Anesthetic management of a patient with obstructive prosthetic aortic valve dysfunction: a case report
A 55-year-old woman (height 153 cm, weight 59.5 kg) was scheduled for burr-hole drainage due to a subdural hematoma. Previous medical history revealed rheumatic involvement of heart valves resulting in moderate mitral stenosis and severe aortic stenosis with a preserved LV ejection fraction (EF) of 83%. Accordingly, the patient had undergone a double heart valve replacement (DVR) surgery 6 years ago with mechanical valves (Sorin®, Sorin group, Milano, Italy) #18 and #25 for the aortic and mitral valve, respectively. Echocardiography performed immediately after DVR revealed a LVEF of 60% and significant reductions in the peak and mean systolic pressure gradient (PSPG/MSPG) across the prosthetic valves. In detail, the PSPG/MSPG across the aortic valve was reduced from 122/74 mmHg to 29/12 mmHg. Follow-up echocardiography performed 2 years after DVR revealed an increased pressure gradient across the prosthetic aortic valve (PSPG/MSPG = 91/57 mmHg) due to PPM and possibly from pannus formation, with good motion of the prosthetic mitral valve and normal LVEF. Echocardiography performed a year ago revealed similar findings with persistence of the pressure gradient across the aortic valve (PSPG/MSPG = 98/50 mmHg) (). While the patient had been asymptomatic regarding obstructive PVD, her treatment plan was close medical observation.\nWarfarin 7.5 mg and olmesartan 10 mg was given orally per\nday after DVR, and warfarin was discontinued as soon as the diagnosis of a subdural hematoma was confirmed. The patient's electrocardiography (ECG) showed a sinus rhythm with first-degree AV block and other preoperative laboratory studies were all within the normal limits. As the patient was free of cardiac symptoms, an additional echocardiography was not performed before the burr-hole drainage.\nWe planned to perform general anesthesia under the assumption that her hemodynamic status was similar to a patient with severe, asymptomatic aortic stenosis. Upon arriving at the operating room, the patient was alert and standard monitoring devices were applied including 3-lead ECG, noninvasive blood pressure and pulse-oximetry. Initially assessed vital signs were as follows: arterial blood pressure of 173/72 mmHg, pulse rate of 63 beats/min, and peripheral oxygen saturation (SpO2) of 100% in room air. Glycopyrrolate 0.1 mg was given as premedication and radial artery cannulation under local anesthesia was performed for continuous monitoring of arterial blood pressure before anesthetic induction. Anesthesia was induced via the intravenous route using midazolam 3.5 mg, thiopental sodium 50 mg, and a continuous infusion of remifentanil using a target-controlled infusion device (Orchestra® infusion pump system, Fresenius vial, Brenzins, France). The effect site concentration of remifentanil was gradually increased while paying attention to the patient's vital signs. After loss of consciousness, mask ventilation was maintained with 1.5 % of sevoflurane in 100% oxygen, and 30 mg of rocuronium bromide was injected intravenously. After the effect site concentration of remifentanil reached 4.0 ng/ml, the trachea was intubated and the lungs were mechanically ventilated with 60% oxygen with air. Mechanical ventilation was performed to achieve an end-tidal carbon dioxide level between 35 and 40 mmHg. Her heart rate remained unchanged while her blood pressure was maintained between 130/70 mmHg and 140/80 mmHg during the period of anesthetic induction and tracheal intubation. For anesthesia maintenance, sevoflurane was carefully titrated to maintain a bispectral index score between 40 and 60. The effect site concentration of remifentanil was adjusted to maintain the intraoperative blood pressure and heart rate within 20% of the preoperative values. Major hemodynamic goals during the surgery were to maintain the systolic blood pressure between 130-170 mmHg, diastolic blood pressure between 60-80 mmHg, and pulse rate between 55-70 beats/min. Upon completion of the surgery, sevoflurane was discontinued, and the neuromuscular blockade was antagonized with 0.2 mg of glycopyrrolate and 1 mg of neostigmine. After confirmation of regaining adequate consciousness and spontaneous respiration, the patient was transferred to the post anesthesia recovery unit. The duration of the surgery and anesthesia was 30 and 60 min, respectively, and 200 ml of colloid solution and 300 ml of crystalloid solution were given. There were no remarkable events in the operating room and in the post anesthesia recovery unit.\nTwo days after the operation, transthoracic echocardiography was performed, and it still showed an increased aortic valvular pressure gradient (PSPG/MSPG = 100/55 mmHg), an aortic valve area (AVA) of 0.88 cm2 and an indexed effective orifice area (EOA) of 0.56 cm2. While warfarin could not be restarted immediately, a follow-up transesophageal echocardiography was performed on the tenth day after operation, which revealed a hyperechogenic fixed structure at right coronary cusp side, which seemed to be suspicious of a pannus formation or organized thrombus (). In addition, good motion of the prosthetic aortic valve with flow acceleration, partial motion limitation of the anterolateral leaflets of the prosthetic mitral valve, and moderate mitral stenosis (mid-diastolic pressure gradient = 10 mmHg) probably due to thrombus formation were also observed. Despite these findings, warfarin could not be started until 2 weeks after the surgery to prevent fatal hemorrhagic complications. Heart computer tomography on the eighteenth day after the operation showed no significant coronary artery disease, no prosthetic mitral valve dysfunction, and a well-functioning prosthetic aortic valve. Follow-up echocardiography performed upon discharge 3 weeks after the operation revealed a slightly decreased pressure gradient across the aortic valve (PSPG/MSPG = 89/50 mmHg) and a well-functioning prosthetic mitral valve with loss of the previously observed pressure gradient with a LVEF of 73%. The patient was discharged without any complications.