12-lead Surface ECG Research Articles

Transesophageal electrocardiography using a temporary pacing balloon-tipped electrode in acute cardiac care

The study was undertaken to determine the feasibility of obtaining esophageal ECGs using resterilized 3F temporary pacing balloon-inflated electrodes in place of the more expensive pill-electrode and its associated expensive preamplifier. Tests were conducted in the emergency department and ICU. Subjects were 12 acutely ill patients for whom standard 12-lead surface ECGs were insufficient to afford accurate, immediate arrhythmia diagnosis. Reasonable quality esophageal ECGs were obtained by use of the electrodes, generally with minimal patient discomfort. The test never required more than ten minutes. Of the 12 patients who participated in this preliminary study, esophageal ECGs enabled definitive diagnoses to be made in ten cases. The use of resterilized temporary pacing balloon-inflated electrodes enables esophageal ECGs to be obtained in an acute care setting.

Clinical implications of low QRS complex voltage

Low QRS voltage on the 12-lead surface ECG is present when the amplitude of all six standard limb leads is less than 5 mm. This finding may be a normal variant, but necessitates investigation of the patient for an underlying cause. A variety of cardiac and systemic diseases may be responsible.

Optimal ECG monitoring during percutaneous transluminal coronary angioplasty of the left anterior descending artery.

During percutaneous transluminal coronary angioplasty (PTCA) frontal ECG leads are routinely monitored. The detection of ST segment deviation during the procedure is important for decisions regarding guiding catheter seating and the timing of balloon inflation and deflation. ST segment deviation appears on intracoronary electrograms in the absence of changes on the surface ECG in many patients, while the reverse is true in some individuals. When a precordial lead is employed, V5 or V6 is most commonly selected. The surface ECG leads most sensitive for monitoring ischemia during left anterior descending angioplasty are not known. In nine lead surface ECGs recorded during balloon inflation, a small degree of ST segment elevation occurred in leads I, aVL, and V5. Lead V2 demonstrated an increase in ST displacement from 0.0 +/- 0.03 mV to 0.29 +/- 0.25 mV during coronary occlusion (p less than 0.01). We conclude that if V5 or V6 is used as a single precordial lead, surface ECG alterations are easily overlooked. During left anterior descending occlusion the most sensitive surface lead is V2. Optimal ECG monitoring during PTCA in some cases should involve surface lead V2 or the intracoronary lead.

Role of cardiac electrophysiologic studies in patients with unexplained recurrent syncope.

Cardiac electrophysiologic studies (EPS) with programmed electrical stimulation (PES) were performed in 30 patients with recurrent syncope to uncover possible arrhythmic etiology. All patients had undergone thorough medical and neurologic evaluation prior to EPS without finding a definitive cause for syncope. In the majority of patients an arrhythmic etiology for syncope was suspected but could not be documented utilizing the 12-lead surface ECG, extended in-hospital and/or ambulatory monitoring (for greater than or equal to 48 hours) and exercise testing prior to the EPS. The studies provided a clue to the possible underlying rhythm disturbance which could have caused syncope in 16/30 patients. Sustained or nonsustained ventricular tachycardia and/or ventricular fibrillation was induced in 11/30, sinus node dysfunction in 4/30 and intra-His block in the remaining one. Fourteen of the 16 have remained free of symptoms following therapy based on results of EPS during a follow-up period ranging from 6-30 months (mean 16.5 +/- 7.8). In 2/16 syncope recurred (one arrhythmic and one non-arrhythmic) despite pacemaker therapy for sinus node dysfunction detected during EPS. In the remaining 14/30 patients, EPS and PES did not induce arrhythmia which could account for patient symptomatology and therefore no specific therapy could be recommended. Eleven of these 14 patients experienced a recurrence of symptoms within a 6-25 month period (mean 16.2 +/- 6.8). Of the 16 patients with inducible arrhythmias considered clinically significant, 15 had associated structural heart disease. On the other hand, of the 14 patients without clinically significant arrhythmias, structural heart disease could be detected in only three. It is concluded that cardiac arrhythmias constitute a common cause of unexplained syncope, particularly in patients with structural heart disease, and that EPS with PES can uncover the type of arrhythmic disturbance in a significant number of cases.