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EKG PASS 573

QuestionAnswer
What are the 3 layers of the heart wall? Epicardium, Myocardium, and Endocardium
What are the two basic cell types of the heart? Myocardial and Conducting cells
Myocardial cells are surrounded by what kind of membrane? Sarcolemma
What is the name of the special contact points where myocardial cells connect? Intercalated disks
What holds the myocardial cells together during contraction? Desmosomes
How do myocardial cells contract when stimulated? As a single unit
What is the name of the contraction phase of the cardiac cycle? Systole
What is the name of the relaxation phase of the cardiac cycle? Diastole
Where are the 4 locations in which receptors that monitor cardiac output are found? Blood vessels, kidneys, brain, heart
What 4 methods regulate the heart? Brain, hormones, heart tissue, and receptors monitoring cardiac output
What is the name and locations of receptors that detect changes in pressure in the heart and main arteries? Baroreceptors- found in the aorta and carotid arteries
What is the name for the receptors that detect changes in chemical composition of the blood? Chemoreceptors
Which 2 neurotransmitters are released by the sympathetic nervous system, and what are their effects on the heart when released? Norepinephrine and epinephrine; they increase heart rate, increase force of contraction, increase conduction through the heart, and cause coronary vasodilation
What is the mechanism of action, neurotransmitter, and effects on the heart of the parasympathetic nervous system? The vagus nerve releases acetylcholine, which slows the heart rate (via SA node) and electrical conduction
What are 4 key properties of myocardial cells? Automaticity, excitability, conductivity, and contractility
The ability of certain cells to produce an electrical impulse without outside nerve stimulation is the definition of what key property of myocardial cells? Automaticity
The ability to respond to an electrical stimulus is the definition of what key property of myocardial cells? Excitability
The ability to transmit an electrical stimulus from cell to cell is the definition of what key property of myocardial cells? Conductivity
The ability to contract when electrically stimulated is the definition of what key property of myocardial cells? Contractility
What 2 types of cells are specialized to generate and transmit electrical impulses throughout the myocardium? Pacemaker and Electrical conducting cells
Which cell type in the conductive pathway has the ability to spontaneously generate an impulse at a certain rate? Pacemaker cells
What cell type in the conductive pathway carries the electrical impulses to the appropriate regions of the heart? Electrical conducting cells
Which bundle of cells act as the heart's primary pacemaker? Sinoatrial node
What is the intrinsic rate/normal sinus rhythm of the sinoatrial node? 60-100 bpm
Which bundle of cells in the heart act as the pathway for impulses to reach the ventricles? Atrioventricular node
Where in the heart is the sinoatrial node located? High in the posterior right atrium
Where in the heart is the atrioventricular node located? Low right atrium
What is the intrinsic rate of the atrioventricular node? 40-60 bpm
Which bundle of cells in the heart act as a gatekeeper? The atrioventricular node
What is the flow of electrical activity through the heart? SA node -> AV node -> Bundle of His -> R&L Bundle branches (L. bundle branch branches into anterior and posterior fascicles) -> Purkinje fibers
What is the intrinsic rate of the purkinje fibers? 20-40 bpm
In a polarized/resting state, negatively charged ions are found where in reference to the myocardial cell? Inside the cell
In a polarized/resting state, positively charged ions are found where in reference to the myocardial cell? Outside the cell
What happens during depolarization of myocardial cells? Positive Na ions enter the cell
What happens during repolarization of myocardial cells? Positive Na, Ca, and K ions leave the cell
What is the name for the time after depolarization when the cell becomes resistant to further depolarization? Absolute refractory period
What is the name for the late phase of repolarization in which a very strong electrical stimulus causes depolarization? Relative refractory period
How are bipolar limb leads numbered? I, II, III, etc.
How are unipolar limb leads numbered? V1-V6 for chest/precordial leads; aVR, aVL, or aVF for augmented limb leads
Electrical impulses moving in what direction cause an upright wave/tracing on the EKG? Toward a positive electrode
Electrical impulses moving in what direction cause a negative deflection/below baseline on the EKG? Toward a negative electrode
Many small electrical currents in various directions is the definition of what? Vectors
The overall direction of the sum of the currents (vectors) is the definition of what? Axis
Which leads are in the frontal plane? Limb leads I, II, and III, and aVR, aVF
Which leads are in the horizontal plane? Precordial chest leads V1-V6
The P wave represents what electrical activity in the heart? Atrial depolarization
The QRS complex represents what electrical activity in the heart? Ventricular depolarization
The T wave represents what electrical activity in the heart? Ventricular repolarization
Which electrical activity in the heart is hidden and by what wave? Atrial repolarization is hidden by the QRS complex
What length of time does each small square on an EKG paper represent? 0.04 seconds
What length of time does 5 small squares on EKG paper represent? 0.20 seconds
What is the name of the flat line that occurs either when no electrical activity is occurring, or when electrical impulses are too weak to be detected? Isoelectric line
What is the normal duration of the P wave? 0.06-0.10 seconds
What is the starting and ending point for measuring the PR interval? Start measuring at the beginning of the P wave, end measuring at the end of the QRS complex
What is the normal duration of the PR Interval? 0.12-0.20 seconds
What is the starting and ending point for measuring the PR segment? The PR segment is the isoelectric line between the end of the P wave and the beginning of the QRS complex
What is the normal duration of the QRS complex? 0.06-0.11 seconds
What is the starting and ending point of the ST segment? The ST segment is the isoelectric line that begins at the end of the QRS complex, and ends at the beginning of the T wave
What is the name given for the point where the QRS complex meets the ST segment? The J point
What is the starting and ending point of the QT Interval? The QT Interval begins at the beginning of the QRS complex and ends at the end of the T wave
What electrical activity of the heart is represented by the QT Interval? The time of ventricular depolarization and repolarization
What is the normal duration of the QT Interval? 0.36-0.44 seconds
What is the term given for markings on an EKG that are not a product of the heart's electrical activity? Artifact
Where are the positive and negative electrode placings in the bipolar lead I? Positive on the left arm, negative on the right arm
Where are the positive and negative electrode placings in the bipolar lead II? Positive on the left leg, negative on the right arm
Where are the positive and negative electrode placings in the bipolar lead III? Positive on the left leg, negative on the left arm
Which limb has two negative bipolar electrodes? The right arm
Which limb has two positive bipolar electrodes? The left leg
Which limb does the positive electrode of aVR attach to? The right arm
Which view of the heart does the aVR lead represent? The base of the heart: the atria and great vessels
Which lead gives a base view of the heart: the atria and great vessels? aVR
Which limb does the positive electrode of aVL attach to? Left arm
Which view of the heart does the aVL lead represent? The lateral wall of the left ventricle
Which lead gives a view of the lateral wall of the left ventricle? aVL
Which limb does the positive electrode of aVF attach to? Left leg
Which view of the heart does the aVF lead represent? The inferior wall of the left ventricle
Which lead gives a view of the inferior wall of the left ventricle? aVF
Where is the precordial V1 lead placed on the chest? In the 4th ICS on the right of the sternum
Where is the precordial V2 lead placed on the chest? In the 4th ICS on the left of the sternum
Where is the precordial V3 lead placed on the chest? Halfway between V2 and V4
Where is the precordial V4 lead placed on the chest? In the 5th ICS in Mid-clavicular line
Where is the precordial V5 lead placed on the chest? At the anterior axillary line
Where is the precordial V6 lead placed on the chest? Mid-axillary line
Which leads provide anterior and lateral views of the heart? Precordial leads V1-V6
Which leads provide information about the anterior surface of the heart? V1-V4
Which leads provide information about the lateral surface of the heart? I, aVL, and V5-V6
Which leads provide information about the inferior surface of the heart? II, III, and aVF
What characteristics of a P wave constitute normal sinus rhythm? P waves are upright, round, and one is present before each QRS complex
What characteristics of a QRS complex constitute a normal sinus rhythm? QRS complexes are narrow, and are 0.06-0.11 seconds in duration
What are the 3 methods available for determining heart rate? Multiply the number of QRS complexes in a 6-second interval by 10; start 300 150 100 75 60 50 large boxes between R waves; 1500/the number of small squares between 2 consecutive R waves
When is a person considered to have bradycardia? Heart rate <60 bpm
When is a person considered to have tachycardia? Heart rate >100 bpm
What constitutes a regular rhythm? The distance between RR-intervals is the same, and the distance between P-P intervals is the same
What 7 types of irregular rhythm are there? Occasionally irregular, very irregular, slightly irregular, sudden heart rate acceleration, patterned irregularity, total irregularity (irregularly irregular), and variable conduction ratio
What is an explanation of occasionally irregular heart rhythm? Rhythm is mostly regular, but can be irregular from time to time
What is an explanation of very irregular heart rhythm? There are many areas of irregularity
What is an explanation of a slightly irregular heart rhythm? Pacemaker changes locations = wandering atrial pacemaker. P waves look different (some are smaller, some are inverted, etc.)
What rhythm is seen with a wandering atrial pacemaker? Slightly irregular rhythm
What is an explanation of a sudden heart rate acceleration rhythm irregularity? A normal heart rate suddenly accelerates to tachycardia = paroxysmal tachycardia
What rhythm irregularity is seen with paroxysmal tachycardia? Sudden heart rate acceleration
What is an explanation of a patterned irregularity heart rhythm? Irregularity is repeated in a cyclic fashion
Which rhythm irregularity is seen with sinus dysrhythmia, breathing, or 2nd degree A-V heart block? Patterned irregularity
What is an explanation of a totally irregular/irregularly irregular rhythm? No pattern to the irregularity
Which rhythm irregularity is seen with atrial fibrillation? Irregularly irregular
What is the normal duration and amplitude of a P wave? Duration 0.06-0.10 seconds, Amplitude 0.5-2.5 mm/small boxes
What is the name for a tall P wave (greater than 2.5 mm/small boxes high), and what might it indicate? P pulmonale suggests RAE
What 2 possible heart conditions might be represented by a notched, wide, or biphasic P wave? Increased left atrial pressure or left atrial dilation
What is the name for a wide P wave (greater than 0.10 seconds), and what condition might it indicate? P mitrale suggests LAE
What might the P wave look like in atial tachycardia? It might be buried in the T wave
A saw-toothed pattern between QRS complexes could indicate what condition? Atrial flutter- an ectopic site in the atria fires at 250-300 times per minute
When does atrial fibrillation occur? When ectopic sites in the atria fire faster than 350 times per minute
What is the physiological explanation behind an inverted P wave? Results when a P wave arises from the lower right atrium near the AV node, in the left atrium, or the AV junction
What condition is associated with inverted P waves? Dysrrhythmias originating from the AV junction
What is the explanation for the presence of more P waves than QRS complexes? The pulse was initiated in the SA node or atria, but was blocked before reaching the ventricles
Tall QRS complexes indicate what 3 possible heart conditions? Ventricle(s) hypertrophy, abnormal pacemaker, or aberrant conduction
Short/Low-voltage QRS complexes indicate what 3 possible conditions? Obesity, hypothyroidism, pericardial effusion
Wide, bizarre QRS complexes may be explained by what condition? Right or left bundle branch block resulting from a defect in ventricular conduction
What is the explanation for the wide QRS complex seen in aberrant conduction? An electrical impulse reaches the bundle branch while it is still in a refractory period after a previous impulse. The new impulse travels down
When does atrial fibrillation occur? When ectopic sites in the atria fire faster than 350 times per minute
What is the physiological explanation behind an inverted P wave? Results when a P wave arises from the lower right atrium near the AV node, in the left atrium, or the AV junction
What condition is associated with inverted P waves? Dysrrhythmias originating from the AV junction
What is the explanation for the presence of more P waves than QRS complexes? The pulse was initiated in the SA node or atria, but was blocked before reaching the ventricles
Tall QRS complexes indicate what 3 possible heart conditions? Ventricle(s) hypertrophy, abnormal pacemaker, or aberrant conduction
Short/Low-voltage QRS complexes indicate what 3 possible conditions? Obesity, hypothyroidism, pericardial effusion
Wide, bizarre QRS complexes may be explained by what condition? Right or left bundle branch block resulting from a defect in ventricular conduction
What is the explanation for the wide QRS complex seen in aberrant conduction? An electrical impulse reaches the bundle branch while it is still in a refractory period after a previous impulse. The new impulse travels down the non-refractory bundle branch, and then down the other bundle branch. Separate impulses = wide QRS complex
What 4 conditions would label the PR interval as abnormal? Shorter than 0.12 seconds, longer than 0.20 seconds, absent interval, or interval duration varies
What is the explanation for a short PR Interval? Electrical impulses start from a supraventricular site, but travels to the ventricles via abnormal accessory pathways and causes premature ventricular depolarization = preexcitation
What is the explanation for a long PR interval? Conduction of electrical impulse through the AV node is delayed = 1st degree AV heart block
What 2 conditions may cause varying PR intervals? Wandering atrial pacemaker or 2nd degree AV heart block
What is the varying PR interval pattern seen with 2nd degree AV heart block? PR intervals are progressively longer until a QRS complex is dropped. Repeat.
In what 4 conditions are PR intervals absent? Atrial flutter, atrial fibrillation, 3rd degree AV heart block, and ventricular dysrhythmias
What is the explanation for absent PR intervals in 3rd degree AV heart block? Atria and ventricles are beating independently of each other
What is the characteristic of sinus bradycardia? Normal sinus rhythm with heart rate <60 bpm
What is the characteristic of sinus tachycardia? Normal sinus rhythm with heart rate >100 bpm
What problem with oxygen is associated with tachycardia? Tachycardia can increase oxygen requirements = worsen ischemia, induce infarction
Describe the pattern seen with sinus dysrhythmia. Dysrhythmia is cyclic: slows down, then speeds up with breathing
What 3 conditions might sinus dysrhythmia be normal in? Athletes, children, or older adults
Describe the pattern seen with sinus arrest. A pause in EKG rhythm occurs (isoelectric), normal rhythm resumes
What 3 mechanisms can cause atrial dysrhythmias? Automaticity, triggered activity, and reentry
What key characteristics are seen with atrial dysrhythmias? Abnormal P waves that differ in appearance with each beat, varying PR intervals, narrow-normal QRS complexes
What pattern is seen with premature atrial contraction? Abnormal P-waves, followed by a non-compensatory pause, and wide QRS complexes
What characteristics are seen with atrial tachycardia? Abnormal, consistent P waves with a heart rate of 150-250 bpm
What is the term for short bursts of atrial tachycardia? Paroxysmal atrial tachycardia
What characteristics are seen with multifocal atrial tachycardia? Changing P wave morphology, irregular rhythm, and a heart rate of 120-150 bpm
What characteristics are seen with supraventricular tachycardia? Tachycardia with no P waves
What is the heart rate seen with atrial flutter? 250-350 bpm
What are 2 potential side effects of atrial fibrillation? Decreased cardiac output by 25%, clots form in the atria due to blood stagnating from inefficient atrial contraction... predispose pt. to a systemic emboli
What characteristics are seen with junctional dysrhythmias? Inverted or absent P waves, short PR interval if P waves present, P wave after QRS complex
What characteristics are seen with premature junctional complex? An early electrical impulse and an inverted P wave
Where does the electrical impulse come from with premature junctional complex? AV junction
What characteristics are seen with junctional escape rhythm? Inverted P wave before, during, or after QRS complexes, heart rate of 40-60 bpm, short PR interval
What characteristics are seen with accelerated junctional rhythm? Inverted P waves before, during, or after QRS complexes, short PR interval, heart rate of 60-100 bpm
What characteristics are seen with junctional tachycardia? Inverted P waves before, during, or after QRS complexes, short PR interval, heart rate of 100-180 bpm
Created by: mccullough87