Electrocardiography and Rhythm Interpretation

Flashcards covering stress testing protocols, 12-lead ECG electrode placement and operation, rhythm strip interpretation criteria, sinus rhythms, atrial dysrhythmias, and junctional dysrhythmias.

What are the common alternative names for exercise electrocardiography?

Exercise tolerance test, treadmill stress test, cardiac stress test, stress ECG, and exercise treadmill test.

Why is exercise electrocardiography classified as a noninvasive procedure?

It does not require entrance into a body cavity, tissue, or blood vessel.

For what underlying suspected disease is an exercise treadmill stress test typically performed?

Coronary vascular disease (where narrowed or obstructed arteries alter the ECG tracing, specifically the ST segment).

How does a pharmacologic stress test differ from a standard exercise treadmill stress test?

It is performed on patients unable to exercise by administering cardioactive medications that stimulate the heart to exercise artificially.

What specific substance and dietary restrictions must a patient observe prior to exercise electrocardiography?

No smoking, alcohol, or caffeine for $3\text{ hours}$ prior, and no eating for $2\text{ hours}$ prior to the test.

Which resting conditions serve as contraindications to performing an exercise electrocardiogram?

A change in the resting ECG, dysrhythmia, pericarditis, myocarditis, uncontrolled hypertension, severe aortic stenosis, aneurysm, embolism, or congestive heart failure.

How do the stages and intensity adjustments differ between the Bruce and Naughton stress testing protocols?

The Bruce protocol utilizes $3\text{-minute}$ stages increasing treadmill speed and grade; the Naughton protocol is designed for sicker patients with a constant speed of $2\,\text{mph}$ across $2\text{-minute}$ stages.

What is the formula used to calculate a patient's Target Heart Rate (THR) during a stress test?

$\text{THR} = (220 - \text{patient's age}) \times (60\text{--}85\%)$ (with the percentage determined by the specific protocol).

How long must a patient be monitored in the cooling-off period following an exercise ECG?

$10\text{ to }15\text{ minutes}$.

Which anatomical landmarks correspond to the highlighted points on the thoracic cage used for chest lead placement?

The clavicle, suprasternal notch, manubrium, Angle of Louis, sternum, and the 4th and 5th intercostal spaces.

Where are precordial electrodes $V_1$ through $V_6$ positioned on the chest wall?

$V_1$: 4th ICS at right sternal border; $V_2$: 4th ICS at left sternal border; $V_3$: midway between $V_2$ and $V_4$; $V_4$: 5th ICS at left midclavicular line; $V_5$: 5th ICS at left anterior axillary line; $V_6$: 5th ICS at left midaxillary line.

According to standard mnemonic conventions, what color lead wires connect to the right arm, left arm, right leg, and left leg?

Right Arm (RA) is white ('Salt'), Left Arm (LA) is black ('Pepper'), Right Leg (RL) is green ('Lettuce'), and Left Leg (LL) is red ('Tomato').

In which directions should the tabs of chest and limb electrodes be oriented when applying lead wires?

Chest and arm electrode tabs must point toward the feet; leg electrode tabs must point toward the hands.

What proper lead wire routing practice is illustrated in the correct diagram on the left compared to the right?

Avoid looping lead wires outside the body and verify there is no tension pulling on wires or electrodes.

What type of ECG artifact is demonstrated in this tracing, and what produces it?

Somatic tremor, characterized by large, irregular spikes caused by patient muscle movement.

What distinguishes alternating current (AC) interference from a wandering baseline on an ECG strip?

AC interference presents as small, uniform spikes caused by radiated electrical currents; a wandering baseline consists of shifts in the baseline level caused by improper electrode contact or movement.

Where should the precordial leads be repositioned when recording an ECG on a patient with dextrocardia?

Leads are reversed to the right side of the chest: $V_1R$ through $V_6R$ ($V_4R$ at 5th ICS right midclavicular line, $V_3R$ between $V_1$ and $V_4R$, $V_5R$ right anterior axillary, $V_6R$ right midaxillary).

Where are posterior electrodes $V_7$, $V_8$, and $V_9$ placed during a 15- or 18-lead ECG?

$V_7$: left posterior axillary line; $V_8$: under the left midscapular line; $V_9$: left paraspinal border.

What action should the healthcare professional take if a patient experiences a seizure during an ECG recording?

Stay with the patient, protect them from injury, call for help, and report the seizure; perform the ECG after the seizure ends and label the tracing 'Post Seizure'.

What are the five systematic steps required to analyze an ECG rhythm strip?

Step 1: Rhythm (regularity); Step 2: Heart rate; Step 3: P wave morphology; Step 4: PR interval; Step 5: QRS duration.

What device is shown being used to measure the regularity of intervals on this rhythm strip?

ECG calipers.

What criteria distinguish a regular ECG rhythm from an irregular rhythm during Step 1 analysis?

A rhythm is regular if the $R\text{-}R$ (or $P\text{-}P$) intervals vary by $1\frac{1}{2}\text{ small boxes}$ or less; it is irregular if intervals vary by $2\text{ or more small boxes}$.

How are heart rates calculated using the 1500 method versus the 6-second method?

The 1500 method divides $1500$ by the number of small boxes between identical wave points ($P\text{-}P$ for atrial, $R\text{-}R$ for ventricular); the 6-second method multiplies the total number of complete complexes in a $6\text{-second}$ strip by $10$.

What are the measurement boundaries and normal duration range of the PR interval?

Measured from the start of the P wave to the beginning of the QRS complex, with a normal range of $0.12\text{ to }0.20\text{ second}$.

What structural landmark on the ECG complex marks the end of the QRS duration measurement?

The J point (the junction where the QRS complex ends and the ST segment begins).

What are the classification criteria for Normal Sinus Rhythm (SR)?

Regular rhythm originating from the SA node; rate $60\text{ to }100\,\text{bpm}$; uniform upright P wave before every QRS; PR interval $0.12\text{ to }0.20\text{ second}$; QRS duration $0.06\text{ to }0.10\text{ second}$.

What characterizes Sinus Bradycardia compared to Normal Sinus Rhythm?

The heart rate is less than $60\,\text{bpm}$, while the rhythm regularity, P wave configuration, PR interval, and QRS duration all remain within normal limits.

What distinguishing feature defines Sinus Dysrhythmia on an ECG tracing?

The $P\text{-}P$ and $R\text{-}R$ intervals progressively widen and narrow in synchronization with the patient's respiratory cycle and variations in vagal tone.

At what duration is a sinus arrest pause defined as asystole requiring CPR and a Code Blue?

A pause greater than $6\text{ seconds}$.

What are the defining ECG characteristics of a Premature Atrial Complex (PAC)?

An early ectopic beat disrupting rhythm; P wave of the early complex has an altered shape (flattened, notched, biphasic, or buried in a T wave); PR interval $0.12\text{ to }0.20\text{ second}$; QRS duration $0.06\text{ to }0.10\text{ second}$.

What rhythm pattern is present when every third beat is a premature contraction?

Trigeminy.

What rhythm is shown, characterized by a heart rate of $60\text{ to }100\,\text{bpm}$ and at least three differing P wave morphologies in a single lead?

Wandering Atrial Pacemaker (WAP).

What distinguishes Multifocal Atrial Tachycardia (MAT) from Wandering Atrial Pacemaker (WAP)?

MAT shares the continuously changing P wave morphology (at least 3 variations) of WAP but presents with a heart rate of $101\text{ to }150\,\text{bpm}$.

What are the key diagnostic criteria of Atrial Flutter (A Flutter)?

Atrial rate of $250\text{ to }350\,\text{bpm}$; regular flutter-to-flutter waves producing a classic 'saw-tooth' or 'picket fence' appearance in leads II, III, and aVF; unidentifiable PR interval; normal QRS duration ($0.06\text{ to }0.10\text{ second}$).

By what percentage does the loss of the atrial kick reduce cardiac output during Atrial Flutter?

$10\%\text{ to }30\%$.

What is the primary clinical complication associated with Atrial Fibrillation?

Thrombus formation and systemic embolism resulting from blood collecting and stagnating in the fibrillating atria.

What is the inherent intrinsic firing rate of the AV node?

$40\text{ to }60\,\text{beats per minute}$.

What physiological event produces the inverted P waves characteristic of junctional dysrhythmias?

Retrograde (backward) depolarization of the atrial tissue by electrical impulses originating in the AV junction.

What are the distinguishing ECG criteria of a Junctional Escape Rhythm?

Regular rhythm with a rate of $40\text{ to }60\,\text{bpm}$; inverted P waves that may precede, follow, or be buried inside the QRS; PR interval less than $0.12\text{ second}$ when preceding the QRS; QRS duration $0.06\text{ to }0.10\text{ second}$.

How is Accelerated Junctional Rhythm distinguished from Junctional Escape Rhythm and Junctional Tachycardia?

All three share junctional morphology (inverted or absent P waves and normal QRS duration), but Accelerated Junctional Rhythm has a rate of $60\text{ to }100\,\text{bpm}$, compared to $40\text{ to }60\,\text{bpm}$ for Junctional Escape Rhythm and $100\text{ to }150\,\text{bpm}$ for Junctional Tachycardia.

What are the rate criteria and anatomical origin of Supraventricular Tachycardia (SVT)?

Originates above the ventricles (in the atria or AV junction) with a ventricular rate of $150\text{ to }350\,\text{bpm}$ and a narrow, normal QRS duration of $0.06\text{ to }0.10\text{ second}$.