SHORT TERM OUTCOME OF REDO MITRAL VALVE SURGERY: EMERGENCY VERSUS ELECTIVE

Received: 23 December 2016 Final Accepted: 14 January 2017 Published: February 2017 Background: With advances in medical therapy and life expectancy, reoperation to replace dysfunctional mechanical heart valve prosthesis is an increasingly common procedure and there have been gradual decreases in perioperative risk for redo valve surgery over the past 2 decades Aim of the work: The aim of this study was to investigate the overall outcome of adult patients undergoing redo-mitral valve replacement (redo-MVR). Patients and Methods: forty cases had previous mitral valve replacement were admitted for redo mitral valve replacement. They were divided into two groups: Group (A): (Twenty cases) were admitted as emergency cases from the ER. Group (B): (Twenty cases) were admitted from out patient clinic as elective cases. Results:The hospital mortality was (20%). There was no effect regarding age, sex, cardiac rhythm, number of previous operations, type of the previous prosthesis, and interval from last implantation. Taking in consideration that mortality was higher with emergency group (15%). Conclusion: pre operative parameters of morbidity and mortality that showed higher incidence in emergency group were:NYHA functional class, LVEDD , LVESD dimensions, Redo cardiac surgery, Infective endocarditis, left ventricular dysfunction EF less than 35.


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factors may be preventable (Tang, et al., 2007;Rankin, et al., 2006).With advances in medical therapy and life expectancy, reoperation to replace dysfunctional mechanical heart valve prosthesis is an increasingly common procedure and there have been gradual decreases in perioperative risk for redo valve surgery over the past 2 decades, likely due to increased surgical experience, better myocardial protection, and improved patient management. However, mortality rates remain higher than first-time valve replacement surgery (Rankin, et al., 2006;Borger, et al., 2002). Several studies have been studying the predictors of mortality during reoperative valve surgery (Rankin, et al., 2006;Borger, et al., 2002).
Aim of work:-The aim of this study was to investigate the overall outcome of adult patients undergoing redomitral valve replacement (redo-MVR).

Patients and Methods:-
Forty cases had previous mitral valve replacement were admitted for redo mitral valve replacement. They were divided into two groups: Group (A): (Twenty cases) were admitted as emergency cases from the ER. Group (B): (Twenty cases) were admitted from out patient clinic as elective cases. All patients were opened through median sternotomy and cardiopulmonary bypass with aorto-bicaval cannulation. A mechanical valve is inserted with horizontal mattress pledgeted non absorbable sutures.
Inclusion criteria:surgery for prosthetic endocarditis. Surgery for para-valvular leak. Surgery for structural valve degeneration. Surgery for prosthetic valve thrombosis .

Considering intra operative and immediate post operative data:-
Cross clamp time is a little bit shorter in elective cases (55-145) min compared to (65-185)min for emergency cases, and bypass time goes with the same sequence (75-240) min for elective cases and (90-260) min for emergency cases. Prosthetic valve types were as following; 1 patient (2.25%) with monoleaflet valve , 1 patient (2.25%) with ball and cage , 1 patient (2.25%) with bioprothesis , most of cases were bileaflet 37 patient (92.5%). Intra operative events includedCatastrophic blood loss occurred in 6 patients (15%). Epicardial lead temporary pacemaker was needed in 6 patients (15%) also, most of cases needed hemofiltration 27 patients (67.5%). Intra operative mortality were 1 case (2.25%) for elective cases and 4 cases (10%). hospital mortality was 1 case (2.25%) for elective cases and 2 cases for emergency cases due to poor contractility. 2 nd look was needed for 1 case in elecective cases due to bleeding , and 1 case for emergency (open chest ).Considering post operative data :Permenant pacemaker was needed for 1 case. Residual infective endocardidtis remained in 1 case (fungal type).1 case had cardiac tamponade (patient was discharged and came back 3 week later to emergency department with severe dyspnea , echo revealed massive effusion that was drained with subxiphoid incicsion )and 1 case left hospital with lt side hemiparesis.
(It is worth saying that these complications occurred in the emergency group.)Considering post operative 6 month echo data : Ejection fraction improved in most of cases , also left ventricle dimensions. Residual tricuspid regurge in 6 patients (15%) of each group a sum of 12 patients (30%). Gradients also decreased in all patients , maximum gradient ranged from (6-12) mmHg for elective group , and almost the same for emergency group (6-14) mmHg. Also mitral valve area ranged from (1.8-3.1) cm2 for both groups.Elective cases had a much better outcome considering mortality (2 cases for elective group compared for 6 cases for emergency group) and morbidities.
712    (Vohra et al., 2012).In particular, it is necessary to identify the perioperative variables (including technical complications and the patients' preoperative condition in both emergency and elective cases) in order to offer patients the most appropriate interventions. (Vohra et al., 2012) .In this study, the overall hospital mortality was 8 patients (20%), (2 cases for elective group (5%) one intra operative mortality and one ICU mortality compared to 6 cases for emergency group (15%) with four cases intra operative mortality and two cases ICU mortality  et al., 2003). Such difference in mortality may be; as mentioned by Wauthy, related to technological evolutions of cardiac critical care units (e.g. defibrillation patches,improved ECC technology, the use of ECMO, the Cell Saver, etc.) and increased surgical experience.In this study, mortality in relation to NYHA classification were 2 cases (5%) from the elective group NYHA III, while it was 6 cases (15%) for emergency group (5 cases (12.5%) NYHA IV) and (1 case (2.5%) NHYA III). NYHA functional class IV was also a risk factor in short term survival as mentioned by Akay and associates and others in many studies (Akay et al., 2008). Our conclusion regarding NYHA classification as a statistically significant factors for mortality in both groups. Vohra et al also confirmed that New York Heart Association functional class was highly significant for operative mortality; as operative mortality in their study was 4% for functional classes (I through III), and 19% for functional class (IV), they reported NYHA functional class as an important risk factor for hospital mortality. NYHA FC is considered as the most frequently quoted risk factor associated with death in redo valve surgery.This was due to that mortality in their study reached up to 30% with stage IV (half cases were emergency) compared to less than 10% in stage II and III (all cases were elective). (Vohra et al., 2012). Considering morbidities, reopening was done in 1 case (2.5%) for elective group and 1 case (2.5%) that was left open chest for emergency group. This morbidity was not statistically significant between the two groups. Akay and associates reported bleeding in 5.6% of his patients with equal incidence for both emergency and elective cases (Akay et al., 2008). Pother et al had excessive postoperative bleeding (more than 1,000 mL in the first 24 postoperative hours) occurred in 14.5% (9% were for emergency group) of patients while re-exploration was done in only 8% of them (Potter et al., 2004). In this study, need for dialysis 1 case (2.5%) due to constant rising creatinine and potassium levels in emergency group. 6 cases (15%) had renal dysfunction 4 cases in emergency group (10%) and 2 cases in elective group (5%) in form of rising creatinine level that responded to diuretics and drug dose adjustment. Akay and associates reported 14.2% with postoperative renal dysfunction 10% for emergency group (Akay et al., 2008). Preoperative renal impairment, CVS, prolonged bypass time and cross clamp time are risk factors for postoperative renal dysfunction. In this study, permenant pacemaker was installed in 1 case (2.5%) in emergency group due to complete heart block that did not recover after 14 days. This morbidity was not statistically significant between the two groups. Pother et al had complete heart block and brady arrhythmia in 3% of cases of redo mitral valve surgery only 0.3% of cases needed premenant pacemaker (one case after redo aorta and mitral ). (Potter et al., 2004). In this study, cerebrovascular accident (inform of left hemiparesis) was noticed in 1 case (2.5%) in emergency group. Hemodynamic instability and disturbed conscious level in absence of evidence of stroke were noticied in 5 patients (12.5%) in emergency group with 1 case (2.5%) that arrested with induction . this makes this parameter of statistically significance between the two groups. Potter in his study in 2004 documented 2.8% stroke in patients with repeated mitral valve replacement (75% of cases occurred in emergency cases. (Potter et al., 2004). Residual infective endocarditis evidenced by blood culture was 714 noticed in 1 case (2.5) in the emergency group. This morbidity was not statistically significant between the two groups. In our study the cause of this prolonged time for bypass was in most cases due to extra time needed for circulatory support due to associated left ventricular dysfunction. Mean cross clamp time for elective cases were 100 min and for emergency cases 125 min, as for bypass time were 157.5 min and 175 min respectively. This was not statistically significant for both groups. McGrath et al stated that long bypass time and long cross clamp time are predictors of mortality (Wauthy et al., 2003). Brandão mentioned that among the intraoperative variables associated with higher hospital mortality was Cross clamp time longer than 120 min(de Almeida Brandão et al.,  2002). Global myocardial ischemic time alone was a strong predictor of hospital mortality in many studies. In contrary others had denied both factors as significant predictors for the hospital mortality (Potter et al., 2004). In our study, the sex (11 male, 9 female ) for elective group and (6 male, 14 female) for emergency group and age of patients mean for elective group (39.5 years) and mean for emergency group (40 years) were not statistically significant in both groups. Vohra et al showed that sex and age did not affect the outcome in both elective and emergency groups (Vohra et al., 2012). Another study done by Akay and co-workers shows that re-do cardiac surgery in patients over the age of 70 can be undertaken with acceptable operative morbidity and mortalityAdvanced age is associated with decreased physiologic reserve and increased comorbid factors. Their functional reserve capacity is diminished compared with younger patients. They confirmed that females are significantly labile to mortality than males (Akay et al., 2008) et al., 2002). In our study Atrial fibrillation was observed in all patients (100%), this may be attributed to the fact that the main cause of the primary surgery for valve replacement was due to rheumatic affection but its effect on hospital mortality was not significant. Atrial fibrillation has been identified as a risk factor for mortality and morbidity associated with valve surgery (Maciejewski et al., 2011), as it may cause low cardiac output during the postoperative period or predispose to thromboembolic events. In our series, atrial fibrillation was not identified as a risk factor for hospital mortality. In our study, 33 patient (82.5%) had the operation once before (18 cases (45%) from elective group and 15 cases (37.5%) from emergency gropu). And 6 cases (15%) had it twice before (2 cases (5%) for elective group and 4 cases (10%) for emergency group. 1 case (2.5%) from elective group had it three times before. Number of prior operations did not show a significant effect on outcome on both groups. Although there was a trend to higher operative mortality with increasing number of prior cardiac operations, this factor was not significant in multivariable analysis.. Some reported that second reoperations were not more risky than first reoperations, but by the third reoperation, risks were high for all subgroups. This was confirmed by Beghi et al where the number of previous reoperations was independent determinant for reoperation (Beghi et al., 2002).Our study suggests that left ventricular dysfunction was associated with higher hospital mortality in both groups (1 case (2.5%) for elective group and 2 cases (5%) for emergency group). This was statistically significant. Low left ventricular ejection fraction (less than 35%) and increased LVEDD more than 50 mm have been reported of significance in mortality by Akay and associates (Akay et al.,  2008). According toMaciejewski et al operative mortality was significantly higher in those patients who were had impaired left ventricular function (Maciejewski et al., 2011).

Conclusion:-
Redo valve surgery is an increasingly common problem. Recent decades have seen a steady increase in the number of cases referred for redo cardiac surgery, which are associated with increased risk of morbidity and mortality compared to the first-time operations. Many studies were done to address the outcome ( mortality and morbidities) following redo mitral valve replacement. forty cases had previous mitral valve replacement were admitted for redo mitral valve replacement. They were divided into two groups: Group (A): (Twenty cases) were admitted as emergency cases from the ER. Group (B): (Twenty cases) were admitted from out patient clinic as elective cases. The hospital mortality was (20%). There was no effect regarding age, sex, cardiac rhythm, number of previous operations, type of the previous prosthesis, and interval from last implantation. Taking in consideration that mortality was higher with emergency group (15%). In conclusion, pre operative parameters of morbidity and mortality that showed higher incidence in emergency group were: NYHA functional class , LVEDD , LVESD 715 dimensions, Redo cardiac surgery sternotomy and adhesio-lysis carries a significant risk of catastrophic bleeding especially with the rush accompanning hemodynamic instability, Infective endocarditis, left ventricular dysfunction EF less than 35. Post operative morbidities noticed in emergency group were : (cardiac tamponade, permenant pacemaker, residual infective endocarditis , need for dialysis and cerebro vascular accidents ) were not statistically significant.