Download Replacement of the aortic valve with a

Replacement of the aortic valve with a bioprosthesis
at the time of continuous flow ventricular assist device
implantation for preexisting aortic valve dysfunction
Brian Lima, MD, Themistokles Chamogeorgakis, MD, Maria Mountis, MD, and Gonzalo V. Gonzalez-Stawinski, MD
Left ventricular assist device (LVAD) implantation has become a mainstay
of therapy for advanced heart failure patients who are either ineligible for,
or awaiting, cardiac transplantation. Controversy remains over the optimal
therapeutic strategy for preexisting aortic valvular dysfunction in these
patients at the time of LVAD implant. In patients with moderate to severe
aortic regurgitation, surgical approaches are center specific and range from
variable leaflet closure techniques to concomitant aortic valve replacement
(AVR) with a bioprosthesis. In the present study, we retrospectively analyzed
our outcomes in patients who underwent simultaneous AVR and LVAD
implantation secondary to antecedent aortic valve pathology. Between
January 2004 and June 2010, 144 patients underwent LVAD implantation
at a single institution. Of these, 7 patients (4.8%) required concomitant
AVR. Five of the 7 patients (71%) survived to hospital discharge and suffered no adverse events in the perioperative period. One-year survival for
the discharged patients was 80%, and no prosthetic valve-related adverse
events were observed in long-term follow-up. Given our experience, we
conclude that bioprosthetic AVR is a plausible alternative for end-stage
heart failure patients at the time of LVAD implantation.
C
ontinuous flow pump technology has revolutionized
long-term ventricular assist device therapy. Results from
the HeartMate II trial show a considerable improvement in both survival and quality of life in recipients
of this technology (1, 2). A proportion of these patients have
associated aortic regurgitation (AR) that if left untreated may
progress and impact the effectiveness of the pump by limiting
forward flow (3). There are several methods of managing AR at
the time of left ventricular assist device (LVAD) implantation.
Each has its own merits and flaws. Techniques include patch
closure of the outflow tract (4), primary aortic cuspal closure
with felt strips (5), coaptation stitching of the valve cusps (6),
and aortic valve replacement (7). Since our initial experience
with the HeartMate II device, we have treated patients with
significant AR at the time of HeartMate II implantation by
replacing the aortic valve with a bioprosthesis. This report describes the outcomes associated with this approach.
METHODS
A retrospective review of end-stage heart failure patients
who had undergone LVAD implantation with the HeartMate II
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continuous flow pump with concomitant aortic valve replacement at a single institution was conducted. Etiology of heart
failure encountered in this study included ischemic and valvular
cardiomyopathies. The latter was defined as end-stage heart failure secondary to untreated aortic or mitral valve disease. Medical
records provided demographic and echocardiographic information as well as short- and long-term outcomes. This study was
conducted with the approval of the institutional review board
of the Cleveland Clinic.
All procedures were performed through a full median sternotomy. Aortic valve replacements preceded pump implantations. A pump pocket for the HeartMate II was initially created,
and subsequently patients were heparinized and cannulated.
With an appropriate activated clotting time (>400 seconds), patients were placed on cardiopulmonary bypass. Myocardial protection was achieved using intermittent cold blood cardioplegia.
Aortic valves were replaced through a hockey stick aortotomy. Once the valve was excised, an appropriate-sized bioprosthesis was selected and sutured into place with horizontal
mattress pledgeted sutures placed on the ventricular side of the
annulus. As described previously, ‘annulus’ was defined as the
virtual, circular ring delineated by the nadirs of the semilunar
leaflet attachments (8). The aortotomy was closed and the LVAD
implanted. In all cases the outflow graft was anastomosed to
the ascending aorta distally beyond the suture line employed
for the valve replacement.
The anticoagulation regimen for patients receiving a HeartMate II device consisted of warfarin, dipyridamole, and aspirin. Early in our experience with the HeartMate II, the target
international normalized ratio (INR) ranged from 2.0 to 3.0.
More recently, given the current understanding of the physiologic alterations in the coagulation system that occur with this
device, we have targeted an INR of 1.7 to 2.5. Immediately
From the Department of Cardiac Surgery, Baylor University Medical Center
at Dallas, Dallas, Texas (Lima, Chamogeorgakis), and the Department of
Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland,
Ohio (Mountis, Gonzalez-Stawinski). Dr. Gonzalez-Stawinski is now affiliated with
Baylor University Medical Center at Dallas.
Corresponding author: Brian Lima, MD, Baylor University Medical
Center at Dallas, 3900 Junius Street, Suite 415, Dallas, TX 75246
(e-mail: [email protected]).
Proc (Bayl Univ Med Cent) 2015;28(4):454–456
Table. Demographic and outcome data for seven patients receiving simultaneous AVR and LVAD
Age
(years)
Sex
1
56
M
DT
*
VC
6
No
0
2
65
M
BTT
4+
VC
159
No
0
VC
711
Intermittently
–
Patient
Indication for
LVAD insertion
Degree of AR
(0–4+)
Etiology of
heart failure
Days with
LVAD
Bioprosthesis opens at
last echocardiogram
Thrombus on
bioprosthesis
3
57
M
DT
0†
4
64
F
BTT
2+
IC
421
No
‡
5
54
M
DT
1+
IC
99
No
–
6
71
M
DT
1–2+
VC
9
No
0
7
59
M
DT
2+
IC
391
Intermittently
–
AR indicates aortic regurgitation; AVR, aortic valve replacement; BTT, bridge-to-transplantation; DT, destination therapy; IC, ischemic cardiomyopathy; LVAD, left ventricular assist
device; VC, valvular cardiomyopathy; –, no information available.
*Excision of mechanical prosthesis.
†Valve stenotic.
‡None on valve but occluding thrombus in subaortic valve area.
postoperatively, the speed of the pump was set between 8200
and 8800 revolutions per minute (rpm). This allowed for easier
hemodynamic management in the immediate postoperative
period because of fluid shifts encountered in the first few days
following HeartMate II implantation. The speed typically was
adjusted so that there was adequate left ventricular unloading
and midline septal alignment, with the aortic valve opening
at every third cardiac beat. For patients who underwent aortic
valve replacement, we attempted to adjust the pump’s rpm so
that the valve opened with every beat. These adjustments were
typically conducted with echocardiographic assistance.
RESULTS
Between January 2004 and June 2010, 144 patients underwent implantation of a HeartMate II at the Cleveland Clinic
for the management of end-stage heart disease. Among these,
7 (4.8%) underwent concomitant aortic valve replacement
(Table). Indications for HeartMate II support included valvular cardiomyopathy (n = 4) and ischemic cardiomyopathy
(n = 3). The end goal for LVAD therapy was destination therapy
in five patients and bridge-to-transplantation in two. Indications
for aortic valve replacement included four cases of pure AR, one
case of mixed AR and aortic stenosis, one case of aortic stenosis,
and one case of an in situ mechanical aortic valve prosthesis that
needed to be exchanged for a bioprosthesis.
Five of seven patients (71%) survived to discharge and suffered
no adverse events during their hospitalization. Two perioperative
deaths occurred at 6 and 9 days, respectively. These included one
patient who underwent a primary aortic valve replacement and
HeartMate II implantation. This patient succumbed to severe and
refractory vasoplegia, a form of vasodilation not associated with
sepsis or neurologic etiologies. Another patient had undergone a
redo sternotomy with aortic and mitral valve exchanges from mechanical to bioprosthetic valves, as well as tricuspid valve repair and
HeartMate II implantation. This patient died of severe pulmonary
dysfunction secondary to acute respiratory distress syndrome and
multisystem organ failure. At autopsy, both bioprosthetic valves
were well seated with no evidence of thrombus formation.
October 2015
At last follow-up, four of the five patients were alive and
well. One patient died of sepsis after 99 days of support. Echocardiographic examination of the bioprosthetic valve prior to
the patient’s demise suggested that the valve was well seated
with no evidence of thrombus or pannus formation. An autopsy
was not performed.
The remaining patients had no thromboembolic complications at a mean length of support of 395 days (range, 159 to
711). Echocardiographic examination of these patients revealed
valves that were well seated with no evidence of thrombosis
or pannus formation. Bioprosthetic valves in two destination
therapy patients (time on support 391 days and 711 days)
intermittently opened on examination. Two other patients
underwent transplantation at 159 and 421 days of support.
Their echocardiograms showed well-seated bioprosthetic valves
that were not opening, with no thrombus or pannus deposited
around the valve. Examination of the valves in explanted hearts
revealed well-seated valves, without cuspid fusion or cusped
thrombi. However, in the patient who was supported 159 days,
the left ventricular outflow tract was completely open, while in
the one supported for 421 days a fibrous membrane completely
occluded the undersurface of the valve.
DISCUSSION
The optimal management of patients with coexisting AR at
the time of continuous flow pump LVAD implantation is not
well established. Several options exist, each with its own advantages and disadvantages. Supporters of valve procedures aimed
at closing the ventricular outflow with either patch coverage of
the valve or leaflet closure suggest that these approaches may
theoretically decrease the risk of pump, aortic valve, or subaortic
valve thrombus formation by directing flow entirely through the
pump (5, 9). Concerns raised by this approach include the mandatory dependence on the pump, which, if it were to malfunction,
would potentially be lethal if the ventricle had not recovered to
accommodate a high regurgitant backflow. Additionally, these
approaches may be applicable only to patients who are transplant
candidates, not to patients in whom recovery may be possible.
Replacement of the aortic valve with a bioprosthesis at the time of continuous flow ventricular assist device implantation
455
Others suggest treating AR with a coaptation stitch of the
leaflets (Park’s stitch) (6). Different from outflow closure techniques, this approach permits partial flow through the root,
which may prevent thrombus formation while treating the AR.
A second benefit of this technique is that it does not render the
patient’s circulation completely LVAD dependent. Issues associated with this approach lie in the potential for valve pathology
progression, disruption of the repair causing severe AR, and
unknown long-term success (10). Similar to ventricular outflow
closure, this technique may not be applicable to those in whom
left ventricular recovery is possible.
Bioprosthetic valve replacement has the advantage of
eliminating valve pathology altogether while not rendering
the patient LVAD dependent. If patients are allowed to eject
through the valve with some frequency during the cardiac cycle,
thrombus formation and leaflet fusion may be prevented. Valve
replacement with a bioprosthesis may be a better approach for
patients who are recovery candidates, because the LVAD may
be explanted without the need to add a valve procedure. The
concern of this approach is subvalvular obstruction, which may
occur as a result of stagnant blood underneath the bioprosthetic
valve (7, 11, 12). Thrombus in this location may embolize during the cardiac cycle or alternatively mature into a fibrous membrane obstructing the outflow tract. The latter event, as seen
in one of our patients, may be difficult to detect by standard
screening techniques such as echocardiography.
Thrombus/pannus formation is not a universal occurrence
following valve replacement with a bioprosthesis. Certainly we
do not believe that this event is happening in those patients
whose valves are intermittently opening while on support, but
it may occur, particularly with longer support times. A second
issue associated with valve replacement therapy is the added
cost incurred when replacing the valve. Furthermore, the time
spent replacing the valve may add morbidity to an already complicated procedure.
When to replace an incompetent valve may be a challenging decision. The decision has to be balanced not only with
the degree of AR but also the objective for which the LVAD
is used. For patients awaiting transplantation who have mild
to moderate AR and a short waiting time, replacing the valve
may not be necessary. Conversely, for patients who are destination therapy candidates who have anything greater than trivial
AR (+1 or greater), addressing the valve at the time of LVAD
implant seems reasonable.
Based on our experience and previously published reports, we
believe that a tailored approach to AR at the time of LVAD implantation is warranted. For patients who have a foreseeable short
456
support time, such as bridge-to-transplantation or frail patients,
it seems reasonable to treat AR with any one of the coaptation
or patch techniques previously described. However, for patients
in whom recovery is possible, long-term destination therapy patients, and those with extremely friable aortic valves, aortic valve
replacement with a bioprosthetic valve may be a better option.
Limitations of this study include the small number of patients,
the short follow-up, and the retrospective nature of this report.
1.
Rogers JG, Aaronson KD, Boyle AJ, Russell SD, Milano CA, Pagani
FD, Edwards BS, Park S, John R, Conte JV, Farrar DJ, Slaughter MS;
HeartMate II Investigators. Continuous flow left ventricular assist device
improves functional capacity and quality of life of advanced heart failure
patients. J Am Coll Cardiol 2010;55(17):1826–1834.
2. Slaughter MS, Rogers JG, Milano CA, Russell SD, Conte JV, Feldman D,
Sun B, Tatooles AJ, Delgado RM 3rd, Long JW, Wozniak TC, Ghumman
W, Farrar DJ, Frazier OH; HeartMate II Investigators. Advanced heart
failure treated with continuous-flow left ventricular assist device. N Engl
J Med 2009;361(23):2241–2251.
3. Atkins BZ, Hashmi ZA, Ganapathi AM, Harrison JK, Hughes GC,
Rogers JG, Milano CA. Surgical correction of aortic valve insufficiency
after left ventricular assist device implantation. J Thorac Cardiovasc Surg
2013;146(5):1247–1252.
4. Rao V, Slater JP, Edwards NM, Naka Y, Oz MC. Surgical management of
valvular disease in patients requiring left ventricular assist device support.
Ann Thorac Surg 2001;71(5):1448–1453.
5. Adamson RM, Dembitsky WP, Baradarian S, Chammas J, May-Newman
K, Chillcott S, Stahovich M, McCalmont V, Ortiz K, Hoagland P, Jaski
B. Aortic valve closure associated with HeartMate left ventricular device
support: technical considerations and long-term results. J Heart Lung
Transplant 2011;30(5):576–582.
6. Park SJ, Liao KK, Segurola R, Madhu KP, Miller LW. Management
of aortic insufficiency in patients with left ventricular assist devices: a
simple coaptation stitch method (Park’s stitch). J Thorac Cardiovasc Surg
2004;127(1):264–266.
7. Feldman CM, Silver MA, Sobieski MA, Slaughter MS. Management of
aortic insufficiency with continuous flow left ventricular assist devices: bioprosthetic valve replacement. J Heart Lung Transplant 2006;25(12):1410–
1412.
8. Charitos EI, Sievers HH. Anatomy of the aortic root: implications for
valve-sparing surgery. Ann Cardiothorac Surg 2013;2(1):53–56.
9. Cohn WE, Demirozu ZT, Frazier OH. Surgical closure of left ventricular
outflow tract after left ventricular assist device implantation in patients
with aortic valve pathology. J Heart Lung Transplant 2011;30(1):59–63.
10. Goda A, Takayama H, Pak SW, Uriel N, Mancini D, Naka Y, Jorde UP.
Aortic valve procedures at the time of ventricular assist device placement.
Ann Thorac Surg 2011;91(3):750–754.
11. Butany J, Leong SW, Rao V, Borger MA, David TE, Cunningham KS,
Daniel L. Early changes in bioprosthetic heart valves following ventricular
assist device implantation. Int J Cardiol 2007;117(1):e20–e23.
12. Rose AG, Connelly JH, Park SJ, Frazier OH, Miller LW, Ormaza S.
Total left ventricular outflow tract obstruction due to left ventricular assist device-induced sub-aortic thrombosis in 2 patients with aortic valve
bioprosthesis. J Heart Lung Transplant 2003;22(5):594–599.
Baylor University Medical Center Proceedings
Volume 28, Number 4