Aortic valve replacement-surgical techniques, Biology

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Aortic Valve replacement :  The initial steps of the operation have been described earlier. Ascending aorta is cannulated. A single two-stage atrio-venous cannula is inserted through the right atrial appendage to IVC. Cardio plegia cannula is inserted into the ascending aorta and a retrograde cardioplegia cannula into the coronary sinus. A left sided vent is inserted through the right superior pulmonary vein. Aorta is clamped at moderate hypothennia (280C). If there is no aortic regurgitation, antegrade blood cardioplegia is given in the aortic root. Ice slush is applied in the pericardiurn to give additional myocardial protection. After heart is arrested, the rest of the cardioplegia is given retrograde. Hypertrophied ventricles need additional infusion of cardioplegia. If there is aortic regurgitation, the aorta is opened and direct antegrade cardioplegia is administered by cannulating the ostia with special hand held coronary arterial perfusion cannulae. A transverse aortotomy 15 mms above the origin of right coronary artery or an oblique one extending on to the non coronary sinus of aorta is made and stay sutures are taken. Lower aortotoiny flap is retracted and aortic valve is inspected. It is excised one cusp at a time leaving 2mm rim for suturing. When the valve is calcified, it has to be removed piece meal. A wet gauze piece is used to pack the inside of left ventricle to collect loose bits of calcium. Using a sharp knife, scissors or a bone rongeur calcium will have to be removed carefully taking precaution over the anterior mitral leaflet and the septum new the AV bundle (under the comrnissure between light and non coronary cusps). The gauze piece from LV is removed. Aorta and LV are washed with saline that is sucked out. Wet peanut gauze is used to clean the areas from where calcium has been removed. Valve orifice is measured and appropriate 'sized valve is chosen.

 


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