Signing a deputy is looking unlikely with the loan window due to close at the end of this month, so coaching staff have identified possibilities within the squad.
Those include moving centre-back Mihai Popescu to right-back or switching either Stephen Kingsley or Aidy White across from left-back to play on the opposite side of defence.
Teenage right-back Cammy Logan is currently on loan at Cove Rangers and at the moment Hearts are reluctant to recall him to fill in for Smith.
Northern Ireland travel to Italy on March 25 and host Bulgaria six days later in two World Cup qualifying ties. They also have a friendly at home to USA sandwiched in between.
Smith is a regular member of their squad and is expected to be called up alongside Hearts team-mate Liam Boyce. If so, they would miss their club’s Championship home match with Queen of the South on Saturday, March 27.
Hearts’ second-choice right-back Jamie Brandon is out until next season with knee ligament damage, and the club hope Logan will get games at Cove if lower-league football resumes.
They are prepared to improvise if Smith is missing. “It doesn’t look like getting someone in is going to happen,” manager Robbie Neilson admitted to the Evening News. “We just wanted a bit of cover but it has to be done by the end of the month.
“We aren’t sure yet exactly what will happen with Michael. We aren’t sure what the rules will be on quarantine because players might need to isolate coming back from certain countries. It depends where Italy is on the list at the time.
“It’s not ideal if he misses a game for us but we have a few boys who could play that position. Popescu can go there, and either Aidy White or Stephen Kingsley could swap over to the right.
“Cammy Logan might be able to come in. We could cancel his loan and bring him back but the plan is not to do that at the moment. It just depends if the lower leagues are restarting.”
Hearts could also be without goalkeeper Craig Gordon for that Queen of the South fixture if he is called up by Scotland.