Bhave PD, Foster E, Dhaliwal G (NEJM 2012 Dec. 6 issue) (1) described that high cardiac output is defined as a cardiac output >8.0 liters per minute (or a cardiac index >4.0 liters per square meter). Since the patient with the large arteriovenous fistula and symptoms and signs of congestive heart failure had a cardiac output of 9.4 liters per minute, they indicated the patient had high-output heart failure. However, a cardiac output should be interpreted according to the value of right atrial pressure as suggested by the combined curves of venous return and cardiac output (Figure) (2). A cardiac output of 9.0 liters per minute with right atrial pressure of 20 mmHg should be regarded as “relatively low output state”. In fact, high-output heart failure, including one by large arteriovenous fistula, are caused by large venous return rather than low arterial pressure from low systemic vascular resistance (2).
Yasuharu Tokuda, M.D., M.P.H.
1: Bhave PD, Foster E, Dhaliwal G. Clinical problem-solving. A missed connection. N Engl J Med. 2012 Dec 6;367(23):2241-7.
2: John E. Hall. Guyton and Hall Textbook of Medical Physiology. 12nd edition. Saunders, New York. 2010.
Figure from: Guyton and Hall Textbook of Medical Physiology. 12nd edition. Saunders, New York. 201
