Infective endocarditis could occur on-native valve - native valve endocarditis(NVE) or on a prosthetic valve (Prosthetic Valve Endocarditis-PVE).
a) Native Valve Endocarditis
Indications for Surgery in NVE
About two-thirds of patients with native valve endocarditis can be cured with proper medical trkatment. In the rest of the patients, early surgical treatment improves the prognosis For patients with native valve endocarditis who get cured on medical treatment, indications for surgery are the same as patients without endocarditis.
a) Native Valve Endocarditis
Indications for Surgery in NVE
About two-thirds of patients with native valve endocarditis can be cured with proper medical trkatment. In the rest of the patients, early surgical treatment improves the prognosis For patients with native valve endocarditis who get cured on medical treatment, indications for surgery are the same as patients without endocarditis.
b) Prosthetic Valve Endocarditis (PVE)
Prosthetic valve endocarditis (PVE) is called EARLY wheil symptoms begin within 60 days of surgeiy and LATE when the onset is after two months. The most coinmon organism for early PVE is coagulase negative staphylococcus -~taphylococcus epidermidis. Less conlmonly the causative organism could be staph. aureus, gram negative bacilli, diphtheroids or fungi (candida species).
In early PVE the organism responsible could be a nosocomial one and for late endocarditis a community acquired organism is often the culprit. Data suggests that during the initial months after implantation, a mechanical valve is at highe risk than bioprosthetic valve. However, after twelve months the incidence is more on bioprosthetic valves. At five years the incidence is comparable. of sinus of Valsalva after 7-10 days of appropriate antibiotic treatment
Prosthetic valve endocarditis (PVE) is called EARLY wheil symptoms begin within 60 days of surgeiy and LATE when the onset is after two months. The most coinmon organism for early PVE is coagulase negative staphylococcus -~taphylococcus epidermidis. Less conlmonly the causative organism could be staph. aureus, gram negative bacilli, diphtheroids or fungi (candida species).
In early PVE the organism responsible could be a nosocomial one and for late endocarditis a community acquired organism is often the culprit. Data suggests that during the initial months after implantation, a mechanical valve is at highe risk than bioprosthetic valve. However, after twelve months the incidence is more on bioprosthetic valves. At five years the incidence is comparable. of sinus of Valsalva after 7-10 days of appropriate antibiotic treatment
Surgical Treatment
If there is definite indication for early surgely, the current understanding is to proceed with valve replacement irrespective of the duration of antibiotic treatment. Previously it was thought that surgery should be postponed till the
patient has been cured by antibiotics or postpone it as long as possible to suppress bacteremia as much as possible.
In case of prosthetic valve endocarditis, surgely is undertaken earlier. Emergency operation is required for acute aortic regurgitation with mitral valve pre-closure,sinus of Valsalva rupture into heart chamber or pei-icardiuin. Less urgent surgery required for valve obstruction, unstable prosthesis, AR or MR with heart failure, septa1 perforation and pelivalvar extensioil of infection. When a patient has sustained cerebral embolism, if possible it is better to wait for a month, as risk of cerebral haemorrhage during open-heart surgery is as high as 20 to 44 per cent.
Technique of Operation
The operative principle is drainage of abscess, removal of debris and valve r e p or replacement to reverse haemodynamic abnormality. Any acquired defect like VSD ring abscess, fistula or aneurysm has to be repaired. In children congenita' lesion is also rectified.
Availability of intra operative TEE is absolutely essential during surgery.Cardiopulmonary bypass with aortic and bicaval cannulae is instituted. Antegrac and retrograde cardioplegia are administered. Manipulation of heart is kept to a minimum for fear of embolism. For aortic valve endocarditis inspection of anterior mitral leaflet and chordae for drop lesions is a routine procedure. Mitra valve may be repaired and valve perforation could be closed with pericardial patch if infection is under contl-01.
When valve replacement is necessary, the valve is excised and careful check for abscess is done. If present it is drained and debridemeilt done. Abscess that burrows deeper could cause aortoventricular or atrioventricular separation.Inteilupted sutures with pericardial patches are used to treat this and anchor theCardiovascular Shrge1.y valve. Larger disruptions are managed with auto]ogus or bovine pericardial patches. The advantage of a bioprosthesis over mechanical valve in preventing re- infection has not been proved conclusively. However, for aortic prosthetic valve e n d o c ~ d i t i a ~ cryopreserved,free homograft is the best choice. In such cases if there is extensive abscess formation and disruption of aoi-to-ventricular continuity,homografl aortic root replacement with re-implanlation of coronaries is the preferred technique.
Results
The hospital ~nortality for valve replacement for endocarditis varies between 4-30 per cent. Operative mol-tality is higher for urgent operations. It also depends on the patient's pre-operative status. For PVE the mortality is higher. The experience of Brigham and Women's Hospital in Boston showed a mortality of six per cent for native valve endocarditis and 22 per cent for PVE.Late survival after valve replacemcnl for endocarditis is good. It was 81 per cent at the end of eight years in one large series operated for native valve endocarditis. Nasayana Hrudayalaya has cxcellent results with homograft replacement for native and proslhetic aorlic valve endocarditis.
If there is definite indication for early surgely, the current understanding is to proceed with valve replacement irrespective of the duration of antibiotic treatment. Previously it was thought that surgery should be postponed till the
patient has been cured by antibiotics or postpone it as long as possible to suppress bacteremia as much as possible.
In case of prosthetic valve endocarditis, surgely is undertaken earlier. Emergency operation is required for acute aortic regurgitation with mitral valve pre-closure,sinus of Valsalva rupture into heart chamber or pei-icardiuin. Less urgent surgery required for valve obstruction, unstable prosthesis, AR or MR with heart failure, septa1 perforation and pelivalvar extensioil of infection. When a patient has sustained cerebral embolism, if possible it is better to wait for a month, as risk of cerebral haemorrhage during open-heart surgery is as high as 20 to 44 per cent.
Technique of Operation
The operative principle is drainage of abscess, removal of debris and valve r e p or replacement to reverse haemodynamic abnormality. Any acquired defect like VSD ring abscess, fistula or aneurysm has to be repaired. In children congenita' lesion is also rectified.
Availability of intra operative TEE is absolutely essential during surgery.Cardiopulmonary bypass with aortic and bicaval cannulae is instituted. Antegrac and retrograde cardioplegia are administered. Manipulation of heart is kept to a minimum for fear of embolism. For aortic valve endocarditis inspection of anterior mitral leaflet and chordae for drop lesions is a routine procedure. Mitra valve may be repaired and valve perforation could be closed with pericardial patch if infection is under contl-01.
When valve replacement is necessary, the valve is excised and careful check for abscess is done. If present it is drained and debridemeilt done. Abscess that burrows deeper could cause aortoventricular or atrioventricular separation.Inteilupted sutures with pericardial patches are used to treat this and anchor theCardiovascular Shrge1.y valve. Larger disruptions are managed with auto]ogus or bovine pericardial patches. The advantage of a bioprosthesis over mechanical valve in preventing re- infection has not been proved conclusively. However, for aortic prosthetic valve e n d o c ~ d i t i a ~ cryopreserved,free homograft is the best choice. In such cases if there is extensive abscess formation and disruption of aoi-to-ventricular continuity,homografl aortic root replacement with re-implanlation of coronaries is the preferred technique.
Results
The hospital ~nortality for valve replacement for endocarditis varies between 4-30 per cent. Operative mol-tality is higher for urgent operations. It also depends on the patient's pre-operative status. For PVE the mortality is higher. The experience of Brigham and Women's Hospital in Boston showed a mortality of six per cent for native valve endocarditis and 22 per cent for PVE.Late survival after valve replacemcnl for endocarditis is good. It was 81 per cent at the end of eight years in one large series operated for native valve endocarditis. Nasayana Hrudayalaya has cxcellent results with homograft replacement for native and proslhetic aorlic valve endocarditis.
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