bentall and de bono   introduced the initial standardized procedure for aortic root replacement ( arr ) in 1968 , and since then , technical improvements , surgical modifications , and development of new materials during the last 3 decades have made this procedure safer and more reproducible . in the current era , reported surgical outcomes following arr are very favorable in elective cases with hospital mortality rates of less than 5% [ 24 ] . with an increase in cases undergoing aortic root procedures ,
redo - arr is regarded as technically challenging , and related with high morbidity and mortality rates especially in emergency settings [ 57 ] . in the interest of reviewing outcomes of redo - arr in the current era
, we sought to evaluate the early and late outcomes of redo - arr in our institution .
from the institutional prospective cardiac surgical database , we identified 66 consecutive adult patients ( > 17 years old ) who underwent reoperative complete arr following surgery for the aortic valve ( av ) or an aortic root procedure between april 1995 and june 2015 .
the arr was defined by complete replacement of the av and aortic sinus by valved conduits using mechanical protheses , bio - prostheses , or a homograft .
all subject patients underwent coronary reattachment to a new aortic sinus using the coronary button technique .
retrospective medical chart reviews were conducted to collect information on prior aortic root surgeries , baseline demographic and clinical profiles , details on redo - arr surgeries , and postoperative outcomes .
major early adverse events included stroke , renal failure that required new dialysis , bleeding control surgery , pericardial effusion , surgical site wound problems , and permanent pacemaker insertion .
primary outcomes of interest were death and valve - related complications that included hemorrhagic complications secondary to anticoagulation therapy , thromboembolic events , requirement for surgery in the operated aortic root , and infective endocarditis .
emergency surgery was defined as an operation before the beginning of the next working day after the decision to operate based on the new euroscore ii guidelines .
early death was defined as occurring within 30 days following surgery or during index hospitalization .
categorical variables were expressed as percentages or frequencies , and continuous variables were expressed as meanstandard deviation or median with range .
kaplan - meier curves were formulated to delineate the overall survival and event - free survival rates .
differences in these rates between the groups were assessed using the log - rank test . to identify the predictors of primary adverse outcomes ( death and valve - related complications ) , cox - proportional hazard models were used .
covariates listed in tables 1 , 2 , and 3 were evaluated in univariable cox models , and those with p - values of less than 0.1 in the univariable models were candidates for multivariable cox - hazard models .
the multivariable analyses involve a stepwise backward elimination technique and variables with p - values of less than 0.1 were used in the final cox - hazard model .
statistical analyses were performed using ibm spss statistics for windows ver . 21.0 software ( ibm co. , armonk , ny , usa ) .
this study was approved by the asan medical center ethics committee / review board ( s2016 - 1344 - 0001 ) , who waived the need for patient consent .
the mean age of subject patients in this study was 45.212.8 years ( range , 35.3 to 55 years ) and 29 cases ( 43.9% ) were emergency procedures .
fifteen patients ( 22.7% ) presented with systemic vasculitis syndrome such as behcet disease ( n=9 ) and takayasu arteritis ( n=6 ) . among the patients , 53 patients ( 80.3% ) had undergone 1 previous cardiac operation , 11 ( 16.7% ) had undergone 2 , and 2 ( 3.0% ) had undergone 3 or more operations .
the most common prior surgical procedure was an isolated aortic valve replacement ( avr ; n=28 , 42.4% ) , followed by a complete arr ( n=11 , 16.7% ) , and aortic root remodeling ( n=6 , 9.1% ) .
indications for the redo - arr were aneurysm ( n=12 ) , pseudoaneurysm ( n=1 ) , or dissection ( n=6 ) of the residual native aortic sinus in 19 patients ( 28.8% ) , native av dysfunction in 8 patients ( 12.1% ) , structural dysfunction of an implanted bioprosthetic av in 19 patients ( 28.8% ) , and infection of a previously replaced av or previously placed proximal aortic grafts in 30 patients ( 45.5% ) ( table 3 ) .
the mean interval between previous aortic root procedures and index redo - arr was 65.314.7 months .
most patients received mechanical valved - conduits for redo - arr ( 74.2% ) while homograft and bioprosthetic valved conduits were used in 12.1% and 13.6% of patients , respectively .
concomitant arch repair was undertaken in 14 patients ( 21.2% ) , while an additional 11 patients required circulatory arrest during redo - arr with a mean duration of 17.44.2 minutes .
details of concomitant cardiac procedures , and durations of cardiopulmonary bypass ( cpb ) and cardiac ischemia during procedures are summarized in table 4 .
there were 3 early deaths ( 4.5% , all of which occurred in emergency operations ) , in which the indications for redo - arr were residual aortic dissection in which the indications for redo - arr were as follows ; a dissection of residual native aorta in 1 patient and infective endocarditis of prosthetic av in 2 patients .
no patients died following elective procedures . the former mortality case received redo - arr due to severe aortic regurgitation caused by residual aortic dissection in the native aortic root followed by supra - coronary aortic replacement in the setting of acute type a aortic dissection .
the patient died of multi - organ failure despite redo - arr and postoperative extracorporeal membrane oxygenation support .
the latter two mortality cases required emergency operations due to aggravation of infective endocarditis in prosthetic av . however , septic shock followed by multi - organ failure led to death in these two patients .
overall , 18 patients ( 27.3% ) experienced major early complications , details of which are shown in table 5 . during follow - up ( median , 54.65 months ; quartile 13 , 17.93 to 95.71 months ) , there were 14 late deaths ( 21.2% ) , 9 valve - related complications including reoperation of the aortic root in 1 patient , infective endocarditis in 3 patients , and hemorrhagic events in 5 patients ( table 5 ) .
there was 1 case of reoperation of the reoperated aortic root : trido bentall operation was conducted to treat recurred infective endocarditis .
event - free survival rates at 5 and 10 years were 76.4%5.4% and 41.1%11.7% , respectively ( fig .
five - year survival and event - free survival rates according to the baseline presentations were as follows : ( 1 ) emergency group ( n=29 ) ; , 74.9%8.2% , 68.2%9.8% , ( 2 ) vasculitis ( behcet , marfan , takayasu ) group ( n=23 ) ; 85.8%7.6% , 76.5%11.5% , and ( 3 ) av only avp or avr ( avp : aortic valve repair , avr : aortic valve replacement ) group ( n=31 ) ; 85.8% 9.4% , 84.6%10.0% , respectively ( fig .
2 ) . there was no statistical difference in overall survival according to the baseline settings of the patients ( fig .
2 ) . the emergency group had a lower event - free survival rate than that of non - emergency group ( p - value= 0.028 ) . among 66 patients ,
17 had undergone previous arr either by valve - sparing or by valve - replacement , followed by redo - arr .
there were no significant differences between those who had undergone arr and those who had undergone other procedures in overall survival ( p=0.160 ) and event - free survival ( p=0.310 ) ( fig .
emergency surgery ( hazard ratio [ hr ] , 2.80 ; 95% confidence interval [ ci ] , 1.12 to 7.00 ; p=0.027 ) was the only significant and independent predictor of the major adverse outcomes ( death and valve - related complications ) while the baseline hemoglobin level was a marginally significant factor associated with the adverse outcomes ( hr , 0.80 ; 95% ci , 0.63 to 1.03 by 1 g / dl increment ; p=0.079 ) .
the mean age of subject patients in this study was 45.212.8 years ( range , 35.3 to 55 years ) and 29 cases ( 43.9% ) were emergency procedures .
fifteen patients ( 22.7% ) presented with systemic vasculitis syndrome such as behcet disease ( n=9 ) and takayasu arteritis ( n=6 ) . among the patients , 53 patients ( 80.3% ) had undergone 1 previous cardiac operation , 11 ( 16.7% ) had undergone 2 , and 2 ( 3.0% ) had undergone 3 or more operations .
the most common prior surgical procedure was an isolated aortic valve replacement ( avr ; n=28 , 42.4% ) , followed by a complete arr ( n=11 , 16.7% ) , and aortic root remodeling ( n=6 , 9.1% ) .
indications for the redo - arr were aneurysm ( n=12 ) , pseudoaneurysm ( n=1 ) , or dissection ( n=6 ) of the residual native aortic sinus in 19 patients ( 28.8% ) , native av dysfunction in 8 patients ( 12.1% ) , structural dysfunction of an implanted bioprosthetic av in 19 patients ( 28.8% ) , and infection of a previously replaced av or previously placed proximal aortic grafts in 30 patients ( 45.5% ) ( table 3 ) .
the mean interval between previous aortic root procedures and index redo - arr was 65.314.7 months .
most patients received mechanical valved - conduits for redo - arr ( 74.2% ) while homograft and bioprosthetic valved conduits were used in 12.1% and 13.6% of patients , respectively .
concomitant arch repair was undertaken in 14 patients ( 21.2% ) , while an additional 11 patients required circulatory arrest during redo - arr with a mean duration of 17.44.2 minutes .
details of concomitant cardiac procedures , and durations of cardiopulmonary bypass ( cpb ) and cardiac ischemia during procedures are summarized in table 4 .
there were 3 early deaths ( 4.5% , all of which occurred in emergency operations ) , in which the indications for redo - arr were residual aortic dissection in which the indications for redo - arr were as follows ; a dissection of residual native aorta in 1 patient and infective endocarditis of prosthetic av in 2 patients .
the former mortality case received redo - arr due to severe aortic regurgitation caused by residual aortic dissection in the native aortic root followed by supra - coronary aortic replacement in the setting of acute type a aortic dissection .
the patient died of multi - organ failure despite redo - arr and postoperative extracorporeal membrane oxygenation support .
the latter two mortality cases required emergency operations due to aggravation of infective endocarditis in prosthetic av . however , septic shock followed by multi - organ failure led to death in these two patients .
overall , 18 patients ( 27.3% ) experienced major early complications , details of which are shown in table 5 . during follow - up ( median , 54.65 months ; quartile 13 , 17.93 to 95.71 months ) ,
there were 14 late deaths ( 21.2% ) , 9 valve - related complications including reoperation of the aortic root in 1 patient , infective endocarditis in 3 patients , and hemorrhagic events in 5 patients ( table 5 ) .
there was 1 case of reoperation of the reoperated aortic root : trido bentall operation was conducted to treat recurred infective endocarditis .
event - free survival rates at 5 and 10 years were 76.4%5.4% and 41.1%11.7% , respectively ( fig .
five - year survival and event - free survival rates according to the baseline presentations were as follows : ( 1 ) emergency group ( n=29 ) ; , 74.9%8.2% , 68.2%9.8% , ( 2 ) vasculitis ( behcet , marfan , takayasu ) group ( n=23 ) ; 85.8%7.6% , 76.5%11.5% , and ( 3 ) av only avp or avr ( avp : aortic valve repair , avr : aortic valve replacement ) group ( n=31 ) ; 85.8% 9.4% , 84.6%10.0% , respectively ( fig .
2 ) . there was no statistical difference in overall survival according to the baseline settings of the patients ( fig .
the emergency group had a lower event - free survival rate than that of non - emergency group ( p - value= 0.028 ) . among 66 patients ,
17 had undergone previous arr either by valve - sparing or by valve - replacement , followed by redo - arr .
there were no significant differences between those who had undergone arr and those who had undergone other procedures in overall survival ( p=0.160 ) and event - free survival ( p=0.310 ) ( fig .
emergency surgery ( hazard ratio [ hr ] , 2.80 ; 95% confidence interval [ ci ] , 1.12 to 7.00 ; p=0.027 ) was the only significant and independent predictor of the major adverse outcomes ( death and valve - related complications ) while the baseline hemoglobin level was a marginally significant factor associated with the adverse outcomes ( hr , 0.80 ; 95% ci , 0.63 to 1.03 by 1 g / dl increment ; p=0.079 ) .
due to the progress in surgical techniques , reoperation in cardiac surgery is increasingly performed .
re - operative aortic root , ascending aorta , or both are challenging reoperations associated with high mortality rate [ 57 ] . due to great diversity among these operations , however , the reported mortality and morbidity have been highly variable among studies .
in addition , there have been only a few studies that specifically evaluated clinical outcomes of redo - arr . the present study aimed to evaluate a homogeneous cohort who underwent redo - arr following av or aortic root procedures .
although redo - arr had been reported to carry a high postoperative mortality in older studies , more recent series have demonstrated early mortality of 3% to 7% .
our data showed similar outcomes with an in - hospital mortality rate of 4.5% ( n=3 ) .
interestingly , these outcomes are very similar to those for an elective primary arr procedure , which varies from 4.5% to 7.5% . as the number of repeat - sternotomies increases , surgical risks of cardiac procedures are also reportedly increased with a strong positive association . in this study , the number of repeat sternotomies was not associated with any early or late adverse outcomes . of note ,
safe re - entry into the chest is thought to be the most important factor for favorable outcomes .
advances in surgical strategies for re - exploration of the sternum promoted by the use of modern computed tomography imaging are believed to have contributed favorable results during re - entry into the chest . once high - risk patients have been identified with ct , utilization of cpb through other sites like the femoral or axillary vessels
previous studies identified risk factors of in - hospital mortality , which were age of the patient ( 75 years ) , preoperative new york heart association functional class iv , emergency presentation , prior cardiac surgery , unplanned coronary artery bypass grafting , prolonged cpb time , and postoperative renal failure [ 57,9,10,1317 ] . in our study ,
emergency surgery was the only significant and independent predictor of the primary adverse outcomes ( hr , 2.80 ; 95% ci , 1.12 to 7.00 ; p=0.027 ) . among 66 patients , 29 patients had redo - arr in emergency presentation . in subgroup analysis ,
event - free survival rate was significantly lower ( log rank p - value=0.028 ) in the emergency group than in that of the non - emergency group .
due to very limited numbers of early mortality cases ( n=3 out of 66 ) , as well as late adverse outcomes , studies on a larger cohort are needed to determine risk factors of redo - arr . in the present study 3 patients died in the early period , of which 2 patients died of acute prosthetic valve endocarditis ( pve ) .
both patients had undergone a previous arr followed by the current redo - arr due to acute pve .
a pve is known as a catastrophic complication , which carries operative mortality of 25% to 60% [ 18,19 ] . in this study , 13 patients presented with pve and 2 of them died , constituting 15.4% of the early mortality rate for pve , which seemed encouraging considering the challenging nature of such a condition .
this study has several major limitations including the retrospective nature of the analyses and the small sample size .
in addition , results are those of a high - volume tertiary academic center ; therefore , they may not be generalizable to other settings . despite technical challenges and a high rate of emergency conditions in patients requiring redo - arr , early and late outcomes following the procedure were acceptable in these patients .
this study has several major limitations including the retrospective nature of the analyses and the small sample size . in addition
, results are those of a high - volume tertiary academic center ; therefore , they may not be generalizable to other settings .
despite technical challenges and a high rate of emergency conditions in patients requiring redo - arr , early and late outcomes following the procedure were acceptable in these patients .
 backgroundgeneralization of standardized surgical techniques to treat aortic valve ( av ) and aortic root diseases has benefited large numbers of patients . as a consequence of the proliferation of patients receiving aortic root surgeries , 
 surgeons are more frequently challenged by reoperative aortic root procedures . 
 the aim of this study was to evaluate the outcomes of redo - aortic root replacement ( arr).methodswe retrospectively reviewed 66 patients ( 36 male ; mean age , 44.59.5 years ) who underwent redo - arr following av or aortic root procedures between april 1995 and june 2015.resultsemergency surgeries comprised 43.9% ( n=29 ) . 
 indications for the redo - arr were aneurysm ( n=12 ) , pseudoaneurysm ( n=1 ) , or dissection ( n=6 ) of the residual native aortic sinus in 19 patients ( 28.8% ) , native av dysfunction in 8 patients ( 12.1% ) , structural dysfunction of an implanted bioprosthetic av in 19 patients ( 28.8% ) , and infection of previously replaced av or proximal aortic grafts in 30 patients ( 45.5% ) . 
 there were 3 early deaths ( 4.5% ) . during follow - up ( median , 
 54.65 months ; quartile 13 , 17.93 to 95.71 months ) , there were 14 late deaths ( 21.2% ) , and 9 valve - related complications including reoperation of the aortic root in 1 patient , infective endocarditis in 3 patients , and hemorrhagic events in 5 patients . 
 overall survival and event - free survival rates at 5 years were 81.5%5.1% and 76.4%5.4% , respectively.conclusiondespite technical challenges and a high rate of emergency conditions in patients requiring redo - arr , early and late outcomes were acceptable in these patients . 
Introduction
Methods
Results
1) Baseline characteristics
2) Outcomes
Discussion
1) Limitations
2) Conclusions