HEART PHYSIOLOGY and HEART DISORDERS - PowerPoint Presentation

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HEART PHYSIOLOGY

and

HEART DISORDERS

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The Electrocardiogram

The conduction of APs through the heart generates electrical currents that can be read through the skin

AP = Action Potential

Currents picked up by electrodes

The recording is called an

ELECTROCARDIOGRAM (ECG or EKG)

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The Electrocardiogram, cont.

Each heartbeat produces three clearly recognizable waves.

The P wave, the QRS

Complex, and the T wave

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The Electrocardiogram, cont.

P WaveA small upward deflectionThe P wave represents the AP as it spreads throughout the AtriaA second after the P wave begins, the atria contract

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The Electrocardiogram, cont.

QRS ComplexQRS complex occurs as the AP spreads through the ventriclesAfter the QRS complex begins, the ventricles contract

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The Electrocardiogram, cont.

T WaveUpward deflection that occurs just before the ventricles relax

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The Cardiac Cycle

A single

Cardiac Cycle

includes all events associated

with one heartbeat

The two atria contract while the two ventricles relax; ventricles contract while atria relax

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The Cardiac Cycle, cont.

Systole

refers to the phase of contraction

Diastole

refers to the phase of relaxation

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HEART DISORDERS

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1. Pericarditis

Inflammation of the pericardium (the membrane that surrounds and protects the heart)

In one form of

pericarditis

, there is a build up of pericardial fluid (fluid that prevents friction between layers of the pericardium)

Too much fluid build-up in the pericardium will compress the heart

Symptoms of

pericarditis

include low blood pressure and difficulty breathing

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1. Pericarditis

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2. Heart Murmur

A heart murmur is an abnormal sound consisting of a clicking, rushing, or gurgling noise that is heart before, between, or after the normal heart sounds

A heart murmur could mask the normal heart sounds

Heart murmurs are very common in children and are usually outgrown

In adults, the heart disorders could indicate a valve disorder

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Stenosis

Stenosis

= Narrowing of a heart valve opening that restricts blood flow

The failure of a valve to close completely is termed insufficiency or incompetence

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3. Mitral Stenosis

Scar formation from an infection or a congenital defect causes narrowing of the mitral valve

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4. Mitral Valve Prolapse

In MVP, one or both cusps of the mitral (bicuspid) valve protrude into the left atrium during ventricular contraction

Backflow of flood from the left ventricle into the left atrium

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5. Aortic Stenosis

The aortic valve is narrowedA backflow of blood from the aorta into the left ventricleValves must be repaired or replaced by human or pig donors or by artificial valves

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6. Artificial Pacemaker

When the heart rate is too low, an artificial pacemaker can restore normal heart rhythmSends out small electrical currents to stimulate the heart to contractPacemaker wires are threaded through the superior vena cava and placed on the right atrium and right ventriclePace makers are implanted beneath the skin inferior to the clavicle

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7. Congestive Heart Failure

In congestive heart failure (CHF), the heart begins to fail

Pumps less and less effectively, leaving blood in the ventricles after every cycle

PULMONARY EDEMA -

If the left ventricle fails first, the heart cannot pump out all the blood it receives and blood backs up in the lungs. Can lead to suffocation.

PERIPHERAL EDEMA –

The right ventricle fails firsts, and blood backs up in systemic blood vessels. First noticeable as swelling in the feet and ankles.

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8. Atherosclerosis

A progressive disease characterized by the formation in the walls of large and medium of lesions called

atherosclerotic plaques

Two proteins are monitored in cholesterols for this disease are LDL and HDL

LDL (low-density lipoprotein) and HDL (high-density lipoprotein)

HDL removes cholesterols – is known as “good cholesterol”

The HDL should be high and the LDL should be low

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9. Myocardial Infarction

A complete obstruction to blood flow in a coronary arteryMyocardial Infarction (MI) = Heart Attack

10. Cardiac Arrest

A clinical term meaning cessation of an effective heartbeat

The heart may be completely stopped or in ventricular fibrillation (spontaneous contractions of individual muscle fibers)

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11. Cardiomegaly

An enlarged heart

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12. Tachycardia

Faster (than normal) heart rate at rest

13. Bradycardia

Slower (than normal) resting heart rate

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14. Rheumatic Fever

A streptococcal infection of the throat that affects the bicuspid (mitral) and aortic valves in the heart

Bacterial infection triggers immune response that inflames damages the tissues – can weaken

entire heart