Cardiovascular features include hypotension, sinus bradycardia, and ventricular arrhythmias. Hypertension and tachycardia alternating with hypotension and bradycardia may develop. These adverse effects are ventricular dysrhythmia, bradycardia, hypotension and shock. Sick sinus syndrome, a sinus node dysfunction, causing alternating bradycardia and tachycardia. Complications include bradycardia, hypotension, and hypothermia. Arrhythmias such as tachycardia, bradycardia, atrioventricular block, and premature ventricular beats have also been reported. Phenylephrine may cause side effects such as headache, reflex bradycardia, excitability, restlessness and cardiac arrhythmias. Atropine and vasopressors act to combat bradycardia and hypotension. All victims developed nausea, vomiting, abdominal pain, sinus bradycardia, and hypotension. Hypertension followed by hypotension, bradycardia, and respiratory depression lower tissue oxygenation in the skin. The adverse effects include lethargy, bradycardia, marked hypotension and loss of consciousness. Two major groups of arrhythmias are bradycardia and tachycardia. Severe hyponatremia leads to both bradycardia and other arrhythmias. Overdose of bisoprolol leads to fatigue, hypotension, low blood sugar, bronchospasms, and bradycardia. Ventricular bradycardias occurs with sinus bradycardia, sinus arrest, and AV block.