All volatile anesthetics increase cerebral blood flow, with halothane having the greatest effect. Autoregulation seems to remain intact in coronary arterioles. Right atrial pressure is increased in a dose-dependent fashion. Halothane does reduce the amount of circulating epinephrine required to elicit ventricular premature contractions. The ability of halothane to impair cardiac conduction appears to be a necessary part of the etiology of these arrhythmias.
Junctional rhythm is common with halothane from suppression of sinus node activity.
Stoelting, Basics of Anesthesia , Chapter 4.