Michael Lohan was rushed to hospital on Saturday (06Mar10) after suffering agonising pains as he prepared for a celebrity boxing match.
He was released later that night, but now the Mean Girls actress' father needs a catheterization - a medical procedure to diagnose certain heart conditions - according to TMZ.com.
Lohan is reportedly taking medication to thin his blood, and is also on anti-angina drug nitroglycerin, reports the website.
He tells TMZ.com, "I've felt better. (The hospital visit) was quick... I don't know if it's a bloodclot or if I need scans for what it is. We'll find out soon... I'm just finding out what's going on, we'll see what happens."
