Pacemaker update 1984. Part II. The pacemaker syndrome.

When ventricular pacemakers are implanted in patients who still retain normal AV conduction, retrograde conduction may activate the atria after ventricular activation. This results in a retrograde flow of blood from the ventricles to the atria with flooding of the jugular and pulmonary veins. Weakness or syncope can then occur as a result of lower cardiac output or congestive heart failure. A change to a dual-chamber pacemaker that produces AV synchrony is often necessary.