Sudden loss of heart is a critical condition due to extreme exhaustion of heart yang and sudden loss of yangqi. This syndrome is the further development of heart yang asthenia. It may be caused by severe impairment of heart yang by pathogenic cold or obstruction of the heart by phlegm.

Clinical manifestations:
Apart from the symptoms of heart yang asthenia, there appear some other symptoms, such as sudden profuse cold sweating, cold limbs, weak breath, pale complexion, or sharp heart pain, cyanotic lips, indistinct pulse, even or unconsciousness and coma, usually seen in cardiogenic shock due to various diseases.
 
Analysis of symptoms:
Profuse cold sweating is due to leakage of body fluid with sudden loss of yangqi; cold limbs is due to decline of yangqi to warm the limbs; weak breath is due to asthenia of yangqi and leakage of thoracic qi to help the lung perform respiration; pale complexion is due to sudden loss of yangqi, weakness in warming the body, inhibited circulation of blood and vacuity of the vessels; sharp heart pain and cyanotic lips are due to inhibited circulation of blood and stagnation of blood in the heart vessels; unconsciousness or coma are due to declination of yangqi, lack of necessary warmth and nourishment of the heart and dispersion of the spirit; indistinct pulse is a sign of the declination of yangqi.
 
Key points for syndrome differentiation:
Asthenia of yangqi, sudden profuse cold sweating, cold limbs, weak breath, pale complexion, cyanotic lips and indistinct pulse.