold increased risk of having EF <50%. R peak delay, a marker of left ventricular function-conduction impairment identifies patients who need valve replacement.

Epicardial Outflow Tract Ventricular Tachycardia: Distal Great Cardiac Vein and Coronary Cusp Origin

The origin of outflow tract ventricular arrhythmia (OT-VA) can be predicted by ECG analysis. Recently, we devised a method to identify an epicardial OT-VA using the peak deflection index (PDI) in an inferior ECG lead. We will present our method of epicardial OT-VA identification and introduce how we determine the ablation site. Methods: An epicardial origin (10[14%] of the 70 patients) indicates that the successful ablation site of the OT-VA was in the distal great cardiac vein (GCV) (n=3) or on the coronary cusps (n=7). PDI is determined in the inferior lead presenting the tallest R wave by dividing the time from QRS onset to peak QRS deflection by total QRS duration. Results: A PDI of >0.6 predicted epicardial cases with a 90% sensitivity and a 95% specificity. In the 7 patients with coronary cusp ventricular arrhythmia (CC-VA), a discrete pre-potential (DPP) was recorded in 4 patients (57%). The DPP recorded at the successful ablation site on the coronary cusp preceded QRS onset by 63±16 ms (range, 50–84 ms). In those patients, excellent pace mapping was not always necessary. Conclusions: A PDI of >0.6 can be predictive of cases of epicardial OT-VA ablation in which the OT-VA origin is the distal GCV or the coronary cusps. In CC-VA, a DPP with activation time of ≥50 ms may be an indicator of successful ablation.

Holter Monitoring and Cardiovascular Events in Patients with Hypertrophic Cardiomyopathy

Background: Patients with hypertrophic cardiomyopathy (HCM) have 3 distinctive modes of cardiovascular events: sudden death, heart failure, and stroke associated with atrial fibrillation. Holter monitoring provides various indexes, though little is known regarding their significance for the long-term prognosis except ventricular tachycardia as a risk marker for sudden death in HCM. Methods: Ambulatory Holter monitoring was performed in 106 HCM patients with normal sinus rhythm in clinically stable conditions. All patients were prospectively followed for the occurrence of sudden death, cardiovascular death and hospitalization for heart failure or stroke associated with atrial fibrillation. Results: Cardiovascular events occurred in 19 patients during an average follow-up period of 10.1 years. Cox proportional hazards regression analysis after adjustment for baseline characteristics showed that the risk of cardiovascular events was associated with a decrease in total QRS count (hazard ratio, 0.94 per 1,000 increase; p=0.011) and in average heart rate (hazard ratio, 0.93; p=0.026). These 2 predictors had little relationship to traditional predictors or the mode of cardiovascular events. Conclusions: Decreased heart rate on ambulatory Holter monitoring is an independent predictor for the long-term prognosis in patients with HCM. These simple indexes may add a new implication to the clinical practice of ambulatory Holter monitoring for the purpose of risk stratification in patients with HCM.

Novel ECG Predictor of Difficult Cases of Outflow Tract Ventricular Tachycardia: Peak Deflection Index on an Inferior Lead

An ECG predictor of ablation success has not been determined for difficult cases of outflow tract ventricular tachycardia/ventricular premature contractions (OT-VT/VPC). ECG analysis and radiofrequency catheter ablation (RFCA) were performed in 70 patients with OT-VT/VPC. The peak deflection index (PDI) was determined in the inferior lead presenting the tallest R wave by dividing the time from QRS onset to peak QRS deflection by total QRS duration. In 10 (14%) of the 70 patients, RFCA performed at a septal or epicardial site was unsuccessful (group 1), but was successful in the remaining 60 patients (group 2). Neither activation time (35+/-15 ms vs 40+/-12 ms, P=0.3) nor QRS duration (141+/-19 ms vs 137+/-19 ms, P=0.6) were significantly different between groups 1 and 2. However, PDI was significantly higher in group 1 than in group 2 (0.62+/-0.06 vs 0.55+/-0.06, P=0.002). A PDI >0.6 identified unsuccessful OT-VT/VPC with 80% sensitivity and 90% specificity, and may indicate that the origin of the OT-VT/VPC is deep within the ventricular septum or at an epicardial site. A PDI >0.6 is more likely to be associated with a higher rate of RFCA failure.

Insulin effects on myocardial function and bioenergetics in l-bupivacaine toxicity in the isolated rat heart

A positive effect of insulin-glucose-potassium infusion in severe bupivacaine-induced cardiovascular collapse has been described in vivo. It has been speculated that an antagonistic influence of insulin on sodium channel inhibition, transient outward potassium current, calcium-dependent adenosine triphosphatase or even improved myocardial energetics may be responsible for this effect. Using an isolated heart model, we therefore sought to further elucidate insulin effects in l-bupivacaine-induced myocardial depression. An isolated rat heart constant-pressure perfused, non-recirculating Langendorff preparation was used. Hearts were exposed to l-bupivacaine 5 microg mL(-1) and insulin 10 mIU mL(-1). Heart rate, systolic pressure, the first derivative of left ventricular pressure (+dP/dt), coronary flow, double product, PR and QRS intervals were recorded. Hearts were freeze-clamped and high-performance liquid chromatography measurement of the total adenine nucleotide pool was performed. l-Bupivacaine led to a significant decrease in heart rate, +dP/dt, systolic pressure, coronary flow and double product, and to an increase in PR and QRS. Insulin exerted a positive inotropic effect, significantly augmenting +dP/dt and systolic pressure in both l-bupivacaine-treated and control hearts. Heart rate, coronary flow, total adenine nucleotides, PR and QRS were not significantly changed by the insulin intervention. Insulin did not have a significant effect on total adenine nucleotides in controls and in l-bupivacaine-treated hearts. However, it does exert a positive inotropic action in bupivacaine-induced myocardial depression. We conclude that the positive effect of insulin application lies in positive inotropic action and not in changes in total adenine nucleotides.

Efficacy of Signal-Averaged Electrocardiography in the Young Orthotopic Heart Transplant Patient to Detect Allograft Rejection

Endomyocardial biopsy is the gold standard survey for cardiac graft rejection. Signal-averaged electrocardiography (SAECG) identifies slowly conducting, diseased myocardium. We sought to determine whether SAECG is a sensitive, noninvasive transplant surveillance method in the young.Ninety-four SAECGs recorded prior to biopsy in 20 young transplant (OHT) patients and those from 15 healthy age-matched controls (CTL) were analyzed. In the OHT group, 56 no-rejection (NOREJ) (ISHLT grades 0 or 1 A) and 37 acute rejection (REJ) (ISHLT grades IB, 2, and 3A) SAECGs were compared, SAECGs were filtered at 40-255 Hz. Total QRS duration (QRSd), duration of terminal low amplitude of QRS under 40 microV (LAS), and root mean square amplitude of terminal 40 msec of QRS (RMS40) were compared.SAECGs were significantly different in CTL vs NOREJ but not in NOREJ vs REJ: QRSd, 81.7 +/- 8, 107.2 +/- 18.4, and 112.3 +/- 21.6 msec, respectively; LAS, (18 +/- 5.8, 23.6 +/- 10.7, and 27 +/- 14.8 msec, respectively; and RMS40, (169.3 +/- 100.4, 68 +/- 48.8, and 57.5 +/- 45.6 microV, respectively. Children following OHT exhibited significant differences in the SAECG compared to controls. Differences between the NOREJ and REJ groups were negligible. Therefore, SAECG may not be effective in detecting OHT rejection in the young.

P6-110: Coronary venous ablation of epicardial ventricular premature contractions with distinctive QRS morphology

The patient was a 50-year-old man with a history of palpitations caused by ventricular premature contractions (VPCs). The number of VPCs was 38464/day. Twelve-lead ECG during VPCs showed rS in I and aVL, RS in V5 and V6, notched wide R wave in II, III, aVF, and wide R wave in V1-4. QRS duration was 192 ms, and peak deflection index (PDI), which was determined as the time from QRS onset to earliest peak deflection in any precordial lead divided by the total QRS duration, was 0.54. Pace mapping at an endocardial site close to the origin showed QRS duration of 170 ms to be shorter and PDI of 0.5 to be lower than those of the clinical VPCs.

Qrs-duration in right venricular outflow tract

ORS duration my have an influence on the outcome of ventricular pacing, the influence of pacing site on QRS duration was investigated. Methods In 20 patients ( 5 female, 15 male) with a mean age of 61.1 years (11-93) the ventricular lead Medtronic SelectsecureTM 3830 was placed in the RVOT. Indication was SSS in 9, AV-block in 11 and AF in 1 patient. 11 leads were placed at the free wall and 9 leads at the septum of the RVOT. Measurements were taken with the Medtronic Analyzer. Results Intraoperative measurements were satisfying (Threshold 0.45 V (0.3-1.2), R-wave 10.8 mV (3.2-30), Impedance 772 Ohm (500-1721)) with no difference between free wall and septum. Total QRS duration of the intrinsic conducted QRS was 99 msec (50-160), and 139 msec of the paced QRS (100-200). The mean QRS prolongation by pacing was 40 msec (− 20 − +120). On free wall pacing site the mean prolongation was 49 msec, in septal pacing 33 msec. ![Figure][1] Conclusion RVOT pacing with the Selectsecure pacing system in feasible, the mean paced QRS duration in RVOT is 40 msec longer than the intrinsic, with shorter paced QRS at the septum, than at the free wall of the RVOT. [1]: pending:yes

Distance correction in the electrocardiographic estimation of left ventricular mass

Assessment of the left ventricular mass (LVM) from electrocardiograms may be improved by the addition of clinical variables into a multivariate equation. As the heart-thorax distance may affect the results, its relationships with electrocardiographic and clinical data have been evaluated in a group of 220 subjects (53 ± 15 years, 126 female, 175 without demonstrated heart disease) who were assessed for echocardiographic LVM and heart-thorax distance. Sokolow, Cornell, and total QRS voltage indexes were obtained. Multiple regression equations with LVM as the dependent variable were fit, with an ECG index, body mass index (BMI), age, and gender as the independent predictors. Each of the 3 ECG indexes, BMI, age, and sex was shown to be independent predictors of LVM, with the ECG and BMI contributing with most of the explanatory power. When added to the model, the distance from the interventricular septum to the precordium (septal-LVD) was not a predictor of LVM, but when BMI was withdrawn, septal-LVD became an independent predictor of LVM ( P < .001). This was not observed when septal-LVD was substituted for any other clinical or ECG variable, thus suggesting that septal-LVD accounts for information contained in BMI but not in the remaining variables. In addition, the distance from the center of LV to the precordium (mid-LVD) achieved significance as an independent LVM predictor, although the coefficient of multiple determination ( R) practically did not change. Almost identical results are obtained when LVM is indexed for body surface area. Body mass index supplies virtually all the information contained in the heart-thorax distance.