LAD most often means the **left anterior descending coronary artery**, one of the main arteries that supplies blood to the heart muscle. It runs on the front surface of the heart and gives off branches that nourish the left ventricle. Clinicians commonly mention LAD in discussions of **coronary artery disease**, heart attacks, stents, and bypass surgery. In some contexts, LAD can also mean **left axis deviation** on an ECG, but this article focuses primarily on the coronary artery meaning.

The Left Anterior Descending Artery is a major coronary artery that supplies blood to the front wall of the heart. It runs along the front groove of the heart toward the tip (apex). Clinicians refer to it often when evaluating chest pain, heart attacks, and coronary artery disease. It is also a key target in stenting procedures and bypass surgery.

The Left Main Coronary Artery is the main blood vessel that supplies oxygen-rich blood to a large portion of the left side of the heart. It arises from the aorta and typically divides into the left anterior descending (LAD) and left circumflex (LCx) arteries. Clinicians refer to it frequently in heart attack evaluation, coronary artery disease workups, and planning of stents or bypass surgery. Because it feeds major branches, disease in this vessel can carry important clinical implications.

Coronary Arteries are the blood vessels that supply oxygen-rich blood to the heart muscle. They run on the surface of the heart and branch into smaller vessels that feed the myocardium. They are commonly discussed when evaluating chest pain, shortness of breath, and heart attack risk. They are also central in cardiology imaging and procedures that restore blood flow to the heart.

Purkinje Fibers are specialized heart cells that rapidly carry electrical signals through the ventricles. They help the lower chambers contract in a coordinated way to pump blood effectively. Clinicians commonly discuss them when interpreting ECG findings or evaluating certain rhythm problems. They are part of the heart’s normal electrical “wiring,” not a device or medication.

The Left Bundle Branch is a key part of the heart’s electrical wiring system. It carries electrical signals from the center of the heart to the left ventricle. Clinicians often discuss it when interpreting an electrocardiogram (ECG/EKG) or evaluating conduction problems. It is also referenced in some pacing approaches that aim to restore coordinated heart contraction.

The Right Bundle Branch is a specialized electrical pathway inside the heart. It carries impulses from the atrioventricular (AV) node area to the right ventricle. It is most commonly discussed when interpreting an electrocardiogram (ECG/EKG) or evaluating a conduction problem such as bundle branch block.

His Bundle is a short segment of specialized heart tissue that carries electrical signals from the upper heart chambers to the lower chambers. It sits in the central part of the heart’s electrical “wiring,” near the atrioventricular (AV) node and the heart’s fibrous skeleton. Clinicians refer to His Bundle when interpreting rhythm problems and when planning certain electrophysiology procedures. It is also a target for a pacing approach called His Bundle pacing in selected patients who need a pacemaker.

The Bundle of His is a small pathway of specialized heart muscle cells that carries electrical signals from the upper to the lower chambers of the heart. It sits in the heart’s central “wiring” system between the atria and the ventricles. Clinicians reference it when explaining heart rhythm problems such as heart block or bundle branch block. It is also a target for certain pacing strategies designed to support a more natural pattern of ventricular activation.

The AV Node is a small cluster of specialized heart cells that helps control how electrical signals travel from the atria to the ventricles. It acts like a timing and filtering station between the upper and lower chambers of the heart. Clinicians talk about the AV Node when evaluating heart rhythm problems, slow heart rates, and certain types of rapid heartbeats. It is commonly referenced when interpreting an ECG, diagnosing heart block, or planning rhythm treatments.

The Atrioventricular Node is a small area of specialized heart tissue that helps control the timing of the heartbeat. It sits between the upper chambers (atria) and lower chambers (ventricles) and relays electrical signals. It is commonly discussed when evaluating heart rhythm problems (arrhythmias) and conduction blocks. It is also a key target in some electrophysiology procedures used for rhythm control.

The SA Node is a small cluster of specialized heart cells that normally starts each heartbeat. It sits in the right atrium, near where a large vein (the superior vena cava) enters the heart. It is commonly discussed when clinicians interpret an electrocardiogram (ECG) or evaluate heart rhythm symptoms. It is often called the heart’s “natural pacemaker,” meaning it sets the typical resting heart rate.

The Sinoatrial Node is a small cluster of specialized heart cells that normally starts each heartbeat. It sits in the right atrium, near where blood returns to the heart through the superior vena cava. It is commonly discussed when clinicians evaluate heart rhythm, pulse rate, and causes of palpitations or fainting.

The Cardiac Conduction System is the heart’s built-in electrical wiring that coordinates each heartbeat. It generates and carries signals that tell the heart muscle when to contract and relax. It is discussed every day in cardiology when interpreting an ECG (electrocardiogram) and evaluating rhythm symptoms. It is also central to understanding pacemakers, heart block, and many arrhythmias.

The Cardiac Skeleton is a firm framework of fibrous (collagen-rich) tissue inside the heart. It supports and shapes the heart valves and helps the heart keep its structure while beating. It also acts as electrical “insulation” between the upper and lower chambers. Clinicians commonly reference it in valve disease, conduction problems, and cardiac imaging or surgery planning.

Cardiac Base refers to the broad, upper part of the heart opposite the apex (the pointed tip). It is formed mainly by the atria and the attachments to the great vessels (such as the aorta and pulmonary artery). Clinicians use the term to describe anatomy during exams, imaging interpretation, and procedural planning. It is also a common reference point when discussing murmurs and disease involving the valves and aortic root.

The **Cardiac Apex** is the pointed, lower tip of the heart. It is formed mainly by the left ventricle and sits toward the left side of the chest. Clinicians use it as an anatomic landmark during physical exams and heart imaging. It is also referenced when describing certain heart diseases and procedure approaches.

The Interatrial Septum is the wall of tissue that separates the heart’s right atrium from the left atrium. It helps keep oxygen-poor and oxygen-rich blood on their correct pathways through the heart. Clinicians commonly refer to it during echocardiograms and other heart imaging tests. It is also an important landmark for catheter-based procedures that need access to the left atrium.

The Interventricular Septum is the wall of heart muscle that separates the right and left ventricles. It helps keep oxygen-poor and oxygen-rich blood from mixing inside the heart. Clinicians assess it on cardiac imaging and during physical evaluation of heart disease. It is also discussed in conditions such as heart muscle thickening, conduction problems, and congenital defects.

The Ventricular Septum is the thick wall of heart muscle that separates the right and left ventricles. It helps keep oxygen-poor blood (right side) and oxygen-rich blood (left side) from mixing. Clinicians reference it in heart imaging, heart murmur evaluation, and structural heart disease care. It is also central to certain heart rhythm pathways and some cardiac procedures.