Lecture 12 (EKG)-Exam 6 Flashcards
What are the different wall layers of the heart muscle?
Epicardium
* Innermost layer of the pericardium & outer surface of the heart
Endocardium
* Lines the inside chambers of the heart & forms the surface of the valves
Subendocardium
* Layer of the cardiac muscle that becomes ischemic first during an MI
Myocardium
* Muscular tissue of the heart
I think this is low yield but it was under a slide
REVIEW EACH STRUCTURE AND WHAT THEY DO
* Superior & inferior vena cava
* Four chambers
* Pulmonary veins
* Pulmonary artery
* Aorta
* Septum
Low yield but under slide
Atrioventricular valves
* What are they? What do they do?
- Tricuspid valve - The tricuspid valve is on the right side of the heart. Itseparates the upper and lower chambers, also known as the right atrium and ventricle. The valve allows deoxygenated blood to flow through both of the chambers. The right ventricle pumps blood to the lungs, where it will be oxygenated.
- Bicuspid/Mitral valve- The mitral valve islocated between the upper left heart chamber (left atrium) and the lower left heart chamber (left ventricle). Controls blood flow from the atria to the ventricles. A healthy mitral valve keeps your blood moving in the right direction. A leaky valve doesn’t close the way it should, allowing some blood to flow backward into the left atrium
Low yield but under slide
Semilunar valves:
* What are they? What do they do?
- Aortic valve - The aortic valvehelps keep blood flowing in the correct direction through the heart. It separates the heart’s main pumping chamber (left ventricle) and the main artery that supplies oxygen-rich blood to your body (aorta).
- Pulmonary valve - the pulmonary valve isone of four valves that regulate blood flow in the heart. Controls blood flow out of the ventricles. The valve lies between the lower right heart chamber (right ventricle) and the pulmonary artery
Coronary Arteries:
* What do they supply?
* Where do they originate?
* Vessels run where?
* When blocked, what happens?
* What wall of the heart becomes ichemic first?
- Supplies blood flow to the cardiac muscle
- Originate from the aorta
- Vessels run both outside & inside the actual heart muscle
- When blocked, cardiac muscle cells normally fed by the artery become ischemic
- This is the beginning of an MI
- The interior wall of the heart (i.e., subendocardium) or inner most layer becomes ischemic first
- Left Coronary Artery (LCA): What does it involve?
- Left Anterior Descending Artery (LAD): What does it supply?
- Left Circumflex Branch (LCX): What does it supply?
- Right Coronary Artery (RCA): What does it supply?
Left Coronary Artery (LCA)
* Involves almost 2/3 of the heart muscle.
Left Anterior Descending Artery (LAD)
* The LAD supplies blood to the anterior portion of the left ventricle, apical including most of the anterior portion of the septum separating the ventricles.
* Bundle Branch Block, AMI, CHF
Left Circumflex Branch (LCX)
* The LCX supplies blood to the lateral portion and the posterior portion of the left ventricle.
Right Coronary Artery (RCA)
* The RCA supplies blood to the inferior & posterior portion of the left ventricle, as well as the posterior portion of the septum
* The RCA supplies blood to the right ventricle, right atrium, SA & AV nodes (regulates heart rate
- What does ischemia cause?
- What happens when Severe/complete blockage that last more than a short time?
- Alteration in current blood flow due to ischemia creates what on ECG?
ST depression on the ECG
12-Lead ECGs
* portion of the heart is affected by what?
* Look at what?
* What does it help point to?
- portion of the heart is affected by a coronary artery blockage
- look at the electrical current in the heart from different angles
- helps point what portion of the heart is affected by a coronary artery blockage creating ischemia andwhat artery is blocked
What is the Blood flow of the CV system?
Cardiac Cycle
* What is it?
* Expressed as what?
- Electrical or physical sequence of events that encompasses a full depolarization (CONTRACTION) & repolarization (RELAXATION). Ventricular contraction to ventricular contraction.
- Expressed as beats per minute (BPM) or your heart rate
- What is systole?
- What is diastole?
- Fill in
- Where does Repolarization of atria happen?
Repolarization of atria happens during QRS complex and therefore cannot be evaluated
What is stroke volume? What is the normal stroke volume?
- Volume of blood being pumped out of the ventricles in a single beat or contraction.
- Normal stroke volume is 60 – 130 mL
Cardiac output (CO)
* What is it?
* What is the normal value?
* How do you calulate it?
- Amount of blood pumped by the left ventricle in one minute
- Normal cardiac output is 4 – 8 L/min
- Stroke Volume (SV) x Heart Rate (HR) = Cardiac Output (CO)
he said FYI
What happens during depolarization?
- Myocardial cells are bathed in electrolyte solution
- Chemical pumps maintain the concentrations of ions within the cell
- The cell interior receives stimulus from conduction and become positive
- Depolarization spreads, causing a mechanical contraction
What happens during repolarization?
- Closing of the sodium & calcium channels
- Cell interior restores the negative charge
- Sodium-potassium pump reestablishes proper distribution
- Refractory period
* Absolute refractory period
* Relative refractory period
Know
What is phase 0?
Cell depolarizes and begins to contract – QRS Complex
Know
What is phase 1
Phase 1: Cell begins to repolarize
know
What is phase 2
Phase 2: Na+ and Ca++ enter the cell; K+ flows out – ST Segment to downslope of T wave (absolute refractory)
know
What is phase 3
Final phase of repolarization –downslope of T Wave (relative refractory)
What is phase 4
Phase 4: Resting phase.
Contraction follows what?
follows depolarization and relaxation follows repolarization
know
Refractory Periods
* What is it?
* What are the two period?
It is the period in which the cell is depolarized or in the process or repolarizing and consists of two separate phases:
- Absolute refractory period – ventricles have not repolarized enough to enable another depolarization - the QRS complex to the downslope of the T Wave (i.e. systole)
- Relative refractory period – some cells have repolarized enough to depolarize again if strong enough stimulus is provided – downslope of T wave
SA node:
* What is the bpm?
* Recieves blood from what?
Internodal pathway:
* What is this?
* Depolarization of what?
* Creates what?
Sinoatrial node (SA)
* Natural dominant pacemaker, rate 60-100 bpm
* Receives blood from the RCA
Internodal Pathway
* Electrical path from SA nodeto AV node
* Depolarization of the atria
* Creates the contraction of the Atria, known as the P-wave
Atrioventricular node (AV)
* What is this/what is the bpm?
* What happens to the conduction?
* Site where what?
Atrioventricular bundle (Bundle of His)
* Where is it located?
* Location of what?
AV node
* Secondary pacemaker,rate 40-60 bpm
* Conduction delayed to allow atria to empty into the ventricles
* Site where the heart blocks occur and if atrial rate is too fast,not all signals will pass
Bundle of His:
* Located in the septum
* Location of the right and left bundle branches
Purkinje fibers
* What are they?
Both Bundle of His &Purkinje fibers
* What do they produce?
Purkinje fibers
* Electrical fibers that surroundthe ventricles & produce the ventricle contraction/depolarization of ventricles,known as the QRS
Both Bundle of His &Purkinje fibers
* Produce spontaneous action potential if the SA & AV nodes fail, rate 20-40 bpm as a backup measure to ensure blood is continually pumped
He said FYI
Conduction pathways that allow current tobypass AV node:
* Where are the james fibers?
* Where are the mahaim fibers?
* The Bundle of Kent enables what?
If the SA node is damaged or suppressed, what happens?
If the SA node is damaged or suppressed, other components in the conduction system that can maintain a heart rate and will become the site of origin of the rhythm.
What are the different bpm of the pacemarkers?
Electrocardiogram
* What is it?
* What can it be used for? (3)
Electrocardiogram - Leads
* Three standard limb leads which consist of what?
* Which lead is the most helpful?
* There are what?
* Each lead creates what?
* The leads are placed how?
Limb leads
* known as standard limb leads consist of what?
* Which leads view the heart from thefront of thebody?
* leads aVR, aVL and aVF are called what?
- known as standard limb leads consist of Leads I, II and III.
- leads I, II and III view the heart from thefront of thebody.
- leads aVR, aVL and aVF are called augmented limb leads, with only one true pole, other is a combinationof information from the other leads
Precordial leads
* known as what?
* Identified as what?
* these leads view what?
- known as chest leads
- identified as V1, V2, V3, V4, V5 and V6
- these leads view the heart from the front and the left side.
Limb leads
* Heart emits what?
* This electrical activity can be represented by what?
* Where is lead 1, 2, 3 placed?
- Heart emits electrical activity with each contraction
- This electrical activity can be represented by what we identify as the P, Q, R, S, and T waves on ECG’s
- Lead I is between to the right and left arms
- Lead II is between right arm and left leg
- Lead III is between left arm and left leg
Augmented Leads
* What is avr, avf, acl?
* Same locations as what?
* What is not needed?
* These sixleads record electrical activity along a single plane, termed what?
- aVR, faces the heart from the right side, all deflections P, QRS and T are normally negative in this lead.
- aVF, augmented left leg lead, oriented to the inferior portion of the heart.
- aVL, faces the heart from the left side and is oriented to the anterolateral surface of the left ventricle.
- Same locations as leads I, II and III.
- No switching of electrodes needed as the ECG recorder does the actual switching and rearranging of electrode designations.
- These sixleads record electrical activity along a single plane, termed thefrontal planerelative to the heart.
For continuous monitoring:
* Where does the white, black, red, green leads go?
12 lead:
* Where does the white, black, red, green leads go?
For continuous monitoring:
* White—right upper chest near shoulder
* Black—left upper chest near shoulder
* Red—left lower abdomen
* Green—right lower abdomen (ground)
For 12-lead ECG:
* White—right wrist
* Black—left wrist
* Red—left ankle
* Green—right ankle
Precordial Leads
* Depict the heart in what plane?
* Representedas what?
* What does Leads V1 and V2 view?
* Leads V3 and V4 looks at what?
* Leads V5 and V6 view what?
- Depict the heart in the horizontal plane
- Representedas V1, V2, V3, V4, V5 and V6
- Leads V1 and V2 view the septum
- Leads V3 and V4 look at anterior wall of the left ventricle
- Leads V5 and V6 view the lateral wall of the left ventricle
Correct and consistent placement of leads is essential to accurate ECG readings
* Where does V1,2,3,4,5,6 go on the body?
- V1 - fourth intercostal space (ICS) to right of the sternum – looks at right ventricle
- V2 – fourth ICS to the left of the sternum
- V3 – directly between leads V2 and V4
- V4 – fifth ICS at the left midclavicular line
- V5 – at level of V4 at left anterior axillary line
- V6 – at level of V4 at midaxillary line
Contiguous Leads
Which leads are lateral, inferior, septal and anterior?
Electrocardiogram – ECG Concepts
- ECG baseline is what? What is it also called?
- Electrical activity that moves toward a positive electrode will show as what?
- Electrical activity that moves in the direction of a negative electrode will show as what?
- ECG baseline is a flat, horizontal line that represents no electrical activity-> Sometimes called the isoelectric line
- Electrical activity that moves toward a positive electrode will show as a deflection ABOVE the baseline.
- Electrical activity that moves in the direction of a negative electrode will show as a deflection BELOW the baseline.
Electrocardiogram – ECG Paper
* One small box is what is seconds?
* One LARGE box, consisting of five small box equals what?
* Vertical axis represents what?
* Calibration box is printed when?
- One SMALL 1 – mm box equals 0.04 seconds.
- One LARGE box, consisting of five small box equals 0.20 seconds.
- Vertical axis represents the amplitude.
- Calibration box is printed the beginning of 12 Lead ECG’s, standardis 10 millimeters per millivolt.
KNOW
Intervals
* What is normal secs for PR, QRS, QTc?
- PR -3-5 small boxes or0.12 – 0.20 seconds.
- QRS -2-3 small boxes or0.08 – 0.12 seconds.
- QTc – 10-11.5 small boxes or 0.35-0.45 (men) and 0.36-0.46 (women)
The 6-second Method
* Can be used for what?
* What do you count?
- Fastest way to measure heart rates
- Can be used for regular or irregular rhythms but best for irregular rhythms.
- Count the number of QRS complexes in a six second strip.
Sequence Method
* Can also be used when?
* What is the sequence?
* How do you do it?
- Can only be used when rhythm is regular.
- Must memorize the following sequence: 300, 150,100, 75, 60.
- Find an “R” wave on a heavy line and count off 300,150, 100, 75,60 for each large box you land on until you reach the next “R”wave.
Electrical conduction events on an ECG consist of a series of what?
- Waves
- Segments
- Intervals
- Complexes
P wave
* What is it?
* What is the shape?
* What is the normal duration?
- first wave of an ECG complex
- represents atrial depolarization
- smooth, round, upright shape
- normal duration of a P wave is less than 0.11 seconds.
What does a notched p wave mean?
wide (enlarged) or biphasic P waves may be seen in increased left/right atrial pressure and left/right atrial dilation
- What does the The first 1/3 of the P wave correspond to? Middle? final?
- What is biphasic?
- The first 1/3 of the P wave corresponds to right atrial activation, the final 1/3 corresponds to left atrial activation; the middle 1/3 is a combination of the two
- If V1 P is biphasic, which part of wave is bigger (1st or 2nd)? If 1st, consider RAE, If 2nd, consider LAE
Inverted P waves
* Produced when a P’ wave arises from
* Results in what?
* May immediately proceed, occurs when?
* Associated with dysrhythmias that originate from what?
- Produced when a P’ wave arises from the lower right atrium near the AV node, in the left atria or the AV junction
- Results in retrograde depolarization of the atria
- May immediately proceed, occur during or follow the QRS complex
- Associated with dysrhythmias that originate from the AV junction
PR Interval (PRI)
* What is it?
* Measures what?
* What is the normal range?
* When does shorter PR happen? Longer?
* What does varible PR mean?
- distance from beginning of P wave to beginning of QRS complex.
- measures time from start of atrial depolarization to start of ventricular depolarization.
- normal range is 0.12 to 0.20 seconds.
- Shorter P’R intervals occur when the impulse originates in the atria close to the AV junction or in the AV junction (Preexcitation)
- Longer P’R intervals occur when there is a delay in impulse conduction through the AV node
- Variable PR – Wandering atrial pacemaker
QRS complex
* What does it represent?
* Greater than what?
* Duration?
* Abnormal when?
* From beginning of Q wave to what?
* What is a normal variant?
* Indicates what?
QRS complex
* Q wave is what?
* R wave is what?
* S wave is what?
* R and S waves represent what?
- Q wave is the first negative deflection and if greater than 0.04 seconds wide or deeper than 1/3 the height
- R wave is the first upward deflection
- S wave is the downward deflection after the R wave
- R and S waves represent depolarization of the right and left ventricles
What is this called?
qs wave. Note that q and s waves are utilized with a lower case indicating pathology.Injured regions of the heart may become electrically inactive. Myocardial infarction is the most frequent cause of this.
- If there is no R wave, the complex is called what?
- If there is no Q wave, the complex is called what?
- While there is only one Q wave there can be more what?
- If there is no R wave, the complex is called a QS complex
- If there is no Q wave, the complex is called an RS complex
- While there is only one Q wave there can be more than one R and S wave
J point
* What is it?
* Often becomes depressed or elevated with what?
* May represent beginning of what?
* J point identification will help you to what?
- Where ST segment takes off from the QRS complex
- Often becomes depressed or elevated with ischemia and is usually the point to look for
- May represent beginning of repolarization
- J point identification will help you to determine ST segment changes
ST Segment
* What is it?
* Indicated what?
* ST elevation may indicate what?
* ST depression may indicate what?
* Difference between injury and ischemia is what?
- Straight line connecting end of the QRS complex with beginning of T wave.
- Indicates end of ventricular depolarization and start of ventricular repolarization.
- ST elevation may indicate myocardial injury or ischemia.
- ST depression may indicate myocardial ischemia.
- Difference between injury and ischemia is based on time.
What is ischemia, injury and infactions?
- Ischemia:Reduction of myocardial oxygen for less than 20 minutes. The damage is reversible. In the electrocardiogram, ischemia produceschanges in T wave.
- Injury:Persistence of oxygen deficiency (more than 20 min). Damage is still reversible. Injury is characterized byST-segment abnormalities.
- Infarction:Persistence of oxygen deficiency for more than two hours. Damage is irreversible. Infarction is characterized bypathological Q waveson the electrocardiogram.
T wave
* What is it?
* Broader than what?
* What is the shape?
* Large T waves are associated with what?
* Tall pointed T waves may be associated what?
* T wave inversion can be secondary to what?
- Represent ventricular repolarization
- Broader then the QRS complex
- Simpler and more rounded because repolarization is much slower than ventricular depolarization
- Large T waves are associated with myocardial ischemia, injury and infarction
- Tall pointed T waves may be associated with hyperkalemia
- T wave inversion can be secondary to ischemia, CNS events of just normal finding