Does having heart surgery recently make me more susceptible to lung infections?

Short answer is yes.: Having had any surgery impacts respiratory mechanics due to pain, the stress and trauma of the surgery. That is why post op instructions include major emphasis on incentive spirometry.

Not really: Duringa hospital stay in patient is at risk for hospital acquired pneumonia but heart surgery in itself is not an independent risk factor.

In a way.: Pneumonia is a known complication after heart surgery. One of the big reasons for this is that it hurts to cough and take deep breaths because of the incisional/sternal pain after surgery. If you don't cough, your don't clear junk out of your lungs.