Table 2.

Concepts Assessed by Measurement Tools

Measurement Tool Item	Palpitations not specified	Heart rate sensations	Heartbeat sensations	Discomfort
Heart discomfort				X
Heart discomfort/palpitation	X			X
Heart discomfort (unusual awareness of heartbeat, heart skipping, heart racing, tightness)		X	X	X
Heart discomfort/cardiac symptoms				X
Cardiac symptoms (palpitations, racing heartbeat, irregular beats, tightness in chest)	X	X	X
Palpitations/heart palpitations	X
Palpitation of heart, excitable/anxiety	X
Palpitations and butterflies	X		X
Breathlessness and palpitations	X
Palpitations (heart beating quickly or strongly)	X	X	X
Irregular heart beats			X
Tachycardia		X
Rapid heartbeat		X
Heart pounding (or racing)		X	X
Heart beating quickly and heart discomfort		X		X