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Devices: Difference between revisions
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A pacemaker rhythm can easily be recognized on the ECG. It shows pacemaker spikes: vertical signals that represent the electrical activity of the pacemaker. Usually these spikes are more visible in unipolar than in bipolar pacing (see below). | A pacemaker rhythm can easily be recognized on the ECG. It shows pacemaker spikes: vertical signals that represent the electrical activity of the pacemaker. Usually these spikes are more visible in unipolar than in bipolar pacing (see below). | ||
[[Image:Paced2.gif ]] | [[Image:Paced2.gif]] | ||
==Patients== | ==Patients== | ||
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==Complications== | ==Complications== | ||
===Undersensing:=== | ===Undersensing:=== | ||
[[Image:Ventricular undersensing.svg|right|thumb| | [[Image:Ventricular undersensing.svg|right|thumb|250px|Ventricular undersensing. Failure of appropriate ventriculation inhibition]] | ||
An intrinsic depolarization that is present, is not sensed by the pacemaker. This can be due to: | An intrinsic depolarization that is present, is not sensed by the pacemaker. This can be due to: | ||
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===Oversensing:=== | ===Oversensing:=== | ||
[[Image:Ventricular oversensing.svg|right|thumb| | [[Image:Ventricular oversensing.svg|right|thumb|250px|Ventricular oversensing. Failure of appropriate ventricular firing]] | ||
The pacemakers senses signals on the marker channel that do not correspond to the ECG pattern. This can be physiologic (e.g. ventricular pulse or myopotentials) or non-physiologic (e.g. lead fracture or if the lead is loose from the pacemaker pulse generator or outside interference such as TENS therapy or surgical diathermy). | The pacemakers senses signals on the marker channel that do not correspond to the ECG pattern. This can be physiologic (e.g. ventricular pulse or myopotentials) or non-physiologic (e.g. lead fracture or if the lead is loose from the pacemaker pulse generator or outside interference such as TENS therapy or surgical diathermy). | ||
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==Implantable cardioverter defibrillators (ICD)== | ==Implantable cardioverter defibrillators (ICD)== | ||
[[Image:Schematicpic.jpg|right|300px|thumb|Schematic display of an ICD]] | |||
An ICD is a device that monitors heart rhythms. If it senses dangerous rhythms, it delivers shocks or anti-tachypacing (ATP) therapy. Many ICDs record the heart's electrical patterns when there is an abnormal heartbeat. | An ICD is a device that monitors heart rhythms. If it senses dangerous rhythms, it delivers shocks or anti-tachypacing (ATP) therapy. Many ICDs record the heart's electrical patterns when there is an abnormal heartbeat. | ||
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==Implantation== | ==Implantation== | ||
[[Image: | [[Image:Xthorax.jpg|right|300px|thumb|X-thorax of a patient with an ICD (in posteroanterior and lateral view)]] | ||
ICDs are implanted under local anaesthesia in a sterile operating room or catheterization laboratory. Transvenous ICD implantation starts, like pacemaker implantation, with inserting the ICD leads in the left or right cephalic vein. Fluoroscopy is used to ensure the appropriate location in the atrium or ventricle. Leads are often positioned in the auricle of the right atrium and/or the right ventricular apex. | ICDs are implanted under local anaesthesia in a sterile operating room or catheterization laboratory. Transvenous ICD implantation starts, like pacemaker implantation, with inserting the ICD leads in the left or right cephalic vein. Fluoroscopy is used to ensure the appropriate location in the atrium or ventricle. Leads are often positioned in the auricle of the right atrium and/or the right ventricular apex. | ||
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==Cardiac resynchronisation therapy (CRT)== | ==Cardiac resynchronisation therapy (CRT)== | ||
[[Image:Schematic.jpg|right|thumb|Schematic display of an CRT device]] | |||
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=== | ||