Add Column Headers in Mirth Transformer

Question

How would I add column headers for the data listed below (same name as in single quotes)? I think I will need a while loop, but I'm not sure how to properly write one in Mirth.

var rev = ""
var delimiter = ","


revspring =     
$('account_number') +
delimiter +     $('responsible_party_first_name') +
delimiter +     $('responsible_party_last_name') +
delimiter +     $('responsible_party_middle_initial') +
delimiter +     $('responsible_party_address_line_1') +
delimiter +     $('responsible_party_address_line_2') +
delimiter +     $('responsible_party_city') +
delimiter +     $('responsible_party_state_code') +
delimiter +     $('responsible_party_zip') +
delimiter +     $('responsible_party_dob') +
delimiter +     $('current_account_balance') +
delimiter +     $('responsible_party_primary_contact_phone') +
delimiter +     $('responsible_party_mobile_phone') +
delimiter +     $('responsible_party_email_address') +
delimiter +     $('latest_payment_amount') +
delimiter +     $('latest_payment_date') +
delimiter +     $('parent_number') +
delimiter +     $('parent_balance') +
delimiter +     $('location_facility') +
delimiter +     $('original_account_number') +
delimiter +     $('original_account_desc') +
delimiter +     $('validation_field_1') +
delimiter +     $('validation_field_2') +
delimiter +     $('validation_field_3') +
delimiter +     $('delivery_preference') +
delimiter +     $('patient_last_name') +
delimiter +     $('patient_first_name') +
delimiter +     $('patient_middle_name_initial') +
delimiter +     $('patient_dob') +
delimiter +     $('patient_ssn_last_4') +
delimiter +     $('custom_data_1') +
delimiter +     $('custom_data_2') +
delimiter +     $('custom_data_3') +
delimiter +     $('custom_data_4') +
delimiter +     $('custom_data_5') + '\r\n';

channelMap.put("rev", rev)