A patient who had a myocardial infarction asks the nurse why they are receiving morphine.
Which benefits of morphine should the nurse explain to this patient? (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.

Choice A rationale:

Pain relief is a primary benefit of morphine administration in the setting of myocardial infarction.

Pain can trigger a stress response, leading to increased heart rate, blood pressure, and myocardial oxygen demand.

Morphine effectively reduces pain, thereby lessening the stress response and its detrimental effects on the heart.

This helps to minimize myocardial ischemia and potential further damage to the heart muscle.

Pain control also improves patient comfort and overall well-being, which can indirectly contribute to better cardiac outcomes.

Choice B rationale:

Sedation is another important benefit of morphine in this context.

It promotes rest and relaxation, which can lower heart rate, blood pressure, and myocardial oxygen demand.

This is crucial for patients with myocardial infarction, as their hearts require reduced workload to heal and recover.

Sedation also helps to alleviate anxiety and agitation, which can further strain the heart.

By inducing a state of calmness, morphine can indirectly protect the heart from additional stress.

Choice C rationale:

While morphine does have diuretic effects, increasing urinary output is not a primary goal in the management of myocardial infarction.

In fact, excessive diuresis could potentially lead to dehydration and hypotension, which could be detrimental to cardiac function.

Therefore, while morphine may slightly increase urine output, this is not a major reason for its use in this setting.

Choice D rationale:

Decreasing myocardial demand is a key benefit of morphine administration in patients with myocardial infarction.

Morphine achieves this by:

Reducing pain and the associated stress response

Promoting sedation and relaxation

Diminishing anxiety and agitation

Exerting a direct vasodilatory effect on blood vessels

This collective action of morphine leads to a decrease in heart rate, blood pressure, and the heart’s overall workload.

As a result, the heart requires less oxygen and experiences reduced strain, allowing for better healing and recovery following a myocardial infarction.