You might like to consider the way that the past intrudes on the present in this excellent play, in particular concerning Blanche's former husband and how he met his end. The device that Williams uses to remind both us and Blanche of his death is the Varouviana, which was the polka tune to which Blance danced with her young husband when he was last alive and before he killed himself. Let us remember that prior to dancing, Blanche had discovered her husband's homosexuality and then, in the middle of the dance, told him how repellent he was to her. This is the event that triggered his suicide.
The way in which this music is played at various points in the play reminds us of the death of Blanche's husband and also indicates her own kind of "death" but in terms of her mental decline and her death of innocence. Just tracing the times when she hears this music shows that it occurs whenever Blanche struggles to hold on to reality, which is therefore richly symbolic of her husband's death but also her own "death" towards which she is plummeting in terms of her mental health.