Disturbances in atrioventricular conduction are well-recognized complications of transcatheter aortic valve replacement. Percutaneous balloon aortic valvuloplasty (BAV) is a requisite step in transcatheter aortic valve replacement; however, the contribution of the BAV to atrioventricular conduction disturbances has not been elucidated. The present analysis was undertaken to ascertain the incidence and type of electrocardiographic changes associated with BAV and to consider the role of BAV in the conduction abnormalities after transcatheter aortic valve replacement. In 271 consecutive patients with symptomatic, severe aortic stenosis undergoing BAV, a standard 12-lead electrocardiogram was obtained before and serially after the procedure. Each was examined by experienced electrocardiographers. The cohort was divided into 2 groups with regard to the post-BAV appearance of conduction disturbances. The clinical and procedural characteristics of patients with these disturbances were compared to those in whom no conduction disturbance appeared. After BAV, 23 patients (8.5%) met the study definition of “new conduction defect”: 4 patients (1.5%) required permanent pacemaker implantation for advanced atrioventricular block. New left bundle branch block appeared in 9 (3.3%) and left anterior hemiblock in 7 (2.6%). New right bundle branch block appeared in 2 and left posterior hemiblock in 1. No significant difference was found in the clinical or procedural characteristics. The ratio of the balloon size to the left ventricular outflow tract diameter was 1.21 ± 1.6 in those with new conduction defects and 1.15 ± 0.12 (p = 0.032) in those without. In conclusion, BAV is associated with a low incidence of cardiac conduction disturbances and a requirement for permanent ventricular pacing. The size of the valvuloplasty balloon should be carefully selected to avoid oversizing, which can lead to the development of postprocedure conduction disturbances.
Percutaneous balloon aortic valvuloplasty (BAV) might relieve the symptoms in patients with severe aortic stenosis and intractable hemodynamic symptoms. It might, therefore, be useful as a bridge to aortic valve replacement, to transcatheter aortic valve implantation (TAVR), or as palliation in inoperable patients. More and more TAVRs are being performed. As evidence of its efficacy emerges, the patients not immediately suitable for surgical intervention are being referred for consideration for this novel procedure. Thus, BAV is more frequently required for 1 of these 3 indications in these high-risk and often, very symptomatic, patients. As experience with TAVR accumulates, a significant incidence of the postprocedure conduction disturbances and the need for permanent pacemaker implantation (PPI) has been encountered. Importantly, BAV is an integral step in TAVR. To our knowledge, its possible contribution to the incidence of PPI after TAVR has not been explored. Although the patients’ clinical characteristics and the procedures’ technical details have been studied for the predictors of the electrocardiographic disturbances after TAVR, none have clarified whether the BAV performed during TAVR plays an important role in the development of cardiac conduction disturbances. Our experience with BAV has been greatly expanded by the large influx of patients referred for TAVR consideration. Taking advantage of this experience, this analysis was undertaken to analyze in detail the incidence and type of electrocardiographic changes associated with BAV.
Methods
From January 2005 to September 2010, the data from 334 consecutive patients undergoing BAV were prospectively entered into a dedicated database. Of these patients, 58 were excluded because they had undergone PPI before BAV and 5 because they had died during the procedure. Those 5 patients died most likely from mechanical complications such as annular rupture, severe aortic regurgitation, and myocardial stunning without reserve. Nevertheless, no autopsies were performed to confirm the cause of death. The remaining 271 patients constituted the study population.
All had severe, symptomatic aortic stenosis confirmed by clinical examination, transthoracic echocardiography, and hemodynamic evaluation. Of the 271 patients, 205 (75.6%) were referred for BAV for palliation of heart failure symptoms, 19 (7.0%) for the treatment of cardiogenic shock or as a bridge to TAVR (36 patients, 13.3%) and surgical aortic valve replacement (11 patients, 4.1%). The Society of Thoracic Surgeons score and the logistic European System for Cardiac Operative Risk Evaluation were calculated for all patients.
All patients underwent diagnostic right and left heart catheterization before the procedure. Heparin was given (10 to 70 U/kg) after the insertion of a 9F to 13F sheath into the femoral artery. BAV was performed according to standard techniques using the retrograde femoral approach. The equality of the sensitivity of the pressure recordings between the catheter intended for the left ventricle and that in the aorta was ensured. The gradient was also confirmed with transaortic pullback measurements. The aortic valve area was calculated with the Gorlin formula, and the peak and mean gradients were ascertained.
The valvuloplasty balloon size was chosen according to the minimal diameter of the sinotubular junction as measured by both aortography and echocardiography. The balloon size selected was 3 to 5 mm smaller than this measurement. To stabilize the balloon position across the valve before inflation, the heart was paced at 180 to 200 beats/min until the blood pressure decreased to <50 mm Hg. Pacing was continued until the balloon was fully deflated. In those cases in which the mean gradients did not decrease significantly (30% to 40%), an additional BAV using a larger balloon was performed.
At the end of the procedure, the pressure gradients and cardiac output were repeated, and the valve area was calculated again. To assess aortic regurgitation, an aortogram was performed. Arterial puncture sites were closed with a closure device (6F Perclose or 10F Prostar, Abbott Laboratories, Abbott Park, Illinois, or 8F Angio-Seal, St. Jude Medical, St. Paul, Minnesota). If the device failed, manual compression was applied.
Electrocardiographic tracings were systematically obtained the day before and serially after the procedure. They were interpreted by experienced cardiologists not involved with the study. Routine electrocardiographic measurements were made, with special emphasis placed on identifying atrioventricular block, bundle branch block, and fascicular block. Fascicular block and left or right bundle branch block was diagnosed according to the criteria recommended by the American Heart Association Electrocardiography and Arrhythmias Committee. The appearance of new atrial fibrillation and the need for permanent pacemaker placement were documented. Permanent atrial fibrillation was defined according to the North American Society of Pacing and Electrophysiology/European Society of Cardiology international consensus as atrial fibrillation that had been present for some time and failed to terminate using cardioversion or was terminated but relapsed within 24 hours.
The cohort was divided into 2 groups: patients with new conduction disturbances, defined as a composite consisting of the need for PPI or the development of new bundle branch block or fascicular block and those who did not.
Continuous variables are presented as the mean ± SD and categorical variables as percentages. Differences between the continuous variables were assessed by Student’s t test. Categorical variables were compared using the chi-square test or Fisher’s exact test, as indicated. Significance was set at p <0.05. All continuous variables were measured in their original scale.
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