Hemostasis and Durability of Automated Left Ventricular Assist Device Apical Cuff Anastomosis with a Sutureless Implant System in Acute and Chronic Bovine Implants
Presented During:
Friday, September 20, 2024: 5:00PM - 6:30PM
Omni King Edward Hotel
Abstract No:
9927
Submission Type:
Abstract Submission
Authors:
Max Mitchell (1), Jeremy Morgan (2), Daniel Sims (2), Jeffrey Steinmetz (2), Christopher Banas (2)
Institutions:
(1) Children's Hospital Colorado, Aurora, CO, (2) ConneX Biomedical, Inc., Aurora, CO
Submitting Author:
*Max Mitchell
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Children's Hospital Colorado
Children's Hospital Colorado
Co-Author(s):
Jeremy Morgan
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ConneX Biomedical, Inc.
ConneX Biomedical, Inc.
Daniel Sims
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ConneX Biomedical, Inc.
ConneX Biomedical, Inc.
Jeffrey Steinmetz
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ConneX Biomedical, Inc.
ConneX Biomedical, Inc.
Christopher Banas
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ConneX Biomedical, Inc.
ConneX Biomedical, Inc.
Presenting Author:
*Max Mitchell
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Children's Hospital Colorado
Children's Hospital Colorado
Abstract:
Objective. Durable Left Ventricular Assist Devices (LVADs) require a manually sutured apical cuff - left ventricular anastomosis. We developed an attachment device to automate this anastomosis for the most common durable LVAD. It is low profile to facilitate minimal exposure. The purpose of this study was to assess implant time, acute hemostasis, and chronic durability of apical cuff anastomosis using this device in acute and chronic (60 days) bovine calf models.
Methods. The device is comprised of 12 helical coil tissue anchors, 4 compression plates, and a delivery tool. Apical cuff anastomoses were performed in bovine calves. Implants were video recorded and photographed. Intravenous (IV) heparin was administered to Activated Clotting Time >300 seconds. Implant time was from first device epicardial contact to delivery tool release. The apex was cored, and the cuff site was occluded with a custom plug. Bleeding was assessed qualitatively by an experienced LVAD surgeon and characterized by Likert Scale (1=unacceptable, 2=poor, 3=acceptable, 4=good, 5 =excellent). ACUTE MODEL (n=6): Implants were by full median sternotomy. A proof-of-concept delivery tool requiring sequential tissue anchor deployment by hand-held driver was used in 3 cases. A fully automated synchronous anchor deployment tool was used in 3 cases. Caval inflow occlusion was used for coring and plugging. Animals were resuscitated to baseline blood pressure (BP). Bleeding was assessed at baseline and at supraphysiologic BP (norepinephrine). Implants and attachment components were examined after euthanasia. CHRONIC MODEL (n=3): The synchronous delivery tool was used via lower partial sternotomy. Coring and plugging were done on cardiopulmonary bypass (CPB-cervical cannulation). Acute hemostasis was assessed after CPB and after protamine. IV heparin was initiated at 12-24 hours and transitioned to warfarin (goal INR >2.5). Serial hematocrit, chest tube outputs, and INR were recorded. Necropsy was performed by a veterinary pathologist with extensive preclinical LVAD experience. Anchor position was compared by acute and necropsy photograph comparison. After gross inspection all hardware was removed and examined. Histopathologic heart and end organ examination was performed.
Results. Acute implant time ranges were: 77-93 (sequential), and 22-32 (synchronous) seconds. Hemostasis score was 3 (acceptable) in 1 and 4 or 5 (good-excellent) in 5 at baseline and induced supraphysiologic BP (range: 192-247 mm Hg). Chronic implant time range was 17-20 seconds. Intra-operative hemostasis score was 5 (excellent) in all cases. No animals were transfused. Twenty-four-hour hematocrit increased from intraoperative baseline by +2% to +5%. All chest tubes were removed within 48 hours. At necropsy (60±4 days) there were minimal pericardial and pleural adhesions, no pseudoaneurysms, or evidence of bleeding. All implants had stable anchor positions and a concentric ring of dense fibrous scar at the junction between the inner circumference of the apical cuff metal cylinder and the cored epicardial edge (see figure). Implant histopathology was similar to sutured apical cuff anastomoses observed in prior preclinical LVAD studies.
Conclusions. The device produced a hemostatic and durable apical cuff anastomosis. Advantages are rapid implant time, hemostasis, standardized technique, and low profile for limited exposure. The technology is adaptable for other intraventricular access requirements.
Methods. The device is comprised of 12 helical coil tissue anchors, 4 compression plates, and a delivery tool. Apical cuff anastomoses were performed in bovine calves. Implants were video recorded and photographed. Intravenous (IV) heparin was administered to Activated Clotting Time >300 seconds. Implant time was from first device epicardial contact to delivery tool release. The apex was cored, and the cuff site was occluded with a custom plug. Bleeding was assessed qualitatively by an experienced LVAD surgeon and characterized by Likert Scale (1=unacceptable, 2=poor, 3=acceptable, 4=good, 5 =excellent). ACUTE MODEL (n=6): Implants were by full median sternotomy. A proof-of-concept delivery tool requiring sequential tissue anchor deployment by hand-held driver was used in 3 cases. A fully automated synchronous anchor deployment tool was used in 3 cases. Caval inflow occlusion was used for coring and plugging. Animals were resuscitated to baseline blood pressure (BP). Bleeding was assessed at baseline and at supraphysiologic BP (norepinephrine). Implants and attachment components were examined after euthanasia. CHRONIC MODEL (n=3): The synchronous delivery tool was used via lower partial sternotomy. Coring and plugging were done on cardiopulmonary bypass (CPB-cervical cannulation). Acute hemostasis was assessed after CPB and after protamine. IV heparin was initiated at 12-24 hours and transitioned to warfarin (goal INR >2.5). Serial hematocrit, chest tube outputs, and INR were recorded. Necropsy was performed by a veterinary pathologist with extensive preclinical LVAD experience. Anchor position was compared by acute and necropsy photograph comparison. After gross inspection all hardware was removed and examined. Histopathologic heart and end organ examination was performed.
Results. Acute implant time ranges were: 77-93 (sequential), and 22-32 (synchronous) seconds. Hemostasis score was 3 (acceptable) in 1 and 4 or 5 (good-excellent) in 5 at baseline and induced supraphysiologic BP (range: 192-247 mm Hg). Chronic implant time range was 17-20 seconds. Intra-operative hemostasis score was 5 (excellent) in all cases. No animals were transfused. Twenty-four-hour hematocrit increased from intraoperative baseline by +2% to +5%. All chest tubes were removed within 48 hours. At necropsy (60±4 days) there were minimal pericardial and pleural adhesions, no pseudoaneurysms, or evidence of bleeding. All implants had stable anchor positions and a concentric ring of dense fibrous scar at the junction between the inner circumference of the apical cuff metal cylinder and the cored epicardial edge (see figure). Implant histopathology was similar to sutured apical cuff anastomoses observed in prior preclinical LVAD studies.
Conclusions. The device produced a hemostatic and durable apical cuff anastomosis. Advantages are rapid implant time, hemostasis, standardized technique, and low profile for limited exposure. The technology is adaptable for other intraventricular access requirements.
Mechanical Support and Thoracic Transplantation Summit:
ECMO/Mechanical Support
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