普罗帕酮对“犬”的起搏阈值影响的实验研究

Effect of propafenone on pacing threshold in dogs

【目的】观察逐步加大普罗帕酮剂量后对起搏阈值、感知和电极阻抗的影响。【方法】动物(犬,n=12)麻醉后,维持自主呼吸。放置心房和心室起搏电极后,静脉给予不同剂量的普罗帕酮,比较用药前后起搏阈值、感知和电极阻抗以及血压、心率等参数的变化。普罗帕酮剂量依次是3.1、3.1、4.65、4.65 mg/kg和6.2mg/kg。每次用药后5 min测定上述指标,并采用高效液相色谱法测定普罗帕酮的血清浓度。【结果】普罗帕酮剂量增至6.2 mg/kg时,心房起搏阈值从(0.98±0.36)V增加至(8.25±1.92)V(P<0.01),增加幅度与普罗帕酮血清浓度呈正相关,r=0.826,P=0.029。心室起搏阈值从(0.55±0.35)V增加至(2.30±1.78)V(P<0.01),增加幅度与普罗帕酮血清浓度无明显相关,r=0.375,P=0.265。P波振幅从(4.8±1.3)mV降至(1.6±0.7)mV(P<0.01),R波振幅从20mV降至(18.3±2.2)mV,(P<0.05)。平均动脉压(MBP)从(142±11)mmHg降至(67±12)mmHg,心率从(163±13)降至(90±10)次/min,(均为P<0.01)。PR间期从(98±10)ms延长至(159±28)ms,QRS间期从(40±5)ms至(102±22)ms,QTc间期从(315±32)ms至(366±18)ms,(均为P<0.01)。【结论】随着普罗帕酮剂量逐渐增加,起搏阈值明显增加,心房起搏阈值尤其明显。

[ Objective ] To increase the doses of propafenone gradually and observe the effect of propafenone on the pacing threshold at larger doses. [Methods] The experiment was performed in 12 adult mongrel dogs weighting 14.21 ± 1.98 kg （13- 17 kg） . Under general anesthesia with intravenous barbital sodium （30 mg/kg）, two electrical catheters were inserted into the right atrium and the right ventricle through jugular vein, respectively. The basic atrial and ventricular pacing threshold, sensing threshold and lead impedance, blood pressure, heart rate （HR）, PR interval, QRS duration and QTc interval were obtained. Propafenone were intravenously administered in different doses （3.1, 3.1, 4.65, 4.65 mg/kg and 6.2 mg/kg） during a 20- minute period. After drugs, the parameters above were determined repeatedly. The serum concentrations of prepafenone were determined by high performance liquid chromatography. [Results] When prepafenone reached a dose of 6.2 mg/kg, Atrial and ventricular pacing threshold increased from （ 0.98± 0.36 ） V to （8.25 ±1.92 ） V and （0.55 ± 0.35） V to （2.30 ± 1.78） V, respectively （all P 〈 0.01） . P or R amplitude decreased from （4.8 ± 1.3） mV to （1.6±0.7） mV （P 〈 0.01） and 20mV to （18.3 ±2.2） mV （P〈0.05）, respectively. MBP and HR decreased from （142± 11） mmHg to （67± 12） mmHg and （163±13） bpm to （90 ± 10） bpm, respectively （allP 〈 0.01）, compared with the baseline. PR interval, QRS duration and QTc interval prolonged from （98±10） ms to （159±28） ms, （40±5） ms to （102±22） ms, （315±32） ms to （366±18） ms, respeetively （all P 〈 0.01 ） . [ Conclusions] With increasing of propafenone doses, MBP and HR decreased, and PR interval, QRS duration and QTc interval prolonged. Atrial pacing threshold incresed much more than ventricular pacing threshold following intravenous propafenone administration.