what is a heart stress test

{"title":"Round Screen BT Call Smart Watch Nice Design Heart Rate Testing","imgUrl":"https:\/\/img.chinax.com\/nimg\/44\/29\/120561a4cdb054a4214351af2460-200x200-1.jpg","attrs":{"Brand Name":"Tsdatech","Model Number":"E300","Minimum Order Quantity":"2(sample)","Certification":"CE, RoHS\uff0cFCC","Place of Origin":"China","Packaging Details":"Single package size: 21.5X18.5X12.5 cm","Feature":"Touch Screen","Function":"Calendar, Sleep Tracker, Answer Call, Dial Call, Heart Rate Tracker, Blood oxygen monitor, Payment","Operation System":"Android, IOS","Screen Size":"41-45mm"}}

{"title":"12 Lead Ecg Machine 1\/ 3\/ 6\/ 12 Channel Stress Test Ekg Electrocardiogram Machine","imgUrl":"https:\/\/img.chinax.com\/nimg\/8e\/4f\/128d0a12f6d3b9a954528292499d-200x200-1.jpg","attrs":{"Price":"$80.00 - $288.00","Brand Name":"Rainbow","Model Number":"ECG-8203\/8206","Minimum Order Quantity":"1 unit","Delivery Time":"within 3 days","Place of Origin":"China","Certification":"ce","Packaging Details":"Anti-collision film+ Carton box ;Package size: 32*25*17CM Gross weight :2.7kg","Payment Terms":"L\/C, T\/T, Western Union, MoneyGram","Supply Ability":"30000units\/year","Power":"AC\/DC","Battery":"Rechargeable","Weight":"Light","Material":"Metal, Plastic","Display":"7 inch LCD\/LED","Size":"26*20*6.5CM","Alarms":"Audible\/Visible","Analysis":"Real-time\/Offline"}}