A team of doctors published a suspicious case report in 2012 of a man whose heart rate increased to 600 beats per minute. It is a full 300 beats more than the theoretical 300 beats per minute.
The case report talks about how a 57-year-old quadriplegic male came to the hospital with complaints of chest pressure and dizziness. After his examination, the doctors gave him nitrates and heparin for acute recovery syndrome. Moreover, they also kept him on tests and observation.
On the third day of his admission, he suffered several chest pain episodes and tachyarrhythmia. Furthermore, during one of the episodes, his heart rate spiked to 600 bpm for approximately 20 seconds before decreasing to 300 bpm gradually. However, it spontaneously returned to normal after the episodes.
Similar Heart Rate Cases
Doctors have noted similar cases in the past where patients’ heart rates spiked with the previous highest being 480 bpm.
The doctors added,
A non-medical literature search has also revealed a case report of a Danish audiologist, Ole Bentzen, who died laughing while watching the movie ‘A Fish Called Wanda’ in 1989
His heart rate was reported between 250 and 500 beats per minute before he succumbed to cardiac arrest.
However, these cases require an explanation because multiple cases including the observed case were above theoretical heart rate.
The team said,
With normal cardiac physiology, it is known that following the action potential (AP), the absolute refractory period (ARP) prevents another AP until the channels are reset at the [Atrioventricular] (AV) Junction,
The ARP of the AV Node lasts about 0.2 seconds limiting the heart rate to 300/min in theory.
Another possible factor is the cardiac myocyte action potential duration which is normally about 200 msec which again theoretically would limit the heart rate to about 300 beats per minute.
Moreover, with abnormal physiology of the heart, a mechanism could be allowing the heart to beat a lot faster.
However, with abnormal cardiac physiology, there could be mechanisms that allow the heart to beat much faster.
Heart rate conduction above 300 beats per minute would thus involve the presence of at least a bypass tract [an accessory pathway that bypasses the AV], shorter cardiac myocyte AP duration and also probable selective cardiac myocyte activation.
Conclusion
The team suggested that the likely explanation was AF and the presence of multiple bypass tracts in the heart.
