Palpitations can be associated with an isolated "skipped beat" sensation or, if the palpitations are prolonged, there can be a feeling of fluttering or fullness in the chest. Sometimes patients describe a marked fullness in their throat associated with shortness of breath, and it may be difficult to decide if the fullness is due to palpitations or due to angina. This is especially so if the palpitations have subsided and are not present when the affected person seeks medical care. Prolonged episodes can be associated with chest pain, shortness of breath, sweating, and, nausea and vomiting. Some types of heart rhythm problems can cause light-headedness or even passing out (fainting).