Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with lon...Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with longterm pacing of the apex of the right ventricle(RV). It has been shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block, with subsequent detrimental effects on cardiac structure and function, and in some cases adverse clinical outcomes such as atrial fibrillation, heart failure and death. There is substantial evidence that patients with reduced left ventricular function(LVEF) are at particular high risk of suffering the detrimental clinical effects of long-term RV pacing. The evidence is, however, incomplete, coming largely from subanalyses of pacemaker and implantable cardiac defibrillator studies. In this group of patients with reduced LVEF and an expected high amount of RV pacing, biventricular pacing(cardiac resynchronization therapy) devices can prevent the negative effects of RV pacing and reduce ventricular dyssynchrony. Therefore, cardiac resynchronization therapy has emerged as an attractive option with promising results and more clinical studies are underway. Furthermore, specific pacemaker algorithms, which minimize RV pacing, can also reduce the negative effects of RV stimulation on cardiac function and may prevent clinical deterioration.展开更多
The subcutaneous implantable cardioverter-defibrillator(S-ICD)has recently been approved for commercial use in Europe,New Zealand and the United States.It is comprised of a pulse generator,placed subcutaneously in a l...The subcutaneous implantable cardioverter-defibrillator(S-ICD)has recently been approved for commercial use in Europe,New Zealand and the United States.It is comprised of a pulse generator,placed subcutaneously in a left lateral position,and a parasternal subcutaneous lead-electrode with two sensing electrodes separated by a shocking coil.Being an entirely subcutaneous system it avoids important periprocedural and long-term complications associated with transvenous implantable cardioverter-defibrillator(TV-ICD)systems as well as the need for fluoroscopy during implant surgery.Suitable candidates include pediatric patients with congenital heart disease that limits intracavitary lead placements,those with obstructed venous access,chronic indwelling catheters or high infection risk,as well as young patients with electrical heart disease(e.g.,Brugada Syndrome,long QT syndrome,and hypertrophic cardiomyopathy).Nevertheless,given the absence of intracavitary leads,the S-ICD is unable to offer pacing(apart from shortterm post-shock pacing).It is therefore not suitable in patients with an indication for antibradycardia pacing or cardiac resynchronization therapy,or with a history of repetitive monomorphic ventricular tachycardia that would benefit from antitachycardia pacing.Current data from initial clinical studies and post-commercialization"real-life"case series,including over 700 patients,have so far been promising and shown that the S-ICD successfully converts induced and spontaneous ventricular tachycardia/ventricular fibrillation episodes with associated complication and inappropriate shock rates similar to that of TV-ICDs.Furthermore,by using far-field electrograms better tachyarrhythmia discrimination when compared to TV-ICDs has been reported.Future results from ongoing clinical studies will determine the S-ICD system’s long-term performance,and better define suitable patient profiles.展开更多
文摘Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with longterm pacing of the apex of the right ventricle(RV). It has been shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block, with subsequent detrimental effects on cardiac structure and function, and in some cases adverse clinical outcomes such as atrial fibrillation, heart failure and death. There is substantial evidence that patients with reduced left ventricular function(LVEF) are at particular high risk of suffering the detrimental clinical effects of long-term RV pacing. The evidence is, however, incomplete, coming largely from subanalyses of pacemaker and implantable cardiac defibrillator studies. In this group of patients with reduced LVEF and an expected high amount of RV pacing, biventricular pacing(cardiac resynchronization therapy) devices can prevent the negative effects of RV pacing and reduce ventricular dyssynchrony. Therefore, cardiac resynchronization therapy has emerged as an attractive option with promising results and more clinical studies are underway. Furthermore, specific pacemaker algorithms, which minimize RV pacing, can also reduce the negative effects of RV stimulation on cardiac function and may prevent clinical deterioration.
文摘The subcutaneous implantable cardioverter-defibrillator(S-ICD)has recently been approved for commercial use in Europe,New Zealand and the United States.It is comprised of a pulse generator,placed subcutaneously in a left lateral position,and a parasternal subcutaneous lead-electrode with two sensing electrodes separated by a shocking coil.Being an entirely subcutaneous system it avoids important periprocedural and long-term complications associated with transvenous implantable cardioverter-defibrillator(TV-ICD)systems as well as the need for fluoroscopy during implant surgery.Suitable candidates include pediatric patients with congenital heart disease that limits intracavitary lead placements,those with obstructed venous access,chronic indwelling catheters or high infection risk,as well as young patients with electrical heart disease(e.g.,Brugada Syndrome,long QT syndrome,and hypertrophic cardiomyopathy).Nevertheless,given the absence of intracavitary leads,the S-ICD is unable to offer pacing(apart from shortterm post-shock pacing).It is therefore not suitable in patients with an indication for antibradycardia pacing or cardiac resynchronization therapy,or with a history of repetitive monomorphic ventricular tachycardia that would benefit from antitachycardia pacing.Current data from initial clinical studies and post-commercialization"real-life"case series,including over 700 patients,have so far been promising and shown that the S-ICD successfully converts induced and spontaneous ventricular tachycardia/ventricular fibrillation episodes with associated complication and inappropriate shock rates similar to that of TV-ICDs.Furthermore,by using far-field electrograms better tachyarrhythmia discrimination when compared to TV-ICDs has been reported.Future results from ongoing clinical studies will determine the S-ICD system’s long-term performance,and better define suitable patient profiles.
