Electrocardiogram

Basic Anatomy Heart is a muscle called myocardium Heart is a muscle called myocardium Heart has 4 chambers- right atrium, right ventricle, left atrium, left ventricle Heart has 4 chambers- right atrium, right ventricle, left atrium, left ventricle Septum divides the sides Septum divides the sides

Circulatory Path Superior/inferior vena cava Superior/inferior vena cava Right atrium Right atrium Tricuspid valve Tricuspid valve Right ventricle Right ventricle Pulmonic valve Pulmonic valve Pulmonary artery Pulmonary artery Lungs Lungs Pulmonary vein Pulmonary vein Left atrium Left atrium Mitral valve Mitral valve Left ventricle Left ventricle Aortic Valve Aortic Valve Aorta Aorta Body Body

Electrocardiography Terms Polarity- Two separate poles: (positive and negative) Polarity- Two separate poles: (positive and negative)

Depolarization- initiates chain that results in contraction of the heart Depolarization- initiates chain that results in contraction of the heart

Repolarization- Period of Electrical Recovery Repolarization- Period of Electrical Recovery

Electrodes- electrical impulse sensors that transmit information from body to machine that produce an electrical tracing. Electrodes- electrical impulse sensors that transmit information from body to machine that produce an electrical tracing.

Cardiac Leads On a routine EKG there are 10 lead positions On a routine EKG there are 10 lead positions Chest wall 6 locations Chest wall 6 locations Left arm Left arm Right arm Right arm Left leg Left leg Right leg Right leg Each lead indicates the walls of the heart. There is front, back, and sides. Each lead indicates the walls of the heart. There is front, back, and sides. Abnormal findings can indicate problems. This is how the location of an MI (heart attack) is determined. Abnormal findings can indicate problems. This is how the location of an MI (heart attack) is determined.

Conduction The heart is a large muscle that acts as a pump, but it has to have an impulse form the brain and electrical stimulation to tell it how fast and when to beat. The heart is a large muscle that acts as a pump, but it has to have an impulse form the brain and electrical stimulation to tell it how fast and when to beat.

Conduction Special tissues in the heart transmit electrical impulses. Special tissues in the heart transmit electrical impulses. These impulses cause the heart to contract and relax. These impulses cause the heart to contract and relax.

Conduction pattern Sinoatrial (SA) node Sinoatrial (SA) node Atrioventricular (AV) node Atrioventricular (AV) node Bundle of HIS Bundle of HIS Purkinje Fibers Purkinje Fibers

Sinoatrial node (SA) node is the pacemaker of the heart. This is where transmission begins and sets the rhythm of the heart. Normal pulse rate is 60 to 100 beats per minute. Sinoatrial node (SA) node is the pacemaker of the heart. This is where transmission begins and sets the rhythm of the heart. Normal pulse rate is 60 to 100 beats per minute. The SA node is located high on the right atrium close to whether the superior vena cava enters the right atrium. The SA node is located high on the right atrium close to whether the superior vena cava enters the right atrium.

Atrioventricular node (AV node)- Pulse rate here about 40 to 60 beats per minute. Atrioventricular node (AV node)- Pulse rate here about 40 to 60 beats per minute. It takes about 0.03 seconds for the impulse to travel from the SA to AV node. It takes about 0.03 seconds for the impulse to travel from the SA to AV node. Atrioventicular node (AV node) is located on the interatrial septum close to the tricuspid valve. Atrioventicular node (AV node) is located on the interatrial septum close to the tricuspid valve.

Bundle of HIS emerges from the AV node to begin the conduction of the impulse from the AV node to the ventricles. Bundle of HIS emerges from the AV node to begin the conduction of the impulse from the AV node to the ventricles. AV node AV node If the SA and AV nodes are injured the ventricular conducting system can take over control of heart rate and rhythm. If the SA and AV nodes are injured the ventricular conducting system can take over control of heart rate and rhythm. Pulse rate is about 30 to 40 beats per minute. Pulse rate is about 30 to 40 beats per minute.

Purkinje Fibers distribute the impulse to the ventricular muscle. These fibers can also compensate if SA and AV nodes are damaged. The rate here is also about 30 to 40 beats per minute or less. Purkinje Fibers distribute the impulse to the ventricular muscle. These fibers can also compensate if SA and AV nodes are damaged. The rate here is also about 30 to 40 beats per minute or less.

Electrical complex- (PQRST)

P wave represents the sinoatrial (SA) node. P wave represents the sinoatrial (SA) node. QRS complex represents the contraction of the ventricle QRS complex represents the contraction of the ventricle

Q- down septum toward purkinje fibers Q- down septum toward purkinje fibers R- impulse through left ventricle R- impulse through left ventricle S- both ventricles S- both ventricles T- repolarization of ventricles (recovery) T- repolarization of ventricles (recovery)

PR interval- time for impulse to travel from SA node to AV node PR interval- time for impulse to travel from SA node to AV node

Q-T interval- time for ventricles to contract, recover, and repolarize Q-T interval- time for ventricles to contract, recover, and repolarize

S-T segment- time between contraction of ventricles and recovery. S-T segment- time between contraction of ventricles and recovery.

U waves- are sometimes found and can indicate low potassium and metabolic disturbances U waves- are sometimes found and can indicate low potassium and metabolic disturbances