EKG Study Guide Flashcards
What Is the QRS complex
-QRS complexes usually consist of several distinct waves, each of which has a letter assigned to it as a label. This labeling system is needed because the precise configuration of the QRS complex can vary from one lead to the next and from one patient to the next. Top establish a standardized labeling system, several guidelines have been developed. If the first deflection of the QRS complex is downward (neg) it is labeled a Q wave. The initial upward (positive) deflection is called an R wave.
-The first negative deflection following an R wave is called an S wave (Figure 11-6) If the QRS complex has a second positive deflection, it is labeled R (R prime), and if a second S wave is also present it is called S (S prime). A negative deflection can be called a Q wave only if it is the first wave of the complex. In clinical practice, each ventricular depolarization complex is called a QRS complex whether it has all three waves or not.
T wave
Ventricular repolarization is seen as the T wave. The T wave is normally upright and rounded.
U wave
Just after the T wave but before the next P wave, a small deflection known as the U wave is sometimes seen . the U wave is thought to represent the final [phase of ventricular repolarization. In most cases the U wave is not seen. The clinical significance of its presence or absence is not know
U wave could be due to Hypokalmia
Counting mV
-On The vertical axis, voltage, or amplitude, of the ECG waves is measured. The exact voltage of any ECG wave can be measured because the electrocardiogram is standardized so that 1 mV produces a deflection 10 mm in amplitude. Therefore, the standard for most ECG recordings is 1 mV= 10mm. Each small square represents 1 mm.
V1 lead
Fourth intercostal space, right srernal mirgin
V2 Lead
fourth intercostal space, left sternal margin
V3
Midway Between V2 and V4
V4
Fifth intercostal space, left midclavicular line
V5
Midway between V4 and V6
V6
Fifth Intercostal Space, left Midaxillary Line
Normal PR Interval
-The PR interval represents the time it takes for the electrical stimulus to spread through the atria and to pass through the AV junction. The normal PR interval is between .12 and .2 second (3 to 5 small boxed) If conduction of the impulse through the AV junction is abnormally delayed, the PR interval will exceed .2 second.
Normal P wave measurements
-The normal P wave is less than 2.5 mm in height and not more than .10 second in length.The PR interval is important regarding conduction time. The interval is measured from the beginning of the P wave, where the P wave lifts off the isoelectric line, to the beginning of the QRS complex.
What’s a normal Heart Rate
60-100 BPM
What is tachycardia
-At the other extreme, an increase in heart rate above 130 beats/min may compromise cardiac performance. This is because an abnormally rapid heart rate ( tachycardia) will increase myocardial oxygen demand, possibly to the point of inducing ischemia if the demand exceeds the supply.
Over 100 bpm
What is Bradycardia
A heart rate below 60 beats/min is referred to as an absolute bradycardia
-However, Bradycardia that may require intervention is relative to the individual PT. For example, a well conditioned runner may present with a heart rate of 50 beats/min with no sign of inadequate cardiac output. On the other hand, a person with poor myocardial contractility that presents with a heart rate of 50 beats/ min is likely to show signs of compromised perfusion or even cardiogenic shock in severe cases.
isoelectric baseline
-To measure the amplitude of a specific wave, the isoelectric baseline must be identified. This is the flat line seen just before the P wave or right after the T or U wave. Any movement of the ECG stylus above the line is considered positive, any downward movement is considered negative.To measure the degree of positive or negative amplitude of a specific wave, the isoelectric line is used as a reference point marking zero voltage.
What Does it mean to see a U line Betwen V2 and V4
Low Potassium, hypokalemia
Why is morphine given cardiac episode
It is a vasodilator
What does dysrhythmias mean
-Disturbances in cardiac conditions are called dysrhythmias. Dysrhythmias can occur even in healthy hearts. Often, minor dysrhythmias produce no symptoms and resolve without any treatment. More serious dysrhtymias indicate significant acute or chronic heart disease
-When serious dysrhythmias occur, medication or electrical therapy often is required to increase or decrease the ventricular rate or to suppress an irritable area within the myocardium. Occasionally surgical intervention or thrombolytic therapy is needed to prevent the progression of injury or infarct, thereby salvaging viable tissue
-the drug adenosine is given to reset the heart reset the heart rate
The normal ST segment is isoelectric
-The normal ST segment is isoelectric ( No positive charge or negative voltage) or at least does not move more than 1 mm above or below baseline. Certain pathologic abnormalities such as myocardial ischemia or injury, cause the ST segment to be elevated or depressed. The duration of the ST segment is not as important as its configuration
mV
-On The vertical axis, voltage, or amplitude, of the ECG waves is measured. The exact voltage of any ECG wave can be measured because the electrocardiogram is standardized so that 1 mV produces a deflection 10 mm in amplitude. Therefore, the standard for most ECG recordings is 1 mV= 10mm. Each small square represents 1 mm.
What does 30 large boxes on EKG Paper represent
6 seconds because .2* 30=6
The most accurate way to figure heart rate is as follows.
-The most accurate way to figure heart rate is as follows. Count the number of small boxes (.04) from R wave to the other R wave and divide that into 1500. If a PT has 10 small boxes from one R to the other R, then it would be as follows, 1500/ 10=150 beats per minute.
R waves are measured from?
-R waves are measured from isoelectric lines to the top of the R wave. Q and S waves are measured from the isoelectric line to the bottom of the wave. P waves can be either positive or negative and are also measured from the isoelectric line to the top (if positive) or bottom ( if negative) of the wave.
-In addition to the amplitude of any wave, the duration of waves, intervals, and segments can be measured. Segment is a straight line between two waves. An interval encompasses at least one wave plus the connecting straight line.
Interverval
line + wave
Segment
line between waves
12 lead
-An ECG (also called an EKG) is an indirect measurement of electrical activity within the heart. A recording of the electrical currents within the heart is obtained by placing electrodes containing a conductive media to each extremity and numerous locations on the chest wall to create a 12 lead ECG. Each specific). The purpose of using 12 leads is to obtain 12 different views of the electrical activity in the heart and therefore a more complete picture.
Bipolar leads
go from point to point and are labeled as I,II,and III (Triangle)
Unipolar lead
-Unipolar lead measure from electrode to center of the heart and are labeled as AVR,AVL, and AVF (Circle)
The right leg is used as a
Ground
lead I
the ECG machine temporarily designates the electrode on the left arm as a positive lead and the electrode on the right arm as negative.
Lead II
For lead 11, the right arm electrode remains negative and the left leg electrode is positive
Lead III
Lead Ill is created by making the left arm negative and the left leg positive.
limb leads (aVR, aVL, and aVF)
-The other three limb leads (aVR, aVL, and aVF) are called augmented leads because the ECG machine must amplify the tracings to get an adequate recording. The augmented leads are created by measuring the electrical voltage at one limb lead, with all other limb leads made negative.
