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53 Cards in this Set
- Front
- Back
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What is the P wave
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Produced as a result of atrial depolarization. Mechanical event of atrial contraction normally follows a fraction of a second after the P wave appears
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Describe the QRS complex
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Produced by ventricular depolarization. Composed of three different waves. Represents the electrical events associated with ventricular contraction (systole)
may not always possess all three waves |
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What produces the T wave
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Ventricular repolarization associated with ventricular relaxation (diastole)
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What is the PR interval
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the time required for the SA node impulse to reach the ventricles
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When is the PR interval measured
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From the beginning of the P wave to the next deflection, whether it is a Q or an R wave
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What is the average adult PR interval
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0.12 to 0.20 seconds
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What does a PR interval greater than 0.20 seconds represent
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Abnormally slow impulse conduction from atria to ventricles
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How long does the QRS complex last in an adult on average
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0.08 to 0.10 seconds
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What does the QRS width represent
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Ventricular depolarization time
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What is the J point
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The point of return at which the QRS complex returns to the baseline
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What is the ST segment
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The segment from the J point to the beginning of the T wave; represents the early phase of ventricular repolarization
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What are bipolar EKG leads
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Meet are composed of two opposite polarity electrodes (positive and negative)
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What is a unipolar lead
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A single positive electrode and its reference point
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The light vertical lines that form the small squares on EKG graph paper or if what measurement in regards to length and time
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they are one millimeter apart and represent 0.04 seconds at a standard sweet speed of 25 millimeters per second
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The heavy vertical lines are how far apart and represent what time length
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5 millimeters and 0. 20 seconds at standard recording speed
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Describe Einthoven's triangle
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1.Axis of lead one is from right arm which is negative to left arm which is positive 2. Axis of lead to is from right arm which is - to left foot which is positive 3. Axis of lead 3 is from left arm which is - to left foot which is positive
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Describe the three unipolar leads
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1. aVr 2. aVl 3. aVf
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What is the access of the unipolar lead
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A line drawn from the positive electrode to the hearts AV node
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Precordial leads consist of how many leaves and are placed where
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6 unipolar, v1 and v2 on either side of the sternum at the fourth intercostal space , v3 through v6 are placed on the left side of the chest at the fifth intercostal space
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Briefly describe a 12 lead EKG components
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Three bipolar limb leads, Three unipolar limb leads, and 6 precodial leads. 12 lead EKG allow for the hearts QRS sector to be viewed from 12 different points
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when does normal sinus rhythm occur
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When the sinus node initiate each depolarizing impulse at a rate of 60 to 100 beats per minute and each impulse is conducted normally through the atria and ventricles
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Define sinus tachycardia
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A heart rate in adults greater than 100 beats per minute
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What is the definition of sinus bradycardia
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A heart rate in adults of less than 60 beats per minute
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Define sinus arrhythmias
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Irregularly generated sinus node impulses all of which are normally conducted throughout the heart
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premature atrial contractions occur when what fires
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Ectopic foci
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PAC's also show a distinction in what complex
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QRS complex is a regularly spaced
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What do PAC's originate from
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Single or multiple ectopic foci in the atria
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Describe the P wave if the ectopic foci is near the S A node
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Appearance is normally positive (upright)
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When the ectopic foci is near the AV node what is the characteristic of the P wave
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It is negative (inverted) because the atria depolarize in a direction that is opposite from normal
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Hey supraventricular tachycardia is known as what
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Atrial flutter caused by a single ectopic pacemaker located above the AV node
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And atrial flutter is represented by what heart rate
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200 to 350 beats per minute
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What are characteristics of atrial flutter seen on EKG's
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The P waves are replaced by slaughter waves that look like sawtooth, flutter waves may precede, be buried in, or follow the QRS complexes or be superimposed on T waves and S T segment
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What is the cause of atrial fibrillation
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Uncordinated chaotic electrical discharge from numerous ectopic foci in the atria
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What is the rate for atrial fibrillation
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300 to 600 times per minute, the average is 400 times per minute
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What is a visual characteristic between flutters and the fibrillation
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flutter is organized, fibrillation is unorganized
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What are symptoms of atrial fibrillation
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Confusion, dizziness, hypotension, and fainting caused by reduction of cardiac output
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What is a major concern in atrial fibrillation
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Pooling of blood in the atria caused by lack of coordinated pumping action
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The stasis predisposes blood to what problem
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Formation of thrombus which can result in thromboembolism if clot breaks loose
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Depending on where a thrombus originates and breaks free depends on a potential problem. Describe conditions that persist from the left and right atrium
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Left atrium thromboembolism may cause blockage in the brain causing stroke, right atrium may plug vessels in the lungs causing a pulmonary embolism
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What are junctional arrhythmias
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Rhythms arising from the AV node and cardiac muscle immediately surrounding the AV node (AV junction), caused when the SA node fails to generate impulses
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Premature junctional contraction is caused by what
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An irritable ectopic foci and the junctional fibers, difficult to distinguish from a PAC, caused by a similar mechanism
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Junctional tachycardia is occur when
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When junctional fibre space to heart at rates greater than 100 beats per minute
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Premature ventricular contraction occurs when
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Initiated by an ectopic foci and the ventricles below the branching portion of the bundle of His. An abnormally irritable foci in the ventricle discharge before the next normal SA node impulse arrives
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who is affected by PVCs
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Normally healthy people after consumption of alcohol, caffeine, or tobacco use
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Characteristics of PVCs
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1. Premature occurrence 2. Shape differs from QRS complexes 3. They generate P waves of opposite polarity from normal 4. Why QRS complex 5. P waves are unrelated to the PVC. 6. There is a full compensatory pause after the PVC
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What is the difference between
unifocal and multifocal PVCs |
When there are two differently shaped PVCs. Multifocal have increased ventricular irritability therefore, have more serious clinical implications
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Describe ventricular tachycardia
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A successive series of PVCs occurring at a rate of 100 to 250 per minute, may occur in short bursts or be sustained more than 30 seconds, it is common in patients with myocardial infarction or coronary artery disease
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What is the most lethal of all cardiac arrhythmias
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Ventricular fibrillation due to multiple ectopic foci firing and unorganized and unsynchronized manners
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What is the only affective treatments for V Fib
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Defibrillation
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How are AV blocks categorized
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First, second, and third degree
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Describe first degree AV block
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All sinus node impulses are conducted to the ventricles, conduction time is slowed through the AV node bundle complex, slowed conduction is marked by an increase in the PR interval greater than 0.2 seconds. QRS are normal
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Describe second degree AV block
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Some but not all SA node and pulses are conducted to the ventricles, type 1 block PR intervals gradually length in until a QRS complex fails to appear after the P wave. Mobitz one or Wenckebach. Type to block the PR intervals are constant but very is conduction ratios. Mobitz 2. In both types of second-degree blocks the QRS complex is normal
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Describe third degree AV block
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Complete heart block, no SA node impulses are transmitted to the ventricles, no relationship exists between the P wave and the QRS complexes, the atria and ventricles are electrically isolated from one another. CPR is necessary
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