Comparison of the Therapeutic Effects of Acupuncture at PC6 and ST36 for Chronic Myocardial Ischemia

Abstract

We aimed to compare the differences of the effects on chronic myocardial ischemia (MI) of acupuncture at PC6 and ST36. The chronic MI model of minipigs was created by implanting an Ameroid constrictor on the left anterior descending coronary artery (LAD) and then two weeks' acupuncture was stimulated at PC6 or ST36, respectively. The results showed that both acupoints' stimulation decreased the serous cardiac troponin T (cTnT) and ischemia modified albumin (IMA) significantly and improved the ischemic ECG changes. The amplitude of pathological Q wave in the PC6 group decreased more significantly than that of the ST36 group. The cardiovascular magnetic resonance imaging (cMRI) results showed that the decreased left ventricular ejection fraction (LVEF) was not improved obviously in both groups. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) enlarged progressively even after acupuncture. The left ventricular wall mass (LVWM) in the ST36 group increased more obviously than that of the PC6 group, which paralleled the decreasing angiotensin II (Ang II) concentration in the plasma. These results suggested that acupuncture at PC6 or ST36 was effective for protecting the myocardium from chronic ischemic injury, and the effect of PC6 seemed to be better.

Figure 1

The experimental procedure.

Figure 2

Examples of lead II and leads V₁–V₃ ECG of the PC6 and ST36 groups minipigs before (baseline) and after the operation and after needle-embedding (NE) and electroacupuncture (EA). (a)-(b) Examples of lead II ECG of the PC6 and ST36 groups before (baseline) and after operation, after NE, and after EA. It showed that the ST segment declined and T wave became bidirectional after operation. After acupuncture, ST segment came back to basic line, T wave became upward, and the QT interval prolonged significantly after acupuncture at PC6 and ST36. (c)-(d) Examples of leads V₁–V₃ ECG of the PC6 and ST36 groups before (baseline) and after operation and after EA. It showed that the pathologic Q wave appeared at lead V₁–V₃ at the 4th week after the operation, and the pathologic Q wave disappeared at leads V₂ and V₃ after acupuncture at PC6 and ST36.

Figure 3

The variation tendency of the ST segment amplitude of lead II. The ECG was taken at the normal condition, at the 4th week after operation, and at the 6th week after operation (before and after EA). The declined ST segment amplitude decreased after acupuncture both in the PC6 group (n = 6) and in the ST36 group (n = 5). But there were no significant statistical differences. Data are expressed as mean ± SEM. Statistical analysis was performed by Wilcoxon signed-ranks and Mann-Whitney.

Figure 4

The changed amplitude of pathological Q wave. The figure shows the changes in pathological Q wave amplitude of lead V₁, which is the differences of pathological Q wave amplitude after needle-embedding (NE) or electroacupuncture (EA) and after the operation. The amplitude of pathological Q wave decreased significantly after NE at PC6 acupoint (^○P = 0.029, compared with 0 mV), and there was statistical difference between the PC6 and ST36 group (^△P = 0.034, compared with that of the ST36 group). Data are expressed as mean ± SEM and were analyzed by t-test. N = 5 in both PC6 group and ST36 group. One minipig in the PC6 group did not record complete ECG.

Figure 5

Lead II QT interval of the PC6 group and ST36 group. Data are expressed as mean ± SEM and were analyzed by t-test. ^∗P < 0.05 and ^∗∗P < 0.01, compared with that after operation in the same group. ^■P < 0.05 and ^■■P < 0.01, compared with the baseline of the PC6 group. The QT interval of the PC6 group prolonged significantly compared with that after operation (P = 0.021, after NE; and P = 0.003, after EA). The QT interval of the ST36 group prolonged significantly after EA compared with that after operation (P = 0.024). The QT interval of the PC6 group prolonged significantly compared with the normal condition (P = 0.021, after NE; and P = 0.004, after EA).