Final answer:
It is true that heart rate intensity should be maintained below the programmed HR threshold for defibrillation for a patient with an ICD to avoid inappropriate activation. ICDs monitor and correct heart rhythms. Correct voltage in open-heart surgery using a defibrillator is determined by resistance and required current.
Step-by-step explanation:
The statement is True. If a patient has an implanted cardiac defibrillator (ICD), their heart rate intensity should be maintained at least 10-15 beats per minute below the programmed heart rate (HR) threshold for defibrillation in order to avoid unintended shocks and maintain effective pacing.
ICDs are sophisticated devices that not only defibrillate the heart but also provide pacing in cases of too slow a heartbeat (bradycardia) or too fast a heartbeat (tachycardia). The device is programmed to intervene at specified thresholds, thus exercising below those thresholds is usually recommended to avoid unnecessary or inappropriate shocks when the patient is not in cardiac distress.
In terms of open-heart surgery, when using a defibrillator, it is crucial to apply the correct voltage considering the resistance of the path and the required current. For example, if the resistance is 500 ohms and a 10.0-mA current is needed, the applied voltage would be 5 volts (Ohm's Law: V = IR = 500 ohms * 10.0 mA = 500 ohms * 0.01 A = 5 V).