1. A sudden pushing or driving force. 2. A sudden, often unreasoning, determination to perform some act. 3. The action potential of a nerve fiber. [L. im-pello, pp. -pulsus, to push against, impel (inp-)]
apex i. conventionally the lowermost, leftmost area of cardiac pulsation that is usually palpable.
cardiac i. movement of the chest wall produced by cardiac contraction.
ectopic i. an electrical i. from an area of the heart other than the sinus node.
escape i. one or more i.'s (atrial, junctional, or ventricular) arising as a result of delay in the formation or arrival of impulses from the prevailing pacemaker.
irresistible i. a compulsion to act such that one feels or claims it cannot be resisted.
morbid i. an i. that drives one to commit some act, usually of a deviant or forbidden nature, notwithstanding efforts to restrain oneself.
right parasternal i.'s cardiac activity as palpable or recordable just to the right of the sternum.
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