Possible underlying causes, which may be treatable and reversible in certain cases, include the Hs and Ts. * Hypovolemia * Hypoxia * Hydrogen ions (acidosis) * Hypothermia * Hyperkalemia or Hypokalemia * Toxins (e.g., drug overdose) * Cardiac Tamponade * Tension pneumothorax * Thrombosis (myocardial infarction or pulmonary embolism) While the heart is<unk> c, there is no blood flow to the brain unless CPR or internal cardiac massage (when the chest is opened and the heart is manually compressed) is performed, and even then it is a small amount. After many emergency treatments have been applied but the heart is still unresponsive, it is time to consider pronouncing the patient dead. Even in the rare case that a rhythm reappears, if<unk>  has persisted for fifteen minutes or more, the brain will have been deprived of oxygen long enough to cause severe hypoxic brain damage, resulting in brain death or persistent vegetative state. Image:Lead II rhythm generated<unk> .ECG lead showing<unk>  (flatline) File:Asystole.Asystole File:Asystole Coarse.Ventricular Fibrillation
Asystole
Junctional tachycardia
Hypopyon
Diastole
Junctional rhythm
Right bundle branch block
Torsades de pointes
Atopy