negative direction of qrs main wave in avl lead

arrow axis human body anatomical ecg education recording heartbeat duration heart rate rhythm cardiology electrocardiography electrodes monitoring electrode electrocardiograph theory cardiovascular medicine cardiogram cardiac anatomy beat cardiac depolarization diagnosis disease ekg electrocardiogram ventricle cycle arrhythmia electric potential excitation chest lead avl qrs wave ventricles leads frontal lead systems limb complexes left right ventricular septum ecg education