PR Interval is an electrocardiogram (ECG) measurement that reflects atrial-to-ventricular conduction time. It spans from the start of the P wave to the start of the QRS complex on the ECG tracing. It is a physiology and diagnostic-test concept used to assess the cardiac conduction system, especially atrioventricular (AV) conduction. It is commonly reviewed in routine 12-lead ECG interpretation, bradycardia evaluation, and suspected heart block.

QT Interval is an electrocardiogram (ECG) measurement that reflects ventricular depolarization plus repolarization. It is read on a diagnostic test, not a symptom or a disease by itself. It is used most often in cardiology, emergency care, and perioperative medicine to assess arrhythmia risk. It is commonly discussed when evaluating medications, electrolytes, syncope, and inherited channelopathies.

Cardiac Repolarization is the electrical “resetting” phase of heart muscle cells after they activate. It is a core concept in cardiac electrophysiology and ECG (electrocardiogram) interpretation. It is most commonly discussed when evaluating ST-segment and T-wave findings and the QT interval. It is clinically relevant in arrhythmias, ischemia, electrolyte disorders, and drug safety.

Cardiac Depolarization is the electrical activation of heart muscle that initiates contraction. It is a core physiology concept in cardiac electrophysiology and the cardiac conduction system. It is most commonly discussed when interpreting an electrocardiogram (ECG/EKG) and cardiac monitoring. It also underpins how arrhythmias form and how therapies like pacing and cardioversion work.

Purkinje Fibers are specialized cardiac conduction cells that rapidly deliver electrical impulses through the ventricles. They are part of cardiac anatomy and physiology, specifically the His–Purkinje conduction system. They are most commonly discussed when interpreting electrocardiograms (ECGs), evaluating arrhythmias, and planning electrophysiology (EP) procedures. They help explain how coordinated ventricular contraction is achieved in normal rhythm and how certain conduction disorders occur.

The Bundle of His is a short tract of specialized cardiac conduction tissue that carries electrical impulses from the atrioventricular (AV) node to the ventricles. It is part of cardiac anatomy and physiology, specifically the cardiac conduction system. Clinically, it is discussed in arrhythmias, atrioventricular block, bundle branch block, and pacing strategies. It is commonly referenced when interpreting the electrocardiogram (ECG) and during electrophysiology (EP) procedures.

AV Node is a small cluster of specialized cardiac conduction tissue that electrically connects the atria to the ventricles. It is part of cardiac anatomy and physiology within the heart’s conduction system. It is commonly discussed in electrocardiography (ECG), arrhythmias, and atrioventricular (AV) conduction blocks. It is also a key target in electrophysiology (EP) testing and some catheter ablation strategies.

The SA Node is a small cluster of specialized heart cells that initiates the normal heartbeat. It is part of cardiac anatomy and physiology, specifically the heart’s electrical conduction system. Clinically, it is discussed in rhythm diagnosis, bradycardia and tachycardia evaluation, and pacemaker decision-making.

The Cardiac Conduction System is the heart’s built-in electrical network that initiates and coordinates each heartbeat. It is a core topic in cardiac anatomy and physiology with direct relevance to arrhythmias and bradycardia. It is commonly assessed using the electrocardiogram (ECG/EKG), telemetry, and ambulatory rhythm monitors. It also guides clinical decisions in electrophysiology, device therapy (pacemakers/ICDs), and perioperative care.

Revascularization means restoring blood flow to tissue that is underperfused. In cardiology, it most often refers to reopening or bypassing narrowed coronary arteries. It is a therapeutic concept that can be delivered by catheter-based intervention or surgery. It is commonly discussed in acute coronary syndrome (ACS) and chronic coronary disease with ischemia.