Figure 6

Patients with a permanent Pace Maker. Upper and middle panels, pacing stress echo: external programming of permanent PM induces a controlled change in heart rate which is independent of the patient capability to exercise; heart rate increase is achieved with sequential atrial-(right) ventricular stimulation with pacing induced left bundle branch block; a dramatic shortening of diastolic time occurs at pacing (from 60 bpm, spontaneous rhythmus to 100 bpm paced rhythmus) with a reversal of the systolic/diastolic ratio at 120 bpm heart rate). Lower panel, exercise stress in a patient with dilated cardiomyopathy (LVEF = 30%) and (sensed atrial rate) BIV pacing: the physiological induced increase in heart rate is accompanied by no reversal of the systolic/diastolic time ratio.