Week 3 - Alterations to Blood Flow Pt. 2

Define heart failure

A general term that described any type of cardiac dysfunction that results in inadequate perfusion of tissue

Name the 2 overall types of heart failure

• Left sided heart failure

• Right sided heart failure

Explain left-sided heart failure

When the left ventricle fails

Name and explain the 2 types of left sided heart failure

• Systolic heart failure - when the left ventricle doesn’t contract normally

• Diastolic heart failure - when the left ventricle is stiff and doesn’t relax properly

List causes of left sided heart failure

• CAD

• Myocardial infarction

• Hypertension

• Valvular heart disease

• Diabetes

Explain valvular heart disease

When valves fail, disrupting the pressure within chambers and therefore the flow of contractions and relaxations

Explain how left sided heart failure can result in pulmonary oedema

1. Failure of the left ventricle

2. Decreases cardiac output as this effects the left ventricles ability to pump blood out to the rest of the body

3. Blood back flowsinto the left atrium and the lungs

4. Pulmonary oedema occurs

List the signs of left sided heart failure

• Pulmonary oedema

• Dyspnea

• Nonproductive cough

• Tachycardia

• S3 and S4 heart sounds

• Cool, clammy skin

Explain why a non-productive cough occurs with left sided heart failure

A response to get fluid out of the lungs

Explain why S3 and S4 heart sounds occur with left sided heart failure

• S3 - extra heart sound due tot extra fluid in the ventricles

• S4 - extra heart sound due to atrial contraction against a non-compliant ventricle

Explain right sided heart failure

When the right ventricles fails

List causes of right-sided heart failure

• Left sided heart failure

• Hypertension

• COPD

• Pulmonary embolism

Explain how right sided heart failure can lead to peripheral oedema

1. Right ventricle fails

2. Decreased blood flow to the lungs as the right ventricle cannot efficiently pump blood

3. Blood back flows into the right atrium and peripheral circulation

4. Peripheral oedema occurs

List signs of right sided heart failure

• Peripheral oedema

• Engorgement of the liver, spleen and kidney

• Ascites

• Jugular venous distension

Explain why ascites occurs in relation to right sided heart failure

When there is increased fluid in venous circulation, pressure increases causing fluid to leak into the peritoneal cavity

Explain why jugular venous distension occurs in relation to right sided heart failure

Blood back flows into the venous system and the jugular vein

Explain why peripheral oedema is also called pitting oedema

After pressure is applied to the skin, a pit is left and the skin due to excess fluid.

List the order of electrical conduction through specific nerves in the heart and state their location

• SA node in the RA

• AV node between the RA and RV

• Bundle of His in the septum between the atria and ventricles

• Bundle branches down through the septum

• Purkinje fibers through the ventricles

List the mechanical events in the cardiac cycle

1. Late diastole

2. Atrial systole

3. Isovolumic ventricular contraction

4. Ventricular ejection

5. Isovolumic ventricular relaxation

Explain late diastole

Atrial and ventricular diastole in which all valve are open and ventricles are being passively filled

Explain atrial systole

Contraction of the atria in which all blood from the atria are forced into the ventricles

Explain isovolumic ventricular contraction

The first phase of ventricular contraction in which ventricular pressure is greater than atrial pressure but not greater than arterial pressure, therefore the AV valves snap shut but the SL valves remain closed.

Explain the purpose of the AV valves shutting

To prevent backflow of blood from the ventricles back into the atria

Explain ventricular ejection

Ventricular pressure rises to be greater than arterial pressure, forcing SL valves open and blood is ejected into the greater arteries

Explain Isovolumic ventricular relaxation

Ventricles relax and ventricular pressure drops to be less than arterial pressure and blood flows back into the cusps of SL valves causing them to snap shut.

Explain some stages are referred to as Isovolumic

As the same volume of blood remains in the ventricles

Name and explain the 2 heart sounds

• S1 - AV valves close

• S2 - SL valves close

State the 5 main components of an ECG

• P wave

• PR interval

• QRS complex

• ST segment

• T wave

• QT interval

Explain the characteristics of a P wave

• Represent atrial depolarisation

• 2-3mm high

• 0.06-0.012 second duration

• Round and upright deflection

Explain the characteristics of a PR interval

• From the start of the P wave to the start of the QRS complex

• Represent the time taken for an action potential to move between atria and ventricles

• 0.12-0.20 second duration

Explain the characteristics a QRS complex

• Represents ventricular depolarisation

• Duration of 0.06-0.12 seconds

• Q and S waves deflect negatively

• R waves deflect positively

Explain the characteristics of an ST segment

• Begins at the end of the S waves and ends at the end of the T wave

• Represents the time between ventricular depolarisation and repolarisation

Explain the characteristics of a T wave

• Reflects ventricular repolarisation

• Round and upright deflection

Explain the characteristics of the QT interval

• Begins at the start of the Q wave and ends at the end of the T wave

• Represents the time taken for ventricular depolarisation and repolarisation

Explain why there is no wave that represents atrial repolarisation

It is masked by the QRS complex

Explain why the P wave is smaller than the QRS complex if they both represent depolarisation

The ventricles have greater muscle mass therefore the depolarisation is larger

Explain the U wave

Upwards deflection rarely seen that represents the recovery period of the Purkinje fibers