Cardiovascular Notes
Anatomy of heart
The heart is a muscular organ located in the mediastinum (center of the chest), between the lungs.
It pumps blood throughout the body.
Artrium receives blood and Ventricle pumps blood.
Arteries are blood vessels that carry blood away from the heart.
1. Chambers of the Heart : The heart has 4 chambers.
A.Right Atrium - Receives deoxygenated blood from:
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Superior vena cava
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Inferior vena cava
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Coronary sinus
B.Right Ventricle- Pumps deoxygenated blood to the lungs through the pulmonary artery.
C.Left Atrium -Receives oxygenated blood from the pulmonary veins.
D.Left Ventricle-Pumps oxygenated blood to the body through the aorta.
Thickest chamber of the heart.
2. Heart Valves : Valve is a structure that allows blood to flow in one direction only and prevents blood from flowing backward.
A.Tricuspid Valve - Between right atrium and right ventricle.
B.Pulmonary Valve - Between right ventricle and pulmonary artery.
C.Mitral (Bicuspid) Valve - Between left atrium and left ventricle.
D.Aortic Valve - Between left ventricle and aorta.
Disease of heart valve
The heart valves can develop diseases that either:
Do not open properly → Stenosis
Do not close properly → Regurgitation (Insufficiency)
What is septum in heart ?
A septum is a wall or partition that separates two chambers or spaces in the body. In the Heart
The septum divides the right side of the heart from the left side of the heart.
Types of Cardiac Septum
1. Interatrial Septum
Separates: Right atrium Left atrium
2. Interventricular Septum
Separates: Right ventricle Left ventricle
Disease of Septum
Atrial Septal Defect (ASD) - A hole in the interatrial septum.
Ventricular Septal Defect (VSD) - A hole in the interventricular septum.
Patent Foramen Ovale (PFO) -A small opening in the interatrial septum that fails to close after birth.
May allow blood clots to pass from the right side to the left side of the heart.
Hypertrophic Obstructive Cardiomyopathy (HOCM) -The interventricular septum becomes abnormally thick.
Can obstruct blood flow from the left ventricle.
Heart Conduction System
The heart conduction system is the heart's electrical system that generates and conducts electrical impulses, causing the heart muscle to contract and pump blood.
Components of the Heart Conduction System
1. Sinoatrial (SA) Node
Located in the right atrium.
Known as the natural pacemaker of the heart.
Generates electrical impulses.
Normal rate:
60–100 beats per minute
2. Atrioventricular (AV) Node
Located between the atria and ventricles.
Receives impulses from the SA node.
Delays the signal briefly so the ventricles can fill with blood.
Que. Why AV nodes delay , what are the purpose of this ?
The AV (Atrioventricular) node delays the electrical signal so that the atria can finish contracting and empty their blood into the ventricles before the ventricles contract.
What Happens Without the Delay?
If the signal traveled directly from the atria to the ventricles:
Atria contract
Ventricles contract immediately
3. Bundle of His
Carries the electrical signal from the AV node into the ventricles.
4. Right and Left Bundle Branches
Run along the interventricular septum.
Conduct impulses to the right and left ventricles.
5. Purkinje Fibers
Spread throughout the ventricular muscle.
Cause the ventricles to contract.
Disease of Cardiac conduction system
1.Atrial Fibrillation (AFib)
Abnormal electrical activity in the atria.
2.Heart Block
Electrical signals are delayed or blocked.
Examples:
First-degree AV block
Second-degree AV block
Third-degree (complete) heart block
3.Sick Sinus Syndrome
SA node does not function properly.
4.Ventricular Tachycardia (VT)
Rapid rhythm arising from the ventricles.
Main Functions of Purkinje Fibers
1. Rapid Conduction of Electrical Signals
Purkinje fibers conduct impulses much faster than ordinary heart muscle cells.
This allows the entire ventricle to be activated almost simultaneously.
2. Coordinate Ventricular Contraction
Ensures both ventricles contract in a synchronized fashion.
Produces an efficient pumping action.
3. Pump Blood Efficiently
Right ventricle pumps blood to the lungs.
Left ventricle pumps blood to the body.
Coordinated contraction maximizes cardiac output.
What Happens If Purkinje Fibers Are Damaged?
Conditions such as:
Bundle branch block - A Bundle Branch Block (BBB) occurs when the electrical signal traveling through one of the heart's bundle branches is delayed or blocked.
When a bundle branch is blocked, one ventricle receives the electrical signal later than the other, causing the ventricles to contract out of sync.
Right Bundle Branch Block (RBBB)- The right bundle branch is blocked.
left Bundle Branch Block (LBBB)- The left bundle branch is blocked.
What are the muscle of Cardiac ?
The muscle of the heart is called the myocardium.
Layers of the Heart
The heart wall has 3 layers:
Endocardium – Inner lining
Myocardium – Middle muscular layer
Epicardium – Outer layer
Myocardial Infarction (MI), commonly called a heart attack, occurs when blood flow through one or more coronary arteries is suddenly reduced or blocked, causing part of the heart muscle (myocardium) to lose oxygen and begin to die.
Meaning of the Term Myo = Muscle Cardial = Heart Infarction = Death of tissue due to lack of blood supply.
Therefore: Myocardial Infarction = Death of heart muscle due to interruption of blood supply.
What is coronary artery ?
A coronary artery is an artery that supplies oxygen-rich blood to the heart muscle (myocardium). Even though the heart pumps blood to the entire body, the heart muscle itself also needs its own blood supply. The coronary arteries provide that blood.
Main Coronary Arteries
1. Left Coronary Artery (LCA)
Short artery arising from the aorta.
It divides into:
A.Left Anterior Descending (LAD)
Supplies:
Front (anterior) wall of the left ventricle
Interventricular septum
A blockage here can cause a major heart attack.
B.Left Circumflex (LCX)
Supplies:
Lateral wall of the left ventricle
Left atrium
2. Right Coronary Artery (RCA)
Supplies:
Right atrium
Right ventricle
Inferior wall of the left ventricle (in most people)
Often the SA node and AV node
Disease of Coronary Artery
Coronary Artery Disease (CAD) -Plaque buildup in coronary arteries.
Coronary Artery Stenosis -Narrowing of the artery.
Coronary Artery Occlusion -Complete blockage.
