Adrenaline. Caffeine. Fatigue. Electrolyte shifts. Hormonal changes. Sometimes the ventricle is irritable for benign reasons. She says, “It feels like a thud in my chest.” “Like my heart drops, then everything resets.” “It catches my breath for a second.” You do an ECG. Normal beat. Then an early, wide beat. Pause. Normal beat. Thud again. That pattern is ventricular bigeminy. So what’s actually happening in the heart? The sinus node fires normally. The heart starts a regular beat. But somewhere