of patients: (a) 135 patients admitted in intensive care unit, yielding a total

of 195 (PEM, standard) ECG pairs; and (b) 24 ambulatory cardiac patients

recorded during their routine visit at the cardiology hospital of Lyon. Both

the standard and the derived 12-lead ECGs have been reprocessed by the

Lyon Program. A quantitative comparison of the computerized global and

lead-by-lead measurements was performed on data set a (Table 1), and a

qualitative comparison was made on data set b (Table 2) by a cardiologist

who blindly analyzed, in measurements and interpretation, the 2 derived

ECGs with reference to the standard 12-lead ECG. In conclusion, the

patient-specific transform provides better results, similar to the Mason-Likar

lead system.

doi:10.1016/j.jelectrocard.2005.06.039

QT measurement performance in a Holter application

Dirk Q. Feild (Advanced Algorithm Research Center, Philips Medical

Systems, USA)

Faced with moderate sampling rates, limited operator interaction, and high

artifact content, obtaining stable QT measurements in an ambulatory

environment is extremely challenging but clinically important. Automatic

analysis is performed on all available channels of electrocardiographic data.

After cubic spline baseline removal on each electrocardiographic channel,

moving average templates are created. Complexes that are not close to the

current composite are rejected. These templates are then combined into a

vector magnitude signal. A Philips proprietary method is used to detect both

the onset of the Q wave and the offset of the T wave. This algorithm is

insensitive to signal amplitudes and residual isoelectric displacements but

slightly sensitive to large U waves.

The results by Jane et al (Comput cardiol 1997) used the human-

determined best-performing channel per record on the best 73 of the

database and on the full database. The results for the Philips algorithm are

nearly equivalent to the manually chosen results of Jane as shown in

Table 1. QT results in Table 2 compare favorably with expert annotation.

The algorithm has proven robust in a commercially available 3-channel

Holter application.

doi:10.1016/j.jelectrocard.2005.06.040

A novel rectangular biphasic waveform from a radio

frequency defibrillator compared with a conventional

waveform for the transvenous cardioversion of chronic

atrial fibrillation in patients

B.M. Glover a,b,C.J. McCanna,b, S.J. Walsha,M.J. Moorea,b,G.Manoharana,

M.J. Robertsa, C.M. Wilsona, J.D. Allen, J.Mc.C. Andersonc, A.A.J. Adgey a

( aRegional Medical Cardiology Centre, Jordanstown, UK; bRoyal Victoria

Hospital, Belfast, Queens University, Jordanstown, UK; cUniversity of

Ulster, Belfast, Jordanstown, UK)

Purpose: The optimal waveform for the transvenous direct current

cardioversion of atrial fibrillation (AF) is unknown. A novel rectangular

biphasic waveform (6/6-milliseconds duration, phase 2 peak voltage 50% of

phase 1) delivered from a radio frequency (RF)–powered defibrillator was

compared with a conventional capacitor–based, exponential biphasic

waveform of equivalent duration and voltage.

Method: Patients with chronic AF (fully anticoagulated) were randomized

to receive either the RF or a conventional trapezoidal waveform (Ventritex

HVS-02). Defibrillation electrodes were positioned in the right atrial

appendage (cathode) and distal coronary sinus (anode). All shocks were

R-wave synchronized. Phase 1 peak voltage was increased in stepwise

progression from 50 to 300 V. Success was defined as return of sinus

rhythm for 30 seconds. Cardiac troponin and creatine kinase–MB were

checked postprocedure.

Results: Patients (n = 16, 11 male) received 83 shocks (RF, 40;

conventional, 43). Mean age was 63 (F11.6) years, mean body mass

index was 28 (F6), and mean duration of AF was 5.8 (F5.7) months. The

groups were matched in age, sex, body mass index, duration of AF,

etiology, drugs, and echocardiographic features. The RF waveform

performed significantly better than the conventional waveform for the

cardioversion of chronic AF (7 [87%]/8 patients vs 1 [12%]/8 patients

Table 1

The mean F SD correlation coefficients between the PEM and the standard ECG measurements of data set a

Global meas (98% of cases) Lead meas for the same wave profiles

I II V2 V1, V3-V6

Ge Sp

0.85 F 1.07 0.84 F 1.06 0.85 F 1.12 0.91 F 0.04 0.70 F 0.16 0.84 F 0.11

Meas indicates measurements; Ge, generic transform; Sp, patient-specific transform.

Table 2

The physician’s evaluation results on data set b

Opinion Diagnosed Meas (%)

Ge+/Sp+ 22 89.7

Ge+/Sp� 0 0

Sp+/Ge� 1 3.4

Ge�/Sp� 1 6.9

Table 1

Automatic measurement results of T end and Q onset on MIT QT database compared with published data (Comput cardiol 1997)

n Qon (ms) SD (ms) Sensitivity PPV Tend (ms) SD (ms) Sensitivity PPV

Jane-best 73 �0.63 19.27 99.7 99.87

Philips-best 73 �0.91 14.01 100.0 100.0 �2.39 18.6 99.92 99.71

Jane-all 105 �7.82 10.86 99.88 99.97 18.68 29.79 98.92 99.91

Philips-all 105 0.09 14.77 100.0 100.0 �6.13 34.38 98.08 89.41

Table 2

Automatic measurement results of QT interval on the same database

n QT (ms) SD (ms) Sensitivity PPV

Philips-best 73 �1.20 22.54 99.92 99.71

Philips-all 105 �5.52 36.62 98.08 89.41

Poster Session I / Journal of Electrocardiology 38 (2005) 33–3934

success; P = .003). The mean leading edge voltage for the RF was 221 V

(range, 100-300 V) and for the conventional waveform was 240 V. No

significant arrhythmias, sinus pauses, or episodes of hypotension occurred.

There was no elevation of cardiac enzymes.

Conclusions: The novel biphasic waveform has a superior efficacy at a

lower voltage compared with the conventional waveform in the trans-

venous cardioversion of AF. There were no arrhythmic, hemodynamic

complications, or elevation of markers of myocardial injury. Use of this

waveform may improve the efficacy of implantable devices for the

treatment of AF.

doi:10.1016/j.jelectrocard.2005.06.041

Electrocardiographic artifact: a frequently misdiagnosed phenomenon

S. Hanon, J.S. Berger, S. Hurwitz, J. Fine, D.L. Brown, P. Schweitzer

Background: Electrocardiographic (ECG) artifact can imitate wide

complex tachycardia, leading to unnecessary diagnostic or therapeutic

interventions. The current study sought to determine the competency of

physicians in different specialties, with various levels of training, in

diagnosing ECG artifact.

Methods: Two ECGs of artifact simulating wide complex tachycardia were

used for analysis. Physicians recorded their rhythm diagnosis and

diagnostic certainty.

Results: Artifact was not recognized in 307 (82%) of 384 attempts. The

most common recorded diagnoses were ventricular tachycardia (54%) and

supraventricular tachycardia (25%). Failure to identify either artifact was

found in 123 (88%) of 140 residents, 8 (26%) of 31 fellows, and 5 (29%) of

17 attendings. Only 1% of residents, 32% of fellows, and 29% of attendings

correctly identified both artifacts. Among 74 physicians who were 100%

certain of their diagnosis, 34 (50%) were mistaken.

Conclusion: This physician survey suggests that ECG artifact is frequently

misdiagnosed. This finding indicates the need for improved training in the

recognition of artifact and the need for a heightened index of suspicion

among physicians who treat patients on telemetry monitoring.

doi:10.1016/j.jelectrocard.2005.06.042

Philips Medical Systems support for open access and use of

electrocardiographic data

Eric Helfenbein, Richard Gregg, Sophia Zhou (Advanced Algorithm

Research Center, Philips Medical Systems, USA)

The Philips extensible markup language (XML)–based electrocardio-

graphic (ECG) format has been published for more than 2 years. This is

the native format used by Philips electrocardiographs and 12-lead capable

bedside monitors and defibrillators. To support research and clinical trials,

Philips Medical Systems is freely distributing a set of 6 software

tools that provide easy access and conversion of the XML ECG files. The

set of software tools consists of the following. (1) The Food and

Drug Administration converter, which translates the ECG file to the HL7

annotated ECG file format adopted by the US Food and Drug Administra-

tion for digital submission of ECG data for pharmaceutical clinical trials. (2)

The Decompressor software provides unrestricted access to the raw ECG

data by decompressing the ECG into plain text sample values because the

ECG waveform data in the Philips XML file is compressed and base-64

encoded to permit efficient transmission and storage. (3) The Scalable Vector

Graphics (SVG) converter translates the ECG file into an XML SVG image

file that can be viewed using a web browser with the Adobe SVG plug-in

installed. The resulting image allows the researcher to review demogra-

phics, interpretation statements, and calibrated waveform data in a format

similar to the original printed cardiograph report. (4) The PC Receiver

software allows ECG files to be sent directly from a cardiograph to a

personal computer (PC) over a network connection. (5) The NewFilename

tool renames the default Globally Unique Identifier ECG filename to a name

containing the patient’s identification, name, and date/time of the ECG; this

allows the ECG files to be effectively managed on a PC. (6) The Directory

Scanner software automatically runs 1 or more of the conversion tools on

ECGs because they arrive in a specified folder in the PC. This collection of

software provides a valuable ECG tool set for use by clinicians, researchers,

and clinical trial sponsors.

doi:10.1016/j.jelectrocard.2005.06.043

Changes in optical map frequency spectra

characteristics before spontaneous termination

of ventricular fibrillation in isolated rabbit heart model

Suresh E. Joel, Peng-Wie Hsia (Virginia Commonwealth University,

Richmond, VA, USA)

Introduction: Once ventricular fibrillation (VF) sets in, it hardly terminates

spontaneously in humans. However, in small young animals, VF

spontaneously reverts back to normal rhythm. We studied frequency

characteristics of activation during a period before spontaneous termination

(SpT) of VF.

Methods: Optical map recordings (87 episodes) were performed during

SpT VF on isolated rabbit hearts (n = 15) using a high-speed CCD camera

(100 � 100, 256 frames per second). Dominant frequency (DF) maps and

dominant bandwidth maps were computed using continuous Fourier

transform. Regional distribution of epicardial DF and dominant bandwidth

values during VF and changes before termination were studied.

Results: An ordered arrangement of DF domains during VF was observed.

Left ventricular apex and right ventricular (RV) apex had the highest DF

values (DF left ventricular apex, DF RV apex N DF RV base, DF RV apex;

P b .0001), revealing the location of the mother rotor. Left and right sides of

the heart did not show significant differences in DF values. Dominant

frequency values reduced significantly ( P b .01) in all regions 1 second

before termination. Dominant bandwidth values dropped significantly only

in the apex before SpT. All regions that had a significant difference in DF

value distribution during VF also showed a significant decrease in difference

during the last second before SpT, leveling off the DF domain distribution.

Changes observed 1 second before termination were not observed during

other time segments during fibrillation.

Conclusions: The ordered regional organization of DF domains is lost

before termination. The mother rotor resides in the apical region of the

heart and terminates during the last second of fibrillation before SpT. Our

data suggest the disappearance of the highest DF domain as the primary

mechanism of SpT VF. Our results further support that a single, dominant,

high-frequency mother rotor maintains VF in isolated rabbit heart.

doi:10.1016/j.jelectrocard.2005.06.044

n 0 Correct 1 Correct 2 Correct

Residents

Internal

medicine

110 94 (85) 14 (13) 2 (2)

Emergency

medicine

17 17 (100) – –

Family

practice

13 12 (92) 1 (8) –

Fellows

Cardiology 24 4 (16) 10 (42) 10 (42)

Critical care 7 4 (57) 3 (43) –

Attendings

Cardiology 11 1 (9) 5 (45) 5 (45)

Emergency

medicine

6 4 (67) 2 (33) –

Values in parentheses are percentages.

Poster Session I / Journal of Electrocardiology 38 (2005) 33–39 35