Palpitations
Larger blood clots or thrombi can produce a reflex to increase ventilation leading to tachypnea which causes palpitations in heart. Heart racing or palpitations mainly appear due to low cardiac output, mismatch in the ratio of ventilation/perfusion, and low oxygen content in blood. The abnormalities arising in pulmonary venous pressure due to blood clots can lead to severe palpitations and severe ventricular arrhythmias which can be fatal for the patients.