In a patient with aortic stenosis, why is sinus rhythm or AV pacing particularly important?

In the context of a patient with aortic stenosis, ensuring optimal stroke volume is crucial because aortic stenosis impedes the flow of blood from the left ventricle into the aorta. This impedance can lead to reduced cardiac output, particularly during exertion or in states of increased demand. Sinus rhythm or AV pacing plays a pivotal role in supporting cardiac function under these circumstances.

When the heart is in sinus rhythm, it typically promotes effective diastolic filling of the ventricle, allowing for better stroke volume. Maintaining a regular and appropriate heart rate is essential, as irregular rhythms can lead to compromised filling times, further limiting stroke volume and exacerbating symptoms of heart failure. With appropriate pacing, the heart can achieve a coordinate contraction that supports adequate blood flow despite the presence of aortic stenosis, thus optimizing the stroke volume and maintaining hemodynamic stability.

In scenarios where heart rate is irregular or too fast, the ventricles may not be able to fill adequately, especially given the outflow obstruction present in aortic stenosis. Therefore, maintaining an optimal heart rhythm directly supports the ability of the heart to pump effectively, ensuring that stroke volume remains as high as possible despite the mechanical challenges imposed by the narrowed valve.