SHARP EKG Cardiac Electrophysiology, Arrhythmias, Conduction System, Pacemakers, ECG Interpretation, and Hemodynamic Management: Comprehensive A+ Review of SA/AV Nodes, Bundle of His, Purkinje Fibers, Action Potentials, Ion Flux, Refractory Periods, Supra

SHARP EKG Cardiac Electrophysiology, Arrhythmias, Conduction System, Pacemakers, ECG Interpretation, and Hemodynamic Management: Comprehensive A+ Review of SA/AV Nodes, Bundle of His, Purkinje Fibers, Action Potentials, Ion Flux, Refractory Periods, Supraventricular & Ventricular Rhythms, Blocks, PACs, PJCs, PVCs, Tachyarrhythmias, Bradyarrhythmias, Atrial Flutter & Fibrillation, AV Blocks, Bundle Branch Blocks, ST-T Wave Abnormalities, Myocardial Ischemia & Infarction, Pacemaker Malfunctions, Torsades de Pointes, V-Fib, Asystole, PEA, and Advanced Cardiac Life Support Protocols Exam Questions Verified and Provided with Complete A+ Graded Rationales Latest Updated 2026 What are the two basic kinds of cardiac cells? 1. myocardial muscle cells 2. myocardial pacemaker cells What are the 4 primary cell characteristics? 1. Automaticity 2. Excitability 3. Conductivity 4. Contractility What are the two major ions that affect cardiac function? 1. sodium 2. potassium What are the primary ions inside the cell? Potassium What are the primary ions outside the cell? Sodium Distribution of ions on either side of the membrane is determined by which several factors? 1. membrane channels 2. concentration gradient 3. electrical gradient 4. sodium-potassium pump Where is the SA node located? In the upper wall of the right atrium/near the inlet of the superior vena cava What is the intrinsic rate of the SA node? 60-100 bpm Pacemaker cells in the AV junction generate electrical impulses at what rate? 40-60 bpm What are the 3 functions of the AV node? 1. slow conduction of the electrical impulse through the AV node to allow atria to empty into the ventricles (atrial kick) 2. to serve as a back pack pacemaker 3. protect ventricles from fast rates After the delay in the AV node, where does the impulse go? To the bundle of His What is the function of the bundle of His? The Bundle of His (AV Bundle) runs from the AV node through the IV septum, splitting into R. and L. branches and eventually breaking into Purkinje fibers as it spreads through the ventricular walls What is the rate of electrical impulse the Purkinje Fibers have? 30-40 bpm What does the P wave represent? atrial depolarization When does atrial repolarization occur? during the QRS complex What does the QRS wave represent? ventricular depolarization What does the ST segment represent? early ventricular repolarization What does the T wave represent? ventricular repolarization What does the QT interval represent? the time of ventricular activity including both depolarization and repolarization What are the two refectory phases of the cardiac cycle? 1. Absolute refractory period 2. Relative refractory period What is "absolute refractory period"? The cardiac cells are unable to respond to an electrical stimulus (from the onset of the QRS to the peak of the T wave) What is the "relative refractory period"? The cardiac cells have depolarized sufficiently to respond to a strong stimulus (peak of T wave to end of T wave) A small square on EKG paper is how long? 0.04 A big square on EKG paper is how long? 0.2 How long is a P wave? .10 What is the duration of the PR interval? 0.12-0.20 What is the duration of the QRS? .10 What are some causes of a abnormally wide QRS? 1. a electrical impulse that originated in an ectopic site in the ventricles 2. BBB 3. an electrical impulse that went thru a accessory conduction pathway that bypasses the AV node What are some causes of a ST elevation? 1. STEMI 2. Coronary artery spasm (Printzmetal angina) 3. hyperkalemia 4. hypothermia 5. ventricular aneurysm What are some causes of ST depression? 1) NSTEMI 2) Digoxin 3) Hypokalemia 4) RBBB or LBBB 5) RVH or LVH What causes abnormal T waves? (7) 1. myocardial ischemia 2. acute MI 3. hyperkalemia 4. pericarditis 5. BBB 6. subarachnoid hemorrhage 7. ventricular enlargement