.
Atrial fibrillation
Heart block
Ventricular fibrillation
Bradycardia
Angina pectoris
Atherosclerosis
Myocarditis
Hypertension
Surgery
Sclerotherapy
Ablation
Transfusions
Sickle cell anemia
Iron-deficiency anemia
Vitamin B12 anemia
All of the above
Severe pain
Fragile RBCs
Vegetarians more at risk
Inherited disease