- Email: [email protected]
New Circulatory Support System: Heartware
New Circulatory Support System: Heartware M. Ozbaran, T. Yagdi, C. Engin, S. Nalbantgil, F. Ayik, E. Oguz, Y. Engin, and P. Özturk ABSTRACT Introduction. Through the new developments in medicine, heart failure therapy has advanced to mechanical circulatory support systems. The HeartWare Ventricular Assist System HVAD; HeartWare, Inc.; Miramar, Fla, USA) is a new device that is a centrifugal, intracorporeal, miniaturized and continuous flow pump that serves simple patient use and enhanced life quality. This article reports the midterm results of patients who underwent the heartware support system. Materials and methods. We retrospectively compiled our data from December 2010, including 10 patients of mean age 51.8 years with 90% males, 70% of the overall patient cohort had dilated cardiomyopathy and remaining ones, ischemic disease. Mean left ventricular ejection fraction was 20.1% and mean systolic pulmonary artery pressure was 49.2 mm Hg. A single patient was grade 1; seven were grade 2; and remaining ones, grade 3 according to the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) scale. All patients were operated with cardiopulmonary bypass (CPB) with moderate hypothermia. Tricuspid ring annuloplasty was performed in 3 (30%) patients. In one patient we removed a left ventricular thrombus. In a case with severe aortic regurgitation, we placed a simple coaptation stitch at the central portion of the three aortic cusps under the aortic cross clamp. The mean CPB duration was 95.5 minutes. Results. There was no operative or in-hospital mortality. Mean support time was 250.67 days. During the early postoperative period, one patient experienced a minor hemorrhagic neurological event also requiring a tracheostomy due to pneumonia. This patient has completely healed and on follow-up continues a normal life. All patients were asymptomatic regarding heart failure. One patient unfortunately died because of possible pancreatic cancer and sepsis. Two patients underwent transplantations on days 159 and 172 of support. Conclusion. The HVAD system provided effective circulatory support for patients with end-stage heart failure with low adverse event rates. Long-term results are needed particularly for destination therapy candidates. HE POOR NATURAL HISTORY of heart failure and growing waiting lists for transplantation have produced an urgent need for mechanical assistance. With the technological advances of ventricular assist devices, new generation pumps now represent viable alternatives to heart transplantation with almost equal life quality at least in the early period.1,2 Herein we have presented our early experience with the HeartWare Ventricular Assist System (HeartWare, Inc, Miramar, Fla, USA), which is a new third-generation pump.
T
PATIENTS AND METHODS We retrospectively analyzed 10 patients with end-stage heart failure who underwent. HeartWare implantation in our center
between December 2010 and August 2011. Their mean age was 51.8 ⫾ 11.05 years range 29 – 66 with 90% males. Seventy percent of patients displayed dilated cardiomyopathy; the remaining ones, ischemic cardiomyopathy. The main reason for mechanical circulatory support was as a bridge to transplantation (n ⫽ 8, 80%) except 2 (20%) for whom it was destination therapy. One patient had undergone previous cardiac surgery via a sternotomy. Mean
From the Departments of Cardiovascular Surgery (M.O., T.Y., C.E., F.A., E.O., Y.E., P.Ö), and Cardiology (S.N.), Ege University Hospital, Izmir, Turkey. Address reprint requests to Cagatay Engin, MD, Ege University Hospital, Department of Cardiovascular Surgery, 35100, Bornova, Izmir, Turkey. E-mail: [email protected]
0041-1345/12/$–see front matter http://dx.doi.org/10.1016/j.transproceed.2012.05.043
© 2012 Published by Elsevier Inc. 360 Park Avenue South, New York, NY 10010-1710
1726
Transplantation Proceedings, 44, 1726 –1728 (2012)
NEW CIRCULATORY SUPPORT SYSTEM left ventricular ejection fraction was 20.1% and mean systolic pulmonary artery pressure, 49.2 ⫾ 16 mm Hg (35– 80). One patient was grade I; seven, grade II; and the remaining two patients, grade III according to the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) scale. In the preoperative period at least double (dopamine and dobutamine) and triple inotropic support with added adrenaline keys in three patients. Three patients (30%) displayed renal dysfunction (creatinine ⱖ 1.5 mg/dL) with elevated hepatic enzymes (ⱖtwofold) observed in six patients. In two patients, intra-aortic baloon pumping was required in the preoperative period.
Implanted VAD The HeartWare HVAD, a small, third-generation, implantable left ventricular assist device (LVAD), is a hydrodynamic centrifugal pump with a short inflow cannula. It is integrated into the device. The cannula design and the device’s small size facilitate intrapericardial placement, thereby eliminating the need for a concomitant abdominal approach for device pockets. It has a displacement volume of just 45 mLcc, weighs 145 g, and can deliver flows up to 10 L/min. The device’s fatigue-resistant percutaneous driveline (cable) is 3 mm in diameter extending from the pump through the skin to an external controller.
Implantation All patients were operated with a fibrilating or beating heart technique under cardiopulmonary bypass (CPB) with moderate hypothermia (32°C) except one who underwent aortic valve procedure using cardioplegic arrest. Prior to implantation, the pump was completely submerged in sterile dextrose, with the outflow graft clamped. The sewing ring was attached epicardially to the left ventricular (LV) apex with a ring-shaped Teflon felt support. The inflow cannula was inserted through the sewing ring into the LV. The outflow graft was anastomosed to the ascending aorta using partial clamping. The driveline then tunneled to the right upper quadrant was connected to the controller. After completing deairing, the clamp on the outflow graft was removed and the LVAD pump speed adjusted to accomplish full flow. Pharmacologic support and volume were adjusted to provide appropriate right heart function for successful weaning from CPB. Mean CPB time was 95.5 ⫾ 38.3 (minutes 62–192).
Additional Procedures Tricuspid ring annuloplasty (TRA) was performed in 3 (30%) patients when the annulus diameter was greater than 4.0 cm with significant regurgitation. In one patient we removed an LV thrombus. In a case with aortic regurgitation (third degree), a simple coaptation stitch was placed at the central portion of the three aortic cusps under an aortic cross-clamp.
Anticoagulation On the first postoperative day, when the bleeding had subsided, ahticoagulation with unfractioned heparin was administered to keep the activated partial thromboplastin time between 50 and 60 seconds. Heparin was replaced with warfarin to a target international normalized ratio of 2.5 to 3.0 once the patient was stable with chest tubes removed and returned gastrointestinal function. Acetylsalicylic acid (80 to 160 mg/d) was started on postoperative days 3 to 4.
1727
RESULTS
Mean support time was 250,67 days (92–342). There was no operative or in-hospital mortality. Two patients underwent succesful transplantation on 159 and 172 days of support. Three patients were reexplored due to bleeding. During the early postoperative period, one patient experienced a minor hemorrhagic neurological event and required a tracheostomy due to pneumonia. This patient has completely healed without any sequelal and continues his normal life. Upon follow-up, all patients were asymptomatic regarding heart failure and associated organ dysfunctions. Gastrointestinal bleeding was detected in one patient who died 237 days on postoperative due to an intra-abdominal malignancy and sepsis.
DISCUSSION
Although we do not have an ideal VAD, better devices are emerging with improved outcomes and lower complication rates. In the last 3 years we have performed approximately 100 VAD implantations. The majority of these devices were first-generation pulsatile paracorporeal VADs. Their disadvantages are well known despite their powerful more physiologic pulsatile flow. Although was used succesfully in small children initially,3 we have now been succesfully using bridging, nonpulsatile devices for long-term due to their longer device durability, less need for anticoagulation therapy, and greater quality of life.4 All patients who have continued with HVAD pump support are now outpatients with few medical problems that have required hospital readmission. The HVAD system has small dimensions that simplify implantation with decreased duration of cardiopulmonary bypass. This minimizes surgical trauma, which is particularly important in critically ill patients. HVAD also has been effective for hemodynamic support with low early complication rates in our study. As continuous devices are being used with increasing rates, disadvantages have been reported acquired von Willebrand disease and gastrointestinal bleeding.5,6 One of our patients experienced gastrointestinal bleeding with gastrointestional symptoms in the early postoperative period, susenmbing due to pancreatic cancer and sepsis. It is unclear how to approach VAD candidates who have associated valve dysfunctions. The options for aortic insufficiency are valve replacement,7 total closure of the valve, or simple coaptation stitches at the Arantii nodules that integrate all cusps.8 Total closure of the aortic valve is believed to be dangerous because of total dependency on the device and increased risk of aortic root thrombosis due to the lack of valvular washing. A simple coaptation stitch lets blood flow through the valve, preventing thrombosis. This repair could be provided also with a bioproshetic valve replacement. But we believe that valve replacement takes a longer time on cross-clamp, which exacerbates right ventricular failure.
1728
There is no consensus about associated severe tricuspid regurgitation.9,10 Tricuspid insufficiency is known to be a risk factor for right ventricular failure after left VAD implantation.11 We believe that to prevent right heart failure, TRA is necessary when there is severe tricuspid regurgitation and the annulus is egual to or greater than 40 mm. In our series, three patients with severe tricuspid regurgitation underwent TRA; there was no sign of right ventricular failure. However, our series did not include a control group, but there is some evidence that TRA can be useful.9 TRA may be more important to prevent late right heart failure for destination rather than bridge-to transplantation therapy.12 In conclusion, the HVAD system provided effective circulatory support for patients with end-stage heart failure with a low adverse event rate. Long-term results are needed particularly among destination therapy candidates. REFERENCES 1. Strueber M, O’Driscoll G, Jansz P, et al: HeartWare Investigators. Multicenter evaluation of an intrapericardial left ventricular assist system. J Am Coll Cardiol 57:1375, 2011 2. John R, Kamdar F, Liao K, et al: Improved survival and decreasing incidence of adverse events with the HeartMate II left ventricular assist device as bridge-to-transplant therapy. Ann Thorac Surg 86:1227, 2008 3. Hetzer R, Potapov EV, Stiller B, et al: Improvement in survival after mechanical circulatory support with pneumatic pul-
OZBARAN, YAGDI, ENGIN ET AL satile ventricular assist devices in pediatric patients. Ann Thorac Surg 82:917, 2006 4. Drews T, Jurmann M, Michael D, et al: Differences in pulsatile and non-pulsatile mechanical circulatory support in longterm use. J Heart Lung Transplant 27:1096, 2008 5. Stern DR, Kazam J, Edwards P, et al: Increased incidence of gastrointestinal bleeding following implantation of the HeartMate II LVAD. J Card Surg 25:352, 2010 6. Crow S, Chen D, Milano C, et al: Acquired von Willebrand syndrome in continuous-flow ventricular assist device recipients. Ann Thorac Surg 90:1263, 2010 7. Feldman CM, Silver MA, Sobieski MA, et al: Management of aortic insufficiency with continuous flow left ventricular assist devices: bioprosthetic valve replacement. J Heart Lung Transplant 25:1410, 2006 8. Mudd JO, Cuda JD, Halushka M, et al: Fusion of aortic valve commissures in patients supported by a continuous axial flow left ventricular assist device. J Heart Lung Transplant 27:1269, 2008 9. Piacentino V 3rd, Troupes CD, Ganapathi AM, et al: Clinical impact of concomitant tricuspid valve procedures during left ventricular assist device implantation. Ann Thorac Surg 92:1414, 2011 10. Saeed D, Kidambi T, Shalli S, et al: Tricuspid valve repair with left ventricular assist device implantation: is it warranted? J Heart Lung Transplant 30:530, 2011 11. Potapov EV, Stepanenko A, Dandel M, et al: Tricuspid incompetence and geometry of the right ventricle as predictors of right ventricular function after implantation of a left ventricular assist device. J Heart Lung Transplant 27:1275, 2008 12. Imamura T, Kinugawa K, Shiga T, et al: A case of late-onset right ventricular failure after implantation of a continuous-flow left ventricular assist device. J Artif Organs 2012 Jan 17 [Epub ahead of print]
T
PATIENTS AND METHODS We retrospectively analyzed 10 patients with end-stage heart failure who underwent. HeartWare implantation in our center
between December 2010 and August 2011. Their mean age was 51.8 ⫾ 11.05 years range 29 – 66 with 90% males. Seventy percent of patients displayed dilated cardiomyopathy; the remaining ones, ischemic cardiomyopathy. The main reason for mechanical circulatory support was as a bridge to transplantation (n ⫽ 8, 80%) except 2 (20%) for whom it was destination therapy. One patient had undergone previous cardiac surgery via a sternotomy. Mean
From the Departments of Cardiovascular Surgery (M.O., T.Y., C.E., F.A., E.O., Y.E., P.Ö), and Cardiology (S.N.), Ege University Hospital, Izmir, Turkey. Address reprint requests to Cagatay Engin, MD, Ege University Hospital, Department of Cardiovascular Surgery, 35100, Bornova, Izmir, Turkey. E-mail: [email protected]
0041-1345/12/$–see front matter http://dx.doi.org/10.1016/j.transproceed.2012.05.043
© 2012 Published by Elsevier Inc. 360 Park Avenue South, New York, NY 10010-1710
1726
Transplantation Proceedings, 44, 1726 –1728 (2012)
NEW CIRCULATORY SUPPORT SYSTEM left ventricular ejection fraction was 20.1% and mean systolic pulmonary artery pressure, 49.2 ⫾ 16 mm Hg (35– 80). One patient was grade I; seven, grade II; and the remaining two patients, grade III according to the INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) scale. In the preoperative period at least double (dopamine and dobutamine) and triple inotropic support with added adrenaline keys in three patients. Three patients (30%) displayed renal dysfunction (creatinine ⱖ 1.5 mg/dL) with elevated hepatic enzymes (ⱖtwofold) observed in six patients. In two patients, intra-aortic baloon pumping was required in the preoperative period.
Implanted VAD The HeartWare HVAD, a small, third-generation, implantable left ventricular assist device (LVAD), is a hydrodynamic centrifugal pump with a short inflow cannula. It is integrated into the device. The cannula design and the device’s small size facilitate intrapericardial placement, thereby eliminating the need for a concomitant abdominal approach for device pockets. It has a displacement volume of just 45 mLcc, weighs 145 g, and can deliver flows up to 10 L/min. The device’s fatigue-resistant percutaneous driveline (cable) is 3 mm in diameter extending from the pump through the skin to an external controller.
Implantation All patients were operated with a fibrilating or beating heart technique under cardiopulmonary bypass (CPB) with moderate hypothermia (32°C) except one who underwent aortic valve procedure using cardioplegic arrest. Prior to implantation, the pump was completely submerged in sterile dextrose, with the outflow graft clamped. The sewing ring was attached epicardially to the left ventricular (LV) apex with a ring-shaped Teflon felt support. The inflow cannula was inserted through the sewing ring into the LV. The outflow graft was anastomosed to the ascending aorta using partial clamping. The driveline then tunneled to the right upper quadrant was connected to the controller. After completing deairing, the clamp on the outflow graft was removed and the LVAD pump speed adjusted to accomplish full flow. Pharmacologic support and volume were adjusted to provide appropriate right heart function for successful weaning from CPB. Mean CPB time was 95.5 ⫾ 38.3 (minutes 62–192).
Additional Procedures Tricuspid ring annuloplasty (TRA) was performed in 3 (30%) patients when the annulus diameter was greater than 4.0 cm with significant regurgitation. In one patient we removed an LV thrombus. In a case with aortic regurgitation (third degree), a simple coaptation stitch was placed at the central portion of the three aortic cusps under an aortic cross-clamp.
Anticoagulation On the first postoperative day, when the bleeding had subsided, ahticoagulation with unfractioned heparin was administered to keep the activated partial thromboplastin time between 50 and 60 seconds. Heparin was replaced with warfarin to a target international normalized ratio of 2.5 to 3.0 once the patient was stable with chest tubes removed and returned gastrointestinal function. Acetylsalicylic acid (80 to 160 mg/d) was started on postoperative days 3 to 4.
1727
RESULTS
Mean support time was 250,67 days (92–342). There was no operative or in-hospital mortality. Two patients underwent succesful transplantation on 159 and 172 days of support. Three patients were reexplored due to bleeding. During the early postoperative period, one patient experienced a minor hemorrhagic neurological event and required a tracheostomy due to pneumonia. This patient has completely healed without any sequelal and continues his normal life. Upon follow-up, all patients were asymptomatic regarding heart failure and associated organ dysfunctions. Gastrointestinal bleeding was detected in one patient who died 237 days on postoperative due to an intra-abdominal malignancy and sepsis.
DISCUSSION
Although we do not have an ideal VAD, better devices are emerging with improved outcomes and lower complication rates. In the last 3 years we have performed approximately 100 VAD implantations. The majority of these devices were first-generation pulsatile paracorporeal VADs. Their disadvantages are well known despite their powerful more physiologic pulsatile flow. Although was used succesfully in small children initially,3 we have now been succesfully using bridging, nonpulsatile devices for long-term due to their longer device durability, less need for anticoagulation therapy, and greater quality of life.4 All patients who have continued with HVAD pump support are now outpatients with few medical problems that have required hospital readmission. The HVAD system has small dimensions that simplify implantation with decreased duration of cardiopulmonary bypass. This minimizes surgical trauma, which is particularly important in critically ill patients. HVAD also has been effective for hemodynamic support with low early complication rates in our study. As continuous devices are being used with increasing rates, disadvantages have been reported acquired von Willebrand disease and gastrointestinal bleeding.5,6 One of our patients experienced gastrointestinal bleeding with gastrointestional symptoms in the early postoperative period, susenmbing due to pancreatic cancer and sepsis. It is unclear how to approach VAD candidates who have associated valve dysfunctions. The options for aortic insufficiency are valve replacement,7 total closure of the valve, or simple coaptation stitches at the Arantii nodules that integrate all cusps.8 Total closure of the aortic valve is believed to be dangerous because of total dependency on the device and increased risk of aortic root thrombosis due to the lack of valvular washing. A simple coaptation stitch lets blood flow through the valve, preventing thrombosis. This repair could be provided also with a bioproshetic valve replacement. But we believe that valve replacement takes a longer time on cross-clamp, which exacerbates right ventricular failure.
1728
There is no consensus about associated severe tricuspid regurgitation.9,10 Tricuspid insufficiency is known to be a risk factor for right ventricular failure after left VAD implantation.11 We believe that to prevent right heart failure, TRA is necessary when there is severe tricuspid regurgitation and the annulus is egual to or greater than 40 mm. In our series, three patients with severe tricuspid regurgitation underwent TRA; there was no sign of right ventricular failure. However, our series did not include a control group, but there is some evidence that TRA can be useful.9 TRA may be more important to prevent late right heart failure for destination rather than bridge-to transplantation therapy.12 In conclusion, the HVAD system provided effective circulatory support for patients with end-stage heart failure with a low adverse event rate. Long-term results are needed particularly among destination therapy candidates. REFERENCES 1. Strueber M, O’Driscoll G, Jansz P, et al: HeartWare Investigators. Multicenter evaluation of an intrapericardial left ventricular assist system. J Am Coll Cardiol 57:1375, 2011 2. John R, Kamdar F, Liao K, et al: Improved survival and decreasing incidence of adverse events with the HeartMate II left ventricular assist device as bridge-to-transplant therapy. Ann Thorac Surg 86:1227, 2008 3. Hetzer R, Potapov EV, Stiller B, et al: Improvement in survival after mechanical circulatory support with pneumatic pul-
OZBARAN, YAGDI, ENGIN ET AL satile ventricular assist devices in pediatric patients. Ann Thorac Surg 82:917, 2006 4. Drews T, Jurmann M, Michael D, et al: Differences in pulsatile and non-pulsatile mechanical circulatory support in longterm use. J Heart Lung Transplant 27:1096, 2008 5. Stern DR, Kazam J, Edwards P, et al: Increased incidence of gastrointestinal bleeding following implantation of the HeartMate II LVAD. J Card Surg 25:352, 2010 6. Crow S, Chen D, Milano C, et al: Acquired von Willebrand syndrome in continuous-flow ventricular assist device recipients. Ann Thorac Surg 90:1263, 2010 7. Feldman CM, Silver MA, Sobieski MA, et al: Management of aortic insufficiency with continuous flow left ventricular assist devices: bioprosthetic valve replacement. J Heart Lung Transplant 25:1410, 2006 8. Mudd JO, Cuda JD, Halushka M, et al: Fusion of aortic valve commissures in patients supported by a continuous axial flow left ventricular assist device. J Heart Lung Transplant 27:1269, 2008 9. Piacentino V 3rd, Troupes CD, Ganapathi AM, et al: Clinical impact of concomitant tricuspid valve procedures during left ventricular assist device implantation. Ann Thorac Surg 92:1414, 2011 10. Saeed D, Kidambi T, Shalli S, et al: Tricuspid valve repair with left ventricular assist device implantation: is it warranted? J Heart Lung Transplant 30:530, 2011 11. Potapov EV, Stepanenko A, Dandel M, et al: Tricuspid incompetence and geometry of the right ventricle as predictors of right ventricular function after implantation of a left ventricular assist device. J Heart Lung Transplant 27:1275, 2008 12. Imamura T, Kinugawa K, Shiga T, et al: A case of late-onset right ventricular failure after implantation of a continuous-flow left ventricular assist device. J Artif Organs 2012 Jan 17 [Epub ahead of print]