Your spasms are likely unrelated, however you might be confusing spasms with cardiac pain.
Unfortunately it does not sound like the doctors gave you a very detailed picture of exactly what is going on with your heart.
SVT is not necessarily a sufficient reason to hospitalize someone. A few exceptions exists. To better understand what types of exceptions may be going on we would need a better description regarding the SPECIFIC type of SVT involved in addition to the rationale for the hospitalization.
99% of SVT cases should not have to stay at the hospital.
Further, you described another, completely independent problem which rather confuses the matter. If the top and the bottom parts of the heart are no longer related to one another the Tachycardia wpuld be considered Ventricular. It would no longer be SVT but rather "VT".
Of course if the top and bottom of the heart were related, but with the top occuring after the bottom (backwards), it would be unlikely that this would be your primary problem or even a concern for a physician. In fact at 180 it would likely be negligible as the reversed contraction may be sufficient to aid in filling the ventricle, at least to a very small degree.
A third scenario exists in which you have an underlyong heart block AS WELL As SVT. However such a scenario would be extremely unlikely as the SVT circuit most likely is dependent on the AV Node for Antegrade (Forward) or Retrograde (Backward) conduction. This scenario would thus be something I would question, unless an exceptional rationale is presented (I.E. AFIB or Flutter with WpW and 3AVB or a scenario with 2 distinct accessory pathways connecting the circuit).