Heart Rate As A Measure Practicalities of measuring heart rate

If HR is used, it is important that an accurate HR can be measured while the patient is actually exercising. It is the HR while the patient is exercising that provides a marker of both whole body and myocardial strain. The use of a palpated radial pulse requires skill, and for the patient's arm to be very still. Except for static exercise cycling (cycle ergometry), the patient needs to stop the exercise briefly for the pulse to be taken. Even in this very brief period HR drops quickly (De Van, et al., 2004), so that measuring the HR, from the radial pulse, to represent the true exercise intensity is difficult to achieve. The use of a handheld pulse oximeter may help overcome such problems but hand and arm movement still needs to remain relatively still.

Personal HR monitors, with a wireless chest-strap electrode transmitter and wristwatch receiver (e.g. Polar, Cardiosport brands), has made a simple, inexpensive and accurate measuring of HR possible. These devices, however, rely on a normal sinus rhythm. If there are disturbances to the normal ECG (e.g. atrial fibrillations or ectopic beats), the monitor will not be able to adjust for these. The next stage up from this is the use of more costly and sophisticated 3-to-12-lead ECG telemetry. For some patients who have undergone coronary bypass surgery, surgical sternal sutures sometimes interfere with the electrodes on the chest strap, and prevent it picking up a valid ECG signal.

As will be discussed in the final section on integrating HR, RPE, observation and METs, many of these limitations can be overcome so as to set exercise intensity safely and effectively for the cardiac patient. A criticism of using equipment to monitor HR is that patients can become over-focused on and obsessive about their HR. There is a good argument for the use of HR monitors for patients who are 'exercise abusers' and require assistance in maintaining a safe intensity.

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