N245: chapter 27 - heart failure, circulatory shock, cardiac function

Right and left coronary arteries

First branches of the ascending aorta --> supply oxygen to the myocardium

The left coronary artery divides into

1. Left anterior descending/interventricular artery

2. Left circumflex artery

The right coronary artery divides into

1. Right marginal artery

2. Posterior interventricular artery

At what phase during heart contractions does blood flow through the coronary arteries?

During ventricular relaxation (paradoxical because all other arteries receive the most blood during ventricular systole)

Coronary Heart Disease/Coronary Artery Disease

Abnormal narrowing or obstruction of coronary arteries --> causing impaired coronary blood flow

What are the dangers of Coronary Heart Disease

Angina, MI, arrhythmias, heart failure, death

The two broad categories of coronary heart disease are:

Chronic ischemic heart disease, acute coronary syndrome

Chronic Ischemic Heart Disease (Angina)

Definition: Chest pain that occurs due to a lack of oxygen delivery to the myocardium

S+S: Triggered by emotional or physical stress

Treatment: Vasodilators

Stable angina

Definition: A type of chronic ischemic heart disease; pain during exercise or exertion (when heart's O2 demand increases)

Treatment: vasodilators

Variant (vasospastic) angina

Definition: A type of chronic ischemic heart disease; chest pain not related to physical activity (possibly bc of nitric oxide deficiency?) --> occurs when coronary arteries spasm

Treatment: vasodilators

What does nitric oxide do?

Nitric oxide causes blood vessels to dilate

Silent myocardial ischemia

Definition: A type of chronic ischemic heart disease; clinical evidence of decreased blood flow/O2 to the heart without angina

Unstable angina

Definition: A type of chronic ischemic heart disease/acute coronary syndrome; chest pain that occurs while a person is at rest and not exerting himself --> will probs lead to MI

not relieved by vasodilators

How is angina diagnosed?

Using a stress test or echocardiograph

Where will angina manifest on the body?

Substernal pain that radiates to the jaw and left arm

How is angina managed?

1. Statins

2. Aspirin

3. Sublingual nitroglycerin

4. Calcium channel blockers

5. Beta-blockers

How will statins help angina?

By reducing cholesterol and heart rate

How will aspirin help angina?

By preventing blood clots and reducing pain

How will sublingual nitroglycerin help angina?

By dilating the blood vessels

How will calcium channel blockers help angina?

By preventing the contraction of blood vessels

How will beta-blockers help angina?

By blocking the release of adrenaline --> slowing the heart rate

Emergency Treatment for Angina

1) Stop activity

2) Patient seated in upright position

3) Administration of nitroglycerin and O2

When can you give a second dose of nitroglycerin?

Only when the pt has a history of angina

Acute coronary syndrome

A multitude of conditions; involve symptoms of sudden, reduced blood flow to the heart

What are some possible causes of acute coronary syndrome?

Atherosclerosis, embolism, vasospasm (anything that quickly blocks the arteries)

Myocardial infarction

Death of cardiac muscle due to ischemia (lack of blood)

Signs and Symptoms of MI

Pressure/pain in chest

Sudden shortness of breath

Weakness, fatigue

Nausea, indigestion

Anxiety and fear

Complications of AMI

1. Sudden death

2. Cardiogenic shock

3. Cardiac tamponade

4. Aneurysm

5. Embolism

STEMI

ST elevation myocardial infarction

What is a STEMI?

A type of acute coronary syndrome; a heart attack that is characterized by elevated ST waves --> indicates a complete blockage

The most serious type of HA, called the "widow maker"

Treatment for STEMI

Angioplasty to break up clot/plaque

Percutaneous coronary intervention (PCI)

A balloon-tipped catheter is inserted into a coronary artery to force it open --> stents are put in place

Angioplasty

Mechanically widening a narrowed or obstructed blood vessel

Abnormal Q waves

An ECG seen during a type of acute MI --> indicates necrosis of myocardium --> no contraction

NSTEMI

Non-ST elevation myocardial infarction

What is a NSTEMI?

A type of acute coronary syndrome; a heart attack that is characterized by ST depression and T wave inversion --> indicates a partial blockage

Treatment for NSTEMI

Administer anticoagulants (heparin) to break up the clot --> angioplasty if meds aren't effective

Serum Cardiac Markers

Proteins that are released into the blood from necrotic heart muscle after an MI

Myoglobin

Protein released by necrotic myocardium --> Elevated within 2 hrs of myocardial infarction

Creatine kinase MB (CK-MB)

Protein released by necrotic myocardium --> Elevated within 6-8 hours of myocardial infarction

Troponin I (TnI) and Troponin T (TnT)

Protein released by necrotic myocardium --> Rises within 3 hrs after MI, then decreases slowly over days

Coronary Artery Bypass Graft (CABG)

Open-heart surgery in which a blood vessel (usually a leg vein), is grafted to redirect blood around the blocked coronary artery

Pericarditis

Inflammation of the pericardium, usually secondary another condition

How is pericarditis classified

Pericarditis is classified by the cause or type of exudate

Acute pericarditis

Acute inflammation of the pericardium --> effusion may develop

Pericardial effusion

An accumulation of fluid in the pericardial cavity --> occurs as a result of pericarditis

Effects of pericardial effusion

1. Fluid around heart compresses heart wall

2. Heart cannot expand to fill

3. Blood backs up in systemic circulation

4. Decreased blood flow to lungs and tissues

Chronic pericarditis

Chronic inflammation of the pericardium

What are possible causes of chronic pericarditis?

Viral infections or autoimmune disorders

What are the effects of chronic pericarditis?

Adhesions form between the two membranes, fibrous tissue forms --> heart's movement is limited

Diastole

Relaxion of the heart

Systole

Contraction of the heart

CO

Cardiac output

CO equation

Stroke volume (amount of blood ejected per beat) x HR

Preload (EDV)

How much the heart expands when it fills with blood

Afterload

The amount of pressure that the heart needs to exert to eject the blood during ventricular contraction

Ejection Fraction

Percentage of blood pumped out to the body by the ventricles

Normal: 55-75%

Cardiac reserve

The heart's ability to increase CO during increased activity

Heart Failure

Condition in which the heart is unable to pump out enough blood to meet the body's metabolic demands; EF < 40%

Compensatory Mechanisms Heart Failure

1. Force of contraction increases

2. Myocardium increases

3. HR increases

4. Stimulates RAAS in kidney

How does RAAS affect heart failure?

Activation of RAAS compounds the problem --> aldosterone retains salt + water --> vasoconstriction and blood volume increase --> heart has to work even harder

Systolic Heart Failure

A type of heart failure in which the heart cannot contract and eject blood --> decreased EF

Causes of Systolic Heart Failure

Inability to contract due to MI, increased afterload due to high BP, valve diseases

Diastolic Heart Failure

A type of heart failure in which ventricles can't relax and fill --> decreased SV and CO

Causes of Diastolic Heart Failure

Left ventricular hypertrophy, aortic stenosis (aortic valve won't open)

General consequences of heart failure

Less blood reaches the organs --> decreased cell function --> fatigue and lethargy --> acidosis

Left-sided congestive heart failure

When the left side of the heart fails, blood flows back into the lungs --> causing difficulty breathing, cough, and paroxysmal nocturnal dyspnea

Paroxysmal nocturnal dyspnea

Symptom of left-sided congestive heart failure; shortness of breath that occurs during sleep

Right-sided congestive heart failure

When the right side of the heart fails, blood flows back into the venous system --> high BP in jugular veins, edema of legs, spleen/liver enlargement

Generally, how do you treat heart failure?

Lower blood pressure, dilate blood vessels, if needed, restore contraction ability using an AED

What does Digoxin (Lanoxin) do for heart failure?

This medication helps the heart beat stronger with a more regular rhythm

it was derived from this pretty digitalis plant!

Cardiac anomalies

Structural defects of the heart that appear during embryonic development

Congenital Heart Defects

Structural abnormalities of the heart caused by improper development before birth (valvular or septal defects)

General S+S of Congenital heart disease

Pallor, tachycardia, dyspnea, squatting position, clubbed fingers

Ventricular Septal Defect

A hole between two ventricles --> allows blood to pass from the one ventricle to another

Right-to-Left Shunt (venous to arterial)

Blood from right ventricle moves to left ventricle BEFORE GOING TO LUNGS --> less blood goes to lung --> deoxygenated blood is delivered to tissues --> cyanosis

Left-to-Right Shunt arterial to venous

Oxygenated blood from left ventricle moves to right ventricle INSTEAD OF GOING THROUGH AORTA --> more blood goes to lung --> less blood goes to body

Valvular Defects

Defects of the heart valves, most commonly affect the aortic and pulmonary valves

Valve prolapse

One or more cusps in the valve will protrude in the wrong direction --> causing backflow

Valve Stenosis

A valve that cannot open all the way because it is narrower and stiffer --> less passes through the opening

Heart Murmur

An abnormal sound from the heart produced by defects in the valves

Regurgitant/Incompetent Valve

A valve that cannot close completely --> blood leaks backwards into previous chamber

Tetralogy of Fallot

A congenital heart condition caused by a combination of four heart defects

1. Pulmonary valve stenosis

2. Shunt in ventricular septum

3. Dextroposition of the aorta

4. Right ventricular hypertrophy

S+S of Tetralogy of Fallot

"Blue babies" and "tet spells"

The sudden development of cyanosis and fainting

Rheumatic fever

An inflammatory condition that usually occurs after an infection

Rheumatic heart disease

Heart disease caused by rheumatic fever

Acute stage of rheumatic fever

Inflammation of the heart (pericarditis, myocarditis, or endocarditis)

S+S of Rheumatic fever

Fever, inflammation of the heart, blood vessels, and joints, erythema marginatum

Mitral Valvulitis

Inflammation of the mitral valve; common symptom of rheumatic fever

Mitral Valve Stenosis

Narrowing of the mitral valve opening; caused by scarring from rheumatic fever

Chronic rheumatic heart disease

Valve scarring that arises as a consequence of rheumatic fever

How is rheumatic fever diagnosed?

Using a heart function test and/or electrocardiogram

How is rheumatic fever treated?

Antibacterial and anti-inflammatory agents

Infective endocarditis

Life-threatening inflammation of the endocardium due to a bacterial or fungal infection --> growths (vegetations) cause valve stenosis

Subacute infective endocarditis

Definition: Most commonly caused by streptococcus viridans (low virulence)

Symptoms:

Acute infective endocarditis

Definition: Most commonly caused by staphylococcus aureus (high virulence)

Symptoms: Sudden onset of fever, chills

Risk factors for infective endocarditis

Previous valve damage, bacteremia, compromised immune system

How is infective endocarditis diagnosed?

A blood culture is procured to determine the cause of infection

How is infective endocarditis treated?

Antibiotics for 4-6 weeks

Cardiomyopathies

Diseases of the heart muscles