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Cardiac function and EKG
Terms in this set (102)
are specialized nerve endings affected by changes in the arterial BP and are located in the walls of the aortic arch and the carotid sinus
from an increase in arterial pressure will stimulate the heart rate and decrease arterial pressure
Decrease detected (baroreceptors)
vasoconstriction occurs to increase BP, and raise the heart rate
located in .the vena cava and right atrium respond to pressure changes that affect circulatory blood volume
Antidiuretic hormone and BP
aka vasopressin influences BP indirectly by regulating vascular volume. An increase in blood volume will trigger a stop of ADH being released and reducing the blood volume.
An decrease in blood volume will stimulate ADH being released, which will increase the blood volume and raise the BP
diagnostic test record the electrical activity of the heart and is useful for detecting cardiac dysrhythmia, location & extent of MI, cardiac hypertrophy and effectiveness of treatment
Each small square (ECG)
is .04 seconds
Each large square (ECG)
is .2 seconds
P wave represents what?
atrial depolarization which causes contraction
represents the time it takes an impulse to travel from the atria through the atrioventricular node, bundle of his, and to the bundle branches to the purkinje fibers
Normal PR interval?
measure from beginning of P wave until where the R wave begins(sometimes Q)
Early ventricular repolarization
ventricular refractory time ( the total time required for ventricular depolarization)
0.32 to 0.4 seconds
QT interval - measured from the beginning of the QRS to the end of the T wave
A extended QT interval
prolonged QT interval increases the risk of lethal ventricular arrhythmia.
line represents the absence of electrical activity in the cardiac cells.
A U wave may follow the T wave, and a prominent U wave may indicate an electrolyte abnormality such as hypokalemia
Characteristics - Intervals are all normal, rhythm is regular
Normal sinus rhythm
(60 - 100 / minute)
Rhythm originates from the SA node
Atrial and ventricular filling are regular.
(rate is < 60 / minute)
Atrial and ventricular filling are regular, but the rates are less then 60.
PR and QRS intervals are within the normal limits
Why sinus bradycardia
aerobically trained individuals, sleeping, Valsalva maneuver, Beta blockers
Symptomatic Bradycardia →syncope
Treatment - atropine
attempt to determine cause
-administer O2 as ordered
-Administer atropine (as ordered)
(rate is > 100 / minute)
atrial and ventricular rates are 100-180 but filling normally
-PR and QRS intervals are within normal limits
Sinus tachycardia caused
exercise, fever, pain, hypovolemia, HF, anxiety
If symptomatic - treat the underlying cause. Beta adrenergic blockers may be used
-Multiple rapid impulses from many foci depolarize in the atria in a totally disorganized a manner at a rate of 350-600
-Usually no definitive P wave can be observed only fibrillatory waves before each QRS
rapidly and irregularly, so blood pools in the atria which can lead to formation of thrombi
Systematic approach to ECG interpretation
P wave Is it upright? Is there one for every QRS? Do they look the same?
Rate - Look at the QRS.
6 second strip - count QRS's multiply X 10=heart rate
Rhythm regular or irregular
Intervals (conduction pathway)
ability of cardiac cells to initiate an impulse spontaneously and continuously. SA node possesses automaticity to the greatest extent.
Systole - contraction - left ventricle ejects blood into the aorta
Diastole - period between contractions. Heart is filling!! Twice as long as systole. Coronary arteries are perfused during diastole
Electrical Activity of the heart
The conduction system
The electrical activity stimulates the mechanical activity (pumping) of the heart
Depolarization triggers systole (contraction) and is followed by diastole (relaxation).
Cardiac output is a measurement of mechanical activity.
The heart requires a constant supply of oxygen and nutrients.
Left - Left coronary artery - LAD (left anterior descending) and LCX (left circumflex artery)
Right - RCA (right coronary artery)
*The coronary arteries are perfused during diastole (relaxation of the heart)
ability of cardiac cells to respond to an electrical impulse - refractoriness
Ejection Fraction (EF)
the percentage of blood that's pumped out of a filled ventricle with each heartbeat. Normal >55%
important for transmission of the impulse from one fiber to another. Level of excitability is determined by the length of time after depolarization that the tissues can be stimulated.
Cardiac output (CO)
refers to the amount of blood pumped by the heart each minute. In the normal resting adult, is approximately 3.5 to 8 L per minute
Stroke Volume depends on 3 things...(explained)
1) the amount of blood that enters the heart determines how much the heart can pump out.
2) stroke volume depends on the natural strength of the heart muscle, or its contractility. Well-exercised heart is stronger and more efficient than the weak and (flabby) heart, so it is able to eject a larger volume of blood with each beat.
3) stroke volume depends on the resistance to blood flow in the circulatory system. The main resistance is in the diameter of the arterial system, which is measured by BP. If the BP (resistance) is high, the stroke volume will decrease
Stroke volume depends on: (simple)
Accommodation of incoming blood volume by heart (preload)
Contractility of heart muscle
Resistance to blood flow in the circulatory system (afterload)
In the SA node, small but significant changes in the concentrations of potassium, sodium, and calcium generate a small electrical impulse. This impulse (depolarization) travels through special conduction tissue and normally causes the muscles to contract. After the impulse has passed through the cells, their ionic concentrations return to previous levels (repolarization), and the muscle relaxes.
Electrical Activity of the heart
The electrical activity stimulates the mechanical activity (pumping) of the heart
Depolarization triggers systole (contraction) and is followed by diastole (relaxation).
Cardiac output is a measurement of mechanical activity
contraction - left ventricle ejects blood into the aorta
- period between contractions. Heart is filling!! Twice as long as systole. Coronary arteries are perfused during diastole
Inherent rates of the heart
SA node - 60 - 100 / minute
AV node - 40 - 60 / minute
Ventricles - 20 - 40 / minute
The newborn's heart rate
is normally 130 to 160 bpm, and its rhythm is commonly irregular. Under 100 is cause for alarm
Baby heart rate
ranges between 80 and 150 bpm
Toddler heart rate
the heart rate has decreased to a resting rate of about 70 to 110 bpm
delaye at the AV junction
When the impulse reaches the lower portion of the atria, it is delayed briefly at the AV junction before it continues into the ventricles. This delay allows time for the atria to contract fully. In this way, the atria can add 30% more blood volume to the ventricles before the ventricles contract
Parasympathetic nervous system Vagus nerve
Slows impulse conduction
Decreases force of contraction
Sympathetic nervous system
Increases force of contraction
Filling of the heart at rest
During this time, the atria fill passively, receiving blood from the venae cavae (on the right side of the heart) and the pulmonary veins (on the left).
Atrial muscles contract
When the atrial muscle cells contract, pressure builds within the atrial chambers. The pressure forces the AV valves to open, and the blood is pushed into the ventricle below each atrium.
is the flow of blood through the body tissues.
To maintain life, all living body cells must receive a constant supply of oxygen and nutrients.
Obesity and heart disease
major risk factor for cardiovascular disease because it raises BP, cholesterol, and triglyceride. Excessive weight places increased demands on the cardiovascular system. The extra adipose tissue must be supplied with blood to meet its metabolic requirements. To perform the additional work of pumping blood to these tissues, the heart may become enlarged. BP also increases, but perfusion may decrease.
Risks of heart disease
may face barriers to good cardiovascular health such as poor nutrition, obesity, genetics, stress, and lack of access to medical care.
Community Factors affecting heart disease
A specific community or population may face barriers as a group, such as lack of access to nutritional foods, poor economic conditions, and high unemployment. These factors contribute to disease within the population
Altered cardiovascular function- Vitals
are typically negatively affected. Hypertension, abnormal heart rates, and decreased oxygenation status may occur.
Inadequate tissue perfusion signs
include pain, skin changes, and changes in cognition. Edema and thrombus (clot) formation are manifestations of alterations in blood flow.
sign of decreased CO
Abnormally low BP (less than 90 mm Hg systolic), when accompanied by other indicators of diminished oxygenation
Diminished or absent pulses
may indicate inadequate blood flow to an area. Although the pulse normally diminishes as the distance from the heart increases, absence of pulse may indicate vessel occlusion. Complete vessel occlusion is most often associated with other signs, such as skin changes and pain. In some people, the most distal peripheral pulses (the dorsalis pedis and posterior tibial) may not be palpable but can be confirmed with the use of a Doppler instrument
Major Changes in heart rate
The heart rate increases in response to increased oxygen demand and decreases at rest when oxygen demands are low. A heart rate of greater than 100 bpm at rest may indicate problems with CO if known contributing factors (e.g., fever, pain, medications, anxiety) are absent.
Change in respiration
rate and effort often increase in individuals with cardiovascular dysfunction. Decreased CO or diminished blood flow limits the amount of oxygen available to the tissues.
is a term for red skin discoloration caused by hyperemia, or increased blood flow
If the sympathetic nervous system has caused constriction (e.g., in shock), sweat glands may become activated, and the patient's skin may feel clammy to the touch.
a bluish appearance of skin and mucous membranes, occurs when hemoglobin is not carrying an adequate amount of oxygen. Peripheral cyanosis (of the fingers, toes, and earlobes) occurs when blood flow is restricted. Central cyanosis is a serious sign of decreased oxygenation. It appears around the lips and tissues of the oral cavity.
Pain indicating heart problems...
chest pain. Some symptoms of a heart attack may include chest discomfort; pressure or squeezing sensation; arm, back, neck, jaw, or stomach pain; trouble breathing; or light-headedness.
How women present for heart attacks....
often will complain of sleep problems, lethargy, back or stomach pain, and nausea
FAST test for Stroke
Helping to identify Facial drooping, Arm weakness, Speech changes, and Time (when symptoms began and time to call 911) can get a person experiencing a stroke the care needed in a timely manner
Observing the patient's general behavior and appearance yields significant information about tissue perfusion and CO. Decreased CO, vascular disease, or both can change cognitive and perceptual function. Because the brain is extremely sensitive to any decrease in blood flow, assessment of cognition and level of consciousness provides clues about cerebral perfusion
-Palpate the pulse for quality and rate. Note regularity of rhythm, pulse intensity, and the number of beats per minute.
-Capillary refill time, which reflects peripheral tissue perfusion and CO, is determined by pressing a nail bed until it blanches .
-Palpate for edema and note its extent
A stethoscope is used to determine BP, count the apical pulse, and identify normal and abnormal heart sounds. Auscultate the apical pulse to establish its rate and character
Impaired CO symptoms
changes in mental clarity
decreased urine output
ltered CV functioning
-Muscle damage - ischemia (stable angina) to infarction (STEMI)
-Thrombi - embolism - stroke
-is the alternate circulation around a blocked artery or vein via another path, such as nearby minor vessels
-after an acute myocardial infarction (heart attack) the heart tissue will sometimes bypass the blockage in the main artery and supply enough oxygenated blood to enable the cardiac tissue to survive and recover.
EKG changes - STEMI
-Decreased Cardiac Output and
-Ineffective Peripheral Tissue Perfusion.
- Activity Intolerance also is a significant problem for many patients with cardiovascular dysfunction, although it is not exclusively a cardiovascular problem
- identify risk for ineffective perfusion by body area: cardiac, cerebral, or peripheral
Outcomes and Goals
The patient will demonstrate adequate knowledge concerning cardiovascular dysfunction, prevention, or care.
The patient will maintain adequate CO.
The patient will demonstrate adequate tissue perfusion with adequate oxygenation of body tissue.
The patient will cope effectively with resulting changes in self-concept and lifestyle.
PREVENTING VENOUS STASIS
-Assisting with Leg Exercises
-Applying Antiembolism Stockings
-Using Pneumatic Compression Devices
-Impulse Foot Pump
Any article of clothing that exerts excessive pressure on the calves or thighs may constrict the veins, diminishing venous return and promoting the formation of clots and varicosities.
Impulse Foot Pump device
Impulse foot pumps improve venous return in the immobile patient by stimulating the venous plantar plexus, the large vein on the sole of the foot. On each foot, the patient wears a foot sleeve with a rigid base that is inflated with air and then deflated. Each sleeve is attached via a hose to a controller that controls the inflation and deflation
-Elevation of Limbs
-Reducing Sodium Intake
Body position affects on the heart
Body position affects cardiac work and tissue perfusion. The heart works harder in the supine position than in the upright position. Lying flat promotes venous return. Because all vessels are at the same level of the heart, gravity's effect on the blood is minimized. Blood can flow more freely into the venae cavae. The increased volume of blood entering the atria increases stroke volume and workload of the heart. Those with healthy hearts easily tolerate the enhanced venous return in the supine position.
acute chest pain in a pt
-the patient should stop all activity and rest, sitting comfortably; (lying flat inhibits full chest expansion and limits gas exchange in the lung)
-may be a life-threatening situation, and help should be obtained to evaluate it.
-Document the duration, activity during onset, and vital signs during the episode of pain
Pain can occur when the patient exceeds normal activity tolerance. Effective conservation of energy can promote activity tolerance and thus can help prevent pain.
Patients with newly diagnosed MI should avoid repeated movement of the upper arms. This movement increases the metabolic demands of the arm muscles and forces the heart to pump harder for the blood to overcome gravity.
Initial Management by nurse when cardiac arrest happens
-After quickly establishing that an arrest has occurred, CALL FOR HELP FIRST (shout for help and press the emergency button if available)). -
-Initiate and continue CPR until the rescuers arrive. If a facility emergency response is available, alert the hospital operator. Dial the emergency number and announce to the operator, "There is a cardiac arrest on (location), room (number)."
-The nurse's first calls for help should bring other nurses to the room. They bring the emergency supplies ("crash cart") while the first nurse begins preparations for CPR
Role of the nurse in a code
-Whether or not assistance comes immediately, the discovering nurse must stay with the victim and continue to call for help until it arrives
-If the patient has been sitting upright, lower the bed to a flat position.
-Move extra equipment away from the bed for easy access to the patient.
- Remove the pillow from under the patient's head. -If the bed is elevated to stretcher level, lower it.
-Put the board or other hard surface under the patient's chest; alternatively, some mattresses can be inflated so that they provide a hard surface.
All of these adjustments must be made as quickly as possible, and CPR must be initiated immediately.
Role of Nurse After Resuscitation Begins
- the nurse who discovered the person should remain with the team to provide essential information.
-The circumstances under which the person was found, the patient's status before the arrest, primary diagnoses, recent medications, and recent laboratory data are relevant.
-The nurse also may be needed to assist with procedures.
-Consideration of privacy is important. If another patient shares the room, he or she should be moved elsewhere if possible.
- Provide emotional support during and after the resuscitation to the pts loved ones. Provide honest, up-to-date information, but do not speculate on the patient's condition.
-cardiovascular problems need not permanently prevent them from enjoying a normal lifestyle.
-the purpose of rehabilitation is to help the cardiovascular patient restore or improve lost function.
- depends on physical endurance, which is improved by graded physical activity.
- although rest is an essential part of the management of cardiovascular problems, activity also must play a part.
-Exercise is an important intervention because it reduces BP and produces improvements in the lipid profile
Limit activity 1 hour after meals.
Blood flow is directed to digestive tract to aid digestion; increases workload on the heart.
A patient with renal failure is found to have an elevated potassium of 6.0 mEq/L. The effect of the high potassium is problems with conduction resulting in abnormal cardiac rhythm. Which of the following describes this type of abnormality?
Dysrhythmia is an abnormal conduction through the heart muscle and is the result of a high potassium value, among other factors.
-Dietary Approaches to Stop Hypertension
-Eating whole "real" foods rather than individual nutrients
-Significantly lowers both systolic and diastolic blood pressures as well as cholesterol
-Lowering sodium lowers blood pressure- greatest reduction in blood pressure occurred at 1500 mg of sodium.
DASH Diet Potassium
Potassium intake increases, blood pressure decreases.
DASH Diet Alcohol
Observational studies and clinical trials
Show a direct, dose-dependent relationship between alcohol and blood pressure
Alcohol intake should be limited to 2 drinks or less per day in men and 1 drink or less per day for women
Lead placement for the chest electrodes
V1, fourth intercostal space at the right sternal border;
V2, fourth intercostal space at the left sternal border;
V3, halfway between V2 and V4;
V4, fifth intercostal space at the left midclavicular line;
V5, fifth intercostal space at the anterior axillary line;
V6, fifth intercostal space at the midaxillary line.
Effects of healthy diets
-fruits and vegetables have been shown to lower blood pressure and improve other CVD risk factors.
-People who have a high intake of fruits and vegetables are at lower risk of developing CVD, especially stroke.
Preparation methods should preserve the fiber and nutrient content without adding saturated fat, trans fat, sugar, or salt.
Increased intake of omega-3 fatty acids reduces risk of CVD.
AHA recommends 2 servings (approximately 8 oz.) of fatty fish per week, prepared in ways that do not add saturated or trans fats.
Increases LDL and total cholesterol levels
Choosing lean meats and trimming away visible fat lowers saturated fat intake.
Portion sizes are limited to 6 oz. or less per day.
Monounsaturated and polyunsaturated fats are inversely related to CHD.
The American Heart Association recommends total fat provide 25% to 35% of total calories.
Increases LDL and total cholesterol levels, the ratio of LDL to HDL cholesterol, and the risk of CHD
Found in partially hydrogenated fats
AHA recommends a trans fat intake of less than 1% of total calories.
Dietary cholesterol raises LDL levels, especially in people who are lean.
Found only in foods originating from animals
Moderate alcohol consumption from any source—beer, wine, or distilled liquor—is associated with a reduced risk of CVD.
Alcohol can be addictive, and high intakes are associated with high triglyceride levels, hypertension, liver damage, physical abuse, vehicular and work accidents, and increased risk of breast cancer.
is a minimally invasive, endovascular procedure to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis.
- 1 or more arteries are dilated with a balloon catheter to open the vessel lumen and improve arterial blood flow.
A laser probe is used to vaporize the plaque to open occluded arteries
Coronary artery stents
used in conjunction with angioplasty (PTCA) to provide suuportive scaffolding to eleimimate the risk of acute coronary vessel closure and to improve long term patency of the vessel
-a balloon catheter bearing the stent is inserted into the coronary artery and positioned at the site of occlusion, the balloon is inflated to deploy the stent
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