Episodes of paroxysmal supraventricular tachycardia are often paroxysmal, sudden and of variable duration, with ventricular rates of up to 130-240 beats per minute during the attack.
Most patients without organic heart disease themselves have only palpitations, while those with organic heart disease often experience panic, chest tightness, shortness of breath, dizziness, weakness and other discomforts, and some patients may also present with syncope, angina or even shock.
The severity of the symptoms generally depends on how fast the heart rate is and how long it lasts when the tachycardia occurs.