TABLE 3A-1 Electrocardiographic (ECG) Characteristics and Causes of Atrial Rhythms
Name ECG Characteristics Common Causes PT Consideration
Supraventricular
tachycardia Regular rhythm; rate of 160-250 bpm; may originate from any location above atrioventricular node; can be paroxysmal (comes and goes without reason)
Rheumatoid heart disease (RHD), mitral valve prolapse, cor pulmonale, digitalis toxicity
May produce palpitations, chest tightness, dizziness, anxiety, apprehension, weakness; PT would not treat if in supraventricular tachycardia until controlled
Atrial flutter Regular or irregular rhythm; atrial rate of 250-350; ventricular rate is variable and depends on the conduction ratio (atrial : ventricular, e.g., atrial rate = 250,
ventricular rate = 125; 2 : 1 classic saw tooth P waves)
Mitral stenosis, CAD,
hypertension Signs and symptoms depend on presence or absence of heart disease but can lead to CHF, palpitations, angina, and syncope if cardiac output decreases far enough to reduce myocardial and cerebral blood flow; PT treatment would depend on tolerance to the rhythm
Atrial fibrillation
(AF) Irregular rhythm; atrial has no rate (just quivers); ventricular rate varies
One of most commonly encountered rhythms, CHF, CAD, RHD, hypertension, cor pulmonale
Can produce CHF, syncope secondary to no “atrial kick”; if new diagnosis, hold PT until medical treatment; if chronic and not in CHF, would treat with caution Premature atrial
contractions Irregular rhythm (can be regularly irregular, i.e., skip every third beat); rate normal 60-100
Normal people with caffeine, smoking, emotional disturbances; abnormal with CAD, CHF, electrolyte disturbances
Usually asymptomatic but needs to be considered with other cardiac issues at time of treatment; can proceed with treatment with close monitoring; if they are consistent and increasing, can progress to AF
AF, Atrial fibrillation; CAD, coronary artery disease; CHF, congestive heart failure; RHD, rheumatoid heart disease.
TABLE 3A-2 Electrocardiographic Characteristics and Causes of Ventricular Rhythms
Name ECG Characteristics Common Causes PT Considerations
Agonal rhythm Irregular rhythm, rate <20, no
P wave Near death Do not treat.
Ventricular tachycardia
(VT) Usually regular rhythm, rate >100, no P wave or with retrograde conduction and appears after the QRS complex
CAD most common after acute MI; may occur in
rheumatoid heart disease, cardiomyopathy, hypertension
Do not treat; patient needs immediate medical assistance; patient may be stable (maintain CO) for a short while but can progress quickly to unstable (no CO)—called pulseless VT. Multifocal VT (torsades
de pointes) Irregular rhythm, rate >150, no P waves
Drug induced with
antiarrhythmic medicines (quinidine, procainamide); hypokalemia;
hypomagnesemia; MI; hypothermia
Do not treat; patient needs immediate medical assistance.
Premature ventricular contractions (PVCs) (focal = one ectopic foci and all look the same; multifocal = more than one ectopic foci and will have different waveforms)
Irregular rhythm, (can be regularly irregular, i.e., skipped beat every fourth beat); rate varies but is usually normal 60-100; couplet is 2 in a row; bigeminy is every other beat; trigeminy is every third beat
In normal individuals, secondary to caffeine, smoking, emotional disturbances, CAD, MI, cardiomyopathy, MVP, digitalis toxicity
Frequency will dictate effect on CO; monitor
electrocardiograph with treatment; can progress to VT; more likely if
multifocal in nature or if >6 per minute; stop treatment or rest if change in frequency or quality. Ventricular fibrillation Chaotic Severe heart disease most
common after acute MI, hyperkalemia or
hypokalemia, hypercalcemia, electrocution
Do not treat; patient needs immediate medical assistance.
Idioventricular rhythm Essentially regular rhythm,
rate 20-40 Advanced heart disease; high degree of atrioventricular block; usually a terminal arrhythmia
CHF is common secondary to slow rates; do not treat unless rhythm well tolerated.
CAD, Coronary artery disease; CHF, congestive heart failure; CO, cardiac output; ECG, echocardiographic; MI, myocardial infarction; MVP, mitral valve prolapse; VT, ventricular tachycardia.
Data from Aehlert B: ACLS quick review study guide, St Louis, 1994, Mosby; Chung EK: Manual of cardiac arrhythmias, Boston, 1986, Butterworth-Heinemann.
TABLE 3A-3 Electrocardiographic (ECG) Characteristics and Causes of Junctional Rhythms
Name ECG Characteristics Common Causes PT Considerations
Junctional escape
rhythm Regular rhythm, rate 20-40; inverted P wave before or after QRS complex; starts with ectopic foci in AV junction tissue
Usual cause is physiologic to control the ventricles in AV block, sinus bradycardia, AF, sinoatrial block, drug intoxication
If occasional and intermittent during bradycardia or chronic AF, usually insignificant and can treat (with close watch of possible worsening condition via symptoms and vital signs); if consistent and present secondary to AV block, acute myocardial infarction, or drug intoxication, can be symptomatic with CHF (see Box 3-2).
Junctional
tachycardia Regular rhythm; rate 100-180; P wave as above
Most common with chronic AF; also with coronary artery disease,
rheumatoid heart disease, and cardiomyopathy
May produce or exacerbate symptoms of CHF or angina secondary to decreased cardiac output; PT treatment depends on patient tolerance— if new onset, should wait for medical treatment.
AF, Atrial fibrillation; AV, atrioventricular; CHF, congestive heart failure.
Data from Aehlert B: ACLS quick review study guide, St Louis, 1994, Mosby; Chung EK: Manual of cardiac arrhythmias, Boston, 1986, Butterworth-Heinemann.
TABLE 3A-4 Electrocardiographic Characteristics and Causes of Atrioventricular Blocks
Name ECG Characteristics Common Causes PT Considerations
First-degree AV block Regular rhythm, rate normal 60-100, prolonged PR interval >0.2 (constant).
Elderly with heart disease, acute myocarditis, acute MI
If chronic, need to be more cautious of underlying heart disease; if new onset, monitor closely for progression to higher level block.
Second-degree AV block type I (Wenckebach, Mobitz I)
Irregular rhythm, atrial rate > ventricular rate, usually both 60-100; PR interval lengthens until P wave appears without a QRS complex.
Acute infection, acute MI Symptoms are uncommon, as above.
Second-degree AV block
type II (Mobitz II) Irregular rhythm, atrial rate > ventricular rate, PR interval may be normal or prolonged but is constant for each conducted QRS.
Anteroseptal MI CHF is common; can have dizziness, fainting, complete unconsciousness; may need pacing and PT treatment; should be held for medical management.
Third-degree AV block (complete heart block)
Regular rhythm, atrial rate
> ventricular rate Anteroseptal MI, drug intoxication, infections, electrolyte imbalances, coronary artery disease, degenerative sclerotic process of AV conduction system
Severe CHF; patient will need medical management; a pacer (temporary or permanent, depending on
reversibility of etiology) is almost always necessary.
AV, Atrioventricular; CHF, congestive heart failure; MI, myocardial infarction.
FIGURE 3B-1
Paroxysmal supraventricular tachycardia. Note development from normal sinus rhythm. (From Walsh M, Crumbie A, Reveley S: Nurse practitioners: clinical skills and professional issues, Boston, 1993, Butterworth-Heinemann.)
FIGURE 3B-2
Atrial flutter. Note regular rhythm (P waves), but ventricular rhythm depends on conduction pattern. (From Walsh M, Crumbie A, Reveley S: Nurse practitioners: clinical skills and professional issues, Boston, 1993, Butterworth-Heinemann.)