Transvenous and Subcutaneous Defibrillators (ICDs)

Aside from the slow (bradycardic) heart rhythm disturbances, there are also fast (tachycardic) heart rhythm disturbances (ventricular tachycardias, ventricular fibrillation), which can lead to cardiac arrest (sudden cardiac death) if left untreated.

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Implantation of Transvenous Defibrillators (ICDs)

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What is an ICD (automatic implantable cardioverter-defibrillator)?
Aside from the slow (bradycardic) heart rhythm disturbances, there are also fast (tachycardic) heart rhythm disturbances (ventricular tachycardias, ventricular fibrillation), which can lead to cardiac arrest (sudden cardiac death) if left untreated. Risk factors for sudden cardiac death are (for example) a severely limited pumping function of the heart, certain hereditary cardiac diseases, and previous survival of sudden cardiac death.
An implanted defibrillator detects the heart rhythm disturbances and can end them and re-normalize the heart rhythm either pain-free and unnoticed by the patient by overstimulation (called anti-tachycardic pacing) or by delivery of a shock (defibrillation, painful). Due to the required energy, the defibrillator device is somewhat larger than a conventional pacemaker. All implantable defibrillators always also contain a pacemaker function.

How are defibrillators (ICDs) implanted?

Similar to a pacemaker, a classical transvenous defibrillator is implanted into a tissue pocket under the skin or between the chest muscles below the clavicle under local anesthesia and additional administration of sedatives. One defibrillator lead (single-chamber ICD) or two leads (dual-chamber ICD) are advanced to the right heart through veins leading to the heart, where they are anchored at the cardiac membrane (with a screw mechanism).
The follow-up of the defibrillators take place at fixed intervals (every 4 to 6 months) at our pacemaker outpatient department or at a cardiologist's practice.


Implantation of Subcutaneous Defibrillators (S-ICDs)

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What is a subcutaneous defibrillator (S-ICD)?
Just as transvenous defibrillators, a subcutaneous ICD detects occurring fast (tachycardic) heart rhythm disturbances and can end them by delivering current pulses. A lead situated in the heart, as with a classical transvenous defibrillator, is not needed because the lead is instead placed under the skin in the fatty tissue. Other than with a transvenous ICD system, the device is not implanted below the clavicle but at the left side of the chest next to the rib cage. In contrast to a transvenous ICD, a subcutaneous ICD cannot end occurring fast (tachycardic) heart rhythm disturbances by the painless method of overstimulation (anti-tachycardic pacing) but only by shock delivery (defibrillation, painful). In addition, the subcutaneous ICD has, in contrast to the transvenous ICDs, no pacemaker function, making these systems unsuitable for patients with slow (bradycardic) heart rhythm disturbances.

How are subcutaneous defibrillators (ICDs) implanted?
The subcutaneous ICD is implanted under local anesthesia and additional administration of sedatives. The device is placed at the left chest wall between the chest muscles. The lead is implanted below the skin along the sternum and, in its further course, stretches along below the costal arch, and is connected to the S-ICD device. The heart and the vascular system remain untouched. To test the function of the S-ICD, a fast heart rhythm disturbance (ventricular fibrillation) is triggered during the intervention for a function check.
The follow-up of the subcutaneous defibrillators take place at fixed intervals (every 4 to 6 months) at our pacemaker outpatient department.