The news of the victim's heart attack, while unfortunate, forces us to examine the Texas homicide statutes in case the guy dies.
Texas Penal Code Section 6.03:
"(d) A person acts with criminal negligence, or is criminally negligent, with respect to circumstances surrounding his conduct or the result of his conduct when he ought to be aware of a substantial and unjustifiable risk that the circumstances exist or the result will occur. The risk must be of such a nature and degree that the failure to perceive it constitutes a gross deviation from the standard of care that an ordinary person would exercise under all the circumstances as viewed from the actor's standpoint."
Texas Penal Code Section 19.05:
"CRIMINALLY NEGLIGENT HOMICIDE.
(a) A person commits an offense if he causes the death of an individual by criminal negligence.
(b) An offense under this section is a state jail felony."
A state jail felony is punishable by incarceration between 180 days and two years and a fine of up to $10,000.
Does Cheney's conduct fit the statute? I've seen flimsier cases where the shooter is in jail.