The patient’s cardiac rhythm suddenly changes on the monitor.

There are no P waves, instead there are fibrillatory waves before each QRS complex.

How would the nurse interpret the rhythm?

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.

Choice A rationale:

Sinus tachycardia is a heart rhythm characterized by a rate greater than 100 beats per minute, with normal P waves preceding each QRS complex.

It can be caused by various factors, including exercise, stress, fever, dehydration, medications, and medical conditions such as anemia, hyperthyroidism, and heart failure.

In the given rhythm, the rate is within the normal range (60-100 beats per minute), and the P waves are not clearly visible, making sinus tachycardia unlikely.

Choice B rationale:

Atrial flutter is a type of supraventricular tachycardia characterized by a rapid, regular atrial rate of around 250-350 beats per minute, with a characteristic "sawtooth" pattern on the ECG.

It is typically caused by a re-entry circuit within the atria, often involving the cavo-tricuspid isthmus.

The ventricular rate is usually slower than the atrial rate due to the atrioventricular (AV) node's inability to conduct all atrial impulses.

Atrial flutter can cause symptoms such as palpitations, shortness of breath, lightheadedness, and fatigue.

It can also lead to complications such as stroke and heart failure.

The given rhythm shows a regular atrial rate with a sawtooth pattern, consistent with atrial flutter.

Choice C rationale:

Atrial fibrillation is another type of supraventricular tachycardia characterized by rapid, irregular atrial activity with no discernible P waves on the ECG.

It is also caused by disorganized electrical activity in the atria.

The ventricular rate in atrial fibrillation is also irregular, and the rhythm is often described as "irregularly irregular." The given rhythm shows a regular atrial rate, making atrial fibrillation unlikely.

Choice D rationale:

Normal sinus rhythm is the heart's natural rhythm, characterized by a rate of 60-100 beats per minute, with normal P waves preceding each QRS complex.

The given rhythm does not have normal P waves, making normal sinus rhythm unlikely.