Cardiac Test Flashcards
Cardiac Ischemia ASA Conditions
Age: > or equal to 18
LOA: Unaltered
Other: Able to chew and swallow
Everything else is N/A
Cardiac Ischemia ASA Contraindications
Allergy or sensitivity to NSAIDs
If asthmatic, no prior use of ASA
Current active bleeding
CVA (stroke) or TBI (traumatic brain injury) in the previous 24 hours
Cardiac Ischemia ASA Dosing
Route: PO (by mouth)
Dose: 160-162 mg
Max. Single Dose: 162 mg
Dosing Interval: N/A
Max. # of Doses: 1
Cardiac Ischemia Nitroglycerin Conditions
Age: > or equal to 18
LOA: Unaltered
HR: 60-159 bpm
SBP: Normotension
Other: Prior history of nitroglycerin use OR IV access obtained
Cardiac Ischemia Nitroglycerin Contraindications
Allergy or sensitivity to nitrates
Phosphodiesterase inhibitor use within the previous 48 hours
SBP drops by one-third or more of its initial value after nitroglycerin is administered
12-lead ECG compatible with Right Ventricular MI
Cardiac Ischemia Nitroglycerin Dosing - No STEMI
SBP: > or equal to 100 mmHg
Route: SL (sublingual, beneath the tongue)
Dose: 0.3 mg or 0.4 mg
Max. Single Dose: 0.4 mg
Dosing Interval: 5 min
Max. # of Doses: 6
Cardiac Ischemia Nitroglycerin Dosing - STEMI
Do NOT administer nitroglycerin if patient has RVI
SBP: > or equal to 100 mmHg
Route: SL (sublingual, beneath the tongue)
Dose: 0.3 mg or 0.4 mg
Max. Single Dose: 0.4 mg
Dosing Interval: 5 min
Max. # of Doses: 3
Systemic Circulation
To the body
Left side of heart
Pulmonary Circulation
To the lungs
Right side of heart
Pericardial Cavity
Space filled with fluid (approx.10-15 mls)
Pericardial Sac
Double layered closed sac that surrounds and anchors the heart
Pericardium
Loose fitting, inextensible
Fibrous pericardium outside
Serous pericardium inside 2 layers
Outer Layer of Pericardium
Tough fibrous layer attached to the diaphragm, inner surfaces of the sternum and vertebral column
Inner Layer of Pericardium
Thin outer layer of heart wall
Serous Membranes (Part of Pericardium)
Secrete fluid to lubricate the membranes to reduce friction during contraction
3 Layers of the Heart Wall
Endocardium (inner)
Myocardium (middle)
Epicardium (outer)
Pericardium surrounds all layers and encloses the coronary vessels
Epicardium
Outer layer of the heart
Thin membrane attached to the outer surface of the myocardium.
Blood vessels that nourish the heart are inside the pericardium.
Myocardium
Sandwiched between the 2 layers of membranes (middle layer)
Thickest wall of the heart
Contraction of the myocardium provides the force that pumps the blood through the blood vessels
Endocardium
Single layer of the squamous epithelium on the internal surface of the myocardium.
Lines the chambers of the heart
Continuous with the internal lining of the blood vessels attached to the heart.
Heart Valves
Pulmonary, aortic, bicuspid, tricuspid
Heart Vessels
Aorta, pulmonary arteries and veins, superior and inferior vena cava
Pulmonary Arteries
Carry deoxygenated blood away from the heart, to the lungs.
Aorta
Carries oxygenated blood away from the heart, to the rest of the body.
Atria
Only job is to pump blood to the ventricles
2 superior chambers, right and left
Receive blood from the veins
Walls are relatively thin - they don’t need to generate much impulse as they are only moving blood a small distance to the ventricles.
Ventricles
2 lower chambers of the heart
Considered to be the primary “pumping chambers” as they are responsible to pump the blood out of the heart
Walls are thicker as a result of this
Myocardium of the left ventricle is thicker than the right as it is responsible to push blood to the entire body.
Atrioventricular (AV) Valves
Formed of fibrous connective tissue
2 AV Valves - mitral (bicuspid) and tricuspid
Allows blood from the atrium to the ventricles but not back
Tricuspid Valve (AV Valve)
Right side, 3 cusps of tissue from the fibrous tissues that separate the atria and ventricles
Bicuspid Valve (AV Valve)
A.K.A Mitral valve
Left side, between the left atria and left ventricle; 2 cusps
Strands of tissue - called the chordae tendineae - extend from the cusps to the papillary muscles (located in the walls of the ventricles).
Prevent the valves from being forced into the atria during ventricular contraction.
They are just the right length to allow the cusps to close and seal tightly.
Semilunar Valves
In the bases of the large arteries that carry blood from the ventricles.
2 in the arteries leaving the heart:
1) Pulmonary: at the opening between the right ventricle and the pulmonary trunk.
2) Aortic Semilunar Valves: at the opening between the left ventricle and the aorta
3 pocket like cusps (half moon shaped) allow blood to exit the ventricles and prevent blood flow back into the ventricles.
Left Coronary Artery
Originates at the left cusp of the aortic valve.
Divides into the left anterior descending artery (anterior interventricular)
Supplies 65-75% of the blood supply to the left ventricle and septum
Oxygenation and nourishment to the myocardial cells
Right Coronary Artery
Originates at the right cusp of the aortic valve
Divides into the right marginal artery and posterior interventricular artery
Supplies 25-35% of the blood supply to the left ventricle and all of the right ventricle
Contraction and Relaxation
Contraction - systole
Relaxation - diastole
Atria and ventricles contract alternately. Both relax between beats (left and right atria pump at the same time and left and right ventricle pump at the same time; ventricles pump while atria contract)
Cardiac Cycle Steps
- Blood enters the heart via the vena cava, enters the right atrium
- Goes through the tricuspid valve into the right ventricle
- The deoxygenated blood then leaves the heart through the pulmonary artery.
- The blood then goes to the lungs to get oxygenated.
- Back into the pulmonary veins - towards the heart
- Into the left atrium (oxygenated now).
- Through the mitral valve
- Into the left ventricle
- Out the aorta and to the body/organs.
Regulation of the Heart
The heart is regulated by your autonomic nervous system (involuntary). This is controlled in the medulla of the brain.
Baroreceptors
Senses pressure changes and tells the body what to do because of them (higher or lower the blood pressure)
SNS and Heart Rate
SNS innervation causes an increase in heart rate (tachycardia) and contractility.
Sympathetic = not calm (release of epinephrine and norepinephrine).
Epi/norepi is secreted at the synapses in the heart -> increases heart rate and strength of contraction.
PNS and Heart Rate
Parasympathetic = calm (release of acetylcholine (blocks the release of epi and norepi)).
PNS innervation causes a decrease in heart rate (bradycardia) and contractility (vagus nerve stimulation).
Acetylcholine is secreted at the synapses -> slows the rate (acts on muscarinic and nicotinic cholinergic receptors)
Leaning forward stimulates the vagus nerve which can cause someone to pass out.
Instead of speeding everything up (sympathetic) it slows everything down (eg. heart rate).
Acute Cardiogenic Pulmonary Edema Indications
Moderate to severe respiratory distress
AND
Suspected acute cardiogenic pulmonary edema
Acute Cardiogenic Pulmonary Edema Conditions (Nitro)
Age: > or equal to 18
LOA: N/A
HR: 60-159 bpm
RR: N/A
SBP: Normotension
Other: N/A
Acute Cardiogenic Pulmonary Edema Contraindications (Nitro)
Allergy or sensitivity to nitrates.
Phosphodiesterase inhibitor use within the previous 48 hours.
SBP drops by one-third or more of its initial value after nitroglycerin is administered.
Acute Cardiogenic Pulmonary Edema Treatment if SBP ≥ 100 mmHg to <140 mm Hg
IV or Hx: Yes
Route: SL
Dose: 0.3 mg or 0.4 mg
Max. Single Dose: 0.4 mg
Dosing Interval: 5 min
Max. # of Doses: 6
Acute Cardiogenic Pulmonary Edema Treatment if SBP ≥ 140 mm Hg
IV or Hx: No
Route: SL
Dose: 0.3 mg or 0.4 mg
Max. Single Dose: 0.4 mg
Dosing Interval: 5 min
Max. # of Doses: 6
IV or Hx: Yes
Route: SL
Dose: 0.6 mg or 0.8 mg
Max. Single Dose: 0.8 mg
Dosing Interval: 5 min
Max. # of Doses: 6
Continuous Positive Airway Pressure (CPAP) Indications
Severe respiratory distress
AND
Signs and/or symptoms of acute pulmonary edema or COPD
Continuous Positive Airway Pressure (CPAP) Conditions
Age: ≥ 18
LOA: N/A
HR: N/A
RR: Tachypnea ( ≥ 28 breaths/min)
SBP: Normotension
Other: SpO2 <90% or accessory muscle use
Continuous Positive Airway Pressure (CPAP) Contraindications
Asthma exacerbation
Suspected pneumothorax
Unprotected or unstable airway
Major trauma or burns to the head or torso
Tracheostomy
Inability to sit upright
Unable to cooperate
Continuous Positive Airway Pressure (CPAP) Treatment
Initial Setting: 5 cm H2O OR equivalent flow rate of device as per RBHP direction
Titration Increment: 2.5 cm H2O OR equivalent flow rate of device as per RBHP direction
Titration Interval: 5 min
Max. Setting: 15 cm H2O OR equivalent flow rate of device as per RBHP direction
Continuous Positive Airway Pressure (CPAP) Treatment FiO2
Consider increasing FiO2 (if available):
Initial FiO2: 50-100%
FiO2 Increment (if available on device): SpO3 <92% despite treatment and/or 10 cm H2O pressure or equivalent flow rate of device as per RBHP direction
Max. FiO2: 100%
What Beta Blockers Do
Beta blockers block the effects of epi and norepi (the body still sends them out but they block the effects of it). Someone on beta blockers may get dizzy when exercising because they aren’t getting enough blood/oxygen when they exercise/move because the beta blockers stop the heart from being able to pump fast which normally happens from epi and norepi.
Factors that Increase Heart Rate
Elevated body temp (fever)
Increased environmental temp (humidity)
Exercise
Smoking
Stress
Factors Affecting Heart Rate
Age (HR declines) (as you get older everything slows down)
Sex (faster in females)
Physical conditioning (slower with good conditioning)
Temperature (increases with temperature)
Blood levels of K+ (excessive decreases HR and contraction, low levels can lead to lethal rhythms)
Blood levels of CA++ ions (increased CA++ increases the HR and prolongs contraction)
Potassium is the most dangerous hormone that can affect your heart.
Properties of Cardiac Cells
- Contractility - ability to respond to an impulse by contracting
- Automaticity - ability to generate their own impulses
- Rhythmicity - regular impulse generation
- Conductivity - ability to transmit impulses to adjacent cells
- Refractory period - relaxation without response to another stimulation
Cardiac Output
The volume of blood ejected by a ventricle in one minute. Depends on the heart rate and stroke volume.
CO = HR * SV
SV is the volume pumped from one ventricle in one contraction.
Starlings Law
The more the muscle fibers are stretched, the greater their force of contraction - this is based on an increase in blood volume (like stretching and releasing an elastic).
Pacemaker Settings
SA Node: 60-100 bpm
Atrial Cells: 55-60 bpm
AV Node: 40-60 bpm
Bundle of His: 40-45 bpm
Bundle Branch: 40-45 bpm
Purkinje Fibers: 20-40 bpm
As you move down the pacemaker, the beat gets slower and slower.
Sinoatrial (SA) Node
Hearts natural pacemaker
Found in the upper part of the wall of the right atrium at its junction with the superior vena cava.
The further away the impulse is generated from the SA node the slower it becomes.
If the SA nodes fail to generate an impulse, the atrial cells will take over; pulse should always be started in the SA node.
Internodal Pathways
There are three main ones, then a bunch of other ones.
Main purpose: to transmit the pacing impulse from the SA node to the AV node.
Found in the walls of the right atrium and inter-atrial septum.
Three main pathways:
Anterior
Middle
Posterior
Bachmann Bundle
Small tract of specialized cells that transmits impulses through the inter-atrial septum, preferred path for electrical activity for left atrium. (Bundle branches and bachmann bundle are different; bachmann bundle goes off the SA node).
Atrioventricular (AV) Node
The AV node stops the pulse for a millisecond to make sure the pulse is good and what’s supposed to happen and the sends it down to the ventricle.
Controls heartrate (electrical relay station)
Slows down conduction from atria to ventricles long enough for atrial contraction - then allows the signal to pass into the ventricles.
Always supplied by right coronary artery.
The Bundle of His
Starts at the AV node.
Collection of heart muscle cells specialized for electrical conduction.
Found partially in right atrium, and interventricular septum.
Transmits impulses from the AV node to purkinje fibres, then to the ventricles.
The only route of communication between the atria and ventricles.
Left Bundle Branch (LBB)
Begins at the end of bundle of HIS.
Travels through interventricular septum.
First area to depolarize.
Right Bundle Branch (RBB)
Also starts at the bundle of HIS
Gives rise to fibers that innervate RV and right face of interventricular septum.
Terminates in the purkinje fibers.