The Successful Implantation of Continuous-Flow Left Ventricular Assist Device as a Destination Therapy in Korea: Echocardiographic Assessment
A 75-yr-old male with a prosthetic aortic valve complained of his ongoing exacerbation of dyspnea which started at December, 2010. He had visited regularly the outpatient clinic of cardiology in our institution since June, 2002. Twelve years ago, he had received aortic valve replacement with Medtronic-Hall valve (24 mm) due to severe rheumatic aortic regurgitation. However, in spite of good prosthetic valve function and medical treatment including angiotensin receptor blocker and beta-blocker, his left ventricular (LV) systolic function and LV dilation gradually deteriorated. In consequence, he was suffered from dyspnea of New York Heart Association (NYHA) functional class III to IV. He had no history of hypertension or diabetes mellitus, but had atrial fibrillation. Laboratory findings were within normal range except mild azotemia (serum creatinine 1.75 mg/dL) and prolonged prothrombin time (INR 1.97). Because his old age and functional deconditioning caused by long-term illness prevented him from being a good candidate for heart transplantation, he was recommended for LVAD implant as a destination therapy. The level of LVAD risk was medium with score 12 by Lietz () and high with score 2.95 by HeartMate II Risk Score (). However, because the patient's prolonged INR was caused by anticoagulation for prosthetic valve rather than pathologic coagulopathy, his actual risk of LVAD implant was thought to be lower than the calculated risk score.\nOn preoperative evaluation, he had insignificant stenosis in the coronary arteries in coronary angiography. In transthoracic echocardiography, LV dimensions were dilated (70/69 mm at diastole/systole), and LV ejection fraction by Simpson's method was only 20%. But, the right ventricular (RV) function was relatively preserved and RV cavity size was normal [tricuspid annular plane systolic excursion (TAPSE)=14 mm, s'=0.07 m/sec, RV fractional area change (RVFAC)=60%, and RV diastolic dimension base/mid=33/17 mm]. Mild mitral regurgitation (MR) and moderate tricuspid regurgitation (TR) were observed. Inferior vena cava (IVC) was dilated without plethora, and RV systolic pressure by TR peak velocity was 39 mmHg. The prosthetic valve continued to function well with physiologic aortic regurgitation; Vmax=1.9 m/sec, mean pressure gradient=7.7 mmHg, effective aortic valve area by continuity equation=2.1 cm2. Although the function of prosthetic aortic valve was good, the closure of aortic valve was determined after the surgical consultation in concern of possible secondary pump flow upregulation by physiologic aortic regurgitation.\nAfter informed consent was obtained from the patient and his family, LVAD implantation with HeartMate II (Thoratec, Pleasanton, CA, USA) proceeded. For the surgery of LVAD implantation, he admitted to our hospital on 11th, August, 2012. And the implantation of LVAD was performed on 17th, August, 2012. To insert a propulsion pump in upper abdomen, a midline sternotomy was extended to the upper abdomen. An outflow graft was connected to the aorta with end to side anastomosis. After the removal of some chordae that could cause turbulent flow in the LV chamber, the inflow conduit was inserted at LV apical position. The mechanical prosthetic aortic valve was closed with two round 24 mm and 22 mm-sized Teflon felts. During the procedure, we checked the presence of patent foramen ovale (PFO) with transesophageal echocardiography by injecting agitated saline via a central venous catheter, but microbubbles were not observed in the left side of the heart. We additionally performed cryoablation at cavo-tricuspid isthmus for 2 min and 45 sec and resected left atrial appendage. The postoperative chest X-ray clearly shows the positions of inflow conduit, LVAD as propulsion pump, outflow cannula and power cable connected to extracorporeal controller ().\nOn the day following LVAD implantation, he was extubated in a stable hemodynamic condition. We checked the patient's volume status and the function of LVAD with daily bed-side echocardiographic assessment (). We manipulated the revolutions per minutes (rpm) of LVAD in the range of 8,800-9,200 to maintain midline position of interatrial septum (IAS) and interventricular septum (IVS). The size of IVC was monitored to assess his volume status. For example, at postoperative day (POD) 10, we had to decrease rpm from 8,800 to 8,400 to maintain the mid-position of IAS and IVS, because the septum deviated to the left side at a higher rpm. However, at the same time, the IVC was observed to be collapsed with a diameter of 0.7 cm. So, after enough volume replacement for 2 days, we could elevate rpm to the level of 8,800 again, monitoring the echocardiographic parameters.\nDuring the hospital stay, he acquired aspiration pneumonia several days after the surgery. As a result, he stayed in intensive care unit until postoperative day 11. He could not participate in the cardiac rehabilitation program until he recovered fully from aspiration pneumonia. During the rehabilitative period, he and his family members were properly educated about how to manage the device and potential emergency situations. Eventually, the patient was discharged in a condition of NYHA functional class II with LVAD rpm 9,200, 4 months after the implantation. Additionally, obviously improved hemodynamic change by decreased LV filling pressure was observed in follow-up echocardiography (). LV dimension and IVC diameter were decreased, and IVS and IAS lay in midline position instead of deviating to the right side due to increased LV filling pressure, and functional MR was significantly decreased.\nThe patient maintains NYHA functional class II currently over 240 days after the LVAD implant.