In an electrophysiology study, trifascicular block due to AV nodal disease is represented by a prolonged AH interval (denoting prolonged time from impulse generation in the atria and conduction to the bundle of His) with a relatively preserved HV interval (denoting normal conduction from the bundle of His to the ventricles). Trifascicular block due to distal conduction system disease is represented by a normal AH interval and a prolonged HV interval. In the absence of symptoms, a prolonged AH interval is likely benign while a prolonged HV interval is almost always pathologic. Treatment
An implantable cardiac pacemaker or permanent pacemaker is recommended in the following clinical circumstances. Class 1 recommendation is the strongest recommendation. Level A evidence is the highest level of evidence.Class I

Bifascicular block + complete heart block, even in the absence of symptoms (1b)
Bifascicular block + 2nd degree AV Block Type 2, even in the absence of symptoms (1b)
Alternating bundle branch blocks, even in the absence of symptoms (1c)Class II

Bifascicular block + syncope + alternative causes ruled out (e.g. orthostasis, arrhythmia) (2a)Class III (i.e. pacemaker not recommended)

Bifascicular block without symptoms
Bifascicular block + 1st degree AV Block, without symptoms

References
External links

http://www.ecglibrary.com/trifas.html
http://circ.ahajournals.org/content/97/13/1325.long - new guidelines in which trifascicular block terminology continues to be used.
Cowden syndrome (also known as Cowdens disease and multiple hamartoma syndrome) is an autosomal dominant inherited condition characterized by benign overgrowths called hamartomas as well as an increased lifetime risk of breast, thyroid, uterine, and other cancers. It is often underdiagnosed due to variability in disease presentation, but 99% of patients report mucocutaneous symptoms by age 20–29. Despite some considering it a primarily dermatologic condition, Cowdens syndrome is a multi-system disorder that also includes neurodevelopmental disorders such as macrocephaly.The incidence of Cowdens disease is about 1 in 200,000, making it quite rare. Furthermore, early and continuous screening is essential in the management of this disorder to prevent malignancies. It is associated with mutations in PTEN on 10q23.3, a tumor suppressor gene otherwise known as phosphatase and tensin homolog, that results in dysregulation of the mTOR pathway leading to errors in cell proliferation, cell cycling, and apoptosis. The most common malignancies associated with the syndrome are adenocarcinoma of the breast (20%), followed by adenocarcinoma of the thyroid (7%), squamous cell carcinomas of the skin (4%), and the remaining from the colon, uterus, or others (1%). Signs and symptoms
As Cowdens disease is a multi-system disorder, the physical manifestations are broken down by organ system:
Skin
Adolescent patients affected with Cowden syndrome develop characteristic lesions called trichilemmomas, which typically develop on the face, and verrucous papules around the mouth and on the ears. Oral papillomas are also common. Furthermore, shiny palmar keratoses with central dells are also present.