Devices: Difference between revisions

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===Device measurements===
===Device measurements===
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''R = Impedance''
''R = Impedance''
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[[Image:RedTh.jpg|300px|right|thumb|Determination of stimulation threshold, after the red arrow the stimulus intensify and duration is not sufficient anymore to capture the heart.]]


====Stimulation threshold (in mV@ms):====  
====Stimulation threshold (in mV@ms):====  
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Sensing and stimulation of the myocardium demands a closed electrical circuit. A pacemaker can sense and stimulate in a unipolar and bipolar fashion:
Sensing and stimulation of the myocardium demands a closed electrical circuit. A pacemaker can sense and stimulate in a unipolar and bipolar fashion:
====Unipolar:====  
====Unipolar:====  
[[Image:ECGT.jpg|thumb|right|700px|ECG with unipolar stimulation displaying large pacemaker spikes.            ECG with bipolar stimulation displaying small pacemaker spikes]]
Pacemaker circuit between 1 electrode at the distal end of lead and the pacemaker pulse generator (large circuit ± 40-60 cm).
Pacemaker circuit between 1 electrode at the distal end of lead and the pacemaker pulse generator (large circuit ± 40-60 cm).
*Advantage: large pacemaker spikes (easier interpretation pacemaker ECG)
*Advantage: large pacemaker spikes (easier interpretation pacemaker ECG)
*Disadvantage: extracardiac stimulation (pectoral muscle), sensing of extracardiac signals (such as ventricular depolarisations in the atrial sensing channel (far field R waves) or non-physiological noise)
*Disadvantage: extracardiac stimulation (pectoral muscle), sensing of extracardiac signals (such as ventricular depolarisations in the atrial sensing channel (far field R waves) or non-physiological noise)
====Bipolar:====  
====Bipolar:====  
Pacemaker circuit between 2 electrodes at the distal end of the lead (small circuit ± 10-15 mm)
Pacemaker circuit between 2 electrodes at the distal end of the lead (small circuit ± 10-15 mm)
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===Numbers of intervals to detect / Time to detect===
===Numbers of intervals to detect / Time to detect===
The ICD diagnoses an arrhythmia when a sufficient (and programmable) number of events in an event sequence are binned. This is usually stated in an “X out of Y” pattern, such as 12 out of 16 intervals.
The ICD diagnoses an arrhythmia when a sufficient (and programmable) number of events in an event sequence are binned. This is usually stated in an “X out of Y” pattern, such as 12 out of 16 intervals.
[[Image:ICD.jpg|right|thumb|300px|ICD strook met intracardiale electrocardiogram (EGM): VF met shock. De rode pijl geeft het moment van de shock aan.]]


===Therapy===
===Therapy===
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