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1 3 272, , 51 (3), Acta Physiologica Sinica ( 305,, ), His A, H, V (AA), His (AH), His (HV) (AV) :, 20 AH 14 (A ), 6 (B ) B, AH,, AA A1B AH : ( ) :,,, : Q463 (AV), [1 3 ] AV 9 % 33 %, AV [1,2 ] [3,5 ], AV : (1) AV ; (2) AV ; (3) AV 1, kg (30 35 mg/, ip),,,, 37 AV :, ; 2 [6,7 AV, ] (No198M158)

2 3 : 273,, [7 ] [8 ] [9,10, ] [11,12 His ], His Hz 12, (NEX PC298, ) Hz AV,,, (AA ) : 400,375,350,325,300,275, 250,225,210,200,190,180,170,160 AV (Wenckebach ) AV His AH His ; HV His H ( ) [12,13 ] ; AH L AH ; AHs AH ; 1 1 AV 1 1 ; Wenckebach AV 1 1 [14 ], 30 mim AV ; ; 2 min AV, 30 min AV His A1H1V,, [15 ] AA, AH, HV, AV 10 Hz t ( x s) min, 2, 20 : 14 AH (A ), 6 AH (B ) 211 AV AV 1A 10 min, AV1AH, 3 5 min, AA HV HV, AV AH AH AV 14 AH 1 AH

3 min ; AA1HV 10 min, 10 min ;, 1 (A) (B) AV Fig11 Typical change in AV conduction af2 ter occlusion ( A ) and reperfusion ( B) of the right coronary artery AA, cycle length ; AV, atrial2ventricular interval ; AH, atrial2his interval ; HV, His2ventricular interval. 1 Table 1 Effects of ligation of the right coronary artery (for different duration) on blood pres2 sure and electrophysiological parameters ( Group A) Ligation BP, blood pressure ; AA, cycle length during sinus rhythm ; AH, atrial2his interval ; HV, His2ventricular interval. 3 P < 0105 ; 3 3 P < 0101 compared with control. B (AA) 30 min 2 AA 267 ms, AH, HV ; 212 : 2 Table 2 Effect of ligation of right coronary artery on blood pressure and electrophysiological parameters during fast atrial pacing ( Group B) Ligation Abbreviation see Table 1.

4 3 : 275 AH, AA, AH L (62 7) (71 9) ms ; 1 1 (184 12) (240 36) ms ; AHs AH 2 2 Fig12 Schematic representation of the atrio2 ventricular nodal function curve of normal ( left) and ischemia ( right) condition during multiple2step pacing 2, : (AA) ; AH ; 1 1 (180 15) (250 30) ms ;Wenckebach (173 13) (225 36) ms 213 AV A, AV 1B, AH, 3 5 min AA1HV, AV AH, AH AV 30 min 3 3 Table 3 Effect of reperfusion in right coronary artery on blood pressure and electro2 physiological parameters ( Group A) Reperfusion Abbreviation see Table 1., AH 10 min, AA, HV B, 30 min 4 AA 275 ms,, AH, HV,

5 Table 4 Effect of reperfusion in right coronary artery on blood pressure and electro2 physiological parameters during fast atrial pacing ( Group B) Reperfusion Abbreviation see Table 1. 3 AV [1 3], AV, [6 8], AV,, AV [5], AV, AH AH,, AH AH,, AH, ;, AH AV AH HV,,, HV ( 1 4) AH AV AV AV, AV, AA AH, (Wenckebach ) AHs ; AH AV, 1 1 Wenckebach,, (AA ), 90 %,,,, [1,2] [3] AH,,

6 3 : 277,,,,,,,,, ;, [3],, [1] Feigl D, Ashkenazy J, Kishon Y. Early and late atrioventricular block in acute inferior myocardial infarction. J Am Coll Cardiol, 1984, 4 : [2] Tans AC, Lie KI, Durrer D. Clinical setting and prognostic significance of high degree atrioventricular block in a2 cute inferior myocardial infarction. A study of 144 patients. Am Heart J, 1980, 99 : 4 8. [3] Bassan R, Maia I, Bozza A, et al. Atrioventricular Block in acute inferior wall myocardial infarction : harbinger of associated obstuction of the left anterior descending coronary artery. J Am Coll Cardiol, 1986, 8 : [4] Belardinelli L, Mattos EC, Berne RM. Evidence for adenosine mediation of atrioventricular block in the ischemic canine myocardium. J Clin Invest, 1981, 68 : [5] Wang PJ, Schoen FJ, Reagan K, et al. Modification of atrioventricular conduction by selecive AV nodal artery catheterization. PACE, 1990, 13 : [6] Henning R, Levy MN. Effects of autonomic nerve stimulation, asynchrony, and load on dp/ dt max and on dp/ dt min. Am J physiol, 1991 : H1290 H1298. [7] Cerati D, Schwartz PJ. Single cardiac vagal fiber activity, acute myocardial ischemia, and risk for sudden death. Circ Res, 1991, 69 : [8] Yong T, Cheng J, Martin P, et al. Effects of sretial dispersion of acetylcholine release on AV conductien responses to vagal stimulation in dogs. Am J Physiol, 1991, 261 : H392 H397. [9] Chen SL ( ), Zang YM ( ), Zhu MZ ( ), et al. The relationship between coronary artery stenosis and myocardial metabolism of oxygen demand in dogs. Acta Physiol Sin, 1989, 41 : (in Chinese with English abstract). [10] Lewin RF, Kusniec J, Sclarovsky S, et al. Alternating wenckebach periods in acute inferior myocardial infarction : Clinical, electrocardiographic and therapeutic characterization. PACE, 1986, 9 : [11] Martin P. The influence of the parasympathetic nervous system on atrioventricular conduction. Circ Res, 1977, 41 : [12] Tuna IC, Barragry TP, Walker M, Lillehei T, et al. Effects of transplantation on atrioventricular nodal accom2 modation and hysteresis, Am J Physiol, 1987, 253 : H1514 H1522. [13] Nayebpour M, Talajic M, Villemaire C, et al. Vagal modulation of the rate2dependent properties of the atrioven2 tricular node. Circ Res, 1990, 67 : [14] Page RL, Tang ASL, Prystowsky EN. Effect of continuous enhanced vagal tone on atrioventriculax nodal and sinoa2 trial nodal function in humans. Circ Res, 1991, 68 : [15] Kawada T. Ikeda Y, Smgimachi M, et al. Bidirectional augumentation of heart rate regulation by autonomic ner2 vous system in rabbits. Am J Physiol, 1996, 271 : H288 H295.

7 278 Acta Physiologica Sinica Jun. 1999, 51 (3), ATRIOVENTRICULAR CONDUCTION CHANGES IN ACUTE ISCHEMIC AND REPERFUSED CORONARY ARTERY OF CATS CHEN SHI2L IANG, FENG SHENG2QIANG ( Medical Department, The 305 Hospital of PLA, Beijing ) ABSTRACT Acute inferior wall infarction is freguently complicated by conduction disturbance, but the relationship between ischemia and atrioventricular (AV) conduction disturbance is not well understood. The present experiments were made on cats with heart efferent completely denervated. A, H and V waves were picked up by a template2maching algorithm from His bundle electrogram, AA interval (cardiac cycle length), AH interval (AV conduction time), HV and AV intervals were measured. Of 20 cats, 14 showed prolongation of AH interval ( Group A), while not in 6 cats ( Group B) after ligation of right coronary artery. A fast pacing of right atrium (AA interval = 267 ms) was produced in Group B and AH inter2 val was also prolonged after ligation of the artery. By multiple2step pacing, the curve of AV nodal function shifted to the right, AH intrval which induced AV nodal block was prolonged after ischemia. After reperfusion, AH interval was shortened both in Group A and B. The above results show that myocardial ischemia may cause abnormality of AV conduction and accommodation function. The abnormality appears to be a potential danger which will in2 duce AV conducton block during tachycardia. Key words : myocardial infarction ; AV conduction block ; reperfusion ; atrioventricular accommodation function