MS Ch 28 Cardio Assessment

Primary job of the heart is to

propel blood from its left side into the aorta and the systemic circulation to provide oxygen and nutrients to the tissues

Cardiac output

The amount of blood ejected from the left heart

After circulating throughout the body, the blood returns to

right heart through the great veins, the superior and inferior vena cavae, to be delivered to the lungs to receive oxygen and remove carbon dioxide

The arterial and venous vascular systems consist of

a combination of arteries, veins, and capillaries

The vascular system provides

The delivery of oxygenated blood to the tissues

The removal and transportation of cellular waste for excretion

The return of circulatory volume to the right heart

The return of lymph fluid back into the general circulation

Sequence of vessels

arteries to arterioles to metarterioles to capillaries

Valves

prevent retrograde, or backward, flow

Vessels

carry blood from the capillary bed through venules, then veins, back to the right heart; also have the flexibility to adapt to changes in volume without large changes in pressure

This allows for the infusion of IV fluids and blood products

Capillary bed

It is here where oxygen and nutrients are delivered to the tissues and cellular waste is removed

Precapillary sphincter

at the entrance of each capillary that constrict or dilate to deliver or divert blood to areas of need; sphincters are open, capillaries are filled with blood.

When the sphincter closes, that corresponding capillary shuts down, and blood travels through a thoroughfare channel, going directly from metarteriole to venule

Example of precapillary sphincters at work

during exercise, there is plentiful flow through the skeletal muscle, but the skin can be bypassed

Three layers of the heart

epicardium, myocardium, and endocardium

The heart is located in the

mediastinum; lies behind the sternum and rests on the diaphragm

It is contained in a protective sac called the pericardium

The pericardium consists of two layers

The outer layer, the pericardial sac or parietal pericardium, is a tough fibrous layer that turns inward at the base of the heart, forming the inner layer, the epicardium or visceral pericardium, which covers the heart surface

Between the two layers of the pericardium

a pericardial cavity containing serous fluid that provides a lubricant that allows the heart to beat without friction

Myocardium

is the muscular layer responsible for the mechanical, contractile function of the heart

Endocardium

lines the interior of the heart and the heart valves and is continuous with the inner layer, or endothelium, of the blood vessels

Epicardium

thin outer layer of the heart

Superior vena cava blood

travels into the right atrium

The right atrium blood flow

receives deoxygenated blood from the systemic circulation through the great veins, the inferior and superior vena cava

Blood flows from the right atrium to the

Right ventricle

Blood from the right atrium is

delivered to the pulmonary circuit through the pulmonary artery

Newly oxygenated blood is returned to the left atrium via the

Pulmonary vein

From the pulmonary vein, the blood

flows to the left ventricle and is then ejected into the aorta to the systemic circulation

The AV valve between the right atrium and ventricle is the

Tricuspid valve

The valve between the left atrium and ventricle is the

bicuspid, or mitral, valve

Chordae tendineae

prevent the valves from budging or turning inside out during ventricular contraction

Semilunar valves

between the ventricles and their respective arteries (pulmonary and aortic valves)

The pulmonary valve is located

between the right ventricle and pulmonary artery

The aortic valve is located between the

left ventricle and aorta

When the ventricles are relaxed during filling it’s called

diastole

AV valves are open, allowing blood to flow into the ventricles

during diastole

The major vessels that supply blood to the heart are the

left and right coronary artery

Specialized cardiac muscle cells and a cardiac electrical conduction system are necessary for

the electrical conduction of the heart

The hearts pacemaker

Sinoatrial (SA) node

In the absence of an impulse from the SA node

the atrioventricular (AV) node can generate impulses at rates of 40 to 60 bpm

If the SA and AV nodes fail

ventricular cells can generate impulses at a rate of 20 to 40 bpm

Excitability

is the ability to respond to a stimulus and generate an impulse

Conductivity

allows cardiac tissue to transmit the impulses to neighboring connected cells

Cardiac muscle relies on

extracellular calcium to facilitate calcium release from the sarcoplasmic reticulum to produce its muscular contraction.

This is referred to as calcium-induced calcium release. It is regulated by the slow inward flow of positively charged calcium ions during the action potential

Cardiac action potential

a process in which the membrane potential, the difference in charge between the interior and exterior of the cell, changes or goes up and down in a consistent pattern

Depolarization

is the movement of ions preceding and facilitating cardiac mechanical contraction

Repolarization

is the movement of ions back to the resting state, the cardiac resting membrane potential of –90 mV, to allow for the initiation of another action potential

Absolute refractory period

occurs during and immediately following depolarization. During this time, the cell is unresponsive to any stimulus

EEG

The electrical activity of the heart produces waveforms that can be seen

P Wave

corresponds to atrial depolarization produced by the propagation of the impulse from the SA node through the atria. Atrial contraction takes place milliseconds after depolarization

The PR interval

from the beginning of the P wave to the beginning of the QRS complex reflects the time required for atrial depolarization and the delay of the impulse at the AV node

The PR segment

the time immediately following the P wave to the beginning of the QRS complex—reflects the delay at the AV node

The QRS complex

corresponds to ventricular depolarization. Ventricular contraction occurs after the QRS complex in the ST segment

The QRS interval

reflects the time required for ventricular depolarization

The T wave

corresponds to ventricular repolarization. Atrial repolarization occurs during ventricular contraction. That waveform is not visible but is buried in the QRS complex

The QT interval

reflects the time required for ventricular depolarization and repolarization

The cardiac cycle

defined as the circular sequence of events that produces the eventual muscular contraction that causes the ejection of blood from the right ventricle into the pulmonary circulation or from the left ventricle into the systemic circulation

Systole

facilitates the ejection of blood from the ventricles and occurs during the last one-third of the cycle. This cycle is occurring simultaneously on the left and right sides of the heart

contraction of the heart

Blood pressure

a reflection of the pressures generated during the cardiac cycle. It represents the force exerted against the vessel wall by blood flow

Systolic is the peak pressure generated when blood

is expelled from the left ventricle during ventricular contraction

Diastole

the ventricles are relaxed, with a lower pressure than that of the atria, allowing the AV valves to open. Blood flows into the atria from the superior and inferior vena cava or from the pulmonary veins and then quickly flows into the ventricles

Atrial kick

The final phase of ventricular filling occurs when the atria contract, known as atrial systole, which accounts for the final 30% of ventricular filling

Preload

The final volume in the ventricle at the end of diastole is the end diastolic volume

Baroreceptors

located in the aortic and carotid arches, are sensitive to changes in pressure. An increase in pressure stimulates the parasympathetic nervous system to dilate vessels and reduce the heart rate (HR) to reduce BP

Chemoreceptors

contained in collections of cells called carotid bodies and aortic bodies are located in the aortic arch and in the carotid arteries. They respond to changes in oxygen and CO2 concentrations. Decreased levels of oxygen with increased levels of CO2 produce acidosis. The chemoreceptors respond to decreased oxygen levels and acidosis by inducing vasoconstriction to increase BP and increase blood flow to the lungs, facilitating oxygen and CO2 exchange. The respiratory rate (RR) is also increased

atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)

are released from heart tissue when fluid volumes are high. They stimulate vasodilation and diuresis

How to calculate CO

HR x Stroke volume

Afterload

refers to the resistance to flow the ventricle must overcome to open the semilunar valves and eject its contents. This is related to BP, vessel lumen diameter, and/or vessel compliance

Contractility

refers to the force of the mechanical contraction. Contractile force can be increased with sympathetic stimulation or calcium release. It can be decreased in the face of hypoxia or acidosis

Cardiovascular assessment

A complete and thorough history that includes demographic data, family history, and personal history, including present health problems, is essential in the patient cardiovascular assessment. The patient is the primary source of information, but family members and medical records can also be very informative. Demographic data include age, sex, and ethnic background. These are all nonmodifiable risk factors.

The family history can reveal significant information regarding the age, health status, and cause of death of immediate family members. Information regarding socioeconomic status is also important. Occupation, economic status, marital status, children, insurance, and support systems are important and can hint at a patient’s ability to respond in times of need

Chest pain should be evaluated for

location, intensity, radiation, duration, and quality. Information related to the treatment that provides relief is also significant

Current health problems assessment

Dyspnea and fatigue at rest or dyspnea on exertion are important to note. Palpitations are an indication of abnormal heart rhythms: dysrhythmias. Syncope is an indication of decreased CO resulting from problems with either the mechanical or electrical properties of the heart. Weight gain associated with edema indicates a weakened heart and potentially the presence of heart failure

General assessment

The initial assessment starts with evaluating the patient’s overall appearance, including color, diaphoresis, edema, and demeanor and restlessness, agitation, or confusion

Through observation, you can quickly determine weight and build, symptoms such as shortness of breath (SOB), and mobility

BP and HR

Assessing Apical pulse

auscultated by placing a stethoscope at the junction of the fifth intercostal space and the midclavicular line, the point of maximal impulse (PMI)

Normal BP

<120

<80

Elevated BP

120-129

<80

HTN Stage 1

130-39

80-89

HTN Stage 2

>140

90>

Cyanosis

Poor perfusion produces a pale gray or bluish color

Capillary refill

Should be 3 seconds or less

Sluggish return may indicate arterial spasm or insufficiency

Edema

may be a sign of cardiac or liver issues. Bilateral lower extremity edema, if not associated with a local injury, generally indicates venous insufficiency or heart failure. Unilateral extremity edema, again if not associated with injury, can indicate a venous or lymphatic obstruction

Jugular vein distention

may be present in a patient with a constrictive disease such as pericarditis or cardiac tamponade

It is also seen in patients with right ventricular failure, valvular disease, or hypervolemia. It is often associated with poor contractile function of the heart that is present in heart failure

Clubbing of the fingers and/or toes indicates

long-term perfusion problems produced by a decrease in oxygenated blood flow to the affected extremities. This is typically caused by congenital heart defects or chronic pulmonary disease. It can also be seen in patients with lung cancer

Variations in temperature between different parts of the body may indicate

vasoconstriction or vascular disease in the affected extremities

The first heart sound, S1, is

the closing of the AV valves. It signifies the beginning of ventricular systole

The second heart sound, S2, is the

closing of the semilunar valves. It signifies the beginning of diastole

Combination of S1 S2 and S3

resemble a gallop, thus the name ventricular gallop

S4

is heard in late diastole and occurs after atrial contraction. It also can indicate decreased ventricular compliance. It is known as an atrial gallop

A click

a high-pitched sound heard early in diastole and is typically caused by mitral valve stenosis

Murmurs

are usually caused by turbulent flow through the valves. That turbulence can be caused by regurgitation of blood through an incompetent valve, flow through a narrowed valve, or an increase in flow in hypermetabolic states such as hyperthyroidism or fever

A friction rub

is described as a scratching or grating sound heard during both systole and diastole. The sound is produced by inflammation of the pericardium. It is diagnostic for pericarditis and is referred to as the pericardial friction rub

When describing heart sounds, note the

Pitch: high, medium, or low

Quality, such as blowing or harsh

Intensity, such as faint, quiet, or loud

Timing during systole or diastole

Location where heard best on the chest wall

Cholesterol

is a lipid necessary for the synthesis of hormones and cell walls. It is available through the ingestion of animal products (e.g., meat) and through synthesis in the liver

Low-density lipoproteins (LDL)

primarily transport cholesterol into the cell but can also deposit it on the walls of arterial vessels. Elevated levels, greater than 100 mg/dL, are associated with an increased risk of heart disease

High-density lipoproteins (HDL)

are protective lipoproteins and transport cholesterol away from the cells to the liver for excretion

Total cholesterol levels

below 200

LDL normal level

<100

HDL normal

>40 acceptable

>60 best

Platelet normals

150,00-450,000

PTT levels

25-35

INR levels

<1.0

Lipid panel requires

the patient to fast for approximately 8 to 12 hours before the test

Creatinine kinase (CK)

is a general marker of cellular injury. It is released from cells in the brain, skeletal muscle, and cardiac tissue after muscle damage has occurred

Creatine kinase myocardial bands (CK-MB)

is the marker specific to cardiac tissue. When myocardial damage occurs, CK-MB is released from the cells. Increased levels can be seen at 3 hours after myocardial damage and can remain elevated for up to 36 hours before returning to normal