Clinical Consequences of ECG Artifact Mimicking Ventricular Tachycardia
abstract & commentary
Synopsis: Misinterpretation of an ECG artifact can subject patients to unnecessary diagnostic and therapeutic interventions that increase medical expenditures and subject patients to increased risk.
Source: Knight BP, et al. N Engl J Med 1999;341: 1270-1274.
In this report, knight and colleagues describe a series of 12 patients seen for an electrophysiology consultation by their group after undergoing an inappropriate procedure as a result of an electrocardiogram (ECG) artifact misdiagnosed as nonsustained ventricular tachycardia (VT).
Twelve patients formed the study group. ECG artifact mimicking VT was recorded during in-hospital telemetry monitoring in seven patients, in the emergency room in three patients, and during ambulatory ECG monitoring or treadmill testing in single patients. The artifacts were diagnosed as either monomorphic (5 patients) or polymorphic (7 patients) VT with a rapid rate (226 ± 35 beats/min). Reexamination of the ECG data, however, detected a stable pattern of normal electrocardiographic wave (QRS) complexes that marched through the artifact. As a result of the initial misdiagnosis, the patients were subjected to a number of diagnostic and therapeutic procedures. Three patients underwent diagnostic cardiac catheterization. Seven patients received unnecessary intravenous antiarrhythmic drugs and two received anti-ischemic therapy. Two patients received a precordial thump. One patient received a permanent pacemaker to prevent bradycardia-related arrhythmias and another received an implantable cardioverter defibrillator.
Physicians at every level were responsible for the ECG misdiagnosis. Four cardiologists, four medical residents, three emergency room physicians, and one electrophysiologist made the original mistake. In 10 of 12 cases, a board-certified cardiologist was consulted and agreed with the mistaken diagnosis.
Knight et al conclude that misinterpretation of an ECG artifact can subject patients to unnecessary diagnostic and therapeutic interventions that increase medical expenditures and subject patients to increased risk.
Comment by John P. DiMarco, MD, PhD
Continuous ECG monitoring is now commonly used and practiced in a number of inpatient and outpatient clinical settings. The fidelity of the recording obtained depends on a number of factors influenced by the patient, the equipment used, and the surrounding environment. Signal drop-out can mimic bradycardia or asystole. If paper or tape speed is unstable, false recordings of bradycardia or tachycardia can be obtained. Vigorous extremity motion or patient manipulation of the electrode can produce a tracing resembling ventricular tachycardia. A continuous rapid tremor may produce a recording that resembles atrial flutter. As shown in this paper, misdiagnosis of artifact can result in potentially serious consequences for some patients.
The first step for correction of this problem is to make physicians aware that such problems may occur. These artifacts are usually transient. Although an absence of symptoms during a brief episode is not a reliable indicator of artifact, such absence should raise suspicions. Physicians must carefully examine the ECG tracing they are given. QRS complexes that march through the artifact, as was seen in this study, should be sought.
Psuedoventricular tachycardia is most often caused by:
a. 60-cycle interference.
b. 50-cm/s paper speed.
c. patient electrode manipulation.
d. tremor.
Vascular Biology: Provocative Reports for the Clinician
There has been an explosion of vascular biology basic and clinical research in the past decade. Of importance to the cardiologist are the current interest in inflammation and infection, the assessment of endothelial function in a variety of clinical situations, and the increasing use of assays for vascular adhesion molecules and components of the fibrinolytic system in patients with various coronary syndromes The following three reports are representative of the recent attention to these issues.
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