© 2004 by European Society of Cardiology
Copyright © 2004, The European Society of Cardiology
Echocardiographic evaluation of patients receiving a new left ventricular assist device: the Impella® recover 100
aDivision of Cardiothoracic Anesthesia and Intensive Care, Centro "A. De Gasperis", Ospedale Niguarda Cà Granda, P.zza Ospedale Maggiore 3, 20162 Milan, Italy
bDivision of Cardiac Surgery, "A. De Gasperis" Center, Niguarda Hospital, Milan, Italy
Received 17 December 2003; received in revised form 24 March 2004; accepted after revision 29 March 2004.
* Corresponding author. Tel.: +39-02-64442553; fax: +39-02-64442907. emanuele.catena{at}tin.it ucict{at}ospedaleniguarda.it
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Abstract |
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 Top Abstract IntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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The aim of this study was to suggest a protocol for serial echocardiographic evaluations in patients undergoing circulatory support by a new miniaturized electric axial pump, the Impella® recover 100 (IR 100). IR 100 is implanted through the ascending aorta into the left ventricle drawing blood from the left ventricle to the aorta.
Methods and results: This protocol has been applied in eight patients receiving twelve IR 100 implants. Before implantation echocardiography was useful to rule out anatomic contraindications. During and after implantation echocardiography provided informations for correct positioning and evaluation of left ventricular filling necessary to optimize pump performance. During assistance it gave important informations to assess left and right ventricular function.
Conclusion: Echocardiography has pivotal role in IR 100 management before, during and after implantation.
Keywords: Impella; Ventricular assist device (VAD); End stage cardiac failure; Transoesophageal echocardiography (TEE); Transthoracic echocardiography (TTE)
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Introduction |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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Echocardiography has an increasing role in ensuring successful implantation of left ventricular assist devices (LVADs) nowadays more extensively employed in patients unresponsive to conventional haemodynamics support. Images of the heart, assessment and quantification of its function together with evaluation and optimization of LVAD's performance are proven issues in this setting.1–6
We describe the contribution of echocardiography in the use of a new LVAD: the miniaturized electric axial pump Impella® recover 100 (IR 100) (Impella Cardiotechnik AG, Germany). Currently a trial to evaluate its clinical role is in progress.7–9
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Materials and methods |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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The device
IR 100 is an axial endovascular pump powered by external batteries and driven by a software placed in an external console. This device is positioned in the left ventricle through the ascending aorta (Fig. 1). The pump draws blood from the left ventricle to the ascending aorta and can deliver, at nine levels of performance, a non-pulsatile flow up to 5 l/min.10,11
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The device is equipped by a pressure transducer to detect differential pressure between aorta and left ventricle (Fig. 2).
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IR 100 can be inserted directly into the femoral artery by means of a J guidewire or through a small vascular prosthesis stitched on the ascending aorta at least 7 cm above the valve plane. The tip of the device must lie 4 cm under the aortic valve plane.
Main anatomic contraindications to IR 100 are:
- - aortic valve stenosis/incompetence
- - mixomatous mitral valve
- - hypertrophic cardiomyopathy.
- - mixomatous mitral valve
Its operating time is suggested not to exceed seven days. After that time the pump has to be removed.
Patients
From September 2002 to September 2003 we performed twelve IR 100 implants in eight patients (Table 1).
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All patients showed left ventricle failure with preserved right ventricle function despite adequate haemodynamic conventional support.
The indications for IR 100 included: bridge to heart transplant (4 patients), recovery from acute myocarditis (2 patients) and recovery from postcardiotomy cardiogenic shock (2 patients).
Echocardiographic protocol
A protocol for perioperative echocardiographic evaluations before, during and after IR 100 implantation was developed (Table 2).
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TEE mid-esophageal long axis view at 100–120° for:
- - qualitative and quantitative assessment of aortic root, ascending aorta, Valsalva sinuses, aortic and mitral valves and left ventricular outflow evaluation;
- - assessment of intra-aortic and intraventricular position of the cannula.
- - assessment of intra-aortic and intraventricular position of the cannula.
TEE four chambers view for:
- - right to left atrial shunting exclusion by saline solution injection with Valsalva maneuver;
- - qualitative assessment of right ventricular (RV) function;
- - quantitative assessment of RV function by calculation of RV fractional area change (RVFAC) with the following equation:
- - left ventricular end diastolic diameter (LVEDD) and volume (LVEDV) measurement;
- - quantitative assessment of LV function by calculation of ejection fraction (EF) using Simpson method.
- - qualitative assessment of right ventricular (RV) function;
TEE short axis view at papillary muscle level for:
- - assessment of RV inferior, free wall and ventricular septal motion.
Color Doppler for:
- - mitral and tricuspidal regurgitation evaluation
- - patency assessment of the cannula.
- - patency assessment of the cannula.
Post-operative controls were performed by TTE or by TEE whenever inadequate transthoracic windows were obtained.
Controls were performed daily to assess:
- - position and patency of the cannula
- - loading and function of right and left ventricles
- - mitral and tricuspidal valve competence.
- - loading and function of right and left ventricles
Controls were moreover performed every time IR 100 malfunction was suspected.
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Results |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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In six patients IR 100 was implanted through the ascending aorta in the operating room under general anaesthesia. In two patients IR 100 was implanted through the femoral artery under local anaesthesia. In four patients IR 100 was replaced with another one due to prolonged assistance exceeding eight days.
Qualitative and quantitative assessment of left and right ventricle and ascending aorta by TEE are described in Table 3.
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Echocardiographic assessment before implantation
Our patients did not show any anatomic contraindications to IR 100 positioning.
Mitral regurgitation (++ or higher) and tricuspidal regurgitation (++ or higher) were present in all patients. EF ranged from 10% to 25% and RVFAC was 22% or higher. Dilated left ventricle (>120 ml) was present in four patients.
Echocardiographic assessment during implantation
IR 100 is very echogenic: the cannula appears as two parallel segments with a round tip. During implantation the adequate position and direction of the cannula were achieved by several attempts (at least four) and by repeated TEE controls due to wedging of IR 100 tip into Valsalva sinuses (Fig. 3, top). After overcoming the aortic valve, the tip of the cannula (inlet) was easily positioned at the apex of the anterior leaflet of mitral valve 3.5–4.5 cm under the aortic valve plane (Fig. 3, bottom). Pump outlet was located 1.5 cm above the coronary ostia and pump ouflow did not trouble coronary inflow. IR 100 outflow positioning was documented by color Doppler (Fig. 4).
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Echocardiographic assessment after implantation
Though ventilated patients usually show very poor transthoracic windows TTE supplied satisfying images in seven of eight patients (Fig. 5).
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Abnormal position and consequent malfunction was observed in the two patients having IR 100 inserted through femoral artery (six and four episodes, respectively).
Two patients with LVEDV <120 ml showed episodes of IR 100 malfunction due to contact of inlet area with left ventricular free wall. IR 100 malfunction never occurred in those patients with dilated left ventricle (LVEDV >120 ml) even at the highest level of pump performance.
All patients showed reduction of mitral and tricuspidal regurgitation and unchanged or improved RVFAC.
We found post-operative change of LVEF only in two patients showing an increase from 10% to 55% and from 20% to 40%, respectively, after 19 and 15 days of assistance (Table 3). Both of them were successfully weaned from IR 100. Two patients successfully underwent early heart transplant. Four patients died because of multiorgan system failure.
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Discussion |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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Echocardiographic assessment before implantation
Anatomic contraindications
Aortic regurgitation is a contraindication because the persistent retrograde aorta-to-left ventricle flow reduces the effective pump flow to the aorta.
Redundant mixomatous mitral valve (billowing valve) is a contraindication because inlet pump flow can be reduced by contact with anterior mitral leaflet.
Right ventricular function assessment
Qualitative and quantitative assessments of RV function and tricuspidal regurgitation are predictive of RV failure during any LVAD implantation.
In Scalia's experience1 patients with an RVFAC less than 20% evidenced right ventricular failure when on LVAD.
Our patients showed RVFAC more than 22% without post-operative RV failure.
Left ventricular function assessment
Three parameters are to be underlined: left ventricle volume (LVV), left ventricle ejection fraction (LVEF) and mitral regurgitation.
When left ventricle is severely dilated, IR 100 can work at the highest levels of performance without risk of malfunction due to contact with LV wall. In our experience it was not possible to gain the highest level of IR 100 performance in patients with normal or not massively dilated left ventricle. In these patients it was necessary to check frequently the position of the pump and to optimize LV loading. In patients showing LVEDV >120 ml no problems related to pump position and LV loading were observed.
Pre-operative LVEF is of important concern for recovery and weaning.
Evaluation of pre-operative mitral regurgitation and its post-operative changes is essential to assess the effective contribution of IR 100 on haemodynamics.
Echocardiographic assessment during implantation
Echocardiography is the unique tool to guide the surgeon during positioning of IR 100.
Multiplane TEE in mid-esophageal longitudinal view at 100–120° allows:
- - continuous control of the procedure
- - check of correct positioning
- - check of blood flow through the cannula and correct pump functioning.
- - check of correct positioning
Echocardiographic assessment after implantation
In the intensive care management of patients with IR 100, echocardiography is an invaluable tool to assess the patency and the position of the cannula, the adequate left ventricular loading and the adequate ventricular function.
In patients having IR 100 inserted trough the femoral artery, an abnormal position may frequently occur due to the length of the intra-aortic catheter. Echo-guided repositioning of the device is quick and easy (Fig. 6).
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Even in cases of correct positioning inlet obstruction due to contact with ventricular wall may occur. This event, well documented by TTE or TEE, is more frequent in patients with a non-dilated left ventricle (LVEDV <120 ml) and when the pump is working at the highest level of performance. Reducing the level of performance of the pump and increasing the preload of left ventricle were effective in counteracting this event.
RV function evaluation and management are determinant in post-operative course of patients on LVAD. Adequate LVAD function depends on normal or high left ventricle filling pressure which in turn depends on RV output. Echocardiographic qualitative and quantitative assessment of RV function was crucial in optimizing volume replacement therapy and titrating pharmacological support.
Echocardiography has also an irreplaceable role in evaluating heart function recovery during mechanical circulatory support.
In our experience the only two patients showing significant improvement of LVEF together with reduction of mitral and tricuspidal regurgitations were successfully weaned from IR 100.
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Conclusions |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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In this clinical report we focused the role of echocardiography in patients receiving a new LVAD (Impella® recover 100).
TTE and TEE provided adequate informations concerning anatomic contraindications for implantation. Moreover echocardiography was pivotal for correct positioning of the device, evaluation of adequacy of left ventricular filling and right ventricular function and documenting improvement of left ventricle performance.
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Notes |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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1 Present address: Via Annunzio Cervi 4, 20161 Milano, Italy. Tel.: +39-02-6469213.
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References |
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TopAbstractIntroductionMaterials and methodsResultsDiscussionConclusionsNotesReferences |
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[Abstract/Free Full Text] - 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) 51:312–317.[CrossRef][Web of Science][Medline]
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