Treatment of SVT in pregnancy may affect the fetus. For this reason, pharmacological treatment is best reserved for those with haemodynamic changes, severe symptoms or sustained arrhythmias. Non-pharmacological treatment including vagal manoeuvres such as carotid massage, Valsalva manoeuvre and facial ice immersion are well tolerated and safe for both mother and fetus.
Beta-blockers have been used extensively in pregnancy, to treat maternal hypertension and cardiac problems, and are generally well tolerated. Verapamil, a calcium channel-blocking agent, is also effective and poses no risk to the fetus.
As ireneo stated, speaking to your Dr about your options is best. Best of luck to you!
Depends on the medication. This is definitely something to discuss with the doctor before becoming pregnant. Or if you are already pregnant, talk to him/her ASAP.