Electrocardiographic artifact: a frequently misdiagnosed phenomenon

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

Residents Internal medicine Emergency medicine Family practice Fellows Cardiology Critical care Attendings Cardiology Emergency medicine

n

0 Correct

1 Correct

2 Correct

110

94 (85)

14 (13)

2 (2)

17

17 (100)

–

–

13

12 (92)

1 (8)

–

24 7

4 (16) 4 (57)

10 (42) 3 (43)

10 (42) –

11 6

1 (9) 4 (67)

5 (45) 2 (33)

5 (45) –

Values in parentheses are percentages.

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

35

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 Administration 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 demographics, 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