Ann Thorac Surg 2006;81:e6-e8
© 2006 The Society of Thoracic Surgeons
Case report
Native Aortic Valve Insufficiency in Patients With Left Ventricular Assist Devices
Ayesha S. Bryant, MSPH
a
,
William L. Holman, MD
a
,
*
,
Navin C. Nanda, MD
b
,
Srinivas Vengala, MD
b
,
Margaret S. Blood, RN
c
,
Salpy V. Pamboukian, MD
b
,
James K. Kirklin, MD
a
a Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA
b Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
c Department of Nursing, University of Alabama at Birmingham, Birmingham, Alabama, USA
Accepted for publication August 29, 2005.
* Address correspondence to Dr Holman, Department of Surgery, Room 719, 703 19th St S, Birmingham, AL 35294-0007 (Email: wholman{at}its.uab.edu).
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Abstract
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Management of mild to moderate aortic insufficiency in patients with a left ventricular assist device remains controversial. We report 3 patients with aortic insufficiency and pulsatile left ventricular assist devices treated with a central aortic valve coapting suture. Two of the repairs have been durable for more than 1 year and aspirin appears to be sufficient anticoagulation.
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Introduction
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Aortic valve insufficiency poses a challenge to left ventricular assist device (VAD) support. Backflow through an incompetent aortic valve increases after initiation of left ventricular mechanical assistance. This is due to an increase in the transaortic valvular gradient. Replacement with a prosthetic valve will reduce regurgitant flow. However, even with anticoagulation, clot formation over or under the prosthetic valve can occur with embolization of thrombus or occlusion of the left ventricular outflow orifice [1, 2]. These complications occur with mechanical as well as biologic prostheses.
Another possibility is to occlude the aortic orifice with a patch [2, 3]. This precludes tapering left VAD support to encourage cardiac recovery and it prevents periodic washing of the aortic root by ejection of blood. Such washing may be important for minimizing thrombus in the aortic root. Moreover, if the VAD fails the only paths that remain for left ventricular ejection are through the pump or through an incompetent mitral valve.
Suture closure of the aortic valve commissures either centrally with a single buttressed stitch [4] or along the full length of non-coaptation [2] has been reported as a method to eliminate aortic regurgitation. The purpose of this report is to describe our experience with single-stitch central closure of the aortic valve, including follow-up echocardiograms that assess the durability of repair and flow across the residual aortic orifices.
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Case Reports
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We have now treated 3 patients using central aortic valve sutures (Table 1) (Figs 1, 2).
The present retrospective analysis received approval by the University of Alabama at Birmingham Institutional Review Board on October 6, 2004, and the Institutional Review Board approved our request for waiver of informed consent.
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Table 1. Summary of Echocardiograms to Assess Aortic Valve Insufficiency in Patients With Left Ventricular Assist Devices
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Fig 1. Two-dimensional color Doppler transthoracic echocardiographic image obtained after placement of a central coapting stitch in the aortic valve of patient 1 after placement of the left ventricular assist device. The arrowhead points to flow signals moving from the left ventricle (LV) into the aorta (AO) through the aortic valve (AV). (RV = right ventricle.)
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Fig 2. Two-dimensional color Doppler transthoracic echocardiographic image obtained after placement of a central coapting stitch in the aortic valve of patient 2 after placement of the left ventricular assist device. The arrowhead points to flow signals moving from the left ventricle (LV) into the aorta (AO) through the aortic valve (AV). (RV = right ventricle.)
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Patient 1
The first patient was a 64-year-old man with ischemic cardiomyopathy. His history included prior coronary artery bypass grafting and mitral valve replacement with a mechanical prosthesis. At the time of VAD implant, transesophageal echocardiography confirmed moderate aortic valve insufficiency and there was mild aortic root dilation. The aortic valve was confirmed to be a tricuspid structure with thickening and central noncoaptation of the leaflets. It was repaired using a single pledget-reinforced suture that reapproximated the aortic valve leaflets but did not approximate the commissural edges. After separation from bypass, there was trivial aortic insufficiency and intermittent minimal left ventricular ejection.
The patient had no thromboembolic events during 448 days of support. His anticoagulation included therapeutic warfarin or heparin to minimize thromboembolism related to his mechanical valve prosthesis. The left VAD flows ranged from 4 to 6 L/min. There was one instance of when the device stopped twice for less than 60 seconds due to a short circuit in the controller wiring. The patient remained asymptomatic during hand pumping when diagnostic maneuvers and a controller change were accomplished. A subsequent motor failure in the pump was complicated by acute myocardial infarction and pulmonary injury. The patient died after 448 days of circulatory support. An echocardiogram performed 419 days after the aortic sutures were placed showed trivial aortic insufficiency.
Patient 2
The second patient was a 65-year-old man with ischemic cardiomyopathy who had no cardiac operations prior to VAD placement. Echocardiograms prior to and during VAD placement confirmed the presence of moderate (3 on a scale of 5) aortic insufficiency. At surgery, mild aortic annular dilation and central noncoaptation of the aortic leaflets was confirmed. A single pledgeted monofilament suture was used to approximate the central portion of the three aortic leaflets.
The patient was discharged from the hospital after the implant and remained an outpatient with aspirin as his only anticoagulation until his emergent return to this facility for pump motor failure 520 days after initial implantation and valve repair. He was placed on a pneumatic driver, which produced systolic blood pressures ranging from 100 to 120 mm Hg. Transesophageal echocardiography at the time of surgery showed minimal aortic insufficiency and intermittent opening of the unsutured portions of the aortic commissures. He was discharged 11 days after VAD replacement.
Patient 3
A third patient had emergent VAD placement for management of cardiogenic shock complicated by intractable ventricular arrhythmias after an acute infarction. He had recurrent heart failure develop 11 months later in association with an increase in VAD output as high as 8 to 10 L/min. Transthoracic echocardiograms at the time of implant and 79 days later showed mild to moderate aortic insufficiency. However, echocardiograms obtained 350 and 486 days after left VAD implant showed moderate to severe aortic insufficiency. The heart failure initially responded to afterload reduction and diuretics, but the symptoms recurred. There was no evidence of left VAD inflow or outflow valve insufficiency by transesophageal echocardiography or preoperative cardiac catheterization. At catheterization severe native aortic valve insufficiency was confirmed. At 486 days after initial VAD placement, repair of the aortic valve was accomplished using a single pledgeted monofilament suture. Follow-up echocardiography 234 days after valve repair showed trivial native aortic valve insufficiency. The left VAD flow decreased immediately after aortic valve repair to a range of 5 to 7 L/min. His only anticoagulation was aspirin.
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Comment
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The optimal management of aortic valve pathology in patients with left VADs remains controversial. The issue may ultimately be resolved by the use of total artificial hearts [5, 6], however one is not currently available for use as destination therapy.
When faced with aortic valve insufficiency in a patient with a left VAD, the options for management include medical management (afterload reduction and diuretics), suture repair or closure of the native valve [4, 5], prosthetic valve replacement, and patch closure of the left ventricular outflow tract [2, 7]. Medical management will only provide temporary relief, as shown by the patient who had progressively worsening aortic insufficiency develop and who ultimately developed medically refractory heart failure. There is a tendency for aortic insufficiency to worsen as the duration of the left VAD support increases. This is likely due to progressive dilation of the aortic root and annulus, possibly worsened by radial force generated by pump ejection [8]. Placement of a single central coapting suture in the aortic valve is simple, and in 2 of our patients it has been durable for more than 1 year.
Valve replacement is time consuming compared with a central coapting suture, and a prosthetic valve may be more prone to thrombosis and embolism than a repaired native valve. Two of our patients were maintained on aspirin alone. Moreover, immediately after VAD placement, the left ventricle is typically too weak to eject against the pressure generated by the left VAD. The prosthetic valve is maximally vulnerable to thrombus formation at this time, and therapeutic anticoagulation may be hazardous in the early post-implant patient.
Placement of a central coapting stitch is a simple solution to aortic valve insufficiency in patients undergoing pulsatile left VAD placement. Our experience with mild to moderate degrees of aortic insufficiency suggests that anything greater than trivial insufficiency at the time of implant should be treated, particularly in patients who are expected to require more than 1 to 3 months of circulatory support. In the current era, this includes all destination therapy patients and nearly all patients bridged to transplantation. Use of a monofilament suture with felt buttressing on each leaflet seems to provide durable relief (ie, for at least for 1 year) from aortic insufficiency.
A note of caution is in order. Central aortic valve closure would not be appropriate if there is a high likelihood of ventricular recovery. Moreover, because ejection through the native aortic valve after repair is small, we would not recommend this strategy when a rotary pump is used for which native left ventricular ejection is desirable.
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References
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- 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 two patients with aortic valve bioprosthesis J Heart Lung Transplant 2003;22:594-599.[Medline]
- 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;71:1448-1453.[Abstract/Free Full Text]
- Stevenson LW, Miller LW, Desvigne-Nickens P, et al. Left ventricular assist device as destination for patients undergoing intravenous inotropic therapya subset analysis from REMATCH. Circulation 2004;110:975-981.[Abstract/Free Full Text]
- Park SJ, Liao KK, Segurola R, Madhu KP, Miller LW. Management of aortic insufficiency in patients with left ventricular assist devicesa simple coaptation stitch method (Park's stitch). J Thorac Cardiovasc Surg 2004;127:264-266.[Free Full Text]
- Dowling RD, Gray Jr LA, Etoch SW, et al. Initial experience with the AbioCor implantable replacement heart system J Thorac Cardiovasc Surg 2004;127:131-141.[Abstract/Free Full Text]
- Copeland JG, Smith RG, Arabia FA, et al. Cardiac replacement with a total artificial heart as a bridge to transplantation N Engl J Med 2004;351:859-867.[Abstract/Free Full Text]
- Savage EB, d'Amato TA, Magovern JA. Aortic valve patch closurean alternative to replacement with HeartMate LVAS insertion. Eur J Cardiothorac Surg 1999;16:359-361.[Abstract/Free Full Text]
- May-Newman KD, Hillen BK, Sironda CS, Dembitsky W. Effect of LVAD outflow conduit insertion angle on flow through the native aorta J Med Eng Technol 2004;28:105-109.[Medline]
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Abstract
Introduction
