Final answer:
The positive deflections in standard ECG leads are the P wave and R wave. Increased QT interval duration suggests a decrease in ventricular repolarization velocity. Accelerated heart rate in hyperthyroidism shortens the QT interval.
Step-by-step explanation:
The positive teeth, or positive deflections, in the standard leads of an ECG include the P wave and R wave. When an increase in the duration of the QT interval is observed, it may be indicative of a decrease in ventricular repolarization velocity. In a patient with hyperthyroidism, an increase in heart rate as seen on an ECG is characterized by a reduced duration of the QT interval. This is because a higher heart rate shortens the overall duration of the cardiac cycle, including the time available for ventricular repolarization, which is represented by the QT interval.