Reversible postural tachycardia syndrome due to inadvertent overuse of Red Bull®
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- Terlizzi, R., Rocchi, C., Serra, M. et al. Clin Auton Res (2008) 18: 221. doi:10.1007/s10286-008-0483-y
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Postural tachycardia syndrome associated with a vasovagal reaction was recorded in a young volleyball player after an excess intake of Red Bull® as a refreshing energy drink. Considering the widespread use of Red Bull® among young people who are often unaware of the drink’s drug content, this case report suggest Red Bull® be considered a possible cause of orthostatic intolerance.
Keywordspostural tachycardia syndromevasovagal reactionRed Bull®
A 16–year-old female professional volleyball player (height 1.66 m, weight 53 kg , BMI 19.23) was referred to the Autonomic Nervous System Laboratory at the Bologna University Department of Neurosciences for a 3-month history of orthostatic intolerance and episodes of transient loss of consciousness (TLoC). These TLoC episodes occurred with or without premonitory signs of nausea, dizziness and blurred vision and in one case sudden onset of TLoC led to a head injury with a flesh wound. Because of these symptoms she was unable to tolerate physical exercise and had stopped playing volleyball.
As a professional volleyball player (at least 8 hours of training sessions a week) she had had a full cardiological examination including ECG with carotid sinus stimulation every year since the age of 12 in order to qualify for participation in the volleyball season. Her medical history, including recent viral infections, was not significant and she denied the use of medications or doping. She had a normal neurological examination and sleep-deprived EEG and brain MR imaging.
Autonomic tests (Valsalva maneuver, deep breathing and head-up tilt table test (HUTT) at 65° for 30 minutes) were performed with continuous polygraphic recording of heart rate (HR), blood pressure (BP) and breathing (Task Force Monitor CNSystem) using standard procedures.
The patient was studied in a temperature controlled room (23 ± 1°C) and was tested in the morning between 8 and 12 AM. Before the tests, the patient was allowed to drink water but otherwise had to fast overnight. She had to abstain from drinking alcohol or coffee the day before the study.
During Valsalva maneuver, the following indices of autonomic activity were considered: the ratio between HR in phases II and IV (VR) and the overshoot during phase IV (difference between the highest systolic BP after the expiratory effort and the basal value). At deep breathing, the sinus arrhythmia (calculated in beats per minute using the 10 longest R–R intervals during expiration and the 10 shortest R–R intervals during inspiration) and the I/E ratio (ratio between the mean of highest HR values during 10 deep inspirations and the mean of the lowest HR values during expirations) were calculated. At the HUTT changes in systolic BP (sBP), diastolic BP (dBP) and HR were calculated with respect to basal values. The maneuvers were carried out in the sequence described, allowing a period of rest required to reach basal BP and HR values in between investigations. The results of each test were automatically obtained by means of home-developed software.
Searching for the cause of orthostatic intolerance, we again questioned the patient about of any changes in her habits before the onset of orthostatic symptoms and we discovered that she had started to drink Red Bull® (4–5 cans a day) 1 week before the onset of orthostatic symptoms. The patient was asked to stop drinking Red Bull® and she became asymptomatic in a week. Autonomic tests were repeated 1 month after having stopped drinking Red Bull® and the HUTT was normal and well tolerated for 30 minutes (rest supine: BP 125/80 mmHg, HR 80 bpm; 30’ of HUTT: BP 125/80, HR 108 bpm). One year later the follow-up visit confirmed that orthostatic intolerance had disappeared.
Our patient was referred to us for orthostatic intolerance and episodes of TLoC of unknown origin, one of the most common causes of referral to an autonomic laboratory. Autonomic investigations showed a normal baroreflex function with physiological cardiovagal control of HR, but HUTT clearly demonstrated a postural tachycardia syndrome (increase in HR of 40 bpm without a significant decrease of BP) complicated at the 22nd minute by a relative vasodepression and bradycardia associated with symptoms of reduced brain perfusion. The patient recognized these symptoms as those preceding her episodes of TLoC and we concluded postural tachycardia syndrome complicated with a reflex vasovagal reaction .
The critical point for establishing the cause of the patient’s orthostatic intolerance was the patient’s history taking that revealed she had started to drink four to five cans of Red Bull® a day at the onset of orthostatic and exercise intolerance. She had discovered the drink by accident and she liked the taste. Unaware of the composition of Red Bull® and thinking it was just a thirst-quenching, refreshing and hydrating drink, she started to drink it in large quantities. A standard 250 ml can of Red Bull® contains 80 mg caffeine, 1,000 mg taurine and a variety of other ingredients, including glucuronolactone, niacin, vit. B6, B12, sucrose and glucose. Taurine and caffeine are the ingredients that can directly or indirectly affect cardiovascular functions. In particular, taurine, a nonessential aminoacid found in high concentrations in the brain  has the potential to interfere with cardiovascular regulation in experimental animals  and in humans [1–3].
However, we do not know how or which component of Red Bull® was the cause of orthostatic intolerance in our patient and we cannot exclude that she had a specific susceptibility. We think that overuse of Red Bull® was the cause of orthostatic intolerance in our patient because the beginning of symptoms coincided with intake of large amounts of Red Bull® and symptoms of orthostatic intolerance symptoms disappeared 1 week after suspending Red Bull® intake, and HUTT confirmed normal cardiovascular response to orthostatic stress.
Energy drinks have recently become popular amongst athletes, partygoers and college students. In 2004 Red Bull® was being sold in over 100 markets and was the market leader in the USA and in 12 of the 13 West European markets where it was present. The makers of Red Bull® claim that it “gives you wings,” by improving performance, concentration, reaction speed, vigilance and emotional status, and stimulating metabolism . A recent study reported widespread use of energy drinks among college students accompanied by side-effects including jolt and crash episodes, heart palpitations and headaches .
To our knowledge, this is the first report of postural tachycardia syndrome caused by exaggerated Red Bull® drinking, and further studies are needed to disclose its underlying mechanisms. We recommend specific questions to elicit possible Red Bull® abuse in young people presenting with orthostatic and exercise intolerance of unknown origin.