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Sudden death in a child with ventricular tachycardia
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IJ:llbRS
difficult, but necessary; otherwise, the controversy will remain unchanged. Phllllppe Telller, MD G. Bedlg, MD Paris, France 1. Hlrzel HO, Senn M, Nuasr.h K, Buettner C, Plelffer A, Hell OM, Kreyeosbachl HP. Thallium-201 scintigraphy In complete loft bundle branch block. Am J Cardiol 1984;53:764-769. 2. Gerlla R. Role of coronary vasospasm in the pathogenesis of myocardial ischemis and angina pectoris. Am Heart J 1982;103:589-603. 3. Patterson RE, Eng C, Herowltz SF. Practical diagnosis of cer(xta~ artery disease: a Bayes' 8teorem nomogram to correlate clinical data wRh nonlnvasiveexercise tests. Am J Cardlo11984;53:252-256. 4. Gibson RS, Watson DD, Craddock GB, Crempton RS, Kaiser DL, Denny MJ, Belier GA. Prediction of cardiac events after uncomplicated myocardial infarction: a prospective study comparing predischarge exorcise thallium-201 scintlgraphy and coronary anglography. Circulation 1983;68:321-336. 5. Telller PH, Bedlg G, Marcadet D, Laffay N, Aul:,ry P, Vulpillat M. Contributionde la sclntJgraphlamyocard]que & I'effort au diagnostic positlf et topegraphique de la maledie coronarienne: btude chez 115 patients sans antbcbdents d'lnfarctus du myocarde. Ann Cardiol Angeiol (Paris) 1984;33:87-92.
R E P L Y : Angina pectoris is indeed the leading symptom in CAD. However, many pathophysiologic conditions other than atheromatous alterations of the coronary arteries are frequently associated with angina-like chest pain, such as aortic stenosis, hypertrophic cardiomyopathy, pulmonary hypertension and aortic regurgitation. Moreover, angina can be present despite normal coronary arteriographic results. 1-3 Although we recognize that coronary artery spasm can cause anginal symptoms, it appears unlikely that in all patients studied, a spontaneous spasm occurred during scintigraphy, leading to the observed reduction in thallium uptake within the septum, but that none was detected at angiography. Provocation tests with ergonovine, however, were not performed. With respect to the technical objections made by TeUier and Bedig, the method applied for semiquantitative analysis of digitized scintigraphic images was carefully evaluated beforehand (see Ref. 9 to 11 in the original report). It was further tested in other studies. 4,5 Because differences regarding "control" values obviously do exist, it is mandatory to relate the normal values specific for one's own laboratory. Examination of 27 normal persons 6 revealed little differences in thallium activity between the various regions of the myocardial wall. Also, when the semiquantitative approach described was used, thallium activity was never reduced by more than 15% compared to maximal thallium activity within any region, the "hottest" spot being excluded. Moreover, thallium activity was determined in the canine experiments not only from the externally recorded scintigrams, but also directly within the tissue. Both examinations showed good agreement. Therefore, it is hard to imagine that any clinical interpretation of thallium scintigrams, even in the hands of TeUier and Bedig, could be any better than direct de-
termination of thallium activity in pieces of myocardium removed from the experimental animals. Heinz O. Hlrzel, MD Hans P. Krayenbuehl,MD Zurich, Switzerland 1. James 1N. Angina without coronary disease. Circulation 1970;42:189-191. 2. Darl AM, AIbon Davies H, Dalai J, Ruffle,/M, Henderson AH. "Anglne" and normal coronary arterlograms: a follow-up study. Eur Heart J 1980;1:97-100. 3. Oplmrk D, Zebe H, Welhe F, Mall G, DOrrC, Graved B. Mohmel HC, Schwarz F, KiJbler W. Reduced coronary dilatory capacity and ultrastructurel changes of the myocardlum in patients with angina pectods but normal coronary arterlograms. Circulation 1981;63:817-825. 4. Hlrzel HO, Nummh K, Slaler G, Horld W, Krayenbuehl HP. Thenlum-201 exercise myocardial Imaging to evaluate myocardial porfuslon after coronary artery bypass surgery. Br Head J 1980;43:426--435. 5. Hlrzel HO, Nuasch K. Luetolt UM, Gruec4zlg A, Herld W, Krayenbuehl HP. La sclntlgrephlo du myocarde au thallium 201 dans rbvaluatlon du succ~s d'una Intervention revascularisab'lce solt per pontage aorto-ceronarldn solt par dilatation coronarldone. Arch Mal Coeur 1980;73:651-660. 6. Luetolf UM, Schneider E, Glanzmonn CH, Nueoch K. Pfelffar A, KreyeMmeM HP, Honfl W. Zur Methodik der Myokardszlntigraphle mlt Thallium-201: Grenzen zum Pathologischen. Schwolz Med Wochenschr 1977; 107:1574-1577.
SUDDEN DEATH IN A CHILD WITH VENTRICULAR TACHYCARDIA
In their recent report dealing with a case of sudden death in a child with repetitive paroxysmal ventricular tachycardia (VT) Rowland and Schweiger1 based their decision not to treat their patient on several factors, among them "the absence of underlying cardiac disease." The necropsy data of their patient, which showed "mild dilatation of the right ventricle and tricuspid valve with a slight increase in interstitial tissue," suggests that the anatomic basis of the VT was right ventricular (RV) dysplasia. 2 Arrhythmogenic RV dysplasia has been reported in infants and children. 3 A normal cardiac examination and echocardiogram, as in their patient, are frequently observed in mild forms of RV dysplasia. 3 Furthermore, the QRS complexes of the VT of their patient had a left bundle branch block pattern with a QRS axis of +80 °, similar to that most frequently encountered in patients with arrhythmogenic RV dysplasia. 2 However, RV angiography, which is the clue of the diagnosis of this cardiomyopathy, 2 was not performed, and therefore, the "absence of underlying cardiac disease" could not be ascertained. If the VT were actually the result of RV dysplasia, its response to exercise would be particularly uncommon. In patients with RV dysplasia, VT is frequently induced by exercise,4 and its abolition by exercise, as noted in this case, would have a major clinical implication. This would suggest that abolition of VT by exercise, usually accepted as a reliable argument of benign prognosis in patients with apparently idiopathic VT, should not be considered so unless RV dysplasia has been excluded. Bernard Belhassen, MD Philadelphia, Pennsylvania
1. Rowland TW, Schwelgor MJ. Repetitive paroxysmal ventflcular tachycardla and sudden death in a child. Am J Cardlol 1984;53:1729. 2. Marcol FI, FoMalno GH, Gulraudon G, FraRk R, Laurenceau JL, Malm'gue C, G ~ a t Y. Right ventrlcular dysplasla: a report of 24 adult cases. Circulation 1982;64:384-398. 3. Duogan 1', Gareon A, GlUe#e PC. Arrhy~mogenlc right venb'lcular dysplasla: a cause of vontricular tachycardla In children with apparently normal hearts. Am Heart J 1981;102:745-750. 4. Soklmon SI., Vmt Oedol KD, Mammml A, Werda M, Hall RJ. Exercise-induced rtght ventrlcular tochycardla and arrhythmogenlc right ventrlcular dysplasla: electrophysiologic and therapeutic considemtloos. Texas Heart Inst J 1983;10:351-357.
QT/QS2 RATIO AS INDEX OF AUTOMATIC TONE De Caprio et al I suggest the adoption of a new
index, the QT/QS2 ratio, as a marker of sympathetic activity. From their results we would be justified in concluding that an increased QT/QS2 ratio could identify subjects with an enhanced sympathetic tone. However, our results in a group of 40 highly trained endurance athletes matched against 40 sedentary subjects of the same age do not support this hypothesis. In the athletes, the sympathetic discharge to the heart was reduced during resting conditions and plasma cathecolamines were lower than in non-athletes. 2 Therefore, on the basis of the results of De Caprio et al, we would expect a reduced QT/QS2 in athletes compared with sedentary persons. On the contrary, our results in these groups of trained and untrained subjects showed a higher QT/QS2 ratio in athletes (0.97 ~- 0.08) compared with that in control subjects (0.90 4- 0.09, p <0.005). Athletes, whose heart rate appeared to be significantly lower than that of control subjects (66 4- 11 vs 79 4- 14 beats/min, p <0.001), as an adaptation to physical training, showed a higher QT/QS2 ratio as a consequence of an increase in QT interval (383 4- 31 vs 339 4- 31 ms, p <0.001), whereas the QS2 period was slightly but not significantly reduced. Also, the QT corrected for heart rate according to the Bazett formula appeared to be longer in athletes (401 4- 21 vs 385 4- 18 ms; p <0.005), in agreement with the results of other investigators. 3 In conclusion, QT/QS2 ratio may be used as an index of changes in sympathetic activity within the same subject. However, it does not allow an estimate of the sympathetic tone when comparing different groups of subjects. Paolo PalaUni, MD Padova, italy
1. Oe Caprlo L, Ferro G, Cuomo S, Volpe M, Arllaco D, De Luca N, Rlcclerdelll B. QT/QS2 ratio as an Index of autonomic tone changes. Am J Cardlol 1984;53: 818. 2. Bndeor HS. Cardiovascular edaptaUons in the trained athlete. In: Lublch T, Venarando A, eds. Proceedingsof the International Conference on Sports Can:llology, Rome, April 1978. Bologna: Goggi, 1980:3. 3. PaMano JA. Reply to the letter: An'hythmias and QT interval in athletes. Am Heart J 1984;107:608.
IJ:llbRS
difficult, but necessary; otherwise, the controversy will remain unchanged. Phllllppe Telller, MD G. Bedlg, MD Paris, France 1. Hlrzel HO, Senn M, Nuasr.h K, Buettner C, Plelffer A, Hell OM, Kreyeosbachl HP. Thallium-201 scintigraphy In complete loft bundle branch block. Am J Cardiol 1984;53:764-769. 2. Gerlla R. Role of coronary vasospasm in the pathogenesis of myocardial ischemis and angina pectoris. Am Heart J 1982;103:589-603. 3. Patterson RE, Eng C, Herowltz SF. Practical diagnosis of cer(xta~ artery disease: a Bayes' 8teorem nomogram to correlate clinical data wRh nonlnvasiveexercise tests. Am J Cardlo11984;53:252-256. 4. Gibson RS, Watson DD, Craddock GB, Crempton RS, Kaiser DL, Denny MJ, Belier GA. Prediction of cardiac events after uncomplicated myocardial infarction: a prospective study comparing predischarge exorcise thallium-201 scintlgraphy and coronary anglography. Circulation 1983;68:321-336. 5. Telller PH, Bedlg G, Marcadet D, Laffay N, Aul:,ry P, Vulpillat M. Contributionde la sclntJgraphlamyocard]que & I'effort au diagnostic positlf et topegraphique de la maledie coronarienne: btude chez 115 patients sans antbcbdents d'lnfarctus du myocarde. Ann Cardiol Angeiol (Paris) 1984;33:87-92.
R E P L Y : Angina pectoris is indeed the leading symptom in CAD. However, many pathophysiologic conditions other than atheromatous alterations of the coronary arteries are frequently associated with angina-like chest pain, such as aortic stenosis, hypertrophic cardiomyopathy, pulmonary hypertension and aortic regurgitation. Moreover, angina can be present despite normal coronary arteriographic results. 1-3 Although we recognize that coronary artery spasm can cause anginal symptoms, it appears unlikely that in all patients studied, a spontaneous spasm occurred during scintigraphy, leading to the observed reduction in thallium uptake within the septum, but that none was detected at angiography. Provocation tests with ergonovine, however, were not performed. With respect to the technical objections made by TeUier and Bedig, the method applied for semiquantitative analysis of digitized scintigraphic images was carefully evaluated beforehand (see Ref. 9 to 11 in the original report). It was further tested in other studies. 4,5 Because differences regarding "control" values obviously do exist, it is mandatory to relate the normal values specific for one's own laboratory. Examination of 27 normal persons 6 revealed little differences in thallium activity between the various regions of the myocardial wall. Also, when the semiquantitative approach described was used, thallium activity was never reduced by more than 15% compared to maximal thallium activity within any region, the "hottest" spot being excluded. Moreover, thallium activity was determined in the canine experiments not only from the externally recorded scintigrams, but also directly within the tissue. Both examinations showed good agreement. Therefore, it is hard to imagine that any clinical interpretation of thallium scintigrams, even in the hands of TeUier and Bedig, could be any better than direct de-
termination of thallium activity in pieces of myocardium removed from the experimental animals. Heinz O. Hlrzel, MD Hans P. Krayenbuehl,MD Zurich, Switzerland 1. James 1N. Angina without coronary disease. Circulation 1970;42:189-191. 2. Darl AM, AIbon Davies H, Dalai J, Ruffle,/M, Henderson AH. "Anglne" and normal coronary arterlograms: a follow-up study. Eur Heart J 1980;1:97-100. 3. Oplmrk D, Zebe H, Welhe F, Mall G, DOrrC, Graved B. Mohmel HC, Schwarz F, KiJbler W. Reduced coronary dilatory capacity and ultrastructurel changes of the myocardlum in patients with angina pectods but normal coronary arterlograms. Circulation 1981;63:817-825. 4. Hlrzel HO, Nummh K, Slaler G, Horld W, Krayenbuehl HP. Thenlum-201 exercise myocardial Imaging to evaluate myocardial porfuslon after coronary artery bypass surgery. Br Head J 1980;43:426--435. 5. Hlrzel HO, Nuasch K. Luetolt UM, Gruec4zlg A, Herld W, Krayenbuehl HP. La sclntlgrephlo du myocarde au thallium 201 dans rbvaluatlon du succ~s d'una Intervention revascularisab'lce solt per pontage aorto-ceronarldn solt par dilatation coronarldone. Arch Mal Coeur 1980;73:651-660. 6. Luetolf UM, Schneider E, Glanzmonn CH, Nueoch K. Pfelffar A, KreyeMmeM HP, Honfl W. Zur Methodik der Myokardszlntigraphle mlt Thallium-201: Grenzen zum Pathologischen. Schwolz Med Wochenschr 1977; 107:1574-1577.
SUDDEN DEATH IN A CHILD WITH VENTRICULAR TACHYCARDIA
In their recent report dealing with a case of sudden death in a child with repetitive paroxysmal ventricular tachycardia (VT) Rowland and Schweiger1 based their decision not to treat their patient on several factors, among them "the absence of underlying cardiac disease." The necropsy data of their patient, which showed "mild dilatation of the right ventricle and tricuspid valve with a slight increase in interstitial tissue," suggests that the anatomic basis of the VT was right ventricular (RV) dysplasia. 2 Arrhythmogenic RV dysplasia has been reported in infants and children. 3 A normal cardiac examination and echocardiogram, as in their patient, are frequently observed in mild forms of RV dysplasia. 3 Furthermore, the QRS complexes of the VT of their patient had a left bundle branch block pattern with a QRS axis of +80 °, similar to that most frequently encountered in patients with arrhythmogenic RV dysplasia. 2 However, RV angiography, which is the clue of the diagnosis of this cardiomyopathy, 2 was not performed, and therefore, the "absence of underlying cardiac disease" could not be ascertained. If the VT were actually the result of RV dysplasia, its response to exercise would be particularly uncommon. In patients with RV dysplasia, VT is frequently induced by exercise,4 and its abolition by exercise, as noted in this case, would have a major clinical implication. This would suggest that abolition of VT by exercise, usually accepted as a reliable argument of benign prognosis in patients with apparently idiopathic VT, should not be considered so unless RV dysplasia has been excluded. Bernard Belhassen, MD Philadelphia, Pennsylvania
1. Rowland TW, Schwelgor MJ. Repetitive paroxysmal ventflcular tachycardla and sudden death in a child. Am J Cardlol 1984;53:1729. 2. Marcol FI, FoMalno GH, Gulraudon G, FraRk R, Laurenceau JL, Malm'gue C, G ~ a t Y. Right ventrlcular dysplasla: a report of 24 adult cases. Circulation 1982;64:384-398. 3. Duogan 1', Gareon A, GlUe#e PC. Arrhy~mogenlc right venb'lcular dysplasla: a cause of vontricular tachycardla In children with apparently normal hearts. Am Heart J 1981;102:745-750. 4. Soklmon SI., Vmt Oedol KD, Mammml A, Werda M, Hall RJ. Exercise-induced rtght ventrlcular tochycardla and arrhythmogenlc right ventrlcular dysplasla: electrophysiologic and therapeutic considemtloos. Texas Heart Inst J 1983;10:351-357.
QT/QS2 RATIO AS INDEX OF AUTOMATIC TONE De Caprio et al I suggest the adoption of a new
index, the QT/QS2 ratio, as a marker of sympathetic activity. From their results we would be justified in concluding that an increased QT/QS2 ratio could identify subjects with an enhanced sympathetic tone. However, our results in a group of 40 highly trained endurance athletes matched against 40 sedentary subjects of the same age do not support this hypothesis. In the athletes, the sympathetic discharge to the heart was reduced during resting conditions and plasma cathecolamines were lower than in non-athletes. 2 Therefore, on the basis of the results of De Caprio et al, we would expect a reduced QT/QS2 in athletes compared with sedentary persons. On the contrary, our results in these groups of trained and untrained subjects showed a higher QT/QS2 ratio in athletes (0.97 ~- 0.08) compared with that in control subjects (0.90 4- 0.09, p <0.005). Athletes, whose heart rate appeared to be significantly lower than that of control subjects (66 4- 11 vs 79 4- 14 beats/min, p <0.001), as an adaptation to physical training, showed a higher QT/QS2 ratio as a consequence of an increase in QT interval (383 4- 31 vs 339 4- 31 ms, p <0.001), whereas the QS2 period was slightly but not significantly reduced. Also, the QT corrected for heart rate according to the Bazett formula appeared to be longer in athletes (401 4- 21 vs 385 4- 18 ms; p <0.005), in agreement with the results of other investigators. 3 In conclusion, QT/QS2 ratio may be used as an index of changes in sympathetic activity within the same subject. However, it does not allow an estimate of the sympathetic tone when comparing different groups of subjects. Paolo PalaUni, MD Padova, italy
1. Oe Caprlo L, Ferro G, Cuomo S, Volpe M, Arllaco D, De Luca N, Rlcclerdelll B. QT/QS2 ratio as an Index of autonomic tone changes. Am J Cardlol 1984;53: 818. 2. Bndeor HS. Cardiovascular edaptaUons in the trained athlete. In: Lublch T, Venarando A, eds. Proceedingsof the International Conference on Sports Can:llology, Rome, April 1978. Bologna: Goggi, 1980:3. 3. PaMano JA. Reply to the letter: An'hythmias and QT interval in athletes. Am Heart J 1984;107:608.