The LTC2949 is a high precision current, voltage, temperature, charge and energy meter for electrical and hybrid vehicles and other isolated current sense...
Datasheet LTC2949 on Analog.com
The expected heartbeat waveform is 400kHz 12.5% duty cycle. Although frequency and duty cycle look good here, I'm not sure why the waveform doesn't look like a square wave. Can you check the probe compensation or length of wire used to get to the signal/GND?