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J Thorac Cardiovasc Surg 2000;119:857
© 2000 The American Association for Thoracic Surgery

LETTERS TO THE EDITOR

Vasodilatation after cardiac surgery

Department of Cardiothoracic Surgery, Hammersmith Hospital, Du Cane Rd, East Acton, National Heart and Lung Institute, Imperial College of Science, London W12 0NN, United Kingdom

To the Editor:

Argenziano and associates, ¹ in their article on management of vasodilatory shock after cardiac surgery, provide an excellent study of enormous clinical importance. Identification of low ejection fraction and angiotensin-converting enzyme (ACE) inhibitors as risk factors for vasodilatory shock after cardiopulmonary bypass (CPB) confirms the initial analysis of 2729 patients undergoing CPB in our center.

However, the study raises a number of important issues that were not mentioned:

While discussing the mechanisms for arginine vasopressin deficiency, which may be multifactorial, the authors failed to mention that angiotensin II decreases arginine vasopressin release from the neurohypophysis. ² This implies that the newer selective angiotensin II inhibitors like losartan may also cause vasodilatory shock.

The majority of patients undergoing routine CPB, regardless of left ventricular function, have no sequelae if the ACE inhibitor is withheld on the morning of the operation. Withholding the ACE inhibitor also may decrease the chance of renal complications via the reduced efferent arterial tone caused by ACE inhibitors, which reduces glomerular filtration rate during CPB. ³ Obviously, withholding the ACE inhibitor is not appropriate in patients awaiting cardiac transplantation or left ventricular assist device implantation, but the ACE inhibitor could be changed to a short-acting one from the long-acting one that most patients receive.

Amiodarone, which is a noncompetitive -blocker and ß-blocker, is commonly co-prescribed with ACE inhibitors in patients with end-stage cardiac failure before heart transplantation. ⁴ Amiodarone has been shown to act synergistically with ACE inhibitors in causing vasodilatory shock via a two-hit mechanism. ⁵ Unfortunately no mention was made of this.

Finally, nicorandil, a new potassium channel opener used in the treatment of angina, in our experience, has been associated with decreased systemic vascular resistance and increased need for vasoconstrictor treatment. ⁶ This seems to be especially common when patients have taken a 10-mg dose within 12 hours of CPB.

12/8/105207 doi:10.1067/mtc.2000.105207

References

1. Argenziano M, Chen JM, Choudhri AF, et al. Management of vasodilatory shock after cardiac surgery: identification of predisposing factors and use of a novel pressor agent. J Thorac Cardiovasc Surg 1998;116:973-80. [Abstract/Free Full Text]
   
2. Ishikawa S, Saito T, Yoshida S. Effects of glucose and sodium chloride on the release of vasopressin in response to angiotensin II from the guinea pig hypothalamo-neurohypophyseal complex in organ culture. Neuroendocrinology 1980;31:365-8. [Medline]
   
3. Frohlich ED. Angiotensin converting enzyme inhibitors: present and future. Hypertension 1989;13(5 Suppl):I-125-30.
   
4. Stevenson W, Stevenson L, Middlekauff H, et al. Improving survival for patients with advanced heart failure: a study of 737 consecutive patients. J Am Coll Cardiol 1995;26:1417-23. [Abstract]
   
5. Mets B, Michler RE, Delphin E, et al. Refractory vasodilation after cardiopulmonary bypass for heart transplantation in recipients on combined amiodarone and angiotensin-converting enzyme inhibitor therapy: a role for vasopressin administration. J Cardiothorac Anesth 1998;12:326-9.
   
6. Kamijo T, Kamei K, Sugo I, et al. Hemodynamic and hormonal responses to nicorandil in a canine model of acute ischemic heart failure: a comparison with cromakalim and nitroglycerin. J Cardiovasc Pharmacol 1999;33:93-101.
   [Response declined] [Medline]
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Michael Poullis Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Poullis, M. Search for Related Content PubMed PubMed Citation Articles by Poullis, M.