Your subjective data is what the patient or family tells you. This is in quotes. Ideally, the patient will give you input, but family is ok too. Example: "I get dizzy when I first stand up.". It's what the patient tells you, nothing more and nothing less.
Your objective data would be any meds, dosages, how often taken, as well as blood pressures taken while you were on site. Example if your there two days, I would take a look into the chart and post day, pm, and noc bp. Also, note the apical pulse, and S1, S2 (any other heard), the rate (reg or irreg), and rhythm (reg or irreg). Gallops or murmurs (no or yes), pedal and tibial pulses (are they palpable bilaterally?), Nailbeds (color, capillary refill time less than 3 sec or longer in all extremities), any edema? any jugular venous distension?, mucous membranes (are they moist and intact?), is the pt on telementary (if yes, what does it show?)
List any pertinent labs (are they low/high/ or wnl?) and any other tests
List pertinent hx.
This seems like alot to cover, but it gives you a good pic of cardiac. I hope this helps a bit.