Eur J Cardiothorac Surg 2003;24:307-308
© 2003 Elsevier Science NL
New experience with the paracardial right ventricular axial flow micropump impella elect 600
Thorsten Schmidt*,
Jörg Siefker,
Sotirios Spiliopoulos,
Otto Dapunt
Department of Cardiac Surgery, Klinikum Oldenburg, Dr.-Eden-Straße 10, D-26133 Oldenburg, Germany
Received 23 January 2003;
received in revised form 27 March 2003;
accepted 31 March 2003.
* Corresponding author. Present address: Steinkauzweg 24a, D-26135 Oldenburg, Germany. Tel.: +49-441-4032820; fax: +49-441-4032830
e-mail: schmidt.thorsten{at}klinikum-oldenburg.de
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Abstract
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Beating heart surgery is still challenging and could be made safer using assisted circulation. We evaluated clinical outcome following beating heart myocardial revascularisation using the impella elect system with intracardial left ventricular (LV) and paracardial right ventricular (RV) microaxial pumps in eight patients. Clinical course was uneventful. There were no device-related complications. The paracardial design of the RV-pump is a great advantage compared to the former intracardial design because it eliminates arrhythmia and LV hypovolemia. Support by microaxial pumps can make beating heart surgery safer and applicable for more complex cases.
Key Words: Beating heart surgery • Assisted circulation
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1. Introduction
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We evaluated clinical outcome following beating heart myocardial revascularization using a novel bi-ventricular microaxial pump. The impella elect system consists of an intracardial left ventricular (LV) and a paracardial right ventricular (RV) pump and a control panel for operating the pumps (Impella CardioSystems AG, Aachen, Germany) (Fig. 1
). The system is used in beating heart surgery for assisted circulation. The LV pump has a diameter of 4.5 mm and consists of a flexible inflow cannula which is connected with the impeller-carrying microengine. It is able to deliver a flow of 4.5 l/min at 30000 rpm and is connected with the driving console via a flexible cable. The pump is inserted via the ascending aorta across the aortic valve. The correct position is monitored by the differential pressure sensor and transesophageal echocardiography (TEE). The RV pump consists of an inflow cannula inserted via the right atrial appendage and the outflow cannula inserted via the main pulmonary artery. The microengine with the impeller is placed in the inflow cannula and is able to deliver a flow of 6 l/min at 30000 rpm. We sought to evaluate the practicability of the device in its new paracardial RV design.
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Fig. 1. Paracardial RV micropump (Impella, Aachen, Germany). The inflow-cannula (left) with micropump on the top is introduced via the right atrial appendage and connected with the outflow cannula (middle), which is inserted via the main pulmonary artery. The connection cable with pressure sensor (top).
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2. Materials and methods
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Since October 2000, bi-ventricular intracardiac micropumps were used in our institution for myocardial support during beating heart myocardial revascularizations. Informed consent was obtained from each patient. Baseline characteristics, intraoperative data, such as completeness of revascularization and duration of the procedure and postoperative data including myocardial infarction rate, low-output syndrome, length of hospital stay and cardiac related 30-day-mortality were noted.
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3. Results
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The paracardial RV-pump was applied in eight patients (seven males, one female). The average age was 76±2.7 years and median preoperative ejection fraction was 55±10%. A LV dysfunction was present in four (50%) patients. One-vessel disease was present in only one patient, two-vessel disease in four and three-vessel-disease in three patients. The median number of peripheral anastomoses was 3.0±0.4. Procedure time was 140±31.5 min. Complete revascularization was performed in seven (87.5%) cases whereas in one case, complete revascuarization could not be done due to a small (<1 mm) target vessel diameter. There were no pump-related complications. Positioning of the LV pump under TEE guidance was easy and took a mean time of 25±20 s. The blood loss at the cannulation-sites of the right atrial appendage and the main pulmonary artery was minimal. Even during luxation of the heart, the device was always able to propel a flow between 3.5 and 4.5 l/min. Median postoperative ventilation time was 11.8±1.4 h and median stay in the intensive care unit was 1.125 days. Total blood-loss was 1300±571 ml. There were no events of cardiac infarction, low-output syndrome or cardiac related death. Postoperative transient atrial fibrillation occurred in three cases. There was no need for reexploration or reoperation. No cases of transient or persistent neurological deficit were observed. The median length of hospital stay was 7±1.6 days.
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4. Discussion
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The concept of circulatory support by the hemopump as an intracardial axial micropump was conceived in 1975 and designed in 1982 as a temporary cardiac assist system [1]. In 1997, Lönn [2] reported 16 patients who underwent CABG-procedure using the hemopump for LV circulatory support. The hemopump did not enter into the clinical routine. This might be due to the various complications viz., fractures of the drive cable, expulsion of the cannula out of the ventricle and remarkable hemolysis [3]. A new bi-ventricular intracardial axial micropump became available in 1999. This device consisted of two independent micropumps for both ventricles. In 2001, the design of the RV pump was changed to a pararcardial format, where the inflow cannula is placed in the right atrium and outflow cannula in the main pulmonary artery. This eliminated kinking of the outflow cannula as it was known in the former version of the right intraventricular pump. This configuration allows safe beating heart surgery with revascularization of all target vessels. The pumps perform a flow of 4.5 l/min with an adequate systemic perfusion even under ventricular fibrillation. Meyns et al. [4] showed that the supported unloaded heart is more resistant to repetitive local ischemia using the impella device in sheep. In 2002, Meyns et al. [5] showed in a prospective randomised study that beating heart surgery with impella support causes a significantly reduced inflammatory response. They too had noted that the intracardiac RV pump was difficult to introduce. In our series of eight patients operated with the new paracardial RV-pump, no complications were observed. The advantage of the impella device is that there is no driving cable necessary with its problems of fracture. The new design of the RV-pump is a great advantage compared to the former design, because it eliminates intracardiac RV cannula causing possible arrhythmias. Moreover, there is no possibility of kinking of the right cannula under luxation of the heart that caused hypovolemia in the left ventricle as known with the intracardiac RV-pump [5]. Support by microaxial pumps can make beating heart surgery safer and applicable for more complex cases.
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References
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- Sweeny M.S. The hemopump in 1997: a clinical, political, and marketing evolution. Ann Thorac Surg 1999;68:761-763.[Abstract/Free Full Text]
- Lönn U., Wulf K.Y.K., Wranne B., Ask P., Casimir-Ahn H. Flow characteristics of the hemopump: an experimental in vitro study. Ann Thorac Surg 1997;63:162-166.[Abstract/Free Full Text]
- Wiebalck A.C., Wouters P.F., Waldenberger F.R., Akpinar B., Lauwers P.M., Demeyere R.H., Sergeant P.T., Daenen W.J., Flameng W.J. Left ventricular assist with an axial flow pump (hemeopump): clinical application. Ann Thorac Surg 1993;55:1141-1146.[Abstract]
- Meyns B., Sergeant P.T., Nishida T., Perek B., Zietkewicz M., Flameng W. Micropumps to support the heart during CABG. Eur J Cardiothorac Surg 2000;17:169-174.[Abstract/Free Full Text]
- Meyns B., Autschbach R., Böning A., Konertz W., Matschke K., Schöndube F., Wiebe K., Fischer E. Coronary artery bypass grafting supported with intracardial microaxial pumps versus normothermic cardiopulmonary bypass: a prospective randomized trial. Eur J Cardiothorac Surg 2002;22:112-117.[Abstract/Free Full Text]
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Abstract
1. Introduction
