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MODELING AORTIC VALVE INSUFFICIENCY AND AORTIC VALVE REPAIR: APPLICATIONS FROM BENCH TO THE OPERATING ROOM
S164
only measured following resection. We hypothesize that the measured biomechanics of the aorta in vivo is noninvasively may provide meaningful information regarding aortic risk prediction. In this study we sought to determine whether we could measure aortic biomechanics using speckle tissue tracking during TEE and correlate this with ex vivo measures. METHODS: Biomechanics of the ascending aorta of patients undergoing resection were performed in vivo and ex vivo. In vivo biomechanics were estimated by intra operative TEE with simultaneous ECG tracking. From the short axis the deformation - strain of the tissue was obtained by using the speckled tracking - GE EchoPAC station by mapping of the circumference of the aorta using advanced Q Analysis. The average stress of the tissue was calculated from the circumferential strain and peripheral blood pressure recorded simultaneously by a radial artery line tracing then using the following b¼ ln(SBP⁄DBP)⁄(Ao-S) (b stiffness; Ps Systolic BP; Pd Diastolic BP, Aos circumferential strain). Ascending aortic tissue was obtained intra operatively then mechanical tested using a biaxial tissue tester Bose ELF 3200 to obtain the stress/strain curve around the circumference of Anterior, Posterior, Inner and Outer curvature of aortic wall. We compared the ex vivo apparent stiffness at 25% strain in circumferential direction with echo estimated stiffness in all 4 regions. RESULTS: 19 patients - 11 males with a mean age of 60 years 16 and a mean aortic diameter of 5 cm 1 - 11 TAV and 8 BAV were included in the study. AscAA stiffness depended on location - Two way ANOVA, p¼0.0417. In vivo mean stiffness at IC, Anterior, OC and Posterior walls were 0.054, 0.029, 0.041 and 0.050 MPa respectively. Ex vivo mean stiffness at IC, Anterior, OC and Posterior walls were 0.057, 0.036, 0.040 and 0.033 MPa respectively. The stiffness was not significantly different between the ex vivo and in vivo measures - Two way ANOVA p¼0.8252. However, the variability of the IC was highest and the difference between measured ex vivo stiffness and estimated echo stiffness at the posterior wall was greatest figure 1. CONCLUSION: In vivo speckle tracking echo captures the regional mechanical properties of ascending aortic diseases, and appears to be a promising tool in assessing the mechanics of AscAA in vivo.
311 VALVE SPARING AORTIC ROOT RECONSTRUCTION: DOES GRAFT SIZING MATTER? C Tarola, K Losenno, M Peterson, I El-Hamamsy, M Chu London, Ontario INTRODUCTION:
Aortic root reconstruction with valve sparing techniques have gained widespread acceptance for treatment of patients with aortic root aneurysm with/without aortic insufficiency. Several graft sizing strategies have been described with variable efficacy. Our study aims to evaluate the influence of graft sizing on outcomes after root reconstruction.
Canadian Journal of Cardiology Volume 31 2015 METHODS:
Between 2008 and 2015, 95 consecutive patients underwent aortic valve sparing root reconstruction by three cardiac surgeons at three different institutions. Mean age was 50 16 years, 82 (86.3%) were male. Twenty-four (25.5%) patients had confirmed connective tissue disease. Acute type A aortic dissection was the clinical presentation in 9 (9.5%) patients and greater then or equal to moderate aortic insufficiency was present in 28 (35.4%) patients. Aortic valve morphology was identified as tricuspid, bicuspid and unicuspid in 64 (68.1%), 29 (30.8%), and 1 (1.1%) of patients, respectively. Maximum aortic diameter was 53.3 9.1 mm. Mean cardiopulmonary bypass time was 251 67 minutes, aortic crossclamp time was 209 50 minutes, and hypothermic circulatory arrest time was 39 34 minutes in patients who underwent arch replacement. Mean follow-up was 21.6 15.6 months. RESULTS: In-hospital/30-day mortality occurred in one patient. Mean graft size was 30.6 2.5 mm, with 30 mm in 65.3% patients and < 30 mm in 34.7%. Cuspal plication techniques were employed in 45.9%. Aortic insufficiency decreased from 1.79 1.9 (0-4) preoperatively to 0.35 0.56 (0-2) postoperatively. Multivariate regression analysis demonstrated no significant effect of graft sizing on freedom from moderate aortic insufficiency. Median ICU and hospital length of stay were 1 and 5 days, respectively. Freedom from reoperation at 30 days/in-hospital, 1 year and 5 years was 100%, 100%, and 98%, respectively. Survival at 30 days/in-hospital, 1 year and 5 years was 99%, 99%, and 99%, respectively. CONCLUSION: Graft size selection appears to have little impact on the risk of postoperative aortic insufficiency. Other factors are likely more importantly related to risk of aortic insufficiency and warrant further investigation.
312 MODELING AORTIC VALVE INSUFFICIENCY AND AORTIC VALVE REPAIR: APPLICATIONS FROM BENCH TO THE OPERATING ROOM HD Toeg, M Chamberland, R Jafar, T Al-Atassi, M Labrosse, B Sohmer, M Boodhwani Ottawa, Ontario OBJECTIVES:
Aortic valve repair(AVr) has become an attractive alternative for the correction of aortic insufficiency(AI) as compared to aortic valve replacement; however, little information exists regarding the effects of acute AI and subsequent AV repair(AVr) on ventricular and valvular dynamics. The objective of this study was to measure and compare hemodynamic and echocardiographic properties in a novel, ex-vivo model of severe acute AI due to cusp pathology followed by valve repair. METHODS: Porcine aortic roots with intact aortic valves were placed in a left heart simulator mounted with a high-speed camera for baseline hemodynamic assessment. 3-D echocardiography was used to evaluate valve function, AI, and leaflet coaptation (coaptation surface area [CoSA]). In the first model, an 8mm diameter circular perforation was created in the body
Abstracts
of the non-coronary cusp (NCC) leaving an intact free margin(AI “lesion” assessment) followed by patch repair (AVr “treatment” assessment). In the second model, 75% of the NCC was excised followed by cusp replacement with a pericardial patch. Hemodynamic and echocardiographic data are expressed as medians with interquartile ranges. Finite element modeling (FEM) was performed in both models to understand stress characteristics. Wilcoxon-signed rank tests were used to determine significance between paired sample experiments. RESULTS: The cusp perforation model demonstrated a significant increase in the regurgitant fraction (RF) after AI was created (control¼ 5.2 [5,5.6] % versus AI¼ 50.1 [49,53] %; p¼0.04) and returned to baseline “control” levels after AVr (AVr¼ 11.7 [7.1,11.8] %; p¼0.14). The cusp excision and repair model demonstrated a significant increase in RF after AI was created (control¼ 4.8 [3.2,9.1]% versus AI ¼ 69.6 [69.2,75.3]%; p¼0.04) but returned to baseline with valve repair “treatment” (AVr¼ 10.4[9.7,11] %; p¼0.5). Furthermore, CoSA was significantly reduced after creation of AI (1.54cm2 versus 1.14[0.75,1.18] cm2; p¼0.04) which then returned to baseline levels after AVr (1.54cm2 versus 1.59cm2; p¼0.68). Finally, after comparing all hemodynamic parameters after valve repair in both models, there was no significant difference. Figure 1 summarizes the findings with FEM. CONCLUSION: We successfully simulated acute AI and effective repair due to clinically relevant cusp pathology in an ex-vivo left heart simulator along with 3-D echocardiography. After valve repair, both models demonstrated similar leaflet stress changes (+24% increase) suggesting that no matter the intervention, the repaired cusp retains major stress; making it more vulnerable to failure. Further investigation using this reproducible ex-vivo protocol with FEM will help reveal optimal therapeutic options in more complex models of AI.
S165 BACKGROUND: Reoperative mitral valve surgery in patients with patent coronary bypass grafts can be challenging and harbours high rates of morbidities. We present the results and technical aspects of 10 patients who underwent a reoperative minimally invasive mitral valve surgery, on a non-fibrillating (On-pump) beating heart. METHODS: At the time of surgery, 4 (40%) patients had severe mitral regurgitation, 5 (50%) had moderate to severe and 1 (10%) had moderate. All patients had at least one patent coronary bypass graft and underwent on-pump minimally invasive mitral valve surgery on a beating heart. Five (50%) had mitral valve repair and 5 (50%) had mitral valve replacement. RESULTS: Median age was 68 years and 9 (90%) patients were male. The median EuroSCORE II was 8.4% (range from 3.2 to 22%). Median cardiopulmonary bypass time was 101 minutes (range from 55 to 156 min). Five (50%) patients required blood product transfusion postoperatively. There was no perioperative stroke nor acute myocardial infarction. There was no perioperative death. Four patients developed acute renal failure, among which two had preoperative chronic renal failure. One of them needed temporary hemofiltration. Four patients needed permanent pacemaker implantation. The pre-discharge transthoracic echocardiogram showed successful mitral valve surgery (repair/replacement) with mild or less mitral regurgitation. Median hospital stay was 9 days (range from 5 to 17 days). CONCLUSION: Redo mitral valve surgery in patients with patent coronary bypass grafts can safely be performed via minimally invasive mini-thoracotomy on a beating heart. The main benefit of this approach is the avoidance of sternal reentry, decreasing the risk of injury cardiac structures and subsequent bleeding hazarad.
314 FRAILTY PREDICTS MORTALITY AND BASELINE CARDIAC OUTPUT IN THE ISOLATED RAT HEART A Yorke, C Hancock Friesen, S Howlett, S O’Blenes Halifax, Nova Scotia BACKGROUND:
313 BEATING HEART MINIMALLY INVASIVE MITRAL VALVE SURGERY IN PATIENTS WITH PATENT CORONARY BYPASS GRAFTS A Ghoneim, I Bouhout, W Fortin, A Mazine, I El-Hamamsy, H Jeanmart, M Pellerin, D Bouchard Montréal, Québec
Elderly patients represent the fastest growing population presenting for cardiac surgery. While advanced age is associated with adverse postoperative outcomes, the wide variation in the health status of elderly patients suggests that chronological age (CA) does not necessarily reflect physiological age (PA). Frailty, a geriatric syndrome associated with impaired resiliency to acute stress, is an indicator of PA that predicts negative health outcomes following cardiac surgery. To better understand the impact of CA and frailty on hearts undergoing surgical procedures, there is a need to develop an animal model of frailty in which ischemia-reperfusion injury following cardioplegic arrest can be studied. Our objective was to develop a frailty index (FI) for rats, and assess the impact of age and frailty on cardiac function and recovery from cardioplegic arrest. METHODS/RESULTS: We followed male F344 rats (n¼36) from middle age (13 months) into old age (21 months). Data on survival and 45 variables in health systems known to change
only measured following resection. We hypothesize that the measured biomechanics of the aorta in vivo is noninvasively may provide meaningful information regarding aortic risk prediction. In this study we sought to determine whether we could measure aortic biomechanics using speckle tissue tracking during TEE and correlate this with ex vivo measures. METHODS: Biomechanics of the ascending aorta of patients undergoing resection were performed in vivo and ex vivo. In vivo biomechanics were estimated by intra operative TEE with simultaneous ECG tracking. From the short axis the deformation - strain of the tissue was obtained by using the speckled tracking - GE EchoPAC station by mapping of the circumference of the aorta using advanced Q Analysis. The average stress of the tissue was calculated from the circumferential strain and peripheral blood pressure recorded simultaneously by a radial artery line tracing then using the following b¼ ln(SBP⁄DBP)⁄(Ao-S) (b stiffness; Ps Systolic BP; Pd Diastolic BP, Aos circumferential strain). Ascending aortic tissue was obtained intra operatively then mechanical tested using a biaxial tissue tester Bose ELF 3200 to obtain the stress/strain curve around the circumference of Anterior, Posterior, Inner and Outer curvature of aortic wall. We compared the ex vivo apparent stiffness at 25% strain in circumferential direction with echo estimated stiffness in all 4 regions. RESULTS: 19 patients - 11 males with a mean age of 60 years 16 and a mean aortic diameter of 5 cm 1 - 11 TAV and 8 BAV were included in the study. AscAA stiffness depended on location - Two way ANOVA, p¼0.0417. In vivo mean stiffness at IC, Anterior, OC and Posterior walls were 0.054, 0.029, 0.041 and 0.050 MPa respectively. Ex vivo mean stiffness at IC, Anterior, OC and Posterior walls were 0.057, 0.036, 0.040 and 0.033 MPa respectively. The stiffness was not significantly different between the ex vivo and in vivo measures - Two way ANOVA p¼0.8252. However, the variability of the IC was highest and the difference between measured ex vivo stiffness and estimated echo stiffness at the posterior wall was greatest figure 1. CONCLUSION: In vivo speckle tracking echo captures the regional mechanical properties of ascending aortic diseases, and appears to be a promising tool in assessing the mechanics of AscAA in vivo.
311 VALVE SPARING AORTIC ROOT RECONSTRUCTION: DOES GRAFT SIZING MATTER? C Tarola, K Losenno, M Peterson, I El-Hamamsy, M Chu London, Ontario INTRODUCTION:
Aortic root reconstruction with valve sparing techniques have gained widespread acceptance for treatment of patients with aortic root aneurysm with/without aortic insufficiency. Several graft sizing strategies have been described with variable efficacy. Our study aims to evaluate the influence of graft sizing on outcomes after root reconstruction.
Canadian Journal of Cardiology Volume 31 2015 METHODS:
Between 2008 and 2015, 95 consecutive patients underwent aortic valve sparing root reconstruction by three cardiac surgeons at three different institutions. Mean age was 50 16 years, 82 (86.3%) were male. Twenty-four (25.5%) patients had confirmed connective tissue disease. Acute type A aortic dissection was the clinical presentation in 9 (9.5%) patients and greater then or equal to moderate aortic insufficiency was present in 28 (35.4%) patients. Aortic valve morphology was identified as tricuspid, bicuspid and unicuspid in 64 (68.1%), 29 (30.8%), and 1 (1.1%) of patients, respectively. Maximum aortic diameter was 53.3 9.1 mm. Mean cardiopulmonary bypass time was 251 67 minutes, aortic crossclamp time was 209 50 minutes, and hypothermic circulatory arrest time was 39 34 minutes in patients who underwent arch replacement. Mean follow-up was 21.6 15.6 months. RESULTS: In-hospital/30-day mortality occurred in one patient. Mean graft size was 30.6 2.5 mm, with 30 mm in 65.3% patients and < 30 mm in 34.7%. Cuspal plication techniques were employed in 45.9%. Aortic insufficiency decreased from 1.79 1.9 (0-4) preoperatively to 0.35 0.56 (0-2) postoperatively. Multivariate regression analysis demonstrated no significant effect of graft sizing on freedom from moderate aortic insufficiency. Median ICU and hospital length of stay were 1 and 5 days, respectively. Freedom from reoperation at 30 days/in-hospital, 1 year and 5 years was 100%, 100%, and 98%, respectively. Survival at 30 days/in-hospital, 1 year and 5 years was 99%, 99%, and 99%, respectively. CONCLUSION: Graft size selection appears to have little impact on the risk of postoperative aortic insufficiency. Other factors are likely more importantly related to risk of aortic insufficiency and warrant further investigation.
312 MODELING AORTIC VALVE INSUFFICIENCY AND AORTIC VALVE REPAIR: APPLICATIONS FROM BENCH TO THE OPERATING ROOM HD Toeg, M Chamberland, R Jafar, T Al-Atassi, M Labrosse, B Sohmer, M Boodhwani Ottawa, Ontario OBJECTIVES:
Aortic valve repair(AVr) has become an attractive alternative for the correction of aortic insufficiency(AI) as compared to aortic valve replacement; however, little information exists regarding the effects of acute AI and subsequent AV repair(AVr) on ventricular and valvular dynamics. The objective of this study was to measure and compare hemodynamic and echocardiographic properties in a novel, ex-vivo model of severe acute AI due to cusp pathology followed by valve repair. METHODS: Porcine aortic roots with intact aortic valves were placed in a left heart simulator mounted with a high-speed camera for baseline hemodynamic assessment. 3-D echocardiography was used to evaluate valve function, AI, and leaflet coaptation (coaptation surface area [CoSA]). In the first model, an 8mm diameter circular perforation was created in the body
Abstracts
of the non-coronary cusp (NCC) leaving an intact free margin(AI “lesion” assessment) followed by patch repair (AVr “treatment” assessment). In the second model, 75% of the NCC was excised followed by cusp replacement with a pericardial patch. Hemodynamic and echocardiographic data are expressed as medians with interquartile ranges. Finite element modeling (FEM) was performed in both models to understand stress characteristics. Wilcoxon-signed rank tests were used to determine significance between paired sample experiments. RESULTS: The cusp perforation model demonstrated a significant increase in the regurgitant fraction (RF) after AI was created (control¼ 5.2 [5,5.6] % versus AI¼ 50.1 [49,53] %; p¼0.04) and returned to baseline “control” levels after AVr (AVr¼ 11.7 [7.1,11.8] %; p¼0.14). The cusp excision and repair model demonstrated a significant increase in RF after AI was created (control¼ 4.8 [3.2,9.1]% versus AI ¼ 69.6 [69.2,75.3]%; p¼0.04) but returned to baseline with valve repair “treatment” (AVr¼ 10.4[9.7,11] %; p¼0.5). Furthermore, CoSA was significantly reduced after creation of AI (1.54cm2 versus 1.14[0.75,1.18] cm2; p¼0.04) which then returned to baseline levels after AVr (1.54cm2 versus 1.59cm2; p¼0.68). Finally, after comparing all hemodynamic parameters after valve repair in both models, there was no significant difference. Figure 1 summarizes the findings with FEM. CONCLUSION: We successfully simulated acute AI and effective repair due to clinically relevant cusp pathology in an ex-vivo left heart simulator along with 3-D echocardiography. After valve repair, both models demonstrated similar leaflet stress changes (+24% increase) suggesting that no matter the intervention, the repaired cusp retains major stress; making it more vulnerable to failure. Further investigation using this reproducible ex-vivo protocol with FEM will help reveal optimal therapeutic options in more complex models of AI.
S165 BACKGROUND: Reoperative mitral valve surgery in patients with patent coronary bypass grafts can be challenging and harbours high rates of morbidities. We present the results and technical aspects of 10 patients who underwent a reoperative minimally invasive mitral valve surgery, on a non-fibrillating (On-pump) beating heart. METHODS: At the time of surgery, 4 (40%) patients had severe mitral regurgitation, 5 (50%) had moderate to severe and 1 (10%) had moderate. All patients had at least one patent coronary bypass graft and underwent on-pump minimally invasive mitral valve surgery on a beating heart. Five (50%) had mitral valve repair and 5 (50%) had mitral valve replacement. RESULTS: Median age was 68 years and 9 (90%) patients were male. The median EuroSCORE II was 8.4% (range from 3.2 to 22%). Median cardiopulmonary bypass time was 101 minutes (range from 55 to 156 min). Five (50%) patients required blood product transfusion postoperatively. There was no perioperative stroke nor acute myocardial infarction. There was no perioperative death. Four patients developed acute renal failure, among which two had preoperative chronic renal failure. One of them needed temporary hemofiltration. Four patients needed permanent pacemaker implantation. The pre-discharge transthoracic echocardiogram showed successful mitral valve surgery (repair/replacement) with mild or less mitral regurgitation. Median hospital stay was 9 days (range from 5 to 17 days). CONCLUSION: Redo mitral valve surgery in patients with patent coronary bypass grafts can safely be performed via minimally invasive mini-thoracotomy on a beating heart. The main benefit of this approach is the avoidance of sternal reentry, decreasing the risk of injury cardiac structures and subsequent bleeding hazarad.
314 FRAILTY PREDICTS MORTALITY AND BASELINE CARDIAC OUTPUT IN THE ISOLATED RAT HEART A Yorke, C Hancock Friesen, S Howlett, S O’Blenes Halifax, Nova Scotia BACKGROUND:
313 BEATING HEART MINIMALLY INVASIVE MITRAL VALVE SURGERY IN PATIENTS WITH PATENT CORONARY BYPASS GRAFTS A Ghoneim, I Bouhout, W Fortin, A Mazine, I El-Hamamsy, H Jeanmart, M Pellerin, D Bouchard Montréal, Québec
Elderly patients represent the fastest growing population presenting for cardiac surgery. While advanced age is associated with adverse postoperative outcomes, the wide variation in the health status of elderly patients suggests that chronological age (CA) does not necessarily reflect physiological age (PA). Frailty, a geriatric syndrome associated with impaired resiliency to acute stress, is an indicator of PA that predicts negative health outcomes following cardiac surgery. To better understand the impact of CA and frailty on hearts undergoing surgical procedures, there is a need to develop an animal model of frailty in which ischemia-reperfusion injury following cardioplegic arrest can be studied. Our objective was to develop a frailty index (FI) for rats, and assess the impact of age and frailty on cardiac function and recovery from cardioplegic arrest. METHODS/RESULTS: We followed male F344 rats (n¼36) from middle age (13 months) into old age (21 months). Data on survival and 45 variables in health systems known to change