NUR 146 - Week 7 - Cardiac Review Flashcards by Ebby K

Describe the Atria:

Thin walled chambers; most blood flows passively from atria –> ventricles

Right atrium:
Receives deoxygenated systemic blood from coronary sinus and Vena Cava

Left atrium:
Receives oxygenated blood from lungs via pulmonary vein

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Describe the ventricles

Thick walled; high pressure pump

Right ventricle sends deoxygenated blood to lungs

Left ventricle sends oxygenated blood into systemic circulation

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What are the atrioventricular valves?

Tricuspid - right side of heart

Mitral (bicuspid) - Left side of heart

During ventricular systole the papillary muscles contract

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What are the semilunar valces?

Pulmonic - Right side of heart
Aortic - Left side of heart

Open during ventricular systole

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What are normal heart sounds vs. what abnormal would be?

Normal - S1, S2

Abnormal = anything outside of “lub-dub”

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Describe the right side of the heart

Receives deoxygenated blood from the body
Sends to lungs for gas exchange
Lower pressure than left side of heart

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Describe the left side of the heart

Receives oxygenated blood from the lungs
Sends blood to the body via the aorta
Higher pressure than the right side of heart

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Compare Systole vs. Diastole
How much of the cardiac cycle does each make up?

Diastole:
- Relaxation of ventricles
- Blood fills ventricles
- Semilunar valves are closed, AV valves are open
- 2/3 of the cardiac cycle

Systole:
- Contraction of ventricles
- Blood is ejected from ventricles
- AV valves close, semilunar valves open
- Comprises 1/3 of cardiac cycle

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What are the coronary arteries?
When does blood perfuse?

Supply arterial blood to the myocardium, originating from the proximal portion of aorta

Blood perfuses during diastole
- Coronary arteries are compressed during systole d/t high pressure. This limits blood flow in coronary arteries.

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What are the layers of the heart?

Endocardium:
- Innermost layer; contact w/ blood
- Thin layer of epithelial cells

Myocardium:
- Muscle of the heart
- Provides contractile force to pump blood

Epicardium

Pericardium:
- Visceral (inner)
- Parietal (outer)
- Pericardial space

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Assessment of chest pain

Quantity of pain (0-10)
Radiation of pain
Other signs and symptoms (nausea, SOB)
Duration of symptoms
What helps or worsens the pain?

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Cardiac:

Physical Assessment

General appearance
Skin and extremities
6 P’s: Pain, Pallor, Pulselessnsess, Paresthesia, Poikilothermia, paralysis
Bruising
Edema
Prolonged capillary refill
Clubbing

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What is blood pressure?

Definition: Pressure exerted on the walls of arteries during systole and diastole

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What is pulse pressure?
What is a normal level?
What would warrant further evaluation?

Difference between systolic and diastolic pressured

Normally ~40mmHg
- Narrow or wide pulse pressure warrants further evaluation

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What is orthostatic (postural) hypotension?

Definition: A sustained decrease of >20mmHg SBP or >10 mmHg DBP within 3 minutes of changing position

Increased risk for falls

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Abnormal Heart Sounds:

Vibration of ventricles that resist early, rapid filling

Early in diastole
Normal in children and young adults
Abnormal in adults
May occur in cases of fluid overload (pregnancy, hyperthyroidism)

Abnormal Heart sounds:

Vibration of ventricles that resists forceful filling

Occurs at end of diastole or pre-systole
Atria contract and push blood into a noncompliant ventricle

Abnormal heart sounds:

Murmurs
What is it?
Cause?

Created by turbulent blood flow in the heart;

Often caused by a critically narrowed valve which allows regurgitation of blood flow

Electrophysiology:

Automaticity
Excitability
Conductivity

Automaticity - Heart’s unique ability to initiate its own electrical impulse

Excitability - Heart’s ability to respond to an electrical impulse

Conductivity - Ability to transmit an electrical impulse from one cell to another

What is the pathway of the electricity of the heart?

SA Node (Intrinsic pacemaker)
AV Node (secondary pacemaker); pauses electricity to allow ventricles to fill with blood
Bundle of His
Purkinje Fibers

Cardiac Action Potential:

Depolarization vs. Repolarization

Depolarization:
- Electrical activation of a cell caused by influx of sodium into the cell while potassium exits the cell
- Results in myocardial cell contraction

Repolarization:
- Re-entry of potassium into cell while sodium exits the cell
- Results in the cell returning to its resting state

What is stroke volume?

The amount of blood ejected with each heartbeat

Which factors determines Stroke Volume?

Preload: Degree of stretch of cardiac muscle fibers at end of diastole (increases SV)

Contractility: Ability of cardiac muscle to contract in response to electrical impulse (Increases SV)

Afterload: Resistance to ejection of blood from ventricle –> systemic vascular resistance (Decreases SV)

What is Frank Starling Law?

The greater the amount of stretch before systole will result in a stronger ventricular contraction

Preload: What effects it? What decreases it?

Increased preload = increased cardiac output Increased blood volume = increased preload Causes of decreased preload: - Diuresis - Dehydration - Vasodilation "Less fluid = less preload"

Contractility: What increases it? What decreases it?

Causes for increase: - Catecholamine, sympathetic NS stimulation Meds: Digoxin, dopamine, epinephrine Increased contractility = increased SV Causes for decrease: - Injury (MI) - Disease - Dysrhythmias - Hypoxemia w/ acidosis Meds: Beta blockers Decreased contractility results in decreased stroke volume

Afterload:

Resistance to ejection of blood from the ventricle; low afterload = high stroke volume Systemic vascular resistance (SVR) refers to resistance of systemic vessels to left ventricular ejection Pulmonary vascular resistance (PVR) refers to resistance of pulmonary vessels to right ventricular ejection Arterial vasoconstriction --> increased afterload = decreased stroke volume Arterial vasodilation --> decreased afterload = increased stroke volume

What is cardiac output (CO)?

The amount of blood pumped by the left ventricle in liters per minute; responds to metabolic demands of tissues (Approx 4-6L per min) CO = SV x HR

What is ejection fraction (EF)? What is a normal amount? What would warrant further evaluation or possible problem?

The percentage of end diastolic blood volume which is ejected with contraction; measurement of myocardial contractility Normal range is 55%-65% - If <40% = indication of decreased left ventricular function, possible heart failure

Electrocardiography (ECG/EKG): What are the waves?

P wave: Depolarization of atria P-R interval: beginning of P wave to beginning of QRS = time necessary for atrial depolarization + time for electrical impulse to travel from AV node to ventricles QRS complex: Depolarization of ventricles T Wave: Repolarization of ventricles

What is the purpose of a 12 lead EKG?

Each lead is specific view of the electrical activity of the heart 12 lead EKG looks at the electricity from 12 angles

Cardiac Stress Testing: Purpose Method Patient education

Purpose: Detection of abnormalities in cardiovascular function is more likely during times of increased oxygen demand Method: - Patient walks on treadmill or uses stationary bike with increasing intensity - Vitals, EKG and symptoms are monitored Patient education: - Avoid stimulant drugs/food before test - Patient may need to hold cardiac drugs for 48 hours before test

Pharmacologic Stress Testing: Method Indication Patient education

Vasodilating agents are administered to mimic exercise Indicated: - Pts who would not be able to tolerate an exercise test d/t physical or cognitive disability Patient education: - NPO 3 hours prior to test - Avoid stimulant food/drugs for 24 hours prior

Echocardiography

Noninvasive ultrasound of the heart - Measures the ejection fraction - Examines the size, shape and motion of cardiac structures TransthoraciC

Cardiac Catheterization

Invasive procedure used to diagnose structural and functional disease of the heart and great vessels - Uses insertion of radiopaque catheters and fluoroscopy

Cardiac Catheterization: Nursing Interventions

- Maintain bed rest with straight leg for 2-6 hours - Observe site for bleeding or hematoma - Assess peripheral pulses distal to the insertion site - Evaluate temperature, color and capillary refill - Screen for arrhythmias

Hemodynamic Monitoring:

Provides continuous assessment of critically ill patients - Provides a more accurate measurement of blood pressure