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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=== | ||