Perfusion (Heart) Flashcards
diastole:
period of ventricular relaxation resulting in ventricular filling
myocardium:
muscle layer of the heart responsible for the pumping action of the heart
cardiac conduction system:
heart cells responsible for generating electrical impulses to the myocardial cells
The four valves in the heart, open and close in response
to the movement of blood and pressure changes within the chambers
There are two types of valves:
atrioventricular (AV) and semilunar.
the sinoatrial (SA) node
(the primary pacemaker of the heart)
atrioventricular (AV) node
(the secondary pacemaker of the heart)
The SA node in a normal resting adult heart has an inherent firing rate of
60 to 100 impulses per minute
the AV node has the second-highest inherent rate (
40 to 60 impulses per minute)
the ventricular pacemaker sites have the lowest inherent rate
(30 to 40 impulses per minute)
If the SA node malfunctions,
the AV node generally takes over the pacemaker function of the heart at its inherently lower rate.
Should both the SA and the AV nodes fail,
a pacemaker site in the ventricle will fire at its inherent bradycardic rate of 30 to 40 impulses per minute
The heart is composed of how many layers
three layers
The inner layer, or endocardium,
consists of endothelial tissue and lines the inside of the heart and valves.
The middle layer, or myocardium,
is made up of muscle fibers and is responsible for the pumping
The exterior layer of the heart is called
epicardium
The pumping action of the heart is accomplished by
the rhythmic relaxation and contraction of the muscular walls of its two top chambers (atria) and two bottom chambers (ventricles).
During the relaxation phase, called diastole, all four chambers relax simultaneously, which allows
the ventricles to fill in preparation for contraction.
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The right side of the heart, is made up of
the right atrium and right ventricle,
the right side of the heart distributes venous blood (deoxygenated blood) to
the lungs via the pulmonary artery (pulmonary circulation)
The pulmonary artery is the only artery in the body that carries
deoxygenated blood.
The left side of the heart, composed of
the left atrium and left ventricle
the left side of the heart distributes
oxygenated blood to the remainder of the body via the aorta
The left ventricle is two to three times more muscular than the right ventricle because
It must overcome high aortic and arterial pressures
patients are at risk for myocardial ischemia (inadequate oxygen supply) during tachycardia (heart rate greater than 100 bpm), especially patients with CAD because
there isn’t enough time during diastole to allow perfusion of blood flow
Circle of un-oxygenated blood
Vena cavas > right atrium > tricuspid valve > right ventricle > pulmonary valve > pulmonary artery > lungs
Circle of oxygenated blood
Lungs > pulmonary veins > left atrium >Bicuspid> left ventricle > aortic valve > aorta > rest of body
Each cardiac cycle has three major sequential events:
diastole,
atrial systole, and
ventricular systole
hemodynamic monitoring is
measurement of Chamber pressure
Cardiac output refers to
the total amount of blood ejected by one of the ventricles in liters per minute
The cardiac output in a resting adult is
4 to 6 L/min
Cardiac output is computed by
multiplying the stroke volume by the heart rate
Stroke volume is
the amount of blood ejected from one of the ventricles per heartbeat
The average resting stroke volume is
about 60 to 130 mL
Changes in heart rate are due to
inhibition or stimulation of the SA node mediated by the parasympathetic and sympathetic nervous system.
Stroke volume is primarily determined by three factors:
preload, afterload, and contractility.
Preload refers to
the degree of stretch of the ventricular cardiac muscle at the end of diastole.
Afterload
resistance to ejection of blood from the ventricle
Contractility refers to
the force generated by the contracting myocardium
Orthopnea
is the sensation of breathlessness in the recumbent (flat) position, relieved by sitting or standing.
when assessing chest pain or syncope It is important to identify
- preceding events
- duration of symptoms,
- measures that aggravate or relieve the symptoms.
A loss of function of the cells throughout the conduction system leads to
a slower heart rate.
in gerontologics The size of the heart
increases due to hypertrophy (thickening of the heart walls)
in gerontologics, the valves, due to stiffening, no longer close properly which
results in backflow of blood creates heart murmurs, a common finding in older adults
older adults may generally become symptomatic with
fatigue, shortness of breath, or palpitations
in gerontologics: Left atria is
enlarged causing Irregular heart rhythm
in gerontologics: the valves are
thickened, causing elevated BP
in gerontologics: plaque formation (atherosclerosis) leads to increased risk of
thrombosis and stroke
in gerontologics: Decreased number of pacemaker cells leads to
decreased heart rate
Hypertension is defined as
a persistent elevation of the systolic blood pressure at a level of 140 mmHg or higher and a diastolic blood pressure of 90 mmHg or higher
diagnosis of hypertension must be based on
an average of two or more accurate readings taken one to 4 weeks apart
the prevalence of hypertension among __________ is among the highest in the world
African Americans
normal bp
120/80
prehypertension
120-139/80-89
hypertension stage 1
140-159/90-99
hypertension stage 2
160+/100+
hypertensive crisis
180+/120+
Modifiable Risk Factors for HTN
Obesity Stress Diet – sodium consumption, diabetes control Substance abuse ETOH consumption Cigarette smoking Sedentary lifestyle Socioeconomics
non-modifiable Risk Factors for HTN
Family history
Age
Gender
Ethnicity
Men have greater HTN risk until
64 y of age
Women have greater HTN risk at
65 y of age and later
In prolonged HTN, the walls of arteries
stretch excessively and create problems
papill-edema (swelling of the optic disc)
may be seen In severe hypertension,
Primary hypertension (also called essential hypertension)
is diagnosed when there is no identifiable cause.
Secondary hypertension is defined as
high blood pressure from an identifiable underlying cause
Blood pressure is the calculated by
cardiac output multiplied by peripheral resistance
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The notable exception to HTN diagnosis is when a patient’s average BP is greater than or equal to 160/100 mm Hg, confirmed by
at least two accurate readings on one occasion
Effects of Uncontrolled HTN
Increased work of heart Tissue and organ damage Vascular weakness Vascular scarring Blood clots Plaque build-up
The goal of hypertension treatment
is to prevent complications (i.e., target organ damage) and death by maintaining a blood pressure lower than 130/80 mm
HTN Complications (target organ damage)
Myocardial infarction (MI) Heart failure (HF) Transient ischemic attack (TIA) Cerebrovascular accident (CVA)
Lifestyle Modifications to Prevent and Manage Hypertension:
Weight reduction
Consume a diet rich in fruits, vegetables
Sodium <2 g/day is optimal
Preferred potassium intake is 3500–5000 mg/day.
lower alcohol
Increase activity
First-line antihypertensive medications
Thiazine diuretics like: chlorthalidone
ACE inhibitors like: benazepril
Second-line antihypertensives
Loop Diretics like: furosemide
Hypertensive emergency
180/120 WITH new or worsening target organ damage
antihypertensive medications for HTN emergency include
intravenous drugs such as nicardipine
Taking vital signs every 5 minutes is appropriate if
the blood pressure is changing rapidly
taking vital signs at 15- or 30-minute intervals is appropriate when
the situation is stable
CAD (Coronary Artery Disease)
is disease of the coronary arteries caused by atherosclerosis
atherosclerosis
(plaque buildup on the artery walls, causing thickening)
a disease of the arteries characterized by the deposition of plaques of fatty material on their inner walls causing thickening.
non-modifiable Risk Factors for CAD
Age
Family hx/heredity
Gender
Ethnicity
modifiable Risk Factors for CAD
HTN Diabetes Type 2 Excessive ETOH consumption Metabolic syndrome Hyperlipidemia Cigarette smoking Obesity Physical inactivity Stressful lifestyle
Heart failure results from
impaired ventricular function that prevents the heart from pumping enough blood to meet the demands of the body.
HF is not a disease but is associated with
cardiovascular diseases – HTN, CAD, MI
HF is the most common
cause of hospital admission for patients over 65 years old.
the primary cause of HF
Atherosclerosis of the coronary arteries
Patho of HF
Myocardial dysfunction, leads to decreased cardiac output, that activates barorecepters to increase BP and HR. As the heart works harder, heart muscles thicken and the ventricles increase in size, then myocardial cells struggle to maintain cardiac output, then die.
HF RISK FACTORS
Coronary artery disease (CAD) Hypertension Diabetes Tobacco use Obesity Excessive alcohol High serum cholesterol High sodium intake
HF has 2 categories of symptoms of failures
left-sided failure and right-sided failure
Clinical Manifestations of Left-sided Failure
Restless, anxiety, confusion Basilar crackles (base of lungs) Cough Oliguria (little urine) Faint pulses tachycardia
Clinical Manifestations of Right-sided Failure
Hepato-megaly (liver becomes enlarged) Spleno-megaly (spleen becomes enlarged) Ascites (fluid collection in abdomen) JVD (jugular venous distention) Anorexia Anasarca (swelling of body) edema
hepatomegaly
(enlargement of the liver)
The first step of nursing assessment for the heart
patient interview!
(skip me) The ejection fraction
(skip me) is a measure of ventricular contractility; it is the percentage of the end-diastolic blood volume that is ejected with each heartbeat
A normal expected EF (Ejection Fraction) is
55% to 65% of the ventricular volume
The cornerstone of therapy for HF includes
a diuretic, a beta-blocker, and an angiotensin system blocker
Cardiac assessment Objective data
Physical exam including general appearance, LOC, weight, head, neck, skin and nails, edema, blood pressure, pulse, respirations, heart sounds & lung sounds
Diagnostic data
Cardiac assessment Subjective data
Patient history Dyspnea Chest pain Syncope Palpitations Fatigue
S3 heart sound is an early sign that
increased blood volume fills the ventricle with each beat.
Clubbing of the fingers and toes indicates
chronic hemoglobin desaturation and is associated with congenital heart disease.
Prolonged capillary refill time indicates
inadequate arterial perfusion to the extremities
The difference between the systolic and the diastolic pressures is called
pulse pressure
Normal heart sounds:
S1, S2
Abnormal heart sounds:
S3, S4
S1—First Heart Sound
Tricuspid and mitral valve closure creates the first heart sound (S1). The word “lub” is used to replicate its sound
S1 is usually heard the loudest at
the apical area
S2—Second Heart Sound
Closure of the pulmonic and aortic valves produces the second heart sound (S2), commonly referred to as the “dub” sound
S2 is a softer sound and is heard best
over the pulmonic area. Between 2nd and 3rd intercostal spaces left side.
Murmurs
are created by turbulent flow of blood in the heart.
An angiogram
is a scan that shows blood flow through arteries or veins, or through the heart, using X-rays
Radionuclide imaging
is the production of images of internal body parts obtained by cameras that detect the radioactive emissions of an injection
Lab diagnostics for the heart
- Cardiac biomarkers
- Lipid profile
- Brain B-type
- Electrolytes
- PT/PTT
Cardiac biomarkers are
substances that are released into the blood when the heart is damaged or stressed
which cardiac biomarker levels are increased during myocardial infarction
creatine kinase [CK],
CK isoenzymes (CK-MB),
troponin,
Myoglobin
Lipid profile assesses
Cholesterol, triglycerides, and lipoproteins are measured to evaluate a person’s risk of developing CAD
Brain (B-Type) Natriuretic Peptide (BNP)
is a neurohormone that helps regulate BP and fluid volume.
The level of BNP in the blood increases as the
ventricular walls expand from increased pressure.
C-Reactive Protein (CRP)
is a protein produced by the liver in response to systemic inflammation.
People with high CRP levels of __X mg/L__ may be at greatest risk for CVD
(3 mg/L or greater)
an elevated blood level of homocysteine is thought to indicate
a high risk for CAD
elevated homocysteine = bad
high levels of lactic acid reflect
inadequate tissue perfusion in HF
Cardiac stress testing:
are noninvasive ways to evaluate if there is myocardial ischemia and higher myocardial oxygen requirement during these tests.
Myocardial perfusion imaging (PET)
determines if arterial perfusion to the heart is compromised
Echocardiogram
is an ultrasound of cardiac structures and used to measure the ejection fraction
2 types of echocardiography
transthoracic
transesophageal
A significant limitation of transthoracic echocardiography is
the poor quality of the images produced
transesophageal echocardiography (TEE) involves
threading a small transducer through the mouth and into the esophagus
The high-quality imaging obtained during TEE makes this technique
an important first-line diagnostic tool for evaluating patients with many types of CVD, including HF
Heart failure Medication Management
Cholesterol lowering drugs Vasodilators Beta-blockers Anti-platelets Glycoprotein IIB/IIIa receptor agonists Calcium channel blockers
Cholesterol lowering drugs
Statins:
Atorvastatin (Lipitor)
Vasodilators example medication
nitroglycerin
Beta-blockers example and function
such as metoprolol
reduce myocardial oxygen consumption
Calcium channel blockers
decreases the workload of the heart and slowing the HR.
Antiplatelet medications
are given to prevent platelet aggregation and thrombosis
Glycoprotein IIB/IIIa receptor agonists indicated for
hospitalized patients with unstable angina
