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Treatment of postthoracotomy supraventricular tachyarrhythmias
CORRESPONDENCE Treatment of Postthoracotomy Supraventricular Tachyarrhythmias To the Editor: I read with interest the article on failure of prophylactic digoxin administration to control dysrhythmias after esophageal operations by Ritchie and associates [l]. Supraventricular tachyarrhythmias, especially atrial fibrillation, are frequent occurrences after all types of thoracic surgical procedures including coronary artery bypass grafting and many other types of cardiac, pulmonary, and esophageal operations. Various prophylactic or therapeutic regimens, using mainly digoxin and propranolol, either alone or in combination, have Been most frequently employed. Prophylactic digoxin administration has not been generally effective in preventing atrial fibrillation after coronary artery bypass grafting [2, 31, pulmonary operations [4], and now esophageal operations [l].Furthermore, we became increasingly aware of the potential risk of the drug itself to induce arrhythmias. The incidence of postoperative supraventricular tachyarrhythmias, especially atrial fibrillation, in patients undergoing either coronary artery bypass grafting or any other thoracic operations that involve the handling of the pericardium has generally been underestimated due to its transient and often asymptomatic nature [5]. Intravenous digoxin or diltiazem, oral propranolol, or occasionally both is effective in reducing its incidence. Tsung 0. Cheng, M D Department of Medicine The George Washington University Washington, DC 20037
References 1. Ritchie AJ, Tolan M, Whiteside M, McGuigan JA, Gibbons JRP. Prophylactic digitalization fails to control dysrhythmia in thoracic esophageal operations. Ann Thorac Surg 1993;55: 86-8. 2. Tyras DH, Stothert JC, Kaiser GC, Barner HB, Codd JE, Willman VL. Supraventricular tachyarrhythmias after myocardial revascularization: a randomized trial of prophylactic digitalization. J Thorac Cardiovasc Surg 1979;77310-4. 3. Roffman JA, Fieldman A. Digoxin and propranolol in the prophylaxis of supraventricular tachydysrhythmias after coronary artery bypass surgery. Ann Thorac Surg 1981;31:496501. 4. Ritchie AJ, Bowe P, Gibbons JRP. Prophylactic digitalization for thoracotomy: a reassessment. Ann Thorac Surg 1990;50: 86-8. 5. Cheng TO. Postoperative supraventricular tachyarrhythmias. Ann Thorac Surg 1982;33:528-9.
Reply
To the Editor:
I thank Dr Cheng for his interest in this subject. I agree that the incidence of perioperative and postoperative supraventricular tachyrhythmias in patients undergoing either coronary artery bypass grafting or thoracic pulmonary or esophageal resection has previously been underestimated. The reason why this is of importance lies not only in the immediate hemodynamic consequences in these critically ill patients but also in the longer term potential of atrial thrombus formation and consequent systemic embolization. This risk is now regarded as higher than previously thought [I] but has never been properly studied in this group of patients, in whom I suspect it may too have been underestimated.
0 1993 by The Society of Thoracic Surgeons
Until the etiology of the dysrythmias is understood, prophylactic measures will be undertaken on an empirical basis. It is likely that the factors involved in coronary artery bypass grafting will differ from those for pulmonary or esophageal resection, and we have recently shown that this may be linked to the malignant state [2]. In addition, we looked carefully at surgical handling of the pericardium and could discern no immediate correlation with dysrhythmia. We effectively controlled hypoxia, hypercapnia, hypokalemia, or hyperkalemia as variables in our study groups. The roles of surgical resection, interruption of sympathetic and vagal fibers at the hilum, and interaction with anesthetic agents remain speculative. Studies of these variables in controlled clinical settings could provide valuable information and allow logical preventative or prophylactic measures to be undertaken and similarly tested.
Andrew J. Ritchie, FRCSEd Aberdeen Royal Infirmary Foresterhill, Aberdeen AB92ZB United Kingdom
References 1. Marchant BG, Timmis AD. Benefits and risks of thrombolytic, anticoagulant and antiplatelet therapies in atrial fibrillation. Br J Hosp Med 1993;49:186-9. 2. Ritchie AJ, et al. Cardiac dysrhythmia in total thoracic oesophagectomy: a prospective study. Eur J Cardiothoracic Surg (in press).
Dialdehyde Starch-Tanned Bovine Grafts in the Coronary Position To the Editor: Mitchell and colleagues [ l ] recently reported their long-term clinical evaluation of dialdehyde starch-preserved bovine internal mammary arteries as small diameter arterial substitutes in the coronary position. A total of 26 dialdehyde starch-treated bovine internal mammary artery grafts (Bioflow; Bio-Vascular Inc, St. Paul, MN) in 18 patents were implanted into the left anterior descending, circumflex, or right coronary artery. Three to 23 months after implantation, angiography demonstrated patency in only 3 of 19 grafts in 14 patients. This 16% patency rate was very low compared with 86% and 75% patency for native internal mammary artery and saphenous vein grafts in the same patients. Many acute clinical studies using the Bioflow graft have been reported over the last few years [2], but only Mitchell and associates' report includes a long-term angiographic evaluation. Although the dialdehyde starch treatment itself is very interesting, this current report brings to mind some important concerns with the proposed clinical use of Bioflow grafts for coronary bypass grafting, which Mitchell and associates clearly demonstrated is quite suspect. Is the dialdehyde starch-treated bovine internal mammary artery strong enough to be used as an arterial substitute? Rosenberg and associates [3] have reported a dialdehyde starch-treated bovine iliac graft functioning for nearly 7 years with no evidence of deterioration or aneurysm formation; however, other investigators have not been as successful. In a collective review of 255 bovine femoropopliteal grafts, the manufacturer reported a 20% incidence of aneurysm formation among 30 grafts that were subcutaneously placed [4]. In addition, Sawyer [5] showed that dialdehyde starch-tanned heterografts have a significant incidence of aneurysm formation over the long term, approaching 90% at 5 to 6 years. We have recently implanted Bioflow grafts into the aortocoronary position in dogs, and found that the grafts were quite thin, as the color of the blood was clearly visible Ann Thorac Surg 1993;56:59>7
0003-4975/93/$6.00
References 1. Ritchie AJ, Tolan M, Whiteside M, McGuigan JA, Gibbons JRP. Prophylactic digitalization fails to control dysrhythmia in thoracic esophageal operations. Ann Thorac Surg 1993;55: 86-8. 2. Tyras DH, Stothert JC, Kaiser GC, Barner HB, Codd JE, Willman VL. Supraventricular tachyarrhythmias after myocardial revascularization: a randomized trial of prophylactic digitalization. J Thorac Cardiovasc Surg 1979;77310-4. 3. Roffman JA, Fieldman A. Digoxin and propranolol in the prophylaxis of supraventricular tachydysrhythmias after coronary artery bypass surgery. Ann Thorac Surg 1981;31:496501. 4. Ritchie AJ, Bowe P, Gibbons JRP. Prophylactic digitalization for thoracotomy: a reassessment. Ann Thorac Surg 1990;50: 86-8. 5. Cheng TO. Postoperative supraventricular tachyarrhythmias. Ann Thorac Surg 1982;33:528-9.
Reply
To the Editor:
I thank Dr Cheng for his interest in this subject. I agree that the incidence of perioperative and postoperative supraventricular tachyrhythmias in patients undergoing either coronary artery bypass grafting or thoracic pulmonary or esophageal resection has previously been underestimated. The reason why this is of importance lies not only in the immediate hemodynamic consequences in these critically ill patients but also in the longer term potential of atrial thrombus formation and consequent systemic embolization. This risk is now regarded as higher than previously thought [I] but has never been properly studied in this group of patients, in whom I suspect it may too have been underestimated.
0 1993 by The Society of Thoracic Surgeons
Until the etiology of the dysrythmias is understood, prophylactic measures will be undertaken on an empirical basis. It is likely that the factors involved in coronary artery bypass grafting will differ from those for pulmonary or esophageal resection, and we have recently shown that this may be linked to the malignant state [2]. In addition, we looked carefully at surgical handling of the pericardium and could discern no immediate correlation with dysrhythmia. We effectively controlled hypoxia, hypercapnia, hypokalemia, or hyperkalemia as variables in our study groups. The roles of surgical resection, interruption of sympathetic and vagal fibers at the hilum, and interaction with anesthetic agents remain speculative. Studies of these variables in controlled clinical settings could provide valuable information and allow logical preventative or prophylactic measures to be undertaken and similarly tested.
Andrew J. Ritchie, FRCSEd Aberdeen Royal Infirmary Foresterhill, Aberdeen AB92ZB United Kingdom
References 1. Marchant BG, Timmis AD. Benefits and risks of thrombolytic, anticoagulant and antiplatelet therapies in atrial fibrillation. Br J Hosp Med 1993;49:186-9. 2. Ritchie AJ, et al. Cardiac dysrhythmia in total thoracic oesophagectomy: a prospective study. Eur J Cardiothoracic Surg (in press).
Dialdehyde Starch-Tanned Bovine Grafts in the Coronary Position To the Editor: Mitchell and colleagues [ l ] recently reported their long-term clinical evaluation of dialdehyde starch-preserved bovine internal mammary arteries as small diameter arterial substitutes in the coronary position. A total of 26 dialdehyde starch-treated bovine internal mammary artery grafts (Bioflow; Bio-Vascular Inc, St. Paul, MN) in 18 patents were implanted into the left anterior descending, circumflex, or right coronary artery. Three to 23 months after implantation, angiography demonstrated patency in only 3 of 19 grafts in 14 patients. This 16% patency rate was very low compared with 86% and 75% patency for native internal mammary artery and saphenous vein grafts in the same patients. Many acute clinical studies using the Bioflow graft have been reported over the last few years [2], but only Mitchell and associates' report includes a long-term angiographic evaluation. Although the dialdehyde starch treatment itself is very interesting, this current report brings to mind some important concerns with the proposed clinical use of Bioflow grafts for coronary bypass grafting, which Mitchell and associates clearly demonstrated is quite suspect. Is the dialdehyde starch-treated bovine internal mammary artery strong enough to be used as an arterial substitute? Rosenberg and associates [3] have reported a dialdehyde starch-treated bovine iliac graft functioning for nearly 7 years with no evidence of deterioration or aneurysm formation; however, other investigators have not been as successful. In a collective review of 255 bovine femoropopliteal grafts, the manufacturer reported a 20% incidence of aneurysm formation among 30 grafts that were subcutaneously placed [4]. In addition, Sawyer [5] showed that dialdehyde starch-tanned heterografts have a significant incidence of aneurysm formation over the long term, approaching 90% at 5 to 6 years. We have recently implanted Bioflow grafts into the aortocoronary position in dogs, and found that the grafts were quite thin, as the color of the blood was clearly visible Ann Thorac Surg 1993;56:59>7
0003-4975/93/$6.00