When current flows towards an electrode, a upward deflection is recorded; when current flows away, a downward deflection is recorded. (76)

What is the process of cells returning to resting state? Repolarization (77)

Repolarization is slower than depolarization, so its deflection is wider and has lower magnitude. (78)

The RL electrode serves what purpose? (78) Grounding

The aVR lead records the RA lead as positive and the other limb leads are the negative poles. (79)

Precordial leads are all what type? Unipolar (80)

In the QRS, if the 1st deflection is upward, what is the name of this upward wave? R wave (82)

During normal V-depolarization, why is the net charge directed leftward and posteriorly (towards the LV)? (83) due to the anatomical orientation and activation sequence of the cardiac cells.

Combining unipolar and bipolar, how many different “directions” of planer measurements can be recorded? Twelve (80)

Which precordial lead is the “transition” lead and why? Lead V3 is considered the "transition" lead because it is positioned between the right-sided and left-sided leads, providing a transition between the electrical forces generated by the right and left ventricles.(86)

Normal sinus cardiac rhythm is confirmed by what 4 characteristics? regular rhythm, heart rate within the normal range (60-100 beats per minute), presence of P waves preceding each QRS complex, and a consistent PR interval duration.(87)

Normal axis of the heard is between -30° and +90°. If the axis is < -30° or > +90°, this is considered what, respectively? What pathologies result in this phenomenon? If the axis of the heart is less than -30°, it is considered left axis deviation (LAD). If the axis is greater than +90°, it is considered right axis deviation (RAD). Left axis deviation can be caused by conditions such as left bundle branch block or left ventricular hypertrophy, while right axis deviation can be caused by conditions such as right bundle branch block or right ventricular hypertrophy.(87)

What are the 6 numbers in the "count-off" sequence to quickly estimate heart rate? The "count-off" sequence to quickly estimate heart rate includes the numbers: 300, 150, 100, 75, 60, and 50. By counting the number of large squares between consecutive R waves and using this sequence, one can estimate the heart rate in beats per minute. (87)

What is an isoelectric QRS complex and what does it imply? An isoelectric QRS complex refers to a QRS complex that appears flat with no significant deflection above or below the baseline. It implies that there is no significant abnormal electrical activation or conduction occurring during ventricular depolarization. (91)

If lead aVL is isoelectric and lead II is +, what is the electrical axis of this heart (normal, right, left)? If lead aVL is isoelectric (flat) and lead II is positive, it suggests that the electrical axis of the heart is normal.(91)

What leads become taller because f a large muscular RV wall (hypertrophy)? Hint - right above the RV. V1 and V2 (92)

Why do BBB's prolong the QRS (>0.1 sec)? Bundle branch blocks (BBBs) prolong the QRS duration (>0.1 sec) because they disrupt the normal sequential activation of the ventricles. In a BBB, one of the bundle branches is blocked or delayed, causing a delay in ventricular depolarization and resulting in a wider QRS complex on the electrocardiogram (ECG).(93)

If lead V¹ abnormally terminate on R' (read R-prime), and V6 shows deepened S-wave, what is the block?RBBB is characterized by a delay or blockage in the electrical conduction through the right bundle branch, leading to a widened QRS complex and changes in the ECG morphology. (95)

The left anterior and posterior fascicles travel along their respective sides (A/P) towards what cardiac structures? This initiates LV depolarization/contraction at the base of these structures. The left anterior fascicle and left posterior fascicle (also known as the left posterior hemiblock) travel along their respective sides (A/P) towards specific cardiac structures. The left anterior fascicle initiates left ventricular (LV) depolarization/contraction at the base of the anterior papillary muscle, while the left posterior fascicle initiates LV depolarization/contraction at the base of the posterior papillary muscle.(95)

If LAFB is present, depolarization begins at the healthy posterior papillary, and LV depolarization begins with the left inferior free wall towards leads I and aVL(which leads), then travels towards the superior/anterior of the LV towards V5 and V6 (which leads). (95)

Describe the evolving EKG timeline of an infracting heart as hours, days, weeks, months pass. (100)