الفهرس 
Chapter (1): Aortic Valve and Conduction System AnatomyOnly 14 pages are availabe for public view
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Abstract
Today, the most frequent type of aortic valve disease is senile calcific aortic stenosis (AS). Despite intense efforts to create medical treatment options, medical therapy has no current function in changing the course of the disease, and surgical aortic valve replacement (SAVR) remains the basis of definitive treatment.
However, because aortic stenosis is mostly a disease of the elderly, co-morbidities are a common worry that can render patients inoperable. As a result, for many patients, a percutaneous approach to aortic valve replacement is an appealing option.
Transcatheter aortic valve implantation (TAVI) represents a paradigm shift in the treatment of patients with severe symptomatic aortic stenosis who were at high or prohibitive surgical risk.
With increased experience in this sector, the rate of periprocedural problems has reduced over time, and TAVI has increasingly been conducted with a minimalist approach, evolving into a safe and ”routine practice” operation with predictable outcomes. This provides the basis for expanding TAVI indications to include persons with reduced surgical risk.
However, unlike other procedural complications, the incidence of conduction disturbances, such as His’ bundle branch blocks, atrioventricular blocks, and the need for permanent pacemaker implantation, has not decreased in recent years, with reports indicating an increased risk associated with the use of some newer-generation transcatheter valves.
Consequently, this study was conducted and aimed to determine the predictors of cardiac conduction disturbance and pacemaker dependency
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after transcatheter aortic valve implantation depending on clinical , electrocardiographic , echocardiographic, radiological ( CT) and procedural data.
This observational study was conducted at Cardiovascular Medicine Department, Nasr City health insurance Hospital from December 2022 until May 2023. Patients were aged >65 years, had symptomatic severe aortic valve (AV) stenosis, and assigned to undergo transfemoral TAVI.
The study was conducted on age group ranging from 68 to 78 years, (mean age of 73.38±2.93 years). There were 26 male patients (76.5%) and 8 female patients (23.5%); while ranged of BMI was 21 to 39 with mean 29.18±4.22, ranged of Body surface area (m2) was 1 to 3 with mean 1.94±0.63; ranged of Euro SCORE II was 2 to 19 with mean 10.21±4.90; as for the Creatinine clearance (ml/min) was ranged from 25 to 75 with mean 54.03±13.15; while the was normality conduction 20 patients (58.8%) and 14 patients (41.2%) were abnormalities conduction, out of them 9 patients (64.3%) were LBBB and 5 patients (35.7%) were CHB among study group.
There is no statistically significant difference between groups according to demographic data and clinical data about, Age (years), Sex, Body mass index (kg/m2), Body surface area (m2), Euro SCORE II and Creatinine clearance (ml/min), with p-value (p>0.05).
There is no statistically significant difference between groups according to risk factors as smoking, diabetes mellitus, hypertension, ischemic heart disease, previous cerebrovascular stroke, CABG, chronic lung disease, with p-value (p>0.05).
There was statistically significant higher mean value of PR interval duration (msec) and QRS duration (msec) in abnormal conduction group
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compared to normal conduction, with p-value (p<0.05). Also statistically significant difference between abnormal conduction group and normal conduction group according to BBB, with p-value (p=0.039); while there is no statistically significant difference between groups according to atrial fibrillation “AF”, with p-value (p>0.05).
There was a statistically significant increase frequency of AR grade III in abnormal conduction group comparing to normal conduction, with p-value (p=0.047); while there is no statistically significant difference between groups according to Ejection Fraction (%), SWT (mm), SWTi (mm/m2), PWT (mm), LVEDD (mm), LVEDDi (mm/m2), LVESD (mm), LVESDi (mm/m2), Mean pressure gradient (mmHg) and Aortic valve area (cm), with p-value (p>0.05).
There was a statistically significant increase frequency of Basal septal calcification in abnormal conduction group comparing to normal conduction, with p-value (p<0.001); while there is no statistically significant difference between groups according to Annulus mean diameter, Annulus mean diameter indexed (mm/m2), Annulus area, Annulus area I (mm/m2), LMCA, LMCAi (mm/m2), RCA, RCAi (mm/m2), MS, MSi (mm/m2) and Aortic valve calcification grade IV, with p-value (p>0.05).
There was a highly statistically significant higher mean value of Depth of implantation (mm), Depth of implantation indexed (mm/m2) and DIMS in abnormal conduction group comparing to normal conduction group, with p-value (p<0.001); Also statistically significant difference between abnormalities conduction group and normality conduction group according to Delta MSID, with p-value (p<0.001); while there is no statistically significant difference between groups according to Balloon predilatation, Balloon Postdilatation and Valve size >29 mm, with p-value (p>0.05).
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Receiver operating characteristics (ROC) curve was performed for depth of implantation (mm) and demonstrated an area under the curve of 0.882 (0.661-0.926) with P value <0.001. The best cut off value for prediction of conduction abnormalities was ≥5.9 with sensitivity 91.1% and specificity 89.6%. Also, depth of implantation indexed (mm/m2) and demonstrated an area under the curve of 0.889 (0.661-0.926) with P value <0.001. The best cut off value for prediction of conduction abnormalities was ≥2.4 with sensitivity 95.5% and specificity 84.4%; while DIMS and demonstrated an area under the curve of 0.966 (0.725-1.000) with P value <0.001. The best cut off value for prediction of conduction abnormalities was ≥78.8 with sensitivity 93.7% and specificity 94.4%; as for the Delta MSID and demonstrated an area under the curve of 0.964 (0.723-1.000) with P value <0.001. The best cut off value for prediction of conduction abnormalities was ≤1.52 with sensitivity 88.5% and specificity 87.7%. As for the QRS in significant predictors, with p-value (p>0.05).
In conclusion, conduction abnormalities are still a prevalent consequence of TAVI that can impact prognosis. The association between implantation depth and membranous septum is a substantial procedural predictor of conduction problems after TAVI. The presence of basal septal calcification is the most powerful independent pre-procedural predictor of conduction problems after TAVI.