The nurse is evaluating a patient who is experiencing chest pain beneath the sternum.

Which symptom reports would support a diagnosis of stable angina pectoris over a potential myocardial infarction?

(Select All That Apply)

Answer and explanation

The correct answer is C. Normal Sinus Rhythm.

Choice A rationale:

Asystole is the absence of all electrical activity in the heart, as evidenced by a flat line on the electrocardiogram (ECG). It is a medical emergency that requires immediate cardiopulmonary resuscitation (CPR) and defibrillation.

Key features of asystole on ECG:

No discernible P waves, QRS complexes, or T waves.

A completely flat or nearly flat line on the ECG tracing.

Choice B rationale:

Atrial flutter is a rapid heart rhythm that arises from abnormal electrical activity in the atria. It is characterized by a sawtooth pattern on the ECG, with atrial rates typically between 250 and 350 beats per minute.

Key features of atrial flutter on ECG:

Absence of distinct P waves, instead replaced by flutter waves (sawtooth pattern).

Regular, rapid atrial rate (typically 250-350 bpm).

QRS complexes may be normal or slightly irregular in appearance.

Choice C rationale:

Normal sinus rhythm is the natural, healthy rhythm of the heart. It originates in the sinoatrial (SA) node, the heart's natural pacemaker, and is characterized by a regular rate of 60-100 beats per minute, with consistent P waves, QRS complexes, and T waves on the ECG.

Key features of normal sinus rhythm on ECG:

Presence of distinct P waves, QRS complexes, and T waves.

Regular rhythm with a rate of 60-100 beats per minute.

PR interval (the time between the P wave and QRS complex) is 0.12-0.20 seconds.

QRS duration (the time it takes for the ventricles to depolarize) is less than 0.12 seconds.

Choice D rationale:

Sinus bradycardia is a slow heart rhythm, with a rate below 60 beats per minute. It is often a normal finding in healthy individuals, especially athletes or during sleep. However, it can also be a sign of underlying medical conditions.

Key features of sinus bradycardia on ECG:

Presence of distinct P waves, QRS complexes, and T waves.

Regular rhythm with a rate less than 60 beats per minute.

PR interval and QRS duration are typically normal.

Atrial fibrillation (AF) is characterized by the absence of P waves on the ECG, the presence of fibrillatory waves, and an irregularly irregular rhythm. This is due to chaotic electrical activity in the atria, which results in disorganized atrial contractions. The fibrillatory waves, which are often described as "f" waves or "sawtooth" waves, represent the rapid and irregular electrical activity in the atria. They are typically best seen in lead II, V1, or V2 of the ECG.

Here is a more detailed explanation of the key features of AF that support this answer:

Absence of P waves: In normal sinus rhythm, the P wave represents the electrical impulse that originates in the sinoatrial (SA) node and depolarizes the atria. In AF, the SA node is no longer in control of the atrial rhythm, and there is no organized atrial depolarization. As a result, P waves are absent on the ECG.

Presence of fibrillatory waves: The fibrillatory waves seen in AF represent the disorganized electrical activity in the atria. They are typically irregular in amplitude and frequency, and they can vary in appearance from patient to patient.

Irregularly irregular rhythm: The ventricular rhythm in AF is also irregular because the impulses from the atria are not conducted to the ventricles in a regular pattern. This results in an irregularly irregular rhythm, which is a hallmark feature of AF.

Key points to remember:

AF is the most common type of cardiac arrhythmia.

It can be asymptomatic or cause a variety of symptoms, including palpitations, shortness of breath, fatigue, and lightheadedness.

AF is a risk factor for stroke and heart failure.

Treatment for AF may include medications to control heart rate or rhythm, blood thinners to reduce the risk of stroke, and in some cases, procedures to restore normal heart rhythm.