Heart Palpitations rapid pulse

I am a 44 year old recently retired police officer and now full time personal trainer / nutritionist. I am searching for help with a dilemma that has been causing me major concern. I started testosterone therapy about 5 years ago using pellet implants. At first the results were amazing but after about 2 years I started experiencing heart palpitations and a pulse around 85 when at rest. The doctor and clinic where I was getting my implant therapy swore my heart palpitations and rapid pulse was not from the testosterone. They referred me to a cardiologist and I had two echo-cardiograms which didn't show anything. I ruled out everything I could think of and the only common denominator was the testosterone. I stopped the implants and tried living without the testosterone help but I shortly became deficient and it affected me greatly. I went to my endocrinologist and started testosterone injections which gave me the results I wanted but also the palpitations and rapid pulse came back. I am desperately looking for anything that can help as researching my condition has led to very little help. I'm lost and looking for help if anyone has anything to offer. Thanks

Rapid heart rate or palpitations shouldn't be directly related to the testosterone. However, it could be linked to your estrogen levels.
Has your treatment included checking estradiol?
Has your treatment included basic periodic CBC panels that include RBC and hematocrit?

This would be a good place to start.