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==Cardiac resynchronisation therapy (CRT)==
==Cardiac resynchronisation therapy (CRT)==
[[Image:Schematic.jpg|right|thumb|Schematic display of an CRT device]]
[[Image:Schematic.jpg|right|200px|thumb|Schematic display of an CRT device]]
[[Image:ChestXray.jpg|right|thumb|250px|Chest X-ray of a patient with an CRT device (in posteroanterior and lateral view)<br/>The red arrow is the right atrial lead<br/>The blue arrow is the right ventricular lead<br/>The green arrow is the coronary sinus lead]]
 
CRT-pacemaker (CRT-P) is a biventricular pacemaker with leads in both ventricles to ensure synchronized contraction. A CRT-defibrillator (CRT-D) is an ICD with biventricular pacing option.
CRT-pacemaker (CRT-P) is a biventricular pacemaker with leads in both ventricles to ensure synchronized contraction. A CRT-defibrillator (CRT-D) is an ICD with biventricular pacing option.
It appears that atrio-ventricular and intraventricular conduction delays further aggrevates left ventricular (LV) dysfunction in patients with underlying cardiomyopathies. Notably, left bundle branch block (LBBB) alters the sequence of LV contraction, causing wall segments to contract early or late. Dyssynchrony seems to represent a pathophysiological process that directly depresses ventricular function, causing LV remodelling and congestive heart failure and as a consequence causes a higher risk of morbidity and mortality. Atrio-biventricular pacing (CRT) for patients with symptomatic heart failure and intra- or interventricular conduction disturbances has proved beneficial.  
It appears that atrio-ventricular and intraventricular conduction delays further aggrevates left ventricular (LV) dysfunction in patients with underlying cardiomyopathies. Notably, left bundle branch block (LBBB) alters the sequence of LV contraction, causing wall segments to contract early or late. Dyssynchrony seems to represent a pathophysiological process that directly depresses ventricular function, causing LV remodelling and congestive heart failure and as a consequence causes a higher risk of morbidity and mortality. Atrio-biventricular pacing (CRT) for patients with symptomatic heart failure and intra- or interventricular conduction disturbances has proved beneficial.  
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Also patients with NYHA function class II, LVEF =35%, QRS width = 150 ms (especially LBBB) who are on optimal medical therapy are appropriate patients for CRT-D therapy.
Also patients with NYHA function class II, LVEF =35%, QRS width = 150 ms (especially LBBB) who are on optimal medical therapy are appropriate patients for CRT-D therapy.
[[Image:ChestXray.jpg|right|thumb|300px|Chest X-ray of a patient with an CRT device (in posteroanterior and lateral view)<br/>The red arrow is the right atrial lead<br/>The blue arrow is the right ventricular lead<br/>The green arrow is the coronary sinus lead]]


===Implantation===
===Implantation===
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