Aortic valve replacement in a patient with systemic lupus erythematosus
A 43-year-old hypertensive woman, diagnosed with SLE in 2005, was admitted with complaints of increasing shortness of breath (New York Heart Association (NYHA) class III/IV) and exertional pain in left side of chest. Past history included cerebrovascular accident (right hemiplegia and right facial palsy) with complete recovery. She also had history of renal failure requiring dialysis. Renal biopsy done in 2007 was suggestive of lupus nephritis class V (membranous nephritis). Previous cardiac history included an evidence of endocarditis in 2007. Physical examination was unremarkable except for the presence of malar rash, and obesity (body mass index 38.87 kg/m2). Pre-operative hemoglobin, platelet count and liver function tests were normal. Activated partial thromboplastin time (aPTT) was prolonged (51.6 s, normal 28-43 s) while fibrin D-dimer level (0.33 mg/ml, normal <0.4 mg/ml) and renal parameters (blood urea nitrogen and serum creatinine) were normal. Routine and microscopic evaluation of urine revealed protein 3+. Urinary protein was high (90 mg.dl-1, normal <15 mg.dl-1) and urine protein/creatinine ratio was also high (1.74, normal 0-0.2). Current medications included oral prednisolone 10 mg once daily, and mycophenolate mofetil 1 g twice daily.\nTransthoracic echocardiography showed calcific, non-coapting aortic valve leaflets with severe aortic regurgitation, no aortic stenosis, mild mitral regurgitation, dilated cardiac chambers, mild global hypokinesia of left ventricle with an ejection fraction of 45%, with no intracardiac clot, vegetation, or pericardial effusion. Angiography revealed normal coronary and renal arteries.\nPatient was scheduled for AVR and an informed consent was obtained. Though no airway abnormality was detected, however a “difficult intubation kit” consisting of small size endotracheal tubes, McCoy laryngoscope, intubating laryngeal mask airway, and bronchoscope, was kept ready. She was pre-medicated with lorazepam 2 mg orally and pantoprazole 40 mg orally. Standard cardiac monitoring was instituted including invasive blood pressure, cardiac output (CO) by thermodilution method, and trans-esophageal echocardiography (TEE). Cardiac index (CI) and systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) were calculated using standard formulae. Her pre-operative hemodynamic parameters were: Heart rate 92 beats/min, blood pressure 176/54 (94) mmHg, pulmonary artery pressure 42/18 (25) mmHg, CO = 4.4 L/min, CI = 2.3 L/min/m2, SVR 1648 dynes.sec/cm5, and PVR 196 dynes.sec/cm5.\nCefuroxime 1500 mg and linezolid 600 mg were administered intravenous (IV) as antibiotic prophylaxis. Anesthesia was induced with midazolam 2 mg, fentanyl 3 mcg/kg and thiopentone 150 mg IV. Endotracheal intubation was facilitated with 0.5 mg/kg of atracurium. Anesthesia was maintained with isoflurane in oxygen and air, intermittent doses of fentanyl, and atracurium infusion (0.5 mg/kg/min). After heparinization (4 mg/kg) and achieving an activated clotting time (ACT) of 821 s by Celite method (Hemochron 401, International Technidyne Corporation, Edison, New Jersey, USA), cardiopulmonary bypass (CPB) was instituted by aorto-caval cannulation. During CPB, the hematocrit was maintained between 18% and 25%, perfusion flow between 2.4 L/min/m2 and 2.8 L/min/m2, mean arterial pressure between 50 mmHg and 70 mmHg, systemic temperature between 28°C and 30°C and ACT between 700 s and 800 s. Methyl prednisolone 1 g was administered during CPB. A 19 mm mechanical prosthetic valve (St Jude Medical Inc. Minnesota, USA) was implanted at aortic position. The CPB duration was 93 min and aortic cross clamp time was 66 min. Patient was weaned off CPB with inotropic support of epinephrine 0.1 mcg/kg/min and dobutamine 5 mcg/kg/min. Post CPB TEE showed normal functioning of prosthetic aortic valve with no paravalvular leak. Heparin anti-coagulation was reversed with half dose of protamine (total dose given 220 mg, post-protamine ACT 168 s). Patient was shifted to the intensive-care unit in hemodynamically stable condition and mechanically ventilated for 12 h. IV heparin infusion was started on first post-operative day to keep twice the control aPTT. After removal of chest drains, patient was ambulated on post-operative day 1. Heparin infusion was overlapped with acenocoumarol on third post-operative day to achieve an international normalized ratio (INR) of 2.5-3. Patient was discharged from the hospital on tenth post-operative day. Pathological examination of the excised aortic valve showed fibrosis, focal calcium deposits, and infiltration with inflammatory cells. A follow-up at 3 months showed normal function of the valve, and no signs of sepsis, thrombosis or uremia.