Utility of an Accelerometer Sensor Integrated into a Holter Monitoring System

Background: Patients routinely undergo Holter monitor evaluation for the detection of cardiac arrhythmias. Documentation of daily patient activities is a common shortcoming. Discriminating physiological from pathological heart rate, e.g., sinus tachycardia in response to exercise from supraventricular tachyarrhythmia, can be difficult without an accurate diary. Independent documentation of body activity may help solve this inadequacy. Accelerometer‐based pacing systems have established the utility of general body activity detection for pacemaker rate determination. Methods: An accelerometer sensor was positioned in the left pectoral region in 10 volunteers for measurement of normal daily subject activity. Additionally, the volunteers were asked to keep a detailed diary of daily activities. The accelerometer sensor signal was recorded on one channel of a modified Holter monitor system. The Holter FCG and accelerometer data were analyzed and compared to the detailed diary. The study was then repeated in 10 patients undergoing standard Holter monitor evaluation. Results: In all 20 subjects, reviewing the 24‐hour profiles allowed correlation of heart rate response to activities such as walking, resting, exercise, or sleep and the accelerometer sensor signal. In the patients, a total of 170 minutes of increased heart rate correlated with documented physical activity, while 14 minutes did not. Additionally, 161 minutes of bradycardia during physical activity were also identified. Conclusion: Present‐day Holter systems can detect bradycardias and tachycardias based on ECG characteristics and rate criteria. The addition of acceterometer signal to standard Holter ECG might improve physician interpretation of patient heart rate response to daily patient activities. A.N.E. 2000;5(1):73–78