Chapter 9 - Disorders of the Heart I

What is the primary function of the heart?

To pump blood throughout the body.

What are the two major phases of the cardiac cycle?

Systole (contraction) and diastole (relaxation).

What is the function of cardiac valves?

They ensure one-way blood flow through the heart.

What is ejection fraction?

A measurement of the percentage of blood the left ventricle pumps out with each contraction.

What is the most common cause of cardiac diseases?

Atherosclerosis.

What does an ECG measure?

The electrical activity of the heart.

What are P waves in an ECG associated with?

Atrial depolarization

Atria are contracting and pumping blood into the ventricles

What can tall QRS waves indicate in an ECG?

Ventricular hypertrophy.

What role does the SA node play in cardiac function?

It initiates the electrical signal for each heartbeat.

What is the primary effect of the sympathetic nervous system on the heart?

It increases heart rate and force of contraction.

What is congestive heart failure?

A condition where the heart cannot pump blood at a rate sufficient to meet metabolic demands.

What symptoms are commonly associated with left heart failure?

Dyspnea, tachypnea, fatigue, and pulmonary edema.

What can cause myocardial ischemia?

Obstructed coronary blood flow, often due to atherosclerosis.

What are the main components of heart failure?

Forward failure (low cardiac output) and backward failure (venous congestion).

What is the role of the renin system in heart failure?

It retains H2O and Na+, which increases blood volume and further compromises the failing heart.

What is angina pectoris?

Chest discomfort caused by myocardial ischemia that may arise with activity or emotional stress.

What differentiates stable from unstable angina?

Stable angina rises and falls smoothly, while unstable angina may herald an impending MI.

What is myocardium

Heart muscle

Cardiac myocytes

Heart muscle cells

Systole

The phase of the cardiac cycle when the heart contracts and pumps blood out of the chambers.

Diastole

The phase of the cardiac cycle when the heart relaxes and fills with blood.

Atrial natriuretic peptide

A hormone produced by atrial myocytes that increase vasodilation and release H2O & Na+ to reduce blood pressure

Stenosis

The failure of a heart valve to open fully, restricting blood flow.

Regurgitation / Incompetence

The backward flow of blood through a heart valve that fails to close properly.

Coronary arteries

The blood vessels that supply oxygen-rich blood to the heart muscle.

What are QRS waves in an ECG associated with?

Ventricular depolarization

Ventricles are contracting and pumping blood out to the rest of the body.

What are T waves in an ECG associated with?

Ventricular repolarization.

Ventricles are relaxed and filling back up with blood

Cardiac Conduction System (CCS)

Carries out signals given from the SA to the rest of the heart as a wave of electrical stimulation

Atrioventricular Node (AV)

A part of the cardiac conduction system that receives signals from the SA node and transmits them to the ventricles

Bundle of His

Carries signals from the AV node and propels them into either the right or left bundle branches

Cardiac Conduction System Order

1. SA node

2. AV node

3. Bundle of His

4. Right / Left bundle branches

Pump Failure

Weak contraction due to poor/decreased cardiac output

Obstructed Flow

Increases cardiac work (heart works harder) to force blood past the obstruction

May be due to atherosclerosis

Regurgitant Flow

Backward flow across a valve that leads to decreased cardiac output

Shunted Flow

Blood is diverted from its intended path in the heart leading to increased cardiac effort/work

Abnormal Conduction

Due to mechanically inefficient beats (premature or late). Results in low cardiac output

Heart Failure (HF / Congestive Heart Failure)

Syndrome of ventricular dysfunction where the heart is unable to pump enough blood at a sufficient rate to sustain metabolic demand

Stroke Volume

The volume of blood ejected with each ventricular beat

Systolic Failure

Ventricle contracts poorly and empties incompletely.

Can be due to ischemia, infarction, inflammation, or cardiomyopathies

Diastolic Failure

Ventricular relaxation and filling are impaired.

Can be due to ventricular stiffness, cardiomyopathy, or amyloidosis

Compensated Heart Failure

A state where the heart maintains cardiac output whilst actively experiencing ventricular dysfunction (failing ventricle dilates)

Uncompensated Heart Failure

When the myocardial fibers of the ventricles are stretched out too far, cardiac output decreases significantly and blood “backs up”

Pulmonary Edema

The accumulation of excess fluid in the lungs, which leads to impaired gas exchange and symptoms such as shortness of breath (dyspnea), coughing, and difficulty breathing. It can occur due to heart failure

Coronary Artery Disease (CAD)

Occurs due to complete occlusion of one or more coronary arteries which deprives cardiac muscle of blood and results in ischemia, or infarction of the cardiac muscle

Angina

Chest pain due to reduced blood flow to the heart

Stable Angina

May be caused by exertion and emotions or by heavy meal - rises and falls smoothly over a period of minutes

Unstable Angina

Caused by aggerates of platelets that accumulate on an atherosclerosis plaque. Very serious.

May herald myocardial infarction

Unremitting Angina

An angina that does not fluctuate and is not relieved by therapy

Caused by myocardial infarction

True or False:

Cardiac myocytes contract during diastole to eject blood from the ventricle, and relax during systole to allow the ventricle to fill

False

True or False:

The tricuspid and mitral valve leaflets are tethered by chordae tendineae to papillary muscles

True

Put the following in order from superior to inferior: Right and left bundle branches, AV node, SA node, Bundle of His

SA node, AV nodes, bundle of his, right and left bundle branches

What causes stenosis

Calcification

What causes regurgitation

Dialtion of valves

Which of the four major waveforms is not visible on an ECG?

The small wave of atrial repolarization

What are the five principal mechanisms of cardiac dysfunction?

1. Pump Failure

2. Obstructed Flow

3. Regurgitant Flow

4. Shunted Flow

5. Abnormal Conduction

True or False:

The most common cause of right-sided heart failure is left-sided heart failure.

True

What happens to the ejection fraction in systolic heart failure?

The ejection fraction decreases in systolic heart failure.

Is pulmonary edema associated with right-sided or left-sided heart failure?

Left sided heart failure

What lifestyle changes are important in the treatment/prevention of heart failure?

Weight loss, cessation of smoking, and decreased sodium intake are important in the treatment/prevention of heart failure.

True or False:

A blood test for troponins is more specific in detecting a myocardial infarct than a blood test for creatine kinase.

True

True or False:

Ischemia can occur without coronary artery disease.

True

True or False:

ECG abnormalities mean a myocardial infarct has occurred

False

What is the difference between stable and unstable angina?

Stable angina occurs with exertion and is relieved by rest or nitroglycerin. Unstable angina occurs unprovoked and may arise at rest.

The increased secretion of renin in heart failure is caused by what?

Low cardiac output

What causes the atrioventricular (AV) valves to close

Increased intraventricular pressure

True or False:

Partial coronary occlusion can cause a myocardial infarction

True

True or False:

The patient with isolated diastolic heart failure has a normal ejection fraction

True

What is peripheral venous congestion & edema associated with?

Uncompensated right heart failure

What is pulmonary congestion & edema associated with?

Uncompensated left heart failure

What is normal cardiac output associated with?

Compensated heart failure

What is poor ventricle dilation associated with?

Diastolic failure

What is poor ventricle contraction associated with?

Systolic failure

Stable angina pectoris _________

Is usually relieved by stress

What would result in a decrease in cardiac output?

Increased afterload

If the sympathetic nervous system stimulation of the heart predominates over parasympathetic nervous stimulation, the heart will:

Increase its rate

Left-sided heart failure may lead to right-sided failure because

Increased right ventricular afterload

True or False:

The relationship between ventricular dilation & cardiac performance as indicated by vascular resistance is described by the Frank-Starling Law

False

True or False:

Atrial natriuretic peptide serves as a vasoconstrictor in addition to increasing Na+ and H2O excretion by the kidney

False