Premature Atrial Contraction is an early heartbeat that starts in the atria before the next expected sinus beat. It is a cardiac electrophysiology finding and a common form of supraventricular ectopy. It is most often recognized on an electrocardiogram (ECG) or ambulatory rhythm monitoring. It is discussed in cardiology, emergency care, and primary care when evaluating palpitations or irregular pulse.

Premature Ventricular Contraction is a heartbeat that starts in the ventricles earlier than expected in the normal rhythm. It is a cardiac electrophysiology finding and a common form of ventricular ectopy. It is most often discussed in the context of arrhythmias on electrocardiogram (ECG) and ambulatory monitoring. It can occur in healthy individuals and in patients with structural heart disease.

Right Bundle Branch Block is an electrocardiogram (ECG) pattern showing delayed electrical activation of the right ventricle. It reflects conduction slowing or interruption in the right bundle branch within the His–Purkinje system. It is a diagnostic finding (not a disease by itself) that is interpreted in clinical context. It is commonly discussed in ECG interpretation, emergency care triage, and evaluation of structural heart and pulmonary disease.

Left Bundle Branch Block is an electrocardiogram (ECG) pattern caused by delayed electrical activation of the left ventricle. It reflects a conduction abnormality in the His–Purkinje system rather than a primary rhythm problem. It is most often identified on a 12-lead ECG and interpreted in emergency, inpatient, and outpatient cardiology. It matters because it can signal underlying structural heart disease and can change how ischemia and heart failure are evaluated.

Bundle Branch Block is an abnormality of electrical conduction in the heart’s ventricular conduction system. It is defined by delayed or blocked activation of one ventricle, seen as a widened QRS complex on electrocardiogram (ECG). It is primarily a diagnostic finding, not a disease by itself, and it is used across emergency, inpatient, and outpatient cardiology. It commonly appears in evaluations for chest pain, dyspnea, syncope, heart failure, and pre-operative assessment.

Third Degree AV Block is complete failure of atrioventricular (AV) conduction between the atria and ventricles. It is a disorder of the cardiac conduction system involving the AV node and/or His–Purkinje system. It is commonly recognized on electrocardiogram (ECG) and bedside monitoring as AV dissociation with bradycardia. It is a clinically important cause of symptomatic bradyarrhythmia and may require pacing therapy.

Second Degree AV Block is a cardiac conduction abnormality in which some atrial impulses fail to conduct to the ventricles. It is defined and recognized primarily on the electrocardiogram (ECG/EKG). It reflects dysfunction within the atrioventricular (AV) conduction pathway, most commonly the AV node or the His–Purkinje system. It is commonly discussed in cardiology, emergency medicine, inpatient telemetry, and perioperative monitoring.

First Degree AV Block is an electrocardiogram (ECG) finding in which atrioventricular (AV) conduction is delayed but not interrupted. It is defined by a prolonged PR interval with every atrial impulse still conducted to the ventricles. It belongs to the cardiac conduction and electrophysiology domain rather than a structural heart disease diagnosis. It is commonly identified on routine ECGs, inpatient telemetry, and preoperative or sports screening.

Heart Block is a problem with electrical conduction from the atria to the ventricles. It is a conduction-system disorder discussed in cardiac anatomy, physiology, and arrhythmia care. It is commonly identified on an electrocardiogram (ECG) and correlated with symptoms like bradycardia or syncope. It matters in emergency assessment, inpatient cardiology, and long-term pacing decisions.

Tachycardia means a heart rate that is faster than expected for age and clinical context. It is a physiologic and pathologic concept in cardiology and acute care medicine. It is most commonly identified at the bedside by pulse and confirmed on electrocardiogram (ECG). It is used to describe a sign, a symptom-associated finding, or a primary cardiac arrhythmia.