Fontan-Like Hemodynamics Complicated With Ventricular Fibrillation During Left Ventricular Assist Device Support Teruhiko Imamura,1 MD, Koichiro Kinugawa,2 MD, Daisuke Nitta,3 MD, Osamu Kinoshita,4 MD, Kan Nawata,4 MD, and Minoru Ono,4 MD Summary We experienced a patient who had received an implantable continuous-flow left ventricular assist device (LVAD) (HeartMate II, Thoratec Corp, Pleasanton, CA, USA) and was admitted to our hospital because of repeated ventricular tachyarrhythmias refractory to electrical defibrillation as well as intensive pharmacological therapy. We decided to discontinue defibrillating, but under ventricular fibrillation his hemodynamics were maintained without end-organ dysfunction during LVAD support (mean right atrial pressure 18 mmHg; pulmonary vascular resistance 1.6 WU; pulmonary capillary wedge pressure 11 mmHg; cardiac index 2.04 L/minute/m2) due to optimization of the rotation speed (from 8800 to 9200 rpm). Such “Fontan-like circulation” could be accomplished by adequate volume control, lowering pulmonary vascular resistance, and potent LV blood removal by optimal rotation speed of the LVAD, although the precise conditions to maintain the Fontan-like circulation during LVAD therapy remained uncertain. Considering the severe donor heart shortage and high degree of difficulty of the catheter ablation procedure to manage ventricular tachyarrhythmias, constructing a Fontan-like circulation in the presence of ventricular tachyarrhythmias may be one unique strategy. Longterm prognosis in patients with sustained ventricular tachyarrhythmias during LVAD support would be a future concern. (Int Heart J 2016; 57: 000-000) Key words: HeartMate II, Ventricular tachyarrhythmia, Heart failure
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ontinuous flow left ventricular assist devices (LVAD) are recently developed devices that support the systemic circulation and dramatically improve hemodynamics.1) This therapy improves patient quality of life, survival rates, and morbidity compared with conventional medical therapy.2) Though LVAD provides sufficient hemodynamic support in most cases, ventricular tachyarrhythmias (VTs) are sometimes complicated, and often refractory to pharmacologic therapy or even electrical defibrillation. It remains uncertain how to manage patients suffering sustained VTs during LVAD therapy.3) We here describe a patient with sustained ventricular fibrillation (Vf) whose hemodynamics were maintained successfully under LVAD support by optimizing the rotation speeds.
Case Report A 44-year old male patient (170 cm, 61 kg) had received cardiac resynchronization therapy with a defibrillator to treat advanced heart failure (HF) due to dilated cardiomyopathy 4 years previously and then eventually received implantation of a continuous-flow LVAD (HeartMate II, Thoratec Corp, Pleasanton, CA, USA) 3 years later. His postoperative course was
uneventful with carvedilol 30 mg/day, enalapril 2.5 mg/day, aldosterone antagonist 75 mg/day, and furosemide 20 mg/day. He was admitted to our hospital because of repeated VTs necessitating electrical defibrillation. After admission, he suffered repeated VTs refractory to various anti-arrhythmic agents, titration of β-blocker dose, and electrical defibrillation. We eventually decided to manage the patient under sustained ventricular fibrillation (Vf, Figure 1A). Congestive hepatic injury developed temporarily even after introduction of the phosphodiesterase-5 inhibitor (PDE5I) tadalafil, however, optimization of the rotation speed (from 8800 to 9200 rpm, Figure 2) resolved the liver damage. Transthoracic echocardiography showed that LV diastolic diameter was 68 mm along with a moderate degree of aortic regurgitation and no evidence of sucking of the outflow cannula (Figure 1B). The right ventricular (RV) dilatation was accompanied by coaptation failure of the tricuspid valve. Hemodynamic study showed pulseless pressures through the right atrium (RA), RV, and main pulmonary artery (PA), and averaged 17 mmHg at 9200 rpm (Figure 1C). Cardiac index and pulmonary vascular resistance were calculated as 2.0 L/ minute/m2 and 1.6 WU. Hemodynamic and echocardiographic parameters at several rotation speeds (8800-9600 rpm) were
From the 1 Department of Therapeutic Strategy for Heart Failure, Graduate School of Medicine, The University of Tokyo, Tokyo, 2 Second Department of Internal Medicine, Toyama University Hospital, Toyama, Departments of 3 Cardiovascular Medicine and 4 Cardiac Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. Address for correspondence: Koichiro Kinugawa, MD, Department of Therapeutic Strategy for Heart Failure, Graduate School of Medicine, University of Tokyo, 7-31 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. E-mail:
[email protected] Received for publication January 5, 2016. Revised and accepted February 7, 2016. Released in advance online on J-STAGE July 7, 2016. (This is “Advance Publication”.) All rights reserved by the International Heart Journal Association. 1
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IMAMURA, ET AL
Figure 1. Electrocardiography after admission (A), transthoracic echocardiography (B), and pressure waves during hemodynamic study (C) at 9200 rpm. ECG indicates electrocardiography; RA, right atrium; RV, right ventricle; PA, pulmonary artery; and PCW, pulmonary capillary wedge.
Discussion
Figure 2. In-hospital time course. HMII indicates HeartMate II; VT, ventricular tachycardia; Vf, ventricular fibrillation; AST, aspartate aminotransferase; BW, body weight; ICU, intensive care unit; and SG, Swan-Ganz catheter examination.
measured (Table). The patient complained of dyspnea and abdominal distention along with elevated RA pressure at 8800 rpm. Incremental rotation speeds > 9200 rpm increased RA pressure and decreased cardiac output. Considering the results, the rotation speed was set at 9200 rpm, and the dose of furosemide was maintained at 20 mg/day. He was discharged on day 52 and then managed as ambulant with New York Heart Association class III symptoms.
VTs during LVAD support: We sometimes experience VTs in patients receiving LVAD treatment.4) Garan, et al reported that 24% of patients suffered VTs within 30 days after LVAD implantation.5) Some VTs result from apparent causes such as sucking of the outflow cannula during LVAD support, and such VTs may be managed successfully by volume loading or optimization of the rotation speed. However, most VTs are refractory to such non-invasive procedures. We were unable to identify any treatable causes of the VTs in this case. Pecha, et al suggested that implantable cardioverter-defibrillators should be considered before or after LVAD implantation, especially in patients with a previous history of VTs, because such patients remained at higher risk of VTs during LVAD support.6) However, VTs are sometimes refractory to repeated electrical defibrillation.7) Moreover, repeated defibrillation is associated with acute worsening of RV failure.5) Early heart transplantation may be another choice in some countries with many donor hearts. However, Japanese patients usually need to wait for more than 2 years to receive a heart transplantation because of a shortage of donor hearts. Catheter ablation is another procedure for treating VTs, but it is often difficult to manage VTs and is somewhat high risk in patients with advanced HF receiving LVAD. Thus, one therapeutic strategy for refractory VTs during LVAD support may be the management of hemodynamics under VTs. Formation conditions for hemodynamically stable VTs during LVAD support: We experienced a patient whose hemodynam-
ics were maintained under Vf during LVAD support. His pulse-
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VF UNDER LVAD SUPPORT Table. Hemodynamic Study at Each Rotation Speed
Hemodynamics mRAP, mmHg mRVP, mmHg PCWP, mmHg mPAP, mmHg CI, L/minute/m2 PVR, WU SvO2, % Echocardiography LVDd, mm AV opening AR, grade
8800 rpm
9000 rpm
9200 rpm
9400 rpm
9600 rpm
22 21 16 21 1.88 1.47 53.6
19 20 13 19 2.01 1.67 61.1
17 17 11 17 2.04 1.63 65.6
19 18 11 18 2.02 1.92 64.4
19 17 10 18 1.92 2.31 64.2
69 (-) mild
69 (-) mild
68 (-) moderate
66 (-) moderate
66 (-) moderate
mRAP indicates mean right atrial pressure; mRVP, mean right ventricular pressure; PCWP, pulmonary capillary wedge pressure; mPAP, mean pulmonary artery pressure; CI, cardiac index; PVR, pulmonary vascular resistance; SvO2, mixed venous blood saturation; LVDd, left ventricular diastolic diameter; AV, aortic valve; and AR, aortic regurgitation.
less and “Fontan-like” pressure waves among RA, RV, and PA indicated that there is no right ventricular pump activity to propel blood into the PA circulation.8) Under what conditions do such hemodynamics arise? Lower PVR is one of the major factors for a better prognosis in patients with Fontan circulation.9) PDE5Is, instead of endothelin receptor antagonists considering their adverse effect of liver injury, are recommended for improving exercise performance in patients with single-ventricle physiology after the Fontan operation.10) Congestion was not normalized after initiation of the PDE5I tadalafil. PA pressure might have already remained at a lower level during sustained Vf because of no RV contraction. Preserved LV function is also required for the establishment of original Fontan circulation because the LV should vacuum blood from the pulmonary vascular bed without the help of the right side of the heart.9) In this sense, an incremental rotation speed was effective at treating the congestion. However, a higher rotation speed > 9200 rpm did not reduce the RA pressure any further. Too great of a rotation speed may increase venous return, which worsens congestion.11) Higher rotation speeds also may facilitate a leftward shift of the intraventricular septum, which worsens the degree of tricuspid regurgitation and elevates the RA pressure. Furthermore, at a high rotation speed > 9200 rpm, the LV diameter decreased down to a level at which outflow cannula sucking may occur. Therefore, hemodynamic study is an essential procedure for optimizing the rotation speed in such situations. Since there is no ventricular pump power to propel blood into the PA circulation, central venous pressure (CVP) remains elevated in patients undergoing a Fontan operation.12) An increased level of CVP results in congestive hepatic injury as observed in this patient.13) In contrast, CVP is the sole preload power to push blood into the PA circulation. Considering that congestive hepatic injury and abdominal distention emerged probably at a mean RA pressure > 20 mmHg in this patient, it may have been preferable to maintain CVP < 20 mmHg by using a few diuretics. Too much diuretics would decrease the preload and induce low output syndrome refractory to incremental rotation speed. Although the precise mechanism is uncertain, preconditioning of the liver by repeated congestion due to VTs may also induce tolerability of the liver to Fontan-like
circulation with elevated CVP. The hemodynamics are similar to that of severe RV failure during LVAD support. As we previously reported,14) hemodynamics were also maintained under a low PVR of 1.2 WU in a patient with severely impaired RV function (RV stroke work index 0.4 g/m). A lower PVR preoperatively may be a key to managing patients with RV failure by LVAD support without right VAD.15) In this previous case, CVP was somewhat lower than that of the present patient (12 mmHg versus 17 mmHg), most likely due to residual RV function. Patients with Vf should have a higher CVP to push blood into the pulmonary vascular bed without the help of the RV. However, whether all patients with RV failure can be managed successfully as we showed here is unclear. Optimal management procedures for post-LVAD RV failure should be established in the near future. Although the patient could be discharged in an ambulatory condition, the long-term prognosis in patients with sustained Vf during LVAD support remains uncertain. Various complications including venous insufficiency, thrombosis, end-organ dysfunction, and protein-losing enteropathy,16) should be monitored carefully for at least 2 years before heart transplantation.
Disclosure The authors declare that they have no conflicts of interest to disclose.
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