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Mitral valve replacement surgery is the most common open heart surgery performed in the department of cardiothoracic surgery, Ain Shams University Hospital, Egypt. Rheumatic mitral valvular disease is more common than degenerative mitral valve disease. Mitral valve repair is not possible in large number of patients because of rheumatic cicatrized subvalvular mitral valve disease. The prosthetic mitral valve replacement is commonly performed in our center.
The most serious consequence of rheumatic fever is rheumatic heart disease that occurs in roughly 30% of patients. Patients with sudden onset rheumatic fever may present with pancarditis along with valvular pathology, heart failure and pericarditis. Incidence of rheumatic heart disease has dropped during the last 40 years in western world. However, it is still remains a major health challenge in developing countries. It is estimated that 16 million in dividuals are affected by rheumatic heart disease around the globe, with roughly 281,000 new cases and 234,000 deaths every year. One of the most common valvular complications of rheumatic heart disease is mitral stenosis and/or regurgitation. In majority of cases, mitral valve replacement is typically essential, however in few cases mitral valve repair can also be performed.
Mitral valve replacement (MVR) is the second most common valvular replacement procedure after aortic valve replacement (AVR) worldwidely.
The history of mitral valve surgery runs parallel to the development of heart surgery, as at the turn of the last century rheumatic fever was an epidemic disease that led to late cardiac valve lesions, mostly to mitral stenosis.
More than 90 percent of patients who undergo Mitral valve replacement should experience a functional improvement in outcome with significant resolution of heart failure symptoms.
Predictors of poor outcome include advanced patient age, poor functional class, coronary artery disease re-operative status and emergency operations.
The outcome of mitral valve replacement has improved dramatically with adoption of chordal sparing techniques and preservation of ventriculo-annular continuity.
Preservation of the subvalvular apparatus maintains LV function and thus improves survival. Repair is not always feasible or successful, particularly with rheumatic valve disease in young patients and severely disorganized valves.
Postoperative outcome includes:
The most common cause of death following MVR is cardiac failure.
Common causes of early operative mortality include stroke, myocardial infarction, respiratory failure, multisystem organ failure and infection.
And the late causes related to thromboemboli, stroke and hemorrhage due to anticoagulation.
Operative mortality associated with isolated mitral valve replacement is reported to range between 4% and 7% and is influenced by age, premorbid valvular cardiomyopathy, and other comorbidities.
2-Thrombosis & thromboembolism
Thromboembolism is the most common postoperative complication of both bioprosthetic and mechanical valves and occurs at a rate of 1.5% to 2.0% per patient-year and is significantly increased in chronic atrial fibrillation and large left atrial size.
Bleeding rates related to the use of vitamin K antagonists are more frequent with mechanical valves, which are reported to be 2% to 4% per patient-year, of which the majority occur within the first year following surgery.
3- Infective endocarditis
Infective endocarditis is a dreaded late complication following valve surgery, with infection usually located on the replacement device
Early PVE is caused by contamination of the valve during or immediately after implantation, with the culprit organisms therefore reflecting those likely to be acquired in a hospital setting, including resistant strains of Staphylococcal epidermidis, Gram-negative bacilli, and fungi.
PVE is a grave condition, being associated with a reported mortality of 25–60% which is highest for early infections when the degree of valve destruction tends to be greatest.
4- Acute kidney injury
AKI was defined as an abrupt increase (within 48h) in sCr ≥0.3mg/dL postoperatively or a change in sCr by ≥1.5 times of the baseline value within 7 days after surgery.
Risk factors include hypovolemia, need to return to CPB, low hematocrit during CPB, aortic cross-clamp time, hypoperfusion and cardiopulmonary bypass (CPB) duration.
5- Respiratory failure
ARDS is now defined as hypoxemia occurring within 1 week of a known clinical insult or new worsening respiratory symptoms, associated with bilateral opacities on chest imaging not fully explained by effusions and lobar/lung collapse or nodules, and not fully explained by cardiac failure or fluid overload.
6- Deep sternal wound infection (DSWI)
Deep sternal wound infection (DSWI) is one of the most complex and potentially devastating complications following median sternotomy in cardiac surgery with a significant impact on both patient prognosis and hospital budgets. Despite many advances in prevention, it still remains significant and ranges between 0.5% and 6.8%, with in-hospital mortality rates between 7% and 35%, moreover, mid- and long-term survival is significantly reduced in patients that have experienced DSWI.
7- Mechanical complications
Paravalvar leak may occur with both mechanical and biological valves and, in the absence of infection, usually reflects a technical problem relating to suture failure.
The slow in-growth of fibrous tissue (pannus) over the sewing ring, a phenomenon also observed with bioprostheses.
In mechanical valves, sudden failure of the components of the valve is usually fatal.
Pathological changes range from thinning, atrophy, and perforation seen particularly in allografts, through to leaflet calcification, thickening, and tearing seen with porcine and pericardial bioprostheses.
This study was done in department of cardiothoracic surgery, Faculty of Medicine at Ain Shams university, after approval of the local ethical committee from 2015 to 2016.
The study was performed on all patient from 1/1/2015 till 31/12/2016 who underwent mitral valve replacement with or without tricuspid valve repair.
There were 360 cases that underwent mitral valve replacement surgery during this time interval; however 183 patients were excluded from this study due to exclusion criteria including concomitant coronary artery bypass graft surgery or other cardiac operations or infective endocarditis and patients with chronic liver, kidney and parenchymal pulmonary disease, Therefore, 177 adult cases were enrolled in this study (One hundred and thirty one (131) patients underwent mitral valve replacement without tricuspid valve repair, Fourty six (46) patients underwent mitral valve replacement with tricuspid valve repair.
The Study results:
In this study the ejection fraction value ranges from 35% to 78% with a mean of 55.69 ± 7.5
The mitral implant type was mechanical in 169 patients (95.4%) and biological in 8 patients (4.5%)
In this study the mitral chords preserved were posterior in 115 patients (64.9%), none in 57 patients (32.2%) and both in 5 patients (2.82%).
The mitral implant code was St. Jude in 132 patients (74.5%), On-X in 21 patients (11.86%), Sorin in 16 patients (9.03%) and biological valve in 8 patients (4.5%).
116 patients (65.5%) had sinus rhythm, 1 patient (0.56%) had other abnormal rhythm and 60 patients (33.89%) had atrial fibrillation.
The cross-clamp time was in the range from 30 to 150 minutes with a mean of 52 ± 16.5 minutes.
The Bypass time was in the range from 45 to 250 minutes with a mean of 82 ± 25 minutes.
In this study the new post-operative stroke was just in 1 patient (0.56%).
In this study no patient needed post-operative dialysis.
In this study 2 patients (1.13%) had multi system failure.
Re-admission to ICU had occurred in 3 patients (1.69%) due to heart failure and low cardiac output.
Re-intubation had occurred in 2 patients (1.13%), one for neurological insult and the other for low output sundrome.
In this study the patients that had pericardial effusion/tamponade were 10 patients (5.6%).
In this study reoperaion was done in 9 patients (5.08%).
The patient status at discharge was alive in 170 patients (96.04%) and deceased in 7 patients (3.9%).