python: read json and write to csv

import json
import csv

file_name = "timestamp.csv"

prev_spo2 = 0
prev_ecg = 0

csvFile = open(file_name, 'w+')
writer = csv.writer(csvFile)
row = ["seq", "TsEcg", "TsSpo2", "delta_TsEcg", "delta_TsSpo2"]
writer.writerow(row)

lines = open('/home/hmicro/Downloads/RecData_1.json', 'r') # edit file name here
for line in lines:
	 receiver_data = json.loads(line)
	 sensor_data = receiver_data.values()[0]["SensorData"] 
	 if "TsSpO2" in sensor_data.keys():
		tsSpo2 =  sensor_data["TsSpO2"]
	 else:
		tsSpo2 = "-"
	 seq = sensor_data["Seq"]
   	 tsEcg = sensor_data["TsECG"]
	 try:
		 del_spo2 = tsSpo2 - prev_spo2
	 except:
	         del_spo2 = "-"
	 row = [seq, tsEcg, tsSpo2, tsEcg - prev_ecg, del_spo2]
	 prev_spo2 = tsSpo2
	 prev_ecg = tsEcg
	 print row 
	 writer.writerow(row)
lines.close()
csvFile.close()