Table 2.
Electrical properties of Langendorff-perfused heart and isolated AV node preparation from control and PHT rats. Data are presented as mean±SEM. Differences between PHT and control rats assessed by Student’s t-test; Fisher’s exact test was used to compare incidences of complete heart block; *significantly different from control data. AERP, atrial effective refractory period; AVERP, AV node effective refractory period; AVFRP, AV node functional refractory period; VERP, ventricular effective refractory period.
| Control rats | PHT rats | P value | |
|---|---|---|---|
| Isolated Langendorff-perfused heart | |||
| RR interval (ms; n=9/11) | 237±8 | 244±14 | 0.6556 |
| PR interval (ms; n=9/11) | 43±2 | 44±2 | 0.6922 |
| QT interval (ms; n=9/11) | 56±5 | 135±10* | <0.0001 |
| QTc interval (ms; n=9/11) | 116±10 | 275±18* | <0.0001 |
| QRS duration (ms; n=9/11) | 13±1 | 16±3 | 0.3813 |
| AERP (ms; n=9/9) | 34±2 | 43±5 | 0.1508 |
| Wenckebach cycle length (ms; n=10/11) | 111±3 | 117±3 | 0.1640 |
| AVERP (ms; n=10/10) | 88±1 | 94±3* | 0.0364 |
| AVFRP (ms; n=10/10) | 115±2 | 122±2* | 0.0122 |
| VERP (ms; n=6/4) | 40±3 | 98±11* | 0.0003 |
| Isolated right atrium-AV node preparation | |||
| RR interval (ms; n=9/11) | 216±10 | 212±7 | 0.7143 |
| AH interval (ms; n=10/6) | 41±5 | 53±6 | 0.1579 |
| Wenckebach cycle length (ms; n=9/5) | 129±7 | 139±11 | 0.4932 |
| AVERP (200 ms cycle length; n=5/4) | 110±13 | 114±13 | 0.8113 |
| AVERP (150 ms cycle length; n=6/2) | 95±4 | 102±15 | 0.5008 |
| AVFRP (200 ms cycle length; n=2/4) | 133±1 | 138±11 | 0.7759 |
| AVFRP (150 ms cycle length; n=7/2) | 117±5 | 127±6 | 0.3517 |
| Incidence of complete heart block (%; n=10/12) | 0% | 50%* | 0.015 |