Prophylactic digoxin and SVT in cardiac surgery

606

Letters

to the

September, 1983 American Heart Journal

Editor

with residual diastolic filling of the pulmonary artery, suggesting a small ductal shunt. Noninvasive, early diagnosis of a patent ductus arteriosus in cyanotic newborns with TGV is of great importance, since these babies would benefit by prostaglandin therapy prior to septostomy,2 if and when the patent ductus closes. Joram Glaser, M.D. Pediatric Shaare Zedek

Cardiology Medical Jerusalem,

Unit Center Israel

REFERENCES

1. Sahn DJ, Allen HD, George W, Mason M, Goldberg SJ: The utility of contrast echocardiographic techniques in the care of critically ill infants with cardiac and pulmonary disease. Circulation 56:959, 1977. 2. Olley PM, Coceani G, Bodach E: E type prostaglandins: A new emergency therapy for certain cyanotic congenital heart malformations. Circulation 53:728, 1976.

PROPHYLACTIC DIGOXIN AND SW IN CARDIAC SURGERY To the Editor:

I read with great interest the paper by Chee et al.,’ entitled “Postoperative supraventricular arrhythmias and the role of prophylactic digoxin in cardiac surgery,” published in a recent issue of the JOURNAL. I have the following questions and comments: (1) Why were serum digoxin levels measured only when there was suspicion of digitalis toxicity? It is generally thought that in this situation the best decision is to discontinue digoxin, and to measure serum digoxin levels only affirms the diagnosis. (2) Which of the two, serum digoxin level or the patient’s situation, is responsible for the disagreement among the three groups? (3) I believe that digoxin is not responsible for the difference between group I and group II. (4) Why is digoxin responsible for the difference between group II and group III? In the Service of Cardiac Surgery of Santiago de Compostela, serum digoxin levels were measured pre-, during, and postextracorporeal circulation in 20 patients undergoing valvular surgery. Digoxin was not discontinued before surgery and the serum levels decreased gradually. I believe that, because of these results, the role of prophylactic digitalization for patients undergoing cardiac surgery remains controversial. To measure the serum digoxin levels is very important in the management of such patients. J. Rubio Alvarez, M.D., Ph.D. Hospital General De Galicia Santiago de Compostela Avda. de Lugo 257-P izda Santiago, Spain REFERENCE

1. Chee TP, Prakash NS, Desser KB, Benchimol A: Postoperative supraventricular arrhythmias and the role of prophylactic digoxin in cardiac surgery. AM HEART J 104:974, 1982.

REPLY To the Editor:

The letter by Dr. Alvarez comprises four questions and comments. (1) We do not condone the routine use of serum digoxin

levels. Our view is well supported by authorities in the field who hold that such measurement is indicated for suspected toxicity or absence of an expected therapeutic effect.’ In page 976 of our paper we state that serum digoxin levels will provide helpful guidelines if an especially resistant arrhythmia is encountered. (2) It is probable that digitalis administration rather than a specific digoxin level was responsible for the difference between the incidence of atria1 tachyarrhythmias in the three groups. We are confident that patients in group I, who were not taking digitalis, did not have a significant serum digoxin level. On the other hand, those patients in group III who received intravenous digoxin would have had measurable digoxin levels if these had been performed. The fact that 72 % of group I patients and only 5% of group III patients developed postoperative supraventricular tachyarrhythmia attests to the value of digoxin administration without concomitant serum digoxin levels in these patients. (3) Digoxin was indeed responsible for the difference between groups I and II, along with groups II and III. Group I patients did not receive digoxin preoperatively; digoxin was discontinued 1 to 2 days before operation in group II; group III patients were given prophylactic digoxin. Group II received digoxin in the postoperative period only after supraventricular arrhythmia or heart failure appeared. Only 5 ‘; of group III patients developed supraventricular arrhythmia, as compared with 958 of group II patients who required reinstitution of digoxin. Patently, the reason for these observations was the digoxin. (4) We find the unpublished data of Dr. Alvarez irrelevant in this context. If the gradually decreasing digoxin levels were associated with an increased incidence of supraventricular arrhythmia, then their results would be at variance with a jr, prevalence in our study where such levels were not measured. We suggest that digitalis administration, rather than sampling of multiple drug levels, is more important for the prevention and treatment of supraventricular arrhythmias in cardiac surgical patients.

Institute 1111 East

Kenneth B. Desser, M.D. Tong Ping Chee, M.D. N. Sri Prakash, M.D. Albert0 Benchimol, M.D. Good Samaritan Hospital for Cardiovascular Diseases McDowell Rd., PO Box 2989 Phoenix, AZ 85062

REFERENCE

1. Smith TW, Braunwald E: The management of heart failure. In Braunwald E, editor: Heart disease: A textbook of cardiovascular medicine. Philadelphia, 1980, W. B. Saunders Co, p 534.

CORONARY SPASM AND YYOCARDIAL INFARCTION To the Editor:

Dalen et al.,’ in presenting the persuasive evidence for a pivotal role for coronary spasm in myocardial infarction, indicate that much of the evidence is circumstantial and the case remains, at least to a considerable degree, hypothetical. There is further information on this question which I believe will buttress the key role of spasm in initiating myocardial infarction. This information derives from a careful study of the ECG and its evolution in the days immediately following the acute event. Since by definition spasm is a dynamic process, it would be reasonable to assume