Diagnostic dilemma: Rectal exam stabilized man's irregular heartbeat

The patient: A 29-year-old man in Queens, New York

The symptoms: As the man was walking home one night, he suddenly started feeling heart palpitations — accelerated heartbeats at irregular intervals — that alarmed him, prompting an immediate visit to the emergency room.

What happened next: The man told the hospital doctors that he had no history of heart trouble. He was not experiencing symptoms that are normally associated with a heart attack, such as chest pain or pressure, difficulty breathing, dizziness, a cold sweat or shortness of breath. Nor did he have a history of drug use or illness that could have triggered palpitations, the attending physician wrote in a report of the case.

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The diagnosis: Although palpitations are typically fleeting and harmless, according to the Mayo Clinic, they can sometimes be a symptom of serious heart conditions such as arrhythmia, in which electrical signals that regulate the heartbeat are repeatedly disrupted. This can cause the heart to pump blood less efficiently through the body, which can starve tissues of blood and oxygen.

At the hospital, doctors performed an electrocardiogram (EKG), which monitors the heart's electrical activity and rhythm. The test showed signs of atrial fibrillation (AFib), a common type of arrhythmia in which the heart's upper and lower chambers are out of sync. As a result, less blood fills the lower chambers and less blood reaches the lungs and the rest of the body.

AFib is sometimes associated with congestive heart failure, a chronic condition in which the heart doesn't pump blood efficiently, as well as strokes, which are caused by blocked or damaged blood vessels. Although the exact causes of AFib are unknown, the condition has been linked to digestive problems and overactivity of the parasympathetic nervous system, according to the report. (Also known as the "rest and digest" system, the parasympathetic nervous system balances out the activity of the "fight or flight" system.)

It was unclear what was causing the patient's AFib in this case. Doctors admitted the man to the hospital and prepared to perform a cardioversion, a procedure to restore regularity to a disrupted heartbeat.

The treatment: Before receiving the cardioversion, the patient required an anticoagulant to prevent the formation of blood clots. But first, doctors needed to make sure the patient did not have gastrointestinal bleeding, so a physician performed a digital rectal exam to check for blood in the patient's stool. At the time, the man's heartbeat was measured at 140 beats per minute (bpm); the average resting heart rate for an adult is 60 to 100 bpm.

When the rectal exam was over, the doctors noted that the patient's heartbeat had slowed to 80 bpm, and further examination showed that the irregularity in his heartbeat had disappeared. He was discharged from the hospital, and when he came back for a follow-up visit three months later, he said the palpitations had not returned.

What makes the case unique: Treatment for AFib typically involves medications that slow the heart rate and regulate its rhythm, or the use of cardioversion to "reset" the heartbeat. If the patient is at risk of a blockage in a blood vessel, doctors may prescribe an anticoagulant, as well.

Medication usually restores the heart's normal rhythm within hours — but in this case, the rectal exam achieved a similar result instantly.

The author of the report proposed that the exam affected the man's autonomic nervous system, which controls involuntary bodily processes like heartbeat. He suspected that this change was due to the stimulation of the vagus nerve, a structure of the nervous system that extends from the brainstem into organs of the chest and abdomen and is involved in heartbeat regulation.

Notably, during the rectal exam, the patient was instructed to bear down and strain without exhaling, a technique called the "Valsalva maneuver." It's also used to clear pressure from the middle ear and is known to increase activity in the vagus nerve.

Stimulation of the vagus nerve is known to increase activity in the parasympathetic nervous system and slow electricity conduction in heart tissue, the patient's doctor wrote in the report. In this patient, stimulation of his vagus nerve likely counteracted the signals causing the arrhythmia, the doctor suspected.

This type of rectal procedure could be an additional method for treating some patients with AFib, the author concluded, though he added that it should not replace more traditional treatments. More research would be needed to justify adding the procedure to standard practice.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

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