Definitely tell your doctor about this. All these drugs interact with each and Tramadol has a 'major' interaction with Citalopram. In particular it can cause something called 'serotonin syndrome'....Here are the symptoms associated with that. Tachycardia is increased heart rate - which you experienced. Be sure to talk to your physician before you take these drugs together again.
MANAGEMENT: In general, the concomitant use of SSRIs and tramadol should be avoided if possible, or otherwise approached with caution if potential benefit is deemed to outweigh the risk. Patients treated with the combination should be closely monitored for signs and symptoms of excessive serotonergic activity such as CNS irritability, altered consciousness, confusion, myoclonus, ataxia, abdominal cramping, hyperpyrexia (fever), shivering, pupillary dilation, diaphoresis, hypertension (high blood pressure), and tachycardia.
Serotonin syndrome is rare but it can be quite dangerous.