Indications for Definitive Surgical Treatment
Surgery is indicated in all acute proximal dissections.
Indications for surgery for acute distal dissection com p licated by the following:
1) Progression with vital organ compromise.
2) Rupture or impending rupture.
3)Retrograde extension into the ascending aorta.
4)Dissection in Marfans syndrome.
Operation for acute dissection is done to prevent death from cardiac tarnponade or exsanguination by rupture. Operation also helps to restore blood supply to vital organs. It is not always possible to remove the entire false channel in some patients. So the operation is palliative rather than curative. In ascending aorta, the dissection could cause acute valve regurgitation (AR) or obstruction of coronary ostia. In such cases, aortic valve resuspension, aortic valve replacement or replacement of aortic root and ascending aorta with a composite graft (Bental procedure) or with an aortic allograft may be required.
Techniques of Surgical Correction
proximal Dissection (De Bakey type I and IZ or Stanford A)Monitoring lines are inserted in the right radial and left femoral arteries. TEE and Doppler of carotid artery will be very helpful. The light common femoral artery is exposed by a vertical incision. If there is dissection in hat, the channel through which there is forward flow is cannulated for arterial return. At times it may lead to obstruction of retrograde pel-fusion and so provision is made for cannulation of the ascending aorta, aortic arch, axillary artery or left ventricular apex. For CP bypass a venous cannula is passed to right atrium through iight femoral vein. After median sternotomy and pericardiotomy callnulation of both vena cavae are done. If only the ascending aorta needs replacement, circulatory arrest is not required.
Heart is vented through right superior pullnonary vein. A retrograde coronary sinus cannula is passed for cardioplegia administration. Aorta is clamped proximal to innominate artery and opened vertically. First opening is into the false lumen,which may contain clots. Intimal tear and tive channel are visualised. This is opened and by direct cannulation of coronary ostia antegrade cardioplegia is given.Then aorta is transected 4 to 5 cms above the aortic annulus. If dissection has extended to the annulus it can be fixed by interrupted 4 '0' prolene sutures. If coronary ostia are involved they can be raised as buttons with aortic wall and repaired with fine prolene sutures and then re-implanted into the ascending aortic graft. If dissection deep into coronaries exists, coronary artery bypass is indicated.
De Bakey Type I Dissection
Initial steps of the operation are same as previously described. Provision for deep hypothermic circulatory arrest made along with retrograde cerebral pe~fusion.Depending on the site of tear the graft is anastornosed to the descending aortta or to the under aspect of arch or just proximal to innominate artery after cooling to 20" C and achieving circulatory arrest and retrograde cerebral pei-fusion. Then pump is restarted and de-airing through the graft done and re-warming started.
DistaE Dissection (De Bakey Type ZII or Stanford Type B)
Techniques of Surgery
The approach is through a left posterolateral thoracotomy with anaesthesia being given through a double lumen endobronchial tube. Left femoral artery and Pein are cannulated for initiation of femoro femoral bypass. Usually the dissection starts beyond left subclavian artery. Proximal control should be just distal to left subclavian artery or between left carotid and subclavian artery. When there is retrograde dissection to the arch, profound hypothermia and circulatory arrest will have to be utilised for repair. Clamps are applied above and below the area o l proposed resection. Aorta is opened longitudinally and control of the inter costal arterial openings are done as in resection of aneurysm of descending thoracic aorta. Aorta is transccted proximally. If the layers of aorta are separated they are approximated between strips of PTFE felt and resulting cuff is anastornosed to the end of the vascular graft. After anastomosis the proximal clamp is removed, reapplied on the graft and proximal anastomotic site checked for bleeding. Similarly the distal aorta is tsansected and if dissections extend beyond, cuff is prepared by suturing the two layers with reinforcement using PTFE felt. Air is removed from the graft and clamps removed and circulation restored. After discontinuing by pass and decannulation, protanline is given to reverse heparin. After haemostasis chest is closed with two drains.
Results
For acute dissection of different parts of aorta, the mortality is reported as 9 to 33 per cent. In the International Registiy of Aortic dissection, it is 26 per cent.Moi-tality may be due to bleeding, neurological involvement including paraplegia or renal failure.
Surgery is indicated in all acute proximal dissections.
Indications for surgery for acute distal dissection com p licated by the following:
1) Progression with vital organ compromise.
2) Rupture or impending rupture.
3)Retrograde extension into the ascending aorta.
4)Dissection in Marfans syndrome.
Operation for acute dissection is done to prevent death from cardiac tarnponade or exsanguination by rupture. Operation also helps to restore blood supply to vital organs. It is not always possible to remove the entire false channel in some patients. So the operation is palliative rather than curative. In ascending aorta, the dissection could cause acute valve regurgitation (AR) or obstruction of coronary ostia. In such cases, aortic valve resuspension, aortic valve replacement or replacement of aortic root and ascending aorta with a composite graft (Bental procedure) or with an aortic allograft may be required.
Techniques of Surgical Correction
proximal Dissection (De Bakey type I and IZ or Stanford A)Monitoring lines are inserted in the right radial and left femoral arteries. TEE and Doppler of carotid artery will be very helpful. The light common femoral artery is exposed by a vertical incision. If there is dissection in hat, the channel through which there is forward flow is cannulated for arterial return. At times it may lead to obstruction of retrograde pel-fusion and so provision is made for cannulation of the ascending aorta, aortic arch, axillary artery or left ventricular apex. For CP bypass a venous cannula is passed to right atrium through iight femoral vein. After median sternotomy and pericardiotomy callnulation of both vena cavae are done. If only the ascending aorta needs replacement, circulatory arrest is not required.
Heart is vented through right superior pullnonary vein. A retrograde coronary sinus cannula is passed for cardioplegia administration. Aorta is clamped proximal to innominate artery and opened vertically. First opening is into the false lumen,which may contain clots. Intimal tear and tive channel are visualised. This is opened and by direct cannulation of coronary ostia antegrade cardioplegia is given.Then aorta is transected 4 to 5 cms above the aortic annulus. If dissection has extended to the annulus it can be fixed by interrupted 4 '0' prolene sutures. If coronary ostia are involved they can be raised as buttons with aortic wall and repaired with fine prolene sutures and then re-implanted into the ascending aortic graft. If dissection deep into coronaries exists, coronary artery bypass is indicated.
De Bakey Type I Dissection
Initial steps of the operation are same as previously described. Provision for deep hypothermic circulatory arrest made along with retrograde cerebral pe~fusion.Depending on the site of tear the graft is anastornosed to the descending aortta or to the under aspect of arch or just proximal to innominate artery after cooling to 20" C and achieving circulatory arrest and retrograde cerebral pei-fusion. Then pump is restarted and de-airing through the graft done and re-warming started.
DistaE Dissection (De Bakey Type ZII or Stanford Type B)
Techniques of Surgery
The approach is through a left posterolateral thoracotomy with anaesthesia being given through a double lumen endobronchial tube. Left femoral artery and Pein are cannulated for initiation of femoro femoral bypass. Usually the dissection starts beyond left subclavian artery. Proximal control should be just distal to left subclavian artery or between left carotid and subclavian artery. When there is retrograde dissection to the arch, profound hypothermia and circulatory arrest will have to be utilised for repair. Clamps are applied above and below the area o l proposed resection. Aorta is opened longitudinally and control of the inter costal arterial openings are done as in resection of aneurysm of descending thoracic aorta. Aorta is transccted proximally. If the layers of aorta are separated they are approximated between strips of PTFE felt and resulting cuff is anastornosed to the end of the vascular graft. After anastomosis the proximal clamp is removed, reapplied on the graft and proximal anastomotic site checked for bleeding. Similarly the distal aorta is tsansected and if dissections extend beyond, cuff is prepared by suturing the two layers with reinforcement using PTFE felt. Air is removed from the graft and clamps removed and circulation restored. After discontinuing by pass and decannulation, protanline is given to reverse heparin. After haemostasis chest is closed with two drains.
Results
For acute dissection of different parts of aorta, the mortality is reported as 9 to 33 per cent. In the International Registiy of Aortic dissection, it is 26 per cent.Moi-tality may be due to bleeding, neurological involvement including paraplegia or renal failure.
Indications for Surgery
Presence of ventiicular septal iupture is an indication for surgery. Timing of surgery is most important. In patients with large left to right shunt, pulmonary oedema and haemodynamic compromise, urgent surgery is indicated. If patient's condition is very stable and a delay of two to three weeks is safe, operation becomes technically easier as the septum will hold sutures better.
Techniques of Operation
If the patient's condition is stable cardiac catheterisation, coronary angiography and left ventriculography are done. Otherwise patients are taken up based on echo and doppler studies. Pre-operative intra aortic balloon pump (IABP) and pulmonary arterial pressure monitoring (Swan-Ganz catheter) will be of great help. Operation can be safely postponed if there is:
1) Adequate cardiac output with no evidence of cardiogenic shock.
2) Absence of pulmonary oedema and pulmonary venous hypertension.
3)Absence of fluid retention on treatment with diuretics and digitalis.
4)Good renal function.
Repair of Defect
The approach to the defect is through ventriculotolny over the infwcted area. The defect is repaired using a collagen or gelatin impregnated Dacron patch. The muscle around the defect is ilsually very friable and holcls sutures poorly. In one of the techniques, interrupted pledgetted sutures are passed away from the margins of the defect and infarcted muscle. The sutures are passed from the light ventricular aspect with the pledgets positioned on the right ventricular side of the septum. When all sutures are taken they are passed through a large Dacron patch and is lowered to the left velltricular aspect of septum and tied.
In a similar technique two circular patches are used-one on the right ventliculru- aspect, and the second one on the left ventricular side of the septum After repair, left ventriculotomy is closed with two strips of Teflon felt for reinforcement of the suture line.
Infarct Exclusioiz Technique
Left ventriculotomy is done through the infarcted area. No attempt is made lo close the ventricular septa1 defect. An oval patch of pelicardium that is treated with glutaraldehyde is used with continuous sutures through the non-infracted portion of the septum. This covers the entire area of infracted septum, Suture line is continued to the antero lateral wall of left ventricle to exc1ud.e thc ruptured septum completely from lefl ventriculru cavity. The ventriculotomy is closed with two strips of Teflon.
Reinforcement of Patch using Fibriiz Glue
In this technique Dacron graft is first suturcd to the septum beyond inhcted area and then fibrin glue is applied between the patch and ventricular septum.The suture line is completed. The glue helps in sealing the ruptured septum and holding the patch.
Associated Procedures
Coronary artery bypass grafting and repair of mitral valve are also carried out. Patients may require intra aortic balloon pump (IABP) or left ventricular assist device (LVAD) in the post-operative period.
Results
Hospital mortality may be as high as 30 per cent. This depends on the extent of infarction and- pre-operative haemodyna~nic state. Five year survival has been reported as 44 to 57 per cent and ten year survival as low as 29 to 36 per cent.
Presence of ventiicular septal iupture is an indication for surgery. Timing of surgery is most important. In patients with large left to right shunt, pulmonary oedema and haemodynamic compromise, urgent surgery is indicated. If patient's condition is very stable and a delay of two to three weeks is safe, operation becomes technically easier as the septum will hold sutures better.
Techniques of Operation
If the patient's condition is stable cardiac catheterisation, coronary angiography and left ventriculography are done. Otherwise patients are taken up based on echo and doppler studies. Pre-operative intra aortic balloon pump (IABP) and pulmonary arterial pressure monitoring (Swan-Ganz catheter) will be of great help. Operation can be safely postponed if there is:
1) Adequate cardiac output with no evidence of cardiogenic shock.
2) Absence of pulmonary oedema and pulmonary venous hypertension.
3)Absence of fluid retention on treatment with diuretics and digitalis.
4)Good renal function.
Repair of Defect
The approach to the defect is through ventriculotolny over the infwcted area. The defect is repaired using a collagen or gelatin impregnated Dacron patch. The muscle around the defect is ilsually very friable and holcls sutures poorly. In one of the techniques, interrupted pledgetted sutures are passed away from the margins of the defect and infarcted muscle. The sutures are passed from the light ventricular aspect with the pledgets positioned on the right ventricular side of the septum. When all sutures are taken they are passed through a large Dacron patch and is lowered to the left velltricular aspect of septum and tied.
In a similar technique two circular patches are used-one on the right ventliculru- aspect, and the second one on the left ventricular side of the septum After repair, left ventriculotomy is closed with two strips of Teflon felt for reinforcement of the suture line.
Infarct Exclusioiz Technique
Left ventriculotomy is done through the infarcted area. No attempt is made lo close the ventricular septa1 defect. An oval patch of pelicardium that is treated with glutaraldehyde is used with continuous sutures through the non-infracted portion of the septum. This covers the entire area of infracted septum, Suture line is continued to the antero lateral wall of left ventricle to exc1ud.e thc ruptured septum completely from lefl ventriculru cavity. The ventriculotomy is closed with two strips of Teflon.
Reinforcement of Patch using Fibriiz Glue
In this technique Dacron graft is first suturcd to the septum beyond inhcted area and then fibrin glue is applied between the patch and ventricular septum.The suture line is completed. The glue helps in sealing the ruptured septum and holding the patch.
Associated Procedures
Coronary artery bypass grafting and repair of mitral valve are also carried out. Patients may require intra aortic balloon pump (IABP) or left ventricular assist device (LVAD) in the post-operative period.
Results
Hospital mortality may be as high as 30 per cent. This depends on the extent of infarction and- pre-operative haemodyna~nic state. Five year survival has been reported as 44 to 57 per cent and ten year survival as low as 29 to 36 per cent.
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