A 29-year-old man with a dangerously fast and irregular heartbeat was being prepared for further treatment when something completely unexpected happened during a routine hospital examination.

His atrial fibrillation suddenly stopped after a digital rectal examination, with his heart rhythm returning to normal almost immediately. The unusual case was documented in a 2010 peer-reviewed case report and has recently resurfaced after the doctor involved revisited the incident on social media.

While the story may sound bizarre, there is a physiological explanation for what happened. It involves the vagus nerve, the body's parasympathetic nervous system, and the way electrical signals travel through the heart.

The case was reported by Dr Cheng-Huai Ruan, who was an internal medicine intern in Queens, New York, when the incident occurred in 2010. Ruan later went on to become chief executive officer of the Texas Centre for Lifestyle Medicine.

He has since revisited the unusual case publicly, helping bring the long-standing medical report back into the spotlight.

A 29-Year-Old Man Arrived With a Racing, Irregular Heart

The case involved a previously healthy 29-year-old man who developed sudden palpitations while walking home from a shop. According to the published case report, he described fast heartbeats followed by slower beats.

He did not report chest pain, shortness of breath, dizziness, fainting, or other major symptoms. An electrocardiogram (ECG) showed that he was experiencing atrial fibrillation (AF), an abnormal heart rhythm in which the heart's upper chambers beat irregularly.

His heart rate subsequently reached about 140 beats per minute, according to the case report. Doctors admitted him for monitoring and administered metoprolol to control his heart rate.


Because the onset of his atrial fibrillation appeared to have been recent, doctors were also considering cardioversion, a procedure used to restore a normal heart rhythm.

The medical team planned to give him anticoagulant medication in preparation for cardioversion. Before this, however, a digital rectal examination was performed to check for hidden blood in his stool, according to the published account.

Then His Heart Rhythm Suddenly Changed

The examination produced an outcome unexpected outcome.

The patient's heart rhythm converted from atrial fibrillation to normal sinus rhythm immediately after the digital rectal examination. His heart rate fell from approximately 140 beats per minute to 80.

The published report records that the patient's symptoms resolved and that he was discharged from the hospital. He remained asymptomatic during a three-month follow-up.

The case report describes the change as occurring immediately after the examination, making the timing particularly striking.

Why Could a Rectal Examination Affect the Heart?

The answer may lie in the vagus nerve, a major component of the parasympathetic nervous system.

The vagus nerve helps regulate several involuntary functions, including heart rate. Increased parasympathetic activity can slow the heart's electrical activity, particularly conduction through the atrioventricular (AV) node.

In the case report, Dr Cheng-Huai Ruan proposed that the rectal examination may have increased parasympathetic activity through the vagus nerve, helping to terminate the patient's abnormal rhythm.

The paper describes the mechanism as increased parasympathetic activity through the vagus nerve, which can slow impulse formation in the heart's sinoatrial node and alter conduction through the AV node.

The authors also noted that 'vagal manoeuvers cause [an] increase in vagal tone', although the conversion of atrial fibrillation to normal rhythm is not usually associated with these manoeuvres.

The Valsalva Manoeuvre May Have Played a Role

The unusual examination was not necessarily the only factor involved.

The case report explains that the patient was asked to perform a Valsalva manoeuvre during the examination. This involves bearing down while attempting to exhale against a closed airway.

Valsalva manoeuvres can affect autonomic nervous system activity and are commonly associated with vagal stimulation. They are also used in certain clinical situations to help terminate some types of rapid supraventricular heart rhythms.

Ruan suggested that the combination of the rectal examination and the patient's straining may have produced enough vagal stimulation to influence his heart rhythm.

That does not, however, mean that a rectal examination is an established treatment for atrial fibrillation.

Was the Rectal Examination Really What Stopped the AF?

This is where the story requires some caution. The case report demonstrates a striking temporal association: the patient's AF converted immediately after the examination. But a single case cannot establish that the examination caused the conversion.

Atrial fibrillation can sometimes spontaneously return to normal sinus rhythm, particularly in cases where the episode has recently begun. The patient had also already received metoprolol, a medication used for rate control.

The original report argued that the immediate timing made a medication effect less likely, but it nevertheless remains a single-patient observation rather than evidence from a controlled clinical trial.

The case therefore provides an intriguing physiological hypothesis rather than proof that digital rectal examinations can reliably terminate AF.

Cardiologist Questions Part of the Original Story

The case has also prompted discussion about the circumstances surrounding the examination.

As the story resurfaced online, cardiologist Dr Joel Beachey questioned whether a digital rectal examination would normally be required before anticoagulation in a young patient being considered for cardioversion.

In comments reported by IBTimes UK, Beachey responded to Ruan's Instagram post, saying, 'a digital rectal exam is not routine before anticoagulating patients for cardioversion', particularly in a 29-year-old with no apparent signs of gastrointestinal bleeding.

He also described the case as a 'super crazy story and case report', while suggesting that the unusual circumstances surrounding the examination deserved scrutiny.

That distinction matters because medical practice and clinical guidelines can change over time. What happened in this individual case should not be interpreted as evidence of standard practice.

A Fascinating Case, But Not a Treatment for AF

The unusual incident remains medically interesting because it illustrates how closely the nervous and cardiovascular systems interact.

The vagus nerve can influence heart rate and electrical conduction, while manoeuvres that alter autonomic activity can affect certain abnormal rhythms. In this particular patient, those mechanisms may have contributed to the sudden return to normal sinus rhythm.

But there is an important takeaway: a digital rectal examination is not a recognised treatment for atrial fibrillation.

Anyone experiencing a rapid or irregular heartbeat should receive appropriate medical assessment rather than attempting to reproduce an unusual manoeuvre described in a decades-old case report.

The case is remarkable precisely because it was unexpected. More than 15 years after it was first published, it remains an unusual medical curiosity, not a new treatment for AF.

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