ABSTRACT
Background and Objective: ECG is one of the most common diagnostic procedures. Errors related to incorrect placement of electrodes and/or inaccurate connection of them in their standard anatomical location will cause some changes in the ECG waves. These errors may cause therapeutic or diagnostic mismanagements. This study was done to determine the common errors in connection or placement of leads in standard electrocardiograms
Methods: This descriptive-analytical study was performed on 315 patients admitted to an educational and therapeutic hospital in Gorgan, Iran during 2014. The recorded variables included the distance between the positions of the V1, V2, V5 and V6 leads from the standard location, the displacement of the left and right electrodes in bipolar limb lead I and the incorrect right and left connectivity of V1 and V2, the admission section, the urgency of ECGs and the patient's gender. The gender of ECG operator, the standard ECG voltage, staff shift, the average number of ECGs taken by the personnel, and the precise bonding of wires were observed. In the precordial leads, the distance of more than 2 centimetres from the standard leads location was considered as error threshold
Results: The misplacement errors were observed in 149 cases [47.3%]. In 20 cases [13.42%] of ECGs, the standard voltage was not observed. The highest number of misplacement errors was observed in the V5 [30.2%]. Misplacement errors showed a significant differences [P<0.05] for the patient gender [61.77%], the type of department [emergency department 61.67%], the non-urgent application [68.12%], and the average number of ECGs taken by personnel of 5 or less in each shift [11.67%]
Conclusion: Patient's gender and emergency department are the most important factors in misplacement of precordial leads
ABSTRACT
Heart velocity may be influenced by gagging. The medulla oblongata receives the afferents of gag reflex. Neuronal pools of vomiting, salivation and cardiac parasympathetic fibers are very close in this area. So, their activities may be changed by spillover from each other. Using the heart rate variability [HRV] analysis, the effect of gagging on cardiac sympatovagal balance was studied. ECG was recorded from 12 healthy nonsmoker volunteer students for 10 minutes in the sitting position between 10 and 11 AM. Gagging was elicited by tactile stimulation of the posterior pharyngeal wall. At 1 kHz sampling rate, HRV was calculated. The mean of heart rate at low and high frequencies [LF: 0.04-0.15; HF: 0.15-0.4 Hz] were compared before and after the stimulus. The mean of average heart rate, LF and HF in normalized units [nu] and the ratio of them [LF/HF] before and after the gagging were 89.9 +/- 3 and 95.2 +/- 3 bpm; 44.2 +/- 5.8 and 21.2 +/- 4; 31.1 +/- 5.3 and 39.4 +/- 3.8; and 1.7 +/- 0.3 and 0.6 +/- 0.2 respectively. Gagging increased heart velocity and had differential effect on two branches of cardiac autonomic nerves. The paradoxical relation between average heart rate and HRV indexes of sympatovagal tone may be due to unequal rate of change in autonomic fiber activities which is masked by 5 minutes interval averaging