Cardiovascular Function - Chapter 29
What are the AV valves?
Atrioventricular valves which are the tricuspid and mitral(bicuspid) valves
What does ST segment elevation lead to?
Benign condition but if malignant/st-segment = myocardial infraction
The health care provider is concerned that a client has developed a decrease in cardiac output. Cardiac output may be calculated as:
CO = SV x HR
What is the function of the circulatory system?
Consists of the heart and blood vessels and its main function is TRANSPORTATION
What enzymes has a powerful vasodilator effect on arterioles and increases capillary permeability?
Histamine
What changes when the blood EJECTS from the LEFT ventricle?
the aortic pressure rises!
A heart failure client has an echocardiogram performed revealing an ejection fraction (EF) of 40%. The nurse knows this EF is below normal and explains to the client:
"This means your heart is not pumping as much blood out of the heart with each beat."
A client asks why he has not had major heart damage since his cardiac catheterization revealed he has 98% blockage of the right coronary artery. The nurse's best response is:
"You have small channels between some of your arteries, so you can get blood from a patent artery to one severely blocked."
What are determinants of Cardiac Output (CO)
*It measures the amount of blood pumped out of the hear each minute CO = STROKE VOUME x HEART RATE Normal: 5-6l/min ↑ HR OR SV= ↑CO ↓HR OR SV= ↓CO
What does the circulatory system transport?
-delivers oxygen and nutrients needed for metabolic processes to the tissues -carries waste products from the tissues to the kidneys and other excretory organs for elimination. -circulates electrolytes and hormones needed to regulate body function -regulates body temperature
How does the heart transport blood through the circulatory system?
-right heart propels blood through the gas-exchange vessels in the lungs -left heart propels blood through the vessels that supply all the other tissues in the body.
Of the following factors, which one represents the contractile force used by the muscle in order to move blood into the aorta? A. Preload B. ardiac contractility C. Heart rate D. Afterload
AFTERLOAD! Cardiac contractility is the heart's ability to change the force of contraction. The ability to change this force helps the heart overcome afterload, the pressure the heart must exert to move blood out of the heart.
Whats so bad about a high heart rate?
A high heart rate leads to a decreased stroke volume and a decrease in cardiac output. Heart doesn't have adequate time to fill properly!
A client is admitted to the cardiac unit with a diagnosis of pericarditis. The nurse is teaching the patient about the anatomical location of the infection. The nurse evaluates the effectiveness of the teaching when the client correctly identifies which of the following as the location of the pericardium?
A membranous sac that encloses the heart
Stroke Volume (SV)
Amount of blood ejected with each contraction of the ventricle
End-Systolic Volume (ESV)
Amount of blood that remains in the ventricle after ejection
What is the point of the arteries and veins?
Arteries carry blood away from the heart Veins carry blood toward the heart
A client is diagnosed with an abdominal aortic aneurysm that the physician just wants to "watch" for now. When teaching the client about signs/symptoms to watch for, the nurse will base the teaching on which of the following physiological principles?
As the aneurysm grows, more tension is placed on the vessel wall, which increases the risk for rupture.
Isoenzyme CK-MB
Cardiac specific isoenzyme that is specific for cardiac muscle damage! if elevated = MI (heart attack)
Cardiac Catheterization/Coronary
Catheter passed from the femoral or brachial artery into the aorta to the heart: assess L side of the heart = blockage info Catheter passed from the femoral vein to the inferior vena cava to the heart: assess R side of the heart = pressure info *uses contrast dye
Swan Ganz Catheter
Catheter placed into the heart and measures the right atrial pressure which is the central venous pressure and is indicative of volume status *normal is usually up to 10mm Hg
Flow of blood OUT of the heart
Comes from systemic circulation (the body) into the SUPERIOR and INFERIOR Vena Cava→Right Atrium →Through Tricuspid Valve→Right Ventricle →Through Pulmonary Valve→ Pulmonary Arteries → OUT to the LUNGS →LEAVES CO2 & PICKS UP OXYGEN!!!
Holter Monitor
Continuous cardiac ambulatory monitoring over a 24- to 48-hour period
The heart controls the direction of blood flow. What is the role of the aortic valve?
Controls the direction of blood flow from the left side of the heart to the systemic circulation
P Wave
Corresponds to atrial depolarization
Positron Emission Tomography (PET)
Evaluate cardiac perfusion and metabolism
MRI
Imaging of cardiac structures May identify: Myocardial thickening Pericardial sac disease Valvular structures Congenital malformations With contrast media: identifies acute and chronic myocardial infarcts
Explain the atria's purpose
In order for the atria to fill with blood from the vena cava(R) or the pulmonary veins (L) it basically has to drop its pressure → blood goes in →atria stores it until it fills up →valves open their pumps it into the vetntricles
If a client has experienced sympathetic nervous stimulation of the heart. The nurse is aware that the client may manifest what?
Increased heart rate and increased contractility
2 Part of Ventricular Systole
Isovolumetric Contraction Period=ventricular contraction Ejection Period= ventricular ejection
What does the heart's ability to increase its output according to the body's needs depend on ?
It depends on the preload, or filling of the ventricles (end-diastolic volume); the afterload, or resistance to ejection of blood from the heart; cardiac contractility, which determines the force of contraction; and the heart rate, which determines the frequency with which blood is ejected from the heart.
Heart Rate
It determines the frequency with which blood is ejected from the heart. Therefore, as the heart rate increases, cardiac output tends to increase
Creatine Phosphate (CP)
It is a storage for of ATP *an immediately available source of energy for the myocardium
What does stimulation of the Parasympathetic Nervous System (PNS) do?
It results in the reduction of the heart rate and speed of action potential conduction via binding of acetylcholine to muscarinic receptors provides information about the heart's conduction patterns **Stimulates the vagal nerve which can lead to vasovagal response *** → decrease heart rate *Vagal Maneuver: massaging a vaso nerve (ex carotid arteries) to lower heart rate!
Which of the following blood flow patterns reduces friction, allowing the blood layers to slide smoothly over one another?
Laminar
LUB-DUB
Lub(S1) = Tricuspid Valve and Mitral Valve CLOSE (PV & AV OPEN) Dub (S2) = Pulmonary Valve and Aortic Valve CLOSE (TV & MV OPEN) (S1&2= 1st & 2nd heart sound)
What is a measurement of blood volume in the heart?
Mean right arterial pressure = Central Venous Pressure (CVP)
The heart consists of four valves. Which are the heart's atrioventricular valves?
Mitral Tricuspid
What does it mean if the T wave is flattened or inverted and the patient has chest pain?
Myocardial ischemia (heart attack)
Flow of blood INTO the heart
Oxygenated blood from the lungs goes into the pulmonary veins →Left Atrium →Through Mitral Valve →Left Ventricle →Through Aortic Valve →Aorta (aortic arch)(ARTERY) → OUT to the body
As the needs of the body change, the heart's ability to increase output needs to change too. This ability in the heart depends on what factors?
Preload Afterload Cardiac contractility Heart Rate
What are determinants of Stroke Volume
Preload: The volume of blood in the heart Contractility: The contractile capabilities; ability of the heart to squeeze After-load: Impedance opposing ejection of blood from the ventricle; the pressure
U Wave
Present in a slow heart rate and low potassium = hypokalemia*
Nuclear Cardiography
Radioactive substances injected into the bloodstream are used to trace the patterns of blood flow in the heart Assesses the adequacy of blood flow to cardiac tissues
Lusitropy
Rate and degree of ventricular relaxation
Electrocardiography
Recording of the electrical current that is transmitted to the body surface as action potentials spread throughout the myocardium. **identifies irregularities in impulse initiation and conduction rates/pathways
T Wave
Reflects ventricular repolarization
If you have a patient with volume overload they will have detention of atrium and ventricle what is released ?
Release of Natriuretic Peptides; they are diabetics so the patient releases the volume
What does stimulation of the Sympathetic Nervous System (SNS) do?
Release of dopamine norepinephrine, epinephrine has -Ehronotropic Effect on the heart: increases heart rate -Dromotropic Effect : increase the speed of conduction -Inotropic Effect: increases the force of contraction (the squeeze of the heart) all due to the binding of norephinephrine to β receptors
QRS Complex
Represents ventricular depolarization
What is the correct sequence for blood flow through the heart?
Right atrium - tricuspid valve - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - mitral valve - left ventricle - aorta
Ejection Fraction
SV/EDV Normal = 60%-80% *but then she said that clinically norma ranges are 55%-75%
Exercise/stress test
Stressing the heart Increasing the heart rate to the max and if there is no chest pain or EKG changes then test is negative
What is the difference between the end-diastolic and end-systolic volumes?
Stroke Volume
ANP (Atrial Natriuretic Peptide)
Synthesized by myocytes and released in response to atrial stretch
The nurse is reviewing the circulatory system. Which statements are correct about the functional organization of the circulatory system?
The arterial system distributes oxygenated blood to the tissues. The venous system collects deoxygenated blood from the tissues.
What does ST segment depression lead to?
it means myocardial ischemia
Right cardiac catheterization
measures pressure, CVP, pulmonary artery pressure, left atrial pressure, all pressures no dye used **TELLS YOU ABOUT PRESSURES
What happens when the ventricles relax?
The pressure drops! *Just know that as the ventricles are relaxing and the atrium is already filled with blood and ready to pour it into the ventricles again as soon as the aortic/pulm valves close and tricusp/mitral(bicusp) open
What are the SV valves?
The semilunar valves are the aortic and pulmonary valves *put this in here but she refers to them as aortic/pulmonary so will be using that because she she doesn't want us to get confused bc SV=Stroke Volume
What do the ventricles function as?
The ventricles are the main pumping chambers of the heart. The right ventricle pumps blood through the pulmonary artery to the lungs, and the left ventricle pumps blood through the aorta into the systemic circulation.
What does high levels of CK mean?
There is myocardial cell damage.
What is the point of the valves?
They prevent the back flow of blood in the heart (ONE WAY HIGHWAY OF BLOOD FLOW THROUGH THE HEART)
Systolic
Time between S1 and S2 = when the blood is going into the body So basically time between lub and dub **DURING THIS BLOOD IS EJECTED= VENTRICLES CONTRACTING
Dystolic
Time between the first set of S1&S2( and the next set of S1&S2 So basically time between one lib-dub and the next lub-dub **DURING THIS THE HEART IS GETTING FILLED WITH BLOOD = VENTRICLES RELAXING
Echocardiography
Uses reflected sound waves (ultrasound) to provide an image of cardiac structure and motion within the chest Useful in diagnosis of heart enlargement, valvular disorders, collections of fluid in the pericardial space, cardiac tumors, and abnormalities in left ventricular motion
What does BNP elevation mean?
VOLUME OVERLOAD CONGESTIVE HEART FAILURE
Preload represents the volume work of the heart and is largely determined by:
Venous blood return
The cardiac cycle describes the pumping action of the heart. Which statement is correct about systole?
Ventricles contract and blood is ejected from the heart.
End-Diastolic Volume (EDV)
Volume of blood in the ventricle prior to ejection
What does the atria function as?
as a reservoirs for blood returning to the heart from the body and lungs and as auxiliary pumps that assist in filling the ventricles
Ventricular Contraction & Ejection
once the blood goes from the right atrium into the right ventricle the Tricuspid/Mitral Valves SHUT = COTRACTION STARTS! →there is a small amount of time before the aortic/pulmonary valves open→ in this time the the blood has nowhere to go so the ventricular pressure is rising rapidly →then the pressure FORCES the Aortic/Pulmonary Valves to OPEN and the blood RUSHES/EJECTS out to the lungs for oxygen! (buh-bye!) ****Normal amount of blood leaving during this first contraction is 60%*****
BNP (B-type Natriuretic Peptide)
produced and released by ventricles in response to chronic overdistention = proterminal MBNP = measurement of ventricular stretch /pain
Electrocardiogram (ECG/EKG)
provides information about the heart's conduction patterns
Left cardiac catheterization
uses contrast dye and it is injected into the coronary arteries and tells you if there are occlusions of the coronary arteries; if it is traveling freely there is no obstructions if it slows there is some obstruction if it stops there is complete obstruction *TELLS YOU OBSTRUCTION OF CORONARY ARTERIES
Creatine Kinase (CK) Enzyme
when ATP is low it helps convert CP to ATP and it is useful for myocardial cell damage
What does an abnormal QT interval mean?
when it is abnormal if it is too long it can cause ventricular arrhythmias