phontan operation

Dear Doctors,
My husband had fontan operation in 1991when he was 13 years old, and he was on warfarin during these years he is 31 years old now and one month ago he had very high palpitation (240) , in hospital they said he had VT but his dr said after one month and result of holter monitoring he had SVT, and he is on satolol now 2 times  a day. but they cannot recognise what they have to do , because they say if he do Anjio Or electro physio  study it has just 70% of success and it has risk of death.
I dont know what can I do for him and I am really scared.I need help to find out what can I do for him , till he become healthy.

[kenkeith]

An electrophysiology study (EP test or EP study) is a minimally invasive procedure which tests the electrical conduction system of the heart to assess the electrical activity and conduction pathways of the heart. The study is indicated to investigate the cause, location of origin, and best treatment for various abnormal heart rhythms. This type of study is performed by a specialist (an electrophysiologist) and is performed using a single or multiple catheters situated within the heart through a vein or artery.

It may have a 70% success rate for a diagnosis.  

For some insight and it is not as serious as you may have misunderstood if it SVT: Supraventricular tachycardia (SVT). SVT is a broad term that includes many forms of arrhythmia originating above the ventricles (supraventricular). SVTs usually cause a burst of rapid heartbeats that begins and ends suddenly and can last from seconds to hours. These bursts often start when the electrical impulse from a heartbeat begins to circle repeatedly through an extra pathway. SVT may cause your heart to beat 160 to 200 times a minute.

SVT is often caused by an underlying heart condition. Although SVT is generally not life-threatening in an otherwise normal heart, symptoms from the racing heart may feel quite uncomfortable. These arrhythmias are common in young people.