Can pulmonary hypertension cause tachycardia?

Yes: In pulmonary hypertension, the heart and lung physiology are affected such that to deliver good blood flow and oxygen elsewhere in the body, the pulse has to go up...The anatomy of the heart also leads to predisposition to atrial tachycardia ( coming form the upper chambers, not the main pumping chamber). It is also really important to find a cause and classify pulmonary hypertension.

Yes.: However, that's an oversimplification. There are multiple underlying causes of pulmonary hypertension. Most of them can cause increased pressure in one or both atrial chambers of the heart; the pressure increase stretches the atrial walls, thereby causing the irritability which results in tachycardias. The therapy must address the underlying problem.

Yes: If the heart function is reduced (called heart failure) by working against the pulmonary hypertension, then one way the heart compensates to increase blood flow is by increasing the heart rate, i.e. Tachycardia.