Consider the following medical report that includes the patient's historical health records. Use it to predict the disease that the patient is high likely exposed to. 

 Medical Report: history of present illness: mr. is an 82-year-old man with critical aortic stenosis with a .9 cm square valve area, mitral regurgitation, bradycardia with a pacemaker, chronic atrial fibrillation, tricuspid regurgitation, pulmonary hypertension and congestive heart failure. on , the patient underwent aortic valve replacement for critical aortic stenosis with a 27 mm pericardial tissue valve. he has chronic atrial fibrillation at baseline and had several episodes of rapid atrial fibrillation in the first 72 hours postoperatively, treated with intravenous lopressor. he was kept on his standing dose at home of lopressor at 25 mg b.i.d. at time of discharge, the patient was rate controlled. he had an uncomplicated hospital course and progressed well with physical therapy. he will be discharged home on his usual standing dose of coumadin 5 mg alternating with 2.5 mg of coumadin every other day. past medical history: 1. chronic atrial fibrillation. 2. congestive heart failure. 3. aortic stenosis. 4. tricuspid regurgitation. 5. mitral regurgitation. 6. sick sinus syndrome, status post pacemaker. 7. pulmonary hypertension. 8. gastrointestinal bleeding. medications at discharge: 1. coumadin 5 mg po each monday, wednesday and friday. 2. coumadin 2.5 mg po each tuesday, thursday, saturday and sunday. 3. lasix 40 mg po q.d. 4. k-dur 20 milliequivalents po q.d. 5. aspirin 81 mg po q.d. 6. lopressor 25 mg po b.i.d. 7. percocet 1-2 tablets po q. 6 hours prn. 8. colace 100 mg po b.i.d. for seven days. physical examination: temperature 37.2. heart rate 80. afebrile. blood pressure 110/70. respiratory rate 14. lungs: clear to auscultation bilaterally. heart: irregularly irregular rhythm. normal s1, s2 with systolic murmur. abdomen: soft, nontender, nondistended, no masses, no ascites. extremities: no peripheral edema. wounds are well-healed. neurologically, completely intact, no focal deficits. laboratory values at discharge: white blood cell count 9, hematocrit 31.0, platelet count 234,000. inr 2.6. sodium 137, potassium 4.6, chloride 99, co2 27, bun 33, creatinine 1.4, glucose 121, magnesium 2.0. condition at discharge: stable. discharge status: to home with vna. patient is scheduled to have his inr drawn the day after discharge at his facility. discharge diagnosis: status post pericardial aortic valve replacement for critical aortic stenosis. , m.d. dictated by: medquist36 procedure: extracorporeal circulation auxiliary to open heart surgery open and other replacement of aortic valve with tissue graft diagnoses: congestive heart failure, unspecified aortic valve disorders other chronic pulmonary heart diseases diseases of tricuspid valve 

Answer: The patient is high likely exposed to