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Pacemaker Inhibition
356 The Annals of Thoracic Surgery Vol 37 N o 4 April 1984
tional 10%increase in SV (so-called preload reserve). Thus, the slight decrease in preload could have dampened the SV response but certainly could not have abolished it. We still believe that increasing the heart rate is warranted to enhance cardiac output in patients with tetralogy of Fallot after surgical repair. To further test this hypothesis, we [2] have conducted another study. Hemodynamic effects of increasing doses of dobutamine (2.5 to 5.0 to 10.0 pg/kg/min) and isoprenaline (0.05 to 0.1 to 0.2 kg/kg/min) were compared in a group of 12 children immediately after repair of tetralogy of Fallot. Left atrial pressure decreased with isoprenaline but remained unchanged with dobutamine. However, stroke volume did not change significantly with either drug at any dose. Accordingly, cardiac output was directly related to heart rate.
Michel Berner, M . D . lean-Claude Rouge, M . D . Beat Friedli, M . D . Department of Pediatrics Faculty of Medicine Geneva, Switzerland
References Miller DC, Stinson EB, Oyer PE, et al: Postoperative enhancement of left ventricular performance by combined inotropic-vasodilator therapy with preload control. Surgery 88:108, 1980 Jaccard C, Berner M, Oberhansli I, et al: Hemodynamic effect of isoprenaline and dobutamine immediately after correction of tetralogy of Fallot: relative importance of inotropic and chronotropic action in supporting cardiac output. J Thorac Cardiovasc Surg (in press, 1983)
Effect of Sodium Nitroprusside To the Editor: I wish to thank Kenneth Kayser, P.E.,‘ and J. D. Flora, Ph.D.,‘ for pointing out numerical inaccuracies that appeared in ”Effects of Sodium Nitroprusside during the Payback Period of Cardiopulmonary Bypass on the Incidence of Postoperative Arrhythmias” (Ann Thorac Surg 3 4 3 7 , 1982). The errors occurred on the following pages and should be amended accordingly:
1. Page 307 In the twenty-third line of the abstract, “12” should be changed to “21.” 2. Page 307 In the thirtieth line of the abstract, “35%” should be changed to “29%.” 3. Page 307 In the thirty-first line of the abstract, “17%”should be changed to “14%.“ 4. Page 309:In the second column, fourth line from the bottom, the p value should be greater than 0.005 instead of less than 0.005. This is also true for the p value given in the last line of that column. 5. Page 310 In footnotes b and c of Table 4, the p value should be greater than 0.005 instead of less than 0.005. 6. Page 311: In the second column, sixth line from the top, “17%” should be changed to “19%.”
These errors arose from careless proofreading by the authors at some stage in the preparation of the manuscript. The changes will not affect the fundamental results of the study, namely, ‘Personal communication, 1983.
that sodium nitroprusside given during the payback period of cardiopulmonary bypass appeared to minimize only ventricular arrhythmias in the early postoperative period of coronary bypass operation.
Kit V . Arom, M . D . Mirineapolis Heart lnstitute 2545 Chicago Ave S Minneapolis, M N 55404
Pacemaker Inhibition To the Editor: It seems that in his letter (Ann Thorac Surg 35:575, 1983), Dr. G. Frank 0. Tyers has missed the point of our article entitled “Pacemaker Inhibition in Cardiac Surgery” (Ann Thorac Surg 33295, 1982). Dr. Tyers erroneously deduced that inadequate cardioplegia was administered to our patients. The fact remains, however, that he was unclear on the definition of adequate cardioplegia. Cardiac standstill does not necessarily mean adequate cardioplegia, and that is the logic behind giving repeated doses of cardioplegic solution every 20 to 30 minutes, regardless of the heart activity at the time. It is safer to eliminate a s.mrce of stimulation that may act up during the time between caIdioplegia administration, namely, the cooling and the rewarming periods. Visual evidence of lack of activity is not an optimal criterion for determining actual mechanical activity of the heart.
A . Hadi Hakki, M . D . , F.R.C.S. ( C ) lnrler P . Goel, M . D . Elrlred D . Mundth, M . D . Hr!hnemann University Hospital, Suite 6328 239 N Broad St Philadelphia, P A 19102
M.itral Annuloplasty in Endomyocardial Fibrosis To the Editor: We enjoyed the recent case report by Mr. Wood and his associates [ l ] regarding a possible alternative in treatment of endomyocardial fibrosis (EMF) of the left ventricle: transvalvular endocardectomy associated with valvuloplasty. Because of our surgical experience with 46 patients with EMF [2], 20 of whom were described previously [3], we offer the following comments. First, we wish to note that our 1982 report also mentioned the possibility of combining transvalvular endocardectomy with annuloplasty. Second, Wood and colleagues state th.at only 5 patients with isolated left ventricular EMF have reportedly undergone operation. In fact, we have found a total of 31 such patients reported in the literature, including 14 in our series. Our principal comments concern the possibility of performirig transvalvular endocardectomy with preservation of the v.alve, as well as the possibility of surgical intervention in mitral insufficiency due to EMF. Transvalvular endocardectomy is possible in patients with bilateral EMF on the nondominant side. We have done this procedure on the right ventricle in 7 patients with bilateral EMF predominating on the left side; three of these operations were followed by a tricuspid annulo-
tional 10%increase in SV (so-called preload reserve). Thus, the slight decrease in preload could have dampened the SV response but certainly could not have abolished it. We still believe that increasing the heart rate is warranted to enhance cardiac output in patients with tetralogy of Fallot after surgical repair. To further test this hypothesis, we [2] have conducted another study. Hemodynamic effects of increasing doses of dobutamine (2.5 to 5.0 to 10.0 pg/kg/min) and isoprenaline (0.05 to 0.1 to 0.2 kg/kg/min) were compared in a group of 12 children immediately after repair of tetralogy of Fallot. Left atrial pressure decreased with isoprenaline but remained unchanged with dobutamine. However, stroke volume did not change significantly with either drug at any dose. Accordingly, cardiac output was directly related to heart rate.
Michel Berner, M . D . lean-Claude Rouge, M . D . Beat Friedli, M . D . Department of Pediatrics Faculty of Medicine Geneva, Switzerland
References Miller DC, Stinson EB, Oyer PE, et al: Postoperative enhancement of left ventricular performance by combined inotropic-vasodilator therapy with preload control. Surgery 88:108, 1980 Jaccard C, Berner M, Oberhansli I, et al: Hemodynamic effect of isoprenaline and dobutamine immediately after correction of tetralogy of Fallot: relative importance of inotropic and chronotropic action in supporting cardiac output. J Thorac Cardiovasc Surg (in press, 1983)
Effect of Sodium Nitroprusside To the Editor: I wish to thank Kenneth Kayser, P.E.,‘ and J. D. Flora, Ph.D.,‘ for pointing out numerical inaccuracies that appeared in ”Effects of Sodium Nitroprusside during the Payback Period of Cardiopulmonary Bypass on the Incidence of Postoperative Arrhythmias” (Ann Thorac Surg 3 4 3 7 , 1982). The errors occurred on the following pages and should be amended accordingly:
1. Page 307 In the twenty-third line of the abstract, “12” should be changed to “21.” 2. Page 307 In the thirtieth line of the abstract, “35%” should be changed to “29%.” 3. Page 307 In the thirty-first line of the abstract, “17%”should be changed to “14%.“ 4. Page 309:In the second column, fourth line from the bottom, the p value should be greater than 0.005 instead of less than 0.005. This is also true for the p value given in the last line of that column. 5. Page 310 In footnotes b and c of Table 4, the p value should be greater than 0.005 instead of less than 0.005. 6. Page 311: In the second column, sixth line from the top, “17%” should be changed to “19%.”
These errors arose from careless proofreading by the authors at some stage in the preparation of the manuscript. The changes will not affect the fundamental results of the study, namely, ‘Personal communication, 1983.
that sodium nitroprusside given during the payback period of cardiopulmonary bypass appeared to minimize only ventricular arrhythmias in the early postoperative period of coronary bypass operation.
Kit V . Arom, M . D . Mirineapolis Heart lnstitute 2545 Chicago Ave S Minneapolis, M N 55404
Pacemaker Inhibition To the Editor: It seems that in his letter (Ann Thorac Surg 35:575, 1983), Dr. G. Frank 0. Tyers has missed the point of our article entitled “Pacemaker Inhibition in Cardiac Surgery” (Ann Thorac Surg 33295, 1982). Dr. Tyers erroneously deduced that inadequate cardioplegia was administered to our patients. The fact remains, however, that he was unclear on the definition of adequate cardioplegia. Cardiac standstill does not necessarily mean adequate cardioplegia, and that is the logic behind giving repeated doses of cardioplegic solution every 20 to 30 minutes, regardless of the heart activity at the time. It is safer to eliminate a s.mrce of stimulation that may act up during the time between caIdioplegia administration, namely, the cooling and the rewarming periods. Visual evidence of lack of activity is not an optimal criterion for determining actual mechanical activity of the heart.
A . Hadi Hakki, M . D . , F.R.C.S. ( C ) lnrler P . Goel, M . D . Elrlred D . Mundth, M . D . Hr!hnemann University Hospital, Suite 6328 239 N Broad St Philadelphia, P A 19102
M.itral Annuloplasty in Endomyocardial Fibrosis To the Editor: We enjoyed the recent case report by Mr. Wood and his associates [ l ] regarding a possible alternative in treatment of endomyocardial fibrosis (EMF) of the left ventricle: transvalvular endocardectomy associated with valvuloplasty. Because of our surgical experience with 46 patients with EMF [2], 20 of whom were described previously [3], we offer the following comments. First, we wish to note that our 1982 report also mentioned the possibility of combining transvalvular endocardectomy with annuloplasty. Second, Wood and colleagues state th.at only 5 patients with isolated left ventricular EMF have reportedly undergone operation. In fact, we have found a total of 31 such patients reported in the literature, including 14 in our series. Our principal comments concern the possibility of performirig transvalvular endocardectomy with preservation of the v.alve, as well as the possibility of surgical intervention in mitral insufficiency due to EMF. Transvalvular endocardectomy is possible in patients with bilateral EMF on the nondominant side. We have done this procedure on the right ventricle in 7 patients with bilateral EMF predominating on the left side; three of these operations were followed by a tricuspid annulo-