Cardiac Physio

• Functions of the heart include pumping blood towards the different parts of the body.
• The heart consists of two separate pumps: the right heart which pumps blood through the lungs, and the left heart which pumps blood through the systemic circulation.
• The heart is composed of an atrium and a ventricle.
• There are three major types of cardiac muscle: atrial muscle, ventricular muscle, and excitatory and conductive muscle fibers.
• During the depolarization phase (Phase 0), fast sodium channels open.
• During the initial repolarization phase (Phase 1), fast sodium channels close.
• The left atrium receives oxygenated blood from the pulmonary veins, while the right atrium receives deoxygenated blood from the vena cavae.
• The right ventricle is the chamber that pumps blood to the lungs.
• During the plateau phase (Phase 2), calcium channels open and fast potassium channels close.
• During the rapid repolarization phase (Phase 3), calcium channels close and slow potassium channels open.
• During the resting membrane potential phase (Phase 4), the heart is at rest.
• Ventricular fibrillation, the most serious of all cardiac arrhythmias, results from cardiac impulses that have gone berserk within the ventricular muscle mass, stimulating first one portion of the ventricular muscle, then another portion.
• Tetralogy of fallot is the most common cause of blue baby, causing reduced ability of the heart to pump enough blood.
• Conditions affecting the coronary arteries can lead to myocardial ischemia or myocardial infarction.
• Complete AV block (third-degree block) is a condition where the impulse from the atria to the ventricles is completely blocked, resulting in periodic fainting and ventricles establishing their own signal distal to the block.
• Stenosis is a condition where blood cannot flow though the valves normally, with Mitral stenosis causing blood to pass with difficulty from the left atrium to the left ventricle and Aortic stenosis causing blood to pass with difficulty from the left ventricle to the aorta.
• Atrial fibrillation is identical to that of ventricular fibrillation, except that the process occurs only in the atrial muscle mass.
• Premature atrial contractions, premature ventricular contractions, and the QRS complex are usually prolonged are common in Complete AV block.
• Coronary arteries are responsible for venous drainage, with the left ventricle draining into the coronary sinus and the right ventricle draining into cardiac veins.
• Patent ductus arteriosus is an increase in backward flow of blood from the aorta to the pulmonary artery.
• Overdrive suppression occurs when, after a few seconds, some part of the Purkinje system or in the A-V bundle begins discharging rhythmically at a rate of 15 to 40 times per minute and acting as the pacemaker of the ventricles.
• Regurgitation is a condition where the valves do not close fully, with Mitral regurgitation causing blood to flow backward into the left atrium and Aortic regurgitation causing blood to flow backward into the left ventricle.
• Atrial septal defect/ventricular septal defect are increases in backward flow of blood from left to right.
• Cardiac events that occur from the beginning of one heartbeat to the beginning of the next are known as cardiac cycle.
• Blood flows through the tricuspid valve into the right ventricle, then out of the pulmonic valve into the pulmonary artery.
• The cardiac cycle consists of a period of relaxation (diastole), followed by a period of contraction (systole).
• P wave represents atrial depolarization, QRS waves represent ventricular depolarization, and T waves represent ventricular repolarization.
• The atria are primer pumps for the ventricles, responsible for 80% of the blood flow into the ventricles.
• An additional 20% of the filling of the ventricles is done by atrial contraction.
• During diastole, the ventricles fill with blood.
• The left ventricle is the chamber that pumps blood to the rest of the body.
• During ventricular systole, large amounts of blood accumulate in the right and left atria because of the closed AV valves.
• These branches in turn course sidewise around each ventricular chamber and back toward the base of the heart.
• Bradycardia is defined as a slow heart rate that is fewer than 60 beats per minute.
• SA block is when an impulse from the sinus node is blocked before it enters the atrial muscle.
• The atrial muscle is separated from the ventricular muscle by a continuous fibrous barrier.
• After penetrating the fibrous tissue between the atrial and ventricular muscle, the distal portion of the A-V bundle passes downward in the ventricular septum for 5 to 15 millimeters toward the apex of the heart.
• Anterior interatrial band delays impulse conduction from the atria to the ventricles.
• Second-degree block is when there is an atrial P wave but no QRS-T wave, and it is said that there are “dropped beats” of the ventricles.
• Tachycardia is defined as a fast heart rate that is faster than 100 beats per minute.