or a distinct signal transduction disorder in the heart (untreated AV block of more than 300 ms), may represent contraindications. CRT treatment should be considered in lieu of cardiac contractility modulation in patients with left bundle branch block (LBBB) and a QRS duration of over 120 ms, or when the QRS duration is greater than 150 ms and independent of LBBB. As with conventional pacemaker therapy, the cardiac contractility modulation device cannot be implanted if the leads cannot be positioned appropriately in the heart. In cases where there is an artificial heart valve between the right atrium and ventricle (a mechanical prosthetic tricuspid valve), the valve function could be greatly affected by the ventricular leads. In some instances it may be impossible to guide the leads through the main veins in the upper half of the body to the heart due to venous thrombosis, for example VVI pacemakers, in the case of 100% stimulation, are also contraindicated. Side effects The most frequently encountered adverse events related to cardiac contractility modulation therapy are lead fracture or lead dislodgement. Other reported complications include: Infection and bleeding at the IPG implantation site Accumulation of fluid in the pericardium (pericardial effusion) These side effects are similar to those that occur with other electrical stimulation therapies, such as pacemakers, CRT devices or ICD devices. Furthermore, recorded complications did not differ between patients with activated or deactivated cardiac contractility modulation devices. Overall, cardiac contractility modulation treatment was demonstrated to have no negative impact on health markers. Precautions Similarly to patients with other electrical stimulation devices, patients with a cardiac contractility modulation device must follow certain precautions arising from the device implantation and its function. Electromagnetic fields: Strong electromagnetic fields can interfere with the function of the device. Most interference will lead to inhibition of cardiac contractility modulation signal delivery. Once away from the field, the device will resume its normal function in most cases. The electromagnetic fields of household appliances are usually considered harmless. Mobile phones: Similarly to other electrical stimulation devices, such as pacemakers, aside from a recommended safety distance of 10–15 cm (4-6 inches) between the device and mobile phones, there are no restrictions on the use of mobile phones. Security checks: Full body or hand-held metal detectors, such as those used at airport security controls, do not usually affect the function of the device. However, where such detectors are used there are often