European Journal of Echocardiography Advance Access published online on February 7, 2008
European Journal of Echocardiography, doi:10.1093/ejechocard/jen002
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2008. For permissions please email: journals.permissions@oxfordjournals.org
Functional mitral stenosis: a rare complication of the Impella assist device
Stefan Toggweiler,
Peiman Jamshidi and
Paul Erne*
Division of Cardiology, Kantonsspital Luzern, CH-6000 Luzern 16, Switzerland
Received 18 May 2007; accepted after revision 18 November 2007.
* Corresponding author. Tel: +41 41 205 52 08; fax: +41 41 205 22 34. E-mail address: paul.erne{at}ksl.ch
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Abstract
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In patients with left ventricular output failure, the Impella
left ventricular assist device increases the total cardiac output
despite a drop in the output provided by the left ventricle
itself. We present a patient with cardiogenic shock after myocardial
infarction, in whom an Impella recover 2.5 was implanted. Correct
placement was ensured by fluoroscopy, pressure and current signals
displayed on the console of the system and transthoracic echocardiography.
On follow-up, the Impella device was dislocated with the shaft
of the device lying on the anterior mitral leaflet causing a
functional mitral stenosis evident by an increased transmitral
diastolic flow gradient. After removing the device, the haemodynamics
of the patients improved within minutes. Other than a mild regurgitation,
mitral valve was without pathological findings. Although infrequent,
this case shows a possible complication of the Impella ventricular
assist device and highlights the importance of periodical echocardiographic
surveillance, especially in patients who show a poor response
to therapy.
Keywords: Impella; Functional mitral stenosis; Cardiogenic shock; Left ventricular assist device; Echocardiography
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Case report
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A 70-year-old woman with diabetes and hypertension presented
in emergency room with decompensated heart failure because of
myocardial infarction. ECG showed a new complete left bundle
brunch block. Acute coronary angiography revealed significant
stenoses of the left anterior descending (LAD) and the right
coronary arteries (RCA). The RCA was stented with drug-eluting
stents. During the stenting of the LAD, the left main artery
was dissected with the tip of the guiding catheter and immediately
stented with a drug-eluting stent. The patient became unstable
and was intubated and put on inotropes. In order to stabilize
the patient after left main stenting, an Impella left ventricular
assist device (Abiomed Europe, Aachen, Germany) and an intra-aortic
balloon pump were inserted. Correct placement of the Impella
device was ensured by fluoroscopy, the pressure and current
signals displayed on the console of the system, and transthoracic
echocardiography showing the plastic pig tail tip placed nearby
the left ventricular apex without evidence of movement limitation
of the anterior mitral leaflet or an increased mitral valve
gradient. Left ventricular ejection fraction was 43% with the
two devices installed. Mitral valve of the patient was structurally
normal, despite a mild pre-existing regurgitation. Over the
next 2 days, the patient remained stable but catecholamines
could not be reduced. Chest X-ray showed pulmonary congestion,
and follow-up echocardiography revealed a dislocation of the
Impella device with the shaft lying nearby the anterior mitral
leaflet compromising diastolic excursion (see Supplementary
material online, video loops 1 and 2). This caused a mild functional
mitral stenosis (
Figure 1), with a mean transvalvular gradient
of 4.72 mmHg (
Figure 2). After removing the Impella, transmitral
gradient declined to a mean of 2.97 mmHg (
Figure 3). The
patient improved clinically, blood pressure rose from 110/80
to 130/80 mmHg and the heart rate decreased from 118 to 102/min
(sinus tachycardia) within minutes. The next days, the patient
was extubated and intra-aortic balloon pump was removed.
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Discussion
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The Impella left ventricular assist device has been used in
the setting of cardiogenic shock alone or in combination with
other assist devices such as intra-aortic balloon pump counterpulsation.
1–3 The Impella was associated with good results in unstable patients
undergoing coronary revascularization, including stenting of
the left main coronary artery.
4–6 In a case study by Valgimigli
et al.,
6 an increase of 1.43 L/min in the cardiac output was
noticed when running the pump at maximal speed (50 000 rpm).
This increase consisted of a 2.41 L/min gain provided by the
Impella device and a 0.98 L/min drop in the output provided
by the left ventricle. The left ventricular coaxial pump seems
to make complete revascularization in patients with off pump
coronary artery bypass graft surgery possible.
7 Common device-related
complications are sensor failure, pump displacement, and haemolysis.
8 Echocardiography is the most frequently used non-invasive modality
to evaluate placement and function of the Impella device.
9 Before
device implantation, echocardiography is useful to rule out
anatomic contraindications. During and after implantation, correct
positioning and left ventricular filling necessary to optimize
pump performance can be evaluated with echocardiography. During
assistance, echocardiography helps assessing left and right
ventricular function and patient–device interaction.
In this case, an Impella Recover LP 2.5 assist device was used in an unstable patient undergoing coronary revascularization including left main artery stenting. Two days after the procedure, transthoracic echocardiography showed that the formerly correctly placed Impella device dislocated. The shaft of the Impella was lying nearby the anterior mitral valve leaflet, causing a mild functional mitral stenosis by compromising complete diastolic excursion of the anterior leaflet (see Supplementary material online, video loops 1 and 2). After removing the device, haemodynamics improved immediately.
Although this complication is rare, this case highlights the importance of regular echocardiographic evaluation for correct position in patients treated with this assist device, despite normal function of the device based on the pressure and current signals displayed on the console of the system. Among others, myxoid degeneration of the mitral valve is a known contraindication for use, but this patient had a normal mitral valve apart from mild regurgitation.
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Supplementary material
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Supplementary material associated with this article can be found
in the online version.
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References
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- Meyns B, Dens J, Sergeant P, Herijgers P, Daenen W, Flameng W. Initial experiences with the Impella device in patients with cardiogenic shock. Thorac Cardiovasc Surg (2003) 51:312–7.[CrossRef][Web of Science][Medline]
- Vlasselaers D, Desmet M, Desmet L, Meyns B, Dens J. Ventricular unloading with a miniature axial flow pump in combination with extracorporeal membrane oxygenation. Intensive Care Med (2006) 32:329–33.[CrossRef][Medline]
- Garatti A, Colombo T, Russo C, Lanfranconi M, Milazzo F, Catena E, et al. Assessment of hemolysis related quantities in a microaxial blood pump by computational fluid dynamics. J Heart Lung Transplant (2005) 24:481–5.[CrossRef][Web of Science][Medline]
- Henriques JPS, Remmelink M, Baan J, van der Schaaf RJ, Marije V, Koch KT, et al. Safety and feasibility of elective high-risk percutaneous coronary intervention procedures with left ventricular support of the Impella Recover LP 2.5. Am J Cardiol (2006) 97:990–2.[CrossRef][Web of Science][Medline]
- Minden HH, Lehmann H, Meyhöfer J, Butter C. Transradial unprotected left main coronary stenting supported by percutaneous Impella Revocer LP 2.5 assist device. Clin Res Cardiol (2006) 95:301–6.[CrossRef][Medline]
- Valgimigli M, Steendijk P, Sianos G, Onderwater E, Serruys PW. Left ventricular unloading and concomitant total cardiac output increase by the use of percutaneous Impella Recover LP 2.5 assist device during high-risk coronary intervention. Catheter Cardiovasc Interv (2005) 65:263–7.[CrossRef][Medline]
- Isgro F, Kiessling AH, Rehn E, Lang J, Saggau W. Intracardiac left ventricular support in beating heart, multi-vessel revascularization. J Card Surg (2003) 18:240–4.[CrossRef][Medline]
- Meyns B, Dens J, Sergeant P, Herijgers P, Daenen W, Flameng W. Initial experiences with the Impella device in patients with cardiogenic shock—Impella support for cardiogenic shock. Thorac Cardiovasc Surg (2003) 51:312–7.[CrossRef][Web of Science][Medline]
- Catena E, Milazzo F, Merli M, Paino R, Garatti A, Colombo T, et al. Echocardiographic evaluation of patients receiving a new left ventricular assist device: the Impella revocer 100. Eur J Echocardiogr (2004) 5:430–7.[Abstract/Free Full Text]
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