Longer-term outcomes after bicuspid aortic valve repair in 142 patients.

BACKGROUND: The aim of this study was to evaluate the longer-term results of bicuspid aortic valve (BAV) repair with or without aortic root replacement. METHODS: From 1999 to 2017, 142 patients with or without aortic root dilatation who underwent repair of a regurgitant BAV were included in the study. Ninety-four patients underwent isolated BAV repair (Group 1; median age 43 years) and 48 patients underwent valve-sparing aortic root replacement plus BAV repair (aortic valve reimplantation-Group 2; median age 48 years). Median clinical follow-up time was 5.9 years (range 0.5-15) in Group 1 and 3 years (range 0.5-16) in Group 2, respectively. RESULTS: In-hospital mortality was 1% in Group 1, and 2% in Group 2 (p = .6). The 5- and 10-year survival was 93 ± 2.9% and 81 ± 5.8% in Group 1 and 96 ± 3.1% and 96 ± 3.1% in Group 2, respectively (p = .31). Eleven patients of Group 1 (1.7%/patient-year) and five patients of Group 2 (2.2%/patient-year) underwent reoperation of the aortic valve (p = .5). The 5- and 10-year freedom from reoperation were 93.0 ± 2.1% and 77.1 ± 7.1% in Group 1 and 93.0 ± 5.0% and 76.7 ± 9.6% in Group 2 (p = .83), respectively. At the latest follow-up, only two patients of Group 1 and 1 patient of Group 2 had AV regurgitation = 2° (p = .7). The cumulative linearized incidence of all valve-related complications (bleeding, stroke, endocarditis, and reoperation) was 2.9%/patient-year in Group 1% and 4%/patient-year in Group 2, respectively (p = .6). CONCLUSIONS: Isolated BAV repair and combined aortic valve reimplantation plus BAV repair provide good clinical longer-term outcomes with relatively low reoperation rate and durable valve function.

Bicuspid aortic valve repair with hemi-remodeling technique and external ring annuloplasty.

BACKGROUND: Current guidelines recommend root replacement when diameter of the sinuses of Valsalva are superior to 45 mm particularly for bicuspid valve. However, in case of tubular aorta aneurysms with moderate root dilatation (40-45 mm diameter), the approach is still debated regarding the increased risk of coronary reimplantation. We present a modified hemi-remodeling aortic repair technique that includes the replacement of the noncoronary sinus, ascending aorta, and valve repair with external ring annuloplasty in patients with bicuspid aortic valve (BAV) and moderately dilated aortic root. METHODS: Between 2003 and 2017, 18 patients presenting with left-right BAV and an aortic root diameter at 42.3+/-3.3 mm underwent hemi-root and ascending aorta replacement and aortic valve repair with external annuloplasty. RESULTS: Postoperatively, 16 (88.9%) had no aortic insufficiency (AI) and 2 (11.1%) had grade I AI, no patients had grade III or grade IV AI. Overall survival and freedom from grade II AI at 4 years and freedom from aortic valve-related reoperation were 100%. CONCLUSION: The standardized modified hemi-remodeling technique we present is a safe and reproducible procedure, with satisfactory durability at follow-up. This technique represents an interesting alternative to full valve sparing root replacement, as it avoids the operative risk of coronary reimplantation, allows shorter cross-clamping time and a better exposition on the valve for a symmetrical repair, placing the commissure at 180°, compared with valve sparing root replacement.

Quality of life after aortic valve repair is similar to Ross patients and superior to mechanical valve replacement: a cross-sectional study.

BACKGROUND: In patients after aortic valve surgery, the quality of life is hypothesized to be influenced by the type of the valve procedure. A cross-sectional study on the postoperative quality of life was carried out in patients after aortic valve-sparing surgery (with regards to the age of the patient), Ross procedure and mechanical aortic valve replacement. METHODS: Quality of life was studied in 139 patients after aortic valve surgery divided into four study groups (Y - aortic valve-sparing procedure at the age below 50 years, mean age 36.2 years; O - aortic valve-sparing procedure at the age 50 years and over, mean age 59.2 years; R - Ross procedure, mean age 37.8 years and M - mechanical aortic valve replacement at the age below 50 years, mean age 39.2 years). SF-36 Short Form and valve-specific questionnaires were mailed to the patients after 6 months or later following surgery (median 26.9 months). RESULTS: In SF-36, the younger aortic valve repair patients and the Ross patients scored significantly better in 4 of 4 physical subscales and in 2 of 4 mental subscales than the older aortic valve repair and mechanical valve replacement patients. In the valve-specific questionnaire; however, all 3 groups free of anticoagulation (Y, O, and R) displayed greater freedom from negative valve-related concerns. CONCLUSIONS: Postoperative quality of life is influenced by the type of aortic valve procedure and is negatively linked with mechanical prosthesis implantation and long-term anticoagulation. Aortic valve-sparing strategy should be considered in cases with suitable valve morphology due to favorable clinical results and beneficial impact on the long-term quality of life.

One-step supraclavicular approach to the treatment of Dysphagia lusoria.

A one-step supraclavicular approach for the surgical treatment of the aberrant right subclavian artery is described in a case of dysphagia lusoria in a 38-year-old female. The approach allows for safe division of the arteria lusoria and its re-anastomosis to the common carotid artery while the patient benefits from a mini-invasive extrathoracic procedure. doi: 10.1111/jocs.12287 (J Card Surg 2014;29:519-522).

Valve cuspidity: a risk factor for aortic valve repair?

BACKGROUND: The aim of this study was to analyze short- and mid-term results after aortic valve (AV) repair with particular regard to the impact of valve cuspidity (bicuspid versus tricuspid aortic valve). METHODS: One hundred patients with aortic regurgitation (AR) undergoing aortic valve repair between November 2007 and October 2012 were included in the study. Sixty patients had bicuspid AV (BAV group; 11 females) and 40 patients had tricuspid AV (TAV group; 13 females). AR > grade 2 was present in 47 (78%) patients in the BAV and in 35 (88%) patients in the TAV group. Follow-up was complete in 100% and median was 25 months. RESULTS: Isolated aortic valve repair was performed in 27 (45%) of BAV patients and in six (15%) of TAV patients. Replacement of the ascending aorta and/or aortic root was performed in 33 (55%) of BAV patients and in 34 (86%) of TAV patients. There was no death within 30 days postoperatively, while two patients died (TAV group) during the follow-up period. There was no statistical difference between BAV and TAV groups with regard to the survival (100 ± 0% vs. 95 ± 4%, p = 0.102), the three-year freedom from AV-related reoperation (90 ± 5% vs. 89 ± 6%, p = 0.456), and the three-year freedom from AR grade > 2 (86 ± 6% vs. 82 ± 7%, p = 0.866), respectively. CONCLUSIONS: This study demonstrates no difference in mid-term results after regurgitant bicuspid and tricuspid aortic valve repair, suggesting that bicuspid valve may not be a risk factor for aortic valve repair.

Left atrial appendage occlusion: Percutaneous and surgical approaches in everyday practice.

Prophylactic left atrial appendage occlusion has been suggested as a means of reducing cardioembolism risk in patients with atrial fibrillation. Its clinical benefits have been discussed together with potential endocrine or hemodynamic adverse effects, with conflicting conclusions. We aimed to provide a thorough overview of the current literature and a recommendation for daily clinical decision-making. A comprehensive Medline search through PubMed was conducted to search for relevant articles, which were further filtered using the title and abstract. Sixty-five articles were selected as relevant to the topic. Concomitant left atrial appendage occlusion during cardiac surgery for other reasons is effective in terms of thromboembolism risk reduction in patients with a history of atrial fibrillation and higher CHA2DS2-VASc scores. Surgical occlusion is safe, and epicardial closure techniques are preferred. Thoracoscopic and transcatheter techniques are also feasible, and the individual treatment choice must be tailored to the patient. The concerns about endocrine imbalance or risk of heart failure after occlusion are not supported by evidence. Current evidence is conflicting with regard to hemodynamic consequences of appendage occlusion.

Technical considerations and sizing of external annuloplasty in the Ross procedure.

Pure aortic regurgitation and dilation of aortic annulus are the most significant risk factors for the failure of pulmonary autograft after the Ross procedure. Aortic annuloplasty has a positive effect on the durability of the autograft. Previously, we described a technique for external annuloplasty with dedicated CORONEO ring. In the present manuscript, we suggest the sizing of annuloplasty based on the diameter of pulmonary autograft annulus.

Aortic valve performance after remodelling versus reimplantation in a propensity-matched comparison.

OBJECTIVES: Both aortic root remodelling and aortic valve (AV) reimplantation have been used for valve-sparing root replacement in patients with aortic root aneurysm with or without aortic regurgitation. There is no clear evidence to support one technique over the another. This study aimed to compare remodelling with basal ring annuloplasty versus reimplantation on a multicentre level with the use of propensity-score matching. METHODS: This was a retrospective international multicentre study of patients undergoing remodelling or reimplantation between 2010 and 2021. Twenty-three preoperative covariates (including root dimensions and valve characteristics) were used for propensity-score matching. Perioperative outcomes were analysed along with longer-term freedom from AV reoperation/reintervention and other major valve-related events. RESULTS: Throughout the study period, 297 patients underwent remodelling and 281 had reimplantation. Using propensity-score matching, 112 pairs were selected and further compared. We did not find a statistically significant difference in perioperative outcomes between the matched groups. Patients after remodelling had significantly higher reintervention risk than after reimplantation over the median follow-up of 6 years (P = 0.016). The remodelling technique (P = 0.02), need for decalcification (P = 0.03) and degree of immediate postoperative AV regurgitation (P < 0.001) were defined as independent risk factors for later AV reintervention. After exclusion of patients with worse than mild AV regurgitation immediately after repair, both techniques functioned comparably (P = 0.089). CONCLUSIONS: AV reimplantation was associated with better valve function in longer-term postoperatively than remodelling. If optimal immediate repair outcome was achieved, both techniques provided comparable AV function.

Long-term survival after radical surgery for renal cell carcinoma with tumour thrombus extension into the right atrium.

UNLABELLED: What's known on the subject? and What does the study add? Surgical treatment of renal cell carcinoma (RCC) with tumour thrombus extending into the right atrium remains, despite its complexity and specific technical aspects, the only radical therapeutic option. This single-centre study, unique in size for this rare condition, reports early and late results over a period of 18 years. All patients were operated on using a standardised protocol with use of cardiopulmonary bypass and deep hypothermic circulatory arrest. Overall and cancer-specific cumulative survival was better than in other reports. OBJECTIVE: To evaluate the long-term results of radical surgical management of renal cell carcinoma (RCC) with tumour thrombus extension (TTE) level IV into the right atrium (RCC/TTE IV) in a large single-institution series. PATIENTS AND METHODS: Radical complex urological and cardio-surgical procedure was performed over a period of 18 years (1993-2010) on 21 patients with RCC/TTE IV. A radical nephrectomy was performed followed by sternotomy, institution of cardiopulmonary bypass and extraction of the intracardiac tumour thrombus under direct visual control during deep hypothermic circulatory arrest (DHCA). Perioperative and postoperative variables, and long-term overall and cancer-specific survival using the Kaplan-Meier method were analysed. RESULTS: In all patients, precise removal of tumour thrombus was accomplished in a bloodless field during DHCA. The mean (sd) duration of circulatory arrest was 16 (6) min at a mean hypothermia of 20 (3) °C. In-hospital mortality was 9.5% (two patients). The median survival (including in-hospital mortality) was 25 months. In Kaplan-Meier analysis, 2- and 5-year overall cumulative survival rate was 57 (95% confidence interval, CI 36-78)% and 37 (95% CI 15-58)%, respectively. Cancer-specific cumulative survival was 68 (95% CI 49-89)% at 2 years and 51 (95% CI 28-74)% at 5 years. CONCLUSIONS: Late outcome after radical surgical treatment in patients with RCC and TTE reaching up to the right atrium justifies this extensive procedure. Cardiopulmonary bypass with DHCA allows safe and precise extirpation of all intracaval and intracardiac tumour mass.

Cardiac sarcoidosis.

Cardiac sarcoidosis is a rare entity and may be difficult to diagnose prior to cardiac surgery. We review the imaging and diagnostic studies necessary to make the diagnosis and discuss therapeutic algorithms to manage this disease.

External Ring Annuloplasty: A Safe Landing Zone for Transcatheter Aortic Valve Replacement.

Aortic stenosis in patients with previous valve-sparing root replacement represents a challenge, given the substantial morbidity and mortality rates in case of reoperation. Here, we present the case of a patient with late severe aortic stenosis 12 years after valve-sparing aortic root replacement. He was successfully treated by transapical aortic valve implantation. External ring annuloplasty, by reducing the native annuloaortic ectasia, allows transcatheter aortic valve replacement in case of stenotic deterioration of the native valve after valve-sparing aortic root replacement.

Renal cell carcinoma with intracardiac tumor thrombus extension: Radical surgery yields 2 years of postoperative survival in a single-center study over a period of 30 years.

Background: Renal cell carcinoma (RCC) with tumor thrombus extension into the right atrium (level IV) is a rare life-threatening clinical condition that can only be managed by means of a combined urological and cardiac surgical approach. The early and late outcomes of this radical treatment were analyzed in a large single-institution series over a period of 30 years. Methods: In 37 patients with RCC and intracardiac tumor thrombus extension, nephrectomy was performed followed by the extraction of the intracaval and intracardiac tumor thrombus under direct visual control during deep hypothermic circulatory arrest (DHCA). Recently, in 13 patients, selective aortic arch perfusion (SAAP) was instituted during DHCA. Results: In all patients, precise removal of the tumor thrombus was accomplished in a bloodless field. The mean duration of isolated DHCA was 15 ± 6 min, and 31.5 ± 10.2 min in the case of DHCA + SAAP, at a mean hypothermia of 22.7 ± 4°C. In-hospital mortality was 7.9% (3 patients). In Kaplan-Meier analysis, the estimated median survival was 26.4 months whereas the 5-year cancer-related survival rate was 51%. Conclusions: Despite its complexity, this extensive procedure can be performed safely with a generally uneventful postoperative course. The use of cardiopulmonary bypass with DHCA, with the advantage of SAAP, allows for a safe, precise, and complete extirpation of intracaval and intracardiac tumor mass. Late outcomes after radical surgical treatment in patients with RCC and tumor thrombus reaching up in the right atrium in our series justify this extensive procedure.

Aorto-mitral curtain reconstruction in invasive double-valve endocarditis: mid-term outcomes.

Background: Invasive double-valve endocarditis with structural damage (abscess or perforation) of the aorto-mitral curtain is a relatively rare but fatal diagnosis requiring complex surgical reconstruction. This study presents the short-term and mid-term outcomes from a single center. Methods: From 2014 to 2021, 20 patients with double-valve endocarditis with structural damage of the aorto-mitral curtain underwent surgical reconstruction (Hemi-Commando procedure n = 16 and Commando procedure n = 4). Data were obtained retrospectively. Results: In 13 cases, the procedure was a reoperation. The mean cardiopulmonary bypass time was 239 ± 47 min and the mean cross-clamp time was 186 ± 32 min. Concomitant procedures were tricuspid valve repair in two, coronary revascularization in one, closure of a ventricular septal defect in one and hemiarch (using circulatory arrest) in one patient. Eleven patients (55%) required surgical revision for bleeding. Thirty-day mortality was 30% (6 patients)-3 patients from the Hemi-Commando group (19%) and 3 patients from the Commando group (75%). Overall survival at 1, 3 and 5 years was 60%, 50% and 45% respectively. Reoperation was required by 4 patients. Freedom from reoperation at 1, 3 and 5 years was 86%, 71% and 71% respectively. Conclusion: Despite the high postoperative morbidity and mortality, complex surgical reconstruction of the aorto-mitral continuity of patients with double-valve endocarditis represents the only real chance for survival. Mid-term outcomes are acceptable, but strict follow-up is required due to the risk of valve failure.

Bicuspid valve repair outcomes are improved with reduction and stabilization of sinotubular junction and annulus with external annuloplasty.

OBJECTIVE: We investigated long-term outcomes of bicuspid aortic valve (BAV) repair, with external annuloplasty, according to aorta phenotype. METHODS: Between 2003 and 2020, all patients with BAV operated on for aortic insufficiency (AI) and/or aneurysm were included. Repairs included isolated AI repair with subvalvular with or without sinotubular junction (STJ) (single or double) annuloplasty, supracoronary aorta replacement (with or without hemiroot remodeling), and root remodeling with external subvalvular ring annuloplasty. RESULTS: Among 343 patients operated, reparability rate was 81.3% (n = 279; age 46 ± 13.3 years). At 10 years (median follow-up: 3.42 years; interquartile range, 1.1, 5.8), survival was 93.9% (n = 8 deaths, similar to general population), cumulative incidence of reoperation was 6.2% (n = 10), AI grade >2 was 5.8% (n = 9), and grade >1 was 23.0% (n = 30). BAV repair stabilizing both the annulus and STJ with annuloplasty, compared with nonstabilized STJ repair (single annuloplasty), had lower incidence of reoperation (2.6% vs 22.5%, P = .0018) and AI grade >2 (1.2% vs 23.6%, P < .001) at 9 years. Initial commissural angle <160° was not a risk factor for reoperation, compared with angle ≥160° if symmetrical repair was achieved (2.7% and 4.1%, respectively, at 6 years, P = .85). Multivariable model showed that absence of STJ stabilization (odds ratio, 6.7; 95% confidence interval, 2.1-20, P = .001) increased recurrent AI, but not initial commissural angle <160° (odds ratio, 1.01; 95% confidence interval, 0.39-2.63, P = .98). Commissures adjusted symmetrically led to lower transvalvular gradient, compared with nonsymmetrical repair (8.7 mm Hg vs 10.2 mm Hg, P = .029). CONCLUSIONS: BAV repair, tailored to aorta phenotype, is associated with excellent durable outcomes if both annulus and STJ are reduced and stabilized with external ring annuloplasty. Commissural angle <160° is not associated with reoperation if symmetrical repair is achieved.

Early- and longer-term outcomes of David versus Florida sleeve procedure: propensity-matched comparison.

OBJECTIVES: The aim of this study was to compare short- and longer-term outcomes of David (DV) versus Florida sleeve (FS) procedure in patients requiring valve-sparing aortic root replacement. METHODS: Between January 1996 and December 2020 285 patients received a DV procedure (median age 60 years; 26% females) and 57 patients underwent an FS procedure (median age 64 years; 19% females) in our department. Propensity score matching using patient characteristics led to 58 (DV) versus 57 (FS) patients. End points were defined as primary: freedom from aortic valve and/or aortic root-related reoperation and freedom from aortic regurgitation ≥moderate and secondary: early and late survival. RESULTS: Thirty-day mortality was 2% (DV) and 0% (FS) (P = 0.319). There was 1 early stroke in each group (P = 0.990). Follow-up was complete in 99% with only 1 patient (FS) lost. The 5- and 10-year freedom from aortic valve and/or aortic root related reoperation was 98 ± 2% and 96 ± 3% in the DV group and 92 ± 5% and 84 ± 9% in the FS group, respectively (P = 0.095). The 5- and 10-year freedom from aortic regurgitation ≥moderate was 88 ± 5% and 80 ± 8% in the DV group and 92 ± 5% and 78 ± 1% in the FS group, respectively (P = 0.782). The 5- and 10-year survival rates were 93 ± 4% and 82 ± 6% (DV) vs 75 ± 7% and 67 ± 10% (FS), respectively (P = 0.058). No case of endocarditis (DV) and 3 cases of endocarditis (FS) (P = 0.055) were observed during follow-up. CONCLUSIONS: Both DV and FS resulted in similar early and longer-term outcomes with a trend to slightly better performance and survival in the DV group. Florida sleeve procedure might be an alternative approach for patients with higher-risk profiles requiring valve-sparing aortic root replacement.

Ross procedure provides survival benefit over mechanical valve in adults: a propensity-matched nationwide analysis.

OBJECTIVES: The choice of optimal surgical treatment for young and middle-aged adults with aortic valve disease remains a challenge. Mechanical aortic valve replacement (mAVR) is generally preferred despite promising recent outcomes of the Ross procedure. Our goal was to compare the strategies at a nationwide level. METHODS: This study was a retrospective analysis of prospectively recorded data from the National Registry of Cardiac Surgery of the Czech Republic. Using propensity score matching, we compared the outcomes of patients undergoing the Ross procedure in 2 dedicated centres with all mAVRs performed in country between 2009 and 2020. RESULTS: Throughout the study period, 296 adults underwent the Ross procedure and 5120 had an mAVR. We found and compared 291 matched pairs. There were no in-hospital deaths, and the risk of perioperative complications was similar in both groups. Over the average follow-up period of 4.1 vs 6.1 years, the Ross group had a lower all-cause mortality (0.7 vs 6.5%; P = 0.015). This result remained significant even when accounting for cardiac- and valve-related deaths only (P = 0.048). Unlike the Ross group, the mAVR group had a significantly lower relative survival compared with the age- and sex-matched general population. There was no difference in the risk of reoperation (4.5 vs 5.5%; P = 0.66). CONCLUSIONS: The Ross procedure offers a significant midterm survival benefit over mAVR. The procedures have a comparable risk of perioperative complications. Patients after mAVR have reduced survival. Thus, the Ross procedure should be the preferred treatment option for young and middle-aged adults with aortic valve disease in dedicated centres.

Histopathological changes in dilated ascending aorta associated with aortic valve cuspidity.

OBJECTIVES: Patients with a bicuspid aortic valve (BAV) often present with a dilated ascending aorta. However, the underlying pathogenesis for the observed changes in the aortic wall and the resulting aneurysmal dilation remains a subject of debate. This study aims to compare the histological abnormalities of the ascending aorta in BAV and tricuspid aortic valve (TAV) patients and their correlation with aortic diameter and patient age. METHODS: A total of 376 patients from our institution's clinical database were included in the retrospective analysis. These patients underwent either elective surgery for ascending aorta dilation or emergency surgery for aortic dissection, either isolated or with a structurally diseased aortic valve. After excision, the ascending aorta samples were analysed by a pathologist. RESULTS: On histological examination, a higher degree of elastic fibre fragmentation and loss and mucoid extracellular matrix accumulation was present in the samples from TAV patients when compared with that from BAV patients (P < 0.001). However, correlation was poor for all variables when considering aortic diameter and histological abnormalities or age and histological abnormalities in both BAV and TAV patients. CONCLUSIONS: Our study demonstrates a greater incidence of severe histological abnormalities in TAV patients when compared with BAV patients.

Root repair with aortic ring annuloplasty using the standard approach.

Standardization of aortic valve repair techniques with use of a calibrated annuloplasty have led to improved long-term outcomes in dystrophic aortic insufficiency. It can also improve dissemination of techniques and rates of aortic valve repair. Dystrophic aortic insufficiency can be found in three aortic phenotypes: dilated aortic root, dilated ascending aorta and isolated aortic insufficiency. The aortic annulus is invariably dilated above 25 mm in the vast majority of cases of aortic insufficiency, regardless of whether the aorta is dilated or not. A dilated annulus is a risk factor for late failure of aortic valve repair if not addressed at the time of surgery. We perform a calibrated annuloplasty at both sub- and supra-valvular levels in order to restore the ratio of sinotubular junction and annulus. Current evidence shows aortic valve repair reduces valve-related mortality compared to prosthetic valve replacement, with an improved quality of life.

Subcoronary Ross/Ross-Konno operation in children and young adults: initial single-centre experience.

OBJECTIVES: We sought to evaluate the outcome after modified subcoronary Ross/Ross-Konno operation in children and young adults. METHODS: Between January 2013 and January 2019, a total of 50 patients with median age of 6.3 years (range 0.02-36.5 years, 58% males), including 10 infants (20%), received modified subcoronary Ross/Ross-Konno operation at our institution. Survival, morbidity, reinterventions, aortic valve function and aortic root dimensions were analysed. RESULTS: At a median follow-up of 31.2 months (range 14.4-51 months), there were 1 early death and 1 late death, both in the infant group. The overall survival at 5 years after the operation was 95%. Two patients needed aortic valve replacement, 11 and 15 months after their Ross operation. At 5 years, freedoms from reoperation on the autograft and on the right ventricle to pulmonary artery conduit were 94% and 97%, respectively. Freedom from aortic valve regurgitation greater than mild was 97% at 5 years. Median dimensions of the aortic root at all levels remained in normal range at last visit. Forty-four patients (95%) were in New York Heart Association class I with normal left ventricular function. CONCLUSIONS: The initial experience with the subcoronary Ross/Ross-Konno operation in children and young adults showed excellent outcome. The mortality and morbidity among infants remain significant. The described technique is reproducible and might be advantageous in situations when prosthetic supporting techniques interfere with somatic growth.

Modified hockey-stick approach to the mitral valve.

Modified biatrial approach to the mitral valve is described. The hockey-stick incision combines the advantage of excellent exposure with low surgical risk and easy reconstruction.