Effect of Heart Rate on Left Ventricular Performance

Effect of Heart Rate on Left Ventricular Performance

The current study is aimed at determining the normal response to increasing heart rates. For this purpose, atrial pacing will be used to increase heart rate.

Participants will be patients with pacemakers and normal A-V node conduction with a possibility for right atrial pacing mode.

Detailed Echo studies will be performed at baseline. Echo studies will be repeated at each pacing stage, stages defined as 10 bpm increments in paced heart rate. Each stage will last 2-3 min or as long as it takes to record the echo study. Heart rate will be increased to 85% of predicted heart rate for age or at to appearance of signs of ischemia.

Hemodynamic parameters will be recorded and segmental longitudinal strain will be calculated (as well as other Echo data), for each stage.

Inclusion Criteria:

1. Patients with AAI or DDD pacemaker with intact AV nodal conduction that can be set to work in AAI mode.
2. Stable rhythm (either sinus or paced).
3. Good quality baseline echo.
4. Able and willing to sign Informed Consent Form.

Exclusion Criteria:

1. Prior heart failure or ischemic heart disease.
2. Severe valvular lesions.
3. Severe pulmonary hypertension.
4. Known intolerance to rapid pacing.
5. Multiple extrasystoles (more than 1 per echo or monitor screen).
6. Age over 70.