Diagram of Operation
Classic Bentall not performed anymore due to the complications that resulted from the coronary reimplantation. Phlanges are now created for coronary reimplantation, and the procedure is called the "Modified Bentall" procedure.
The combination of aortic valvular disease not appropriate for repair and aneurysm of Aortic root.
Endocarditis with annulus destruction.
The invention of modified Bentall
Repairable aortic valve.
Many asymptomatic ascending aortic aneurysms are first detected on chest x-ray. The enlarged ascending aorta produces a convex contour of the right superior mediastinum. In the lateral view, there is loss of the retrosternal air space. Aneurysms confined to the aortic root can be obscured by the cardiac silhouette and may not be evident on chest radiograph.
Aortography provides precise delineation of the aortic lumen, and certain diseases have very characteristic arteriographic patterns. Annuloaortic ectasia has a "pear-shaped" morphology with prominent dilation of the aortic sinuses and less severe dilation of the ascending aorta tapering to normal caliber at the origin of the innominate artery. Pseudoaneurysms appear as saccular outpouchings with an irregular contour. Syphilitic aneurysms involving the aortic root are often associated with coronary ostial stenosis.
One of the beneficial aspects of aortography is accurate demonstration of the relationship of the aneurysm to the arch vessels. Aortography also detects aortic regurgitation and cephalad displacement of the coronary ostia. In patients over the age of 40 or with a pertinent history, the opportunity is afforded to check for coronary disease and left ventricular dysfunction. Disadvantages include contrast and radiation exposure, puncture site complications, underestimation of aneurysm size in the presence of laminar clot, and the likelihood of missing dissections.
Contrast-enhanced computed tomography (CT) provides rapid and precise evaluation of the ascending aorta. CT scanning detects areas of calcification, and accurately identifies dissections and mural thrombus. When laminar clot is present, CT scanning provides a more accurate assessment of aneurysm size than aortography. However, because structures are visualized in an axial view only, the diameter of a tortuous aorta can be grossly overestimated. Three-dimensional reconstruction of CT scans may prove useful in determining the proximal and distal extent of aortic disease relative to the arch vessels, which can aid the surgeon in operative planning.
The benefits of magnetic resonance imaging (MRI) over CT scanning include visualization in the sagittal and coronal planes, and the avoidance of contrast and radiation exposure. Cardiac imaging with MRI is evolving, and may provide evaluation of cardiac perfusion, myocardial function, and coronary and valve anatomy with a single modality in the future. Currently, however, MRI is expensive, less readily available, and more time consuming than CT scanning.
Matching hole in graft to coronary ostia without any kinks and achieving a blood tight anastomoses is difficult.
Composite graft replacement of the aortic root
Diagram of Operation
(This is actually the modified Bentall)
Composite graft replacement of the aortic root
False aneurysms at coronary reimplantation sites is the specific complication linked to this procedure..
Woven Dacron grafts impregnated with collagen or gelatin are relatively impervious to blood and have reduced blood loss following replacement of the ascending aorta. Anastomotic bleeding is lessened with the use of Teflon pledgets at the aortic and coronary anastomoses. When composite valve-graft insertion is indicated, choosing a valve size that snugly fits the annulus and placing mattress stitches immediately adjacent to each other are helpful. Tension must be avoided at the sites of coronary reimplantation, as this is a frequent site of bleeding. The modified Cabrol method or an interposition graft should be used when any tension is present. The inclusion technique of graft insertion is associated with an increased incidence of bleeding and pseudoaneurysm formation and has largely been abandoned. All coronary and aortic anastomoses should be sewn to the full thickness of the aorta, and wrapping of the graft with residual aorta is not indicated. After the administration of protamine, all anastomoses must be evaluated closely.
Suspected coagulopathy should be documented by laboratory tests and treated accordingly. In cases of refractory coagulopathy, the anastomosis can be wrapped tightly with a small segment of Dacron to reduce tension on the suture line and reduce needle hole bleeding. Homologous blood donation can be avoided in a significant number of patients with the use of blood conservation techniques such as cell savers, autologous blood donation, platelet pheresis, the reinfusion of chest tube drainage, and the use of antifibrinolytics.
Neurologic injury following proximal aortic surgery remains a significant cause of morbidity and mortality. Embolization of atherosclerotic debris or thrombus from the ascending aorta and arch produces focal neurologic deficits. Diffuse injury can be attributed to microemboli of air or cellular debris, insufficient or uneven cooling, and a prolonged circulatory arrest period. After circulatory arrest periods exceeding 40 minutes the incidence of stroke greatly increases. Profound hypothermia may itself be injurious to the central nervous system without associated circulatory arrest.
Stroke due to embolisation is diminished when the aorta is evaluated via epiaortic ultrasound or other imaging modality to detect atherosclerotic plaques and thrombus. This allows appropriate adjustments to be made in clamping and cannulation strategies. The utility of retrograde cerebral perfusion as an adjunct to hypothermic circulatory arrest is controversial, but some groups report an increase in the safe period of circulatory arrest. Laboratory evidence suggests that the primary benefits of retrograde cerebral perfusion are flushing of embolic material and perhaps more homogeneous cooling, rather than effective nutrient delivery, which is far superior with antegrade circulation. Resumption of antegrade circulation through the graft once the distal aortic anastomosis is complete, rather than retrograde via the femoral vessels, after a period of circulatory arrest avoids embolization of distal aortic debris. Patients with severe carotid artery occlusive disease are at increased risk of stroke during ascending aortic procedures, and patients older than 65, those with peripheral vascular disease, or those with pertinent histories should be evaluated.
Cardiopulmonary bypass is known to cause alterations in pulmonary function as evidenced by changes in alveolar-arterial oxygen gradients, pulmonary vascular resistance, pulmonary compliance, and intrapulmonary shunting. Usually these changes are subclinical, but a full-blown adult respiratory distress-like syndrome is reported in 0.5% to 1.7% of patients following cardiopulmonary bypass. The specific cause is the subject of much investigation and debate, but it is generally accepted that exposure of blood elements to the foreign surface of the cardiopulmonary circuit results in the activation of inflammatory cells and the complement cascade resulting in pulmonary injury. The duration of cardiopulmonary bypass, urgency of the procedure, and general condition of the patient may roughly correlate with the occurrence and severity of pulmonary dysfunction, but it can be unpredictable.
Treatment is supportive, with early diagnosis and treatment of any subsequent pulmonary infections. Preventative measures may include preoperative optimization of pulmonary function, minimization of pump time, judicious use of blood products, heparin-coated bypass circuits, and leukocyte depletion.
POSTOPERATIVE CORONARY INSUFFICIENCY
Coronary insufficiency is uncommon in the postoperative period, but may occur following root replacement and coronary reimplantation. Ischemia may be due to kinking of a Dacron or saphenous vein interposition graft. Coronaries implanted under tension, or aortic suture lines, may bleed resulting in compression from an expanding hematoma. Suspicion of coronary insufficiency must be promptly evaluated with angiography and/or reoperation.