In those cases, severe cardiac depression usually ensues, and the patient may go into cardiogenic shock. In cases of suspected coronary obstruction, a bolus angiogram of the aortic root may reveal which coronary vessel is involved. After that, selective intubation of the vessel ensues, followed by balloon dilatation or stenting of the coronary ostium. If the valve is implanted too high and coronary flow is

impaired by the valve skirt, the prostheses must be immediately retracted into the ascending aorta to relieve Inhibitors,research,lifescience,medical the obstruction. The majority of coronary obstruction cases result in emergency cardiopulmonary bypass. If interventional measures fail to reconstitute coronary flow, emergent coronary artery bypass grafting or open removal of a malpositioned valve prosthesis is required. find more conduction Abnormalities Considering the anatomic proximity Inhibitors,research,lifescience,medical of the conduction system to the aortic valve, it is not surprising that conduction abnormalities such as AV or bundle-branch block are known complications of TAVI even in the absence of surgical excision of valve or annulus tissue. The requirement for permanent Inhibitors,research,lifescience,medical pacing has been described as necessary in up to 20% of patients. The occurrence of new-onset left bundle-branch block (LBBB) during the procedure may occur in up to 40% of patients. Possible

explanations include transient periprocedural inflammation, edema, and mechanical stress due to balloon or stent trauma or myocardial necrosis in the basal interventricular septum due to ischemia. In addition, this population of elderly patients, all with underlying organic heart disease, frequently Inhibitors,research,lifescience,medical exhibit pre-existing conduction abnormalities that are known to be associated with aortic stenosis. There are no definitely known risk factors for peri- and postprocedural complete heart block; Inhibitors,research,lifescience,medical however, the occurrence of intraprocedural complete heart block, even when it is transient, and the presence of right bundle-branch block seem to be predisposing factors. In addition, relatively low

positioning of the valve within the left ventricular outflow tract and efforts to oversize the implanted prosthesis to securely fix it within the aortic annulus and thus minimize Oxymatrine paravalvular regurgitation might play a role. Prior to the implantation procedure, conduction abnormalities should be thoroughly documented by a 12-lead ECG to diagnose pre-existing AV block or left and right bundle-branch block. Intra- and postprocedural monitoring with a 3-lead rhythm strip has to be done continuously up to 5 days after the procedure since there have been case reports describing the late occurrence of complete heart block after TAVI. Other pre-existing episodes of bradycardia such as sinus node disease or symptomatic bradyarrhythmia may have been undetected in some patients before the procedure and are unrelated to TAVI.