Belching as a rare cause of sudden and short-lived heart rate decrease during exercise

Abstract

During a maximal incremental exercise testing, a continuous physiological increase is normally seen in heart rate. Sudden cardiac frequency decelerations rarely occur during exercise and its presence is considered to be due to myocardial ischemia [1] and most often represent an important indication for testing interruption. Case reportA 64-year-old man has suffered a myocardial infarction and was submitted to a coronary bypass graft surgery three years later. Being physically active and asymptomatic, he was assessed by a routine exercise testing at January 2009, in which, at the second minute of exercise, a short-lived heart rate decrease occurred that prompted the supervising physician to end the procedure and to immediately contact the referring physician. Evaluation was then followed by an echocardiogram that showed a hypokinetic inferolateral area and slightly augmented left ventricular cavity dimensions but with preserved global systolic function. In the sequence, an angiographic study showed three new significant lesions (two of them in revascularization vessels) and the patient was treated by percutaneous transluminal coronary angioplasty and four pharmacologically-coated stents were implanted. Few weeks after the revascularization procedure, we have the opportunity to see him for a maximal cardiopulmonary exercise testing (CPET) before the admission to our cardiac rehabilitation program. At the time of CPET, he was taking atenolol 100 mg bid, clopidogrel 75 mg once a day and atorvastatin 40 mg three times a week.He was tested using a ramp protocol in a cycle ergometer, starting with 25 W and increasing 1 W/each 7.5 s, aiming to achieve fatigue around 8 to 12 min. Resting heart rate and blood pressure values were, respectively, 54 bpm and 156/94 mm Hg. Except for an atypical heart rate deceleration at very beginning of exercise, normal heart rate and blood pressure responses were observed until the 6th min of exercise, when again, the instantaneous heart rate (measured by RR interval duration) suddenly dropped from 105 to 56 bpm for about 3 or 4 s (Fig. 1) without no clinical symptoms or abnormal pattern of ventilatory variables. Considering this and the recent revascularInternational Journal of Cardiology 151 (2011) e19-e21 ⁎ Corresponding author. Rua Siqueira Campos, 93/101, 22071-030 -Rio de Janeiro -RJBrazil. Tel.: +55 21 2256 7183. E-mail address: cgaraujo@iis.com.br (C.G.S. Araújo).ization procedure, the supervising physician decided to continue the CPET and no other abnormalities were seen or detected up to volitional exhaustion. Obtained maximal values of heart rate -139 bpm, blood pressure -188/92 mm Hg, oxygen uptake -27.4 mL/kg − 1 min − 1 and O2 pulse -14.5 mL bpm − 1 were either at normal (for patients in use of ß-blockers) or better than predicted for physical dimensions, gender and age.No pathological ECG ST changes or arrhythmias were detected other than the short period of relative bradycardia. Recovery pattern was also normal for all variables. Differently from our expectations, the brief...