Interactive Cardiovascular and Thoracic Surgery 3:495-498(2004)
© 2004 European Association of Cardio-Thoracic Surgery
Work in progress report - Assisted circulation |
Efficacy of intracardiac right ventricular microaxial pump support during beating heart surgery
Andreas Boeninga,*,
Christine Friedricha,
Dorothee Caliebeb and
Jochen Cremera
a Department of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Germany
b Department of Anaesthesia and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Germany
* Corresponding author. Tel.: +49-431-597-4400; fax: +49-431-597-4402
aboening{at}kielheart.uni-kiel.de
Received January 16, 2004;
received in revised form April 10, 2004;
accepted April 13, 2004
 |
Abstract
|
|---|
To evaluate the safety and efficacy of a new developed intracardiac right ventricular microaxial pump (elect 300, Impella AG, Aachen) the intracardiac pump (IRVP) was applied to patients undergoing beating heart coronary surgery. To our knowledge, this is the first description of an intracardiac microaxial pump device inserted through the pulmonary artery into the right ventricle. Six patients undergoing coronary surgery for 3-vessel disease were operated on without extracorporeal circulation with the new IRVP device. During the procedure, cardiac output (CO), arterial blood pressure (MAP), central venous pressure (CVP), right ventricular pressure (RVP), pulmonary artery pressure (PAP) and left atrial pressure (LAP) were recorded. Placement of the IRVP was easy, quick and without significant blood loss. During the procedure, all devices worked well. Rhythm disturbances requiring therapeutic measures were not observed. Patients with beating heart surgery and IRVP support maintained CO (87 (73–116) % of baseline) and MAP (101 (69–126) % of baseline). After the Trendelenburg maneuver, CVP raised and RVP remained constant. PAP (150 (117–164) % of baseline) and LAP (290 (75–400) % of baseline) raised, indicating an effective blood transport out of the RV. Our results show that an IRVP can be applied safely and effectively in patients undergoing beating heart coronary surgery.
Key Words: Off pump coronary artery bypass; Coronary artery bypass surgery; Right heart assist
|
1. Introduction
|
|---|
Off-pump coronary artery surgery can be accompanied by unstable hemodynamics especially during exposure of the posterolateral and posterior wall. As a consequence, right ventricular assist devices for short term support during off-pump surgery have been developed [1–4,7,8], which have been shown to stabilize cardiac performance effectively.
However, there were certain difficulties in routing the pump heads via the right atrium and ventricle to the pulmonary artery, making it impossible to place the devices in some patients [2,3]. Therefore, two new designs of a right ventricular pump (intracardiac right ventricular microaxial pump ‘elect 300’ and paracardial right ventricular axial flow micropump ‘elect 600’, Impella AG, Aachen, Germany) have been developed: The IRVP ‘elect 300’consisted of a microaxial pump with a 9 mm pump head, which is placed on the tip of an 8-french catheter at a right angle (Fig. 1). The catheter which contains power supply and measurement wires connects the microaxial pump with the steering console. The pump itself has a maximum capacity of 4.5 l/min under the conditions of a physiological blood pressure and the maximum rotation speed of 32,500 rpm. After the description of the paracardial device [4], this is the first description of the intracardiac microaxial pump device inserted through the PA into the RV.
View larger version (135K):
[in this window]
[in a new window]
|
Fig. 1 Placement of the intracardiac right ventricular microaxial pump (‘elect 300’, Impella AG, Aachen, Germany) in the pulmonary artery and the right ventricle.
|
|
|
2. Material and methods
|
|---|
To confirm the safety and efficacy of the intracardiac right ventricular microaxial pump in a clinical trial approved by the ethics committee, five male and one female patient (age 68.5 (55–72) years, EURO Score 2.0 (1–4)) with normal left ventricular function (LVEF 72.5 (45–85) %) underwent elective coronary surgery for 3-vessel disease with the new IRVP device after having given their informed consent. Two patients received 4, three patients received 3, and one patient received 2 grafts (median 3 anastomoses). Every patient got grafts to the RCX system, in two patients, the RCA system was not grafted.
Under full heparinisation (ACT >400 s), the IRVP device was inserted through a pursestring suture in the pulmonary artery and placed retrogradely in the right ventricle (Fig. 1). After having confirmed the correct position of the device by transesophageal echocardiography (TEE) and the differential pressure sensor, the device was started until a median flow of 2.5 l/min was achieved. The flow rate of 2.5 l/min has been determined in animal experiments and in humans [2,3] as the best compromise between volume-overloading the lung by a higher flow and being not effective by a lower flow.
For all off-pump coronary artery revascularization procedures, movement of the target region was impeded using stabilizers (Axius©, Guidant, Giessen, Germany) and exposure of the coronary vessels was facilitated by the application of an apical suction device (Xpose©, Guidant, Giessen, Germany), additional pericardial sutures were not used. During the coronary anastomoses, the vessels were temporarily occluded by a proximal 4/0 prolene suture and a soft tourniquet, as described earlier [5]. Heparin was administered in a dosage of 300IU/kg before IMA takedown and was fully (1:1) antagonized by protamine after the last coronary anastomosis.
During the procedure, cardiac output (CO), arterial blood pressure (MAP), central venous pressure (CVP), right ventricular pressure (RVP), pulmonary artery pressure (PAP) and left atrial pressure (LAP) were recorded in a paired fashion: in the same patient, pressures were recorded first (during inspection of the coronary arteries) without IRVP support, than (during anstomosis) with IRVP support. Cardiac output was monitored using a pulmonary artery catheter (Edwards Baxter CCO/VIP) with a continuous CO measurement (Edwards Baxter Vigilance). In case of a decrease of the mean arterial pressure below 60 mmHg, Noradrenalin was given. After anaesthesia induction with TIVA, care was taken not to apply boli of anaesthetic agents during the measurement periods. The apical suction device and the Trendelenburg position were used both for inspection of the target vessels (hemodynamic measurements without IRVP) and the anastomosis (hemo-dynamic measurements with IRVP). Inspection of the target vessel and hemodynamic stabilisation took at least 3–5 min, so that measurement of all pressures was done in a stable situation.
Safety endpoints of the study were ease of placement of the device, minimal blood loss during insertion and removing, and avoidance of rhythm disturbances. Efficacy endpoints were the ability to drain blood from the RV without RA distension and the maintenance of hemodynamic stability without an inadequate rise in LAP.
|
3. Results
|
|---|
Placement of the IRVP in each of the 6 study patients could be achieved within 2 min, and the device could be introduced easily, quickly and without significant blood loss. Ventricular rhythm disturbances occurred only during insertion in the form of single ventricular ectopic beats, if the device hit the right ventricular wall. After the placement itself, rhythm disturbances requiring therapeutic measures were not observed. During the procedure, all devices worked well: There was no displacement of an IRVP device from the ventricle back into the PA as well as no attachment of a device in the pulmonary or tricuspid valve. Injuries of the RV wall and the tricuspid or pulmonary valve were observed neither directly nor by TEE. The mean support time for the IRVP was 63.2±27.9 min. Free hemoglobin rose from 44.4±35.0 mg/dl (baseline) to a maximum of 58.2±34.3 mg/dl during IRVP use, and decreased within 24 h to baseline values after surgery.
While the heart was tilted first without pump support for inspection of the coronary vessels, mean CO and MAP showed a decrease (Fig. 2). During lateral and posterior coronary anastomoses with pump support, CO and MAP were maintained (Fig. 2).
View larger version (16K):
[in this window]
[in a new window]
|
Fig. 2 Median values of cardiac output, mean arterial pressure and left ventricular preload during posterior wall anastomoses with and without right ventricular support (IRVP).
|
|
During anastomoses to the different coronary arteries, IRVP support together with a Trendelenburg maneuver increased preload (CVP) by 320% from 7.5 to 22 mmHg. Absolute values are shown in Table 1. RV pressure and PA pressure rose only to 138 and 150%, respectively, whereas LA pressure during subluxation of the heart rose to 290% of baseline, providing enough preload for the slightly compressed LV. The increased LV preload could be the cause for the near normal values of CO and MAP during IRVP support.
|
4. Discussion
|
|---|
After the report about the paracardial impella device [4], this is the description of an intracardiac right ventricular microaxial pump (elect 300, Impella AG, Aachen) inserted retrogradely through the PA into the RV. The safety of this pump is documented by an easy and quick placement without significant blood loss and without major rhythm disturbances as well as by a brief and slight hemolysis. The efficacy is documented by the ability to propel blood from the RV to the PA, resulting in higher PAP and LAP values and maintained CO and MAP during pump support compared to values of the same patients without pump support.
This study shows that—for maintenance of a stable hemodynamic situation during subluxation of the heart—it is sufficient to drain blood from the RV, and that it is not necessary to insert a second cannula into the RA, as proposed with the paracardiac device [4].
From our limited experience with this device, we cannot draw conclusions as to which patient group would profit from the use of the IRVP. This was also not possible in larger studies [3,5,6]. With better knowledge of positioning and stablizing the heart during OPCAB surgery, the intraoperative short-term use of RVADs is becoming more and more obsolete. An IRVP as investigated in this study could have a place in medium- or long term assist after right heart failure, if it would work also for several days or even weeks. The development of the described intracardiac device for a medium or long term use has been postponed by the Impella company in favour of the paracardiac device (Impella recover 600), recently described by Christiansen et al. [8].
In conclusion, our results show that an intracardiac right ventricular microaxial pump (IRVP) can be applied safely and effectively in patients undergoing beating heart coronary surgery. However, it still has to be defined which patients profit most from the expanded employment of an IRVP.
doi:10.1016/j.icvts.2004.04.007
|
References
|
|---|
- Caputo M, Yeatman M, Narayan P, Marchetto G, Ascione R, Reeves BC, Angelini GD. Effect of off-pump coronary surgery with right ventricular assist device on organ function and inflammatory response: a randomised controlled trial. Ann Thorac Surg. 2002;74:2088–2096[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 intracardiac microaxial pumps versus normothermic cardiopulmonary bypass: a prospective randomized trial. Eur J Cardio-thorac Surg. 2002;22:112–117[Abstract/Free Full Text]
- Sharony R, Autschbach R, Porat E, Strüber M, Böning A, Krakor R, Haverich A, Cremer J, Nesher N, Mohr FW, Uretzky G. Right heart support during off-pump coronary artery bypass surgery-a multicenter study. Heart Surg Forum. 2002;5:13–16[Medline]
- Schmidt T, Siefker J, Spiliopoulos S, Dapunt O. New experience with the paracardial right ventricular axial flow micropump impella elect 600. Eur J Cardio-thorac Surg. 2003;24:307–308[Abstract/Free Full Text]
- Cremer JT, Wittwer T, Böning A, Anssar MB, Kofidis T, Mügge A, Haverich A. Minimally invasive coronary artery revascularization on the beating heart. Ann Thorac Surg. 2000;69:1787–1791[Abstract/Free Full Text]
- Hughes P, Hasenkam JM, Severinsen IK, Steinbrüchel DA. Right heart assist for beating coronary artery bypass grafting. Eur J Cardio-thorac Surg. 2003;24:762–769[Abstract/Free Full Text]
- Mathison M, Buffolo E, Jatene AD, Jatene FB, Reichenspurner H, Matheny RG, Shennib H, Mack MJ. Right heart circulatory support facilitates coronary artery bypass without cardiopulmonary bypass. Ann Thorac Surg. 2000;70:1083–1085[Abstract/Free Full Text]
- Christiansen S, Brose S, Demircan L, Autschbach R. A new right ventricular assist device for right ventricular support. Eur J Cardio-thorac Surg. 2003;24:834–836[Abstract/Free Full Text]
|
|
Top
Abstract
1. Introduction