Comparison of Cardiac Pacing Modes in Patients With Chronic Obstructive Pulmonary Disease – Results
All patients with COPD had sinus node dysfunction, including four with chronotropic incompetence. All had AV nodal disease, three 3° AV block, four 1° AV block, and one 2° AV block. Three of these patients had documented retrograde conduction and a history of pacemaker syndrome in the WI mode. However, only one of these patients demonstrated a symptomatic pacemaker syndrome, that is, retrograde conduction and a drop in blood pressure during testing in this study. In patients with normal lung function, all had sinus node disease, including seven with chronotropic incompetence, four had AV nodal disease, one had 3° AV block, and three had 1° AV block. Two patients had demonstrated retrograde conduction in the WWVIR mode during testing in this study, though they did not have a simultaneous fall in blood pressure. Both of these patients had a documented history of pacemaker syndrome in the WI mode. An additional three patients in this group had a documented history of pacemaker syndrome in the WI mode, but this was not observed during testing in this study (Table 1). No cardiac arrhythmias occurred during exercise, and there were no adverse pacemaker interactions with underlying rhythms. asthma inhalers
Patients with pacemaker syndrome frequently complain of increased dyspnea on exertion, dizziness, and a general feeling of fatigue in the WIR pacing mode when compared with the DDDR pacing mode. Previous studies have shown a greater improvement in cardiac output with the DDDR pacing mode in patients with pacemaker syndrome compared with patients without pacemaker syndrome, making DDDR pacing even more important if pacemaker syndrome is present.
The patients with normal lung function exhibited an average FVC of 97 percent of predicted, average FEVj of 97 percent of predicted, and average FEF25/ 75 of 92 percent of predicted. The eight patients with COPD exhibited an average FVC of 65 percent predicted, average FEVj of 58 percent predicted, and average FEF25/75 of 47 percent predicted (Table 2).
With dual-chamber adaptive rate pacing as compared with single chamber adaptive rate pacing, both those patients with COPD and those patients with normal lung function showed a statistically significant improvement in exercise duration, cardiac output at maximum exercise, and cardiac output difference, with the dual chamber mode over that achieved with single chamber rate-adaptive pacing. (Cardiac output difference is defined as the change in cardiac output from rest to maximum exercise [Table 3]).
Those patients with normal lung function also showed a significant improvement in AT and maximum Vco7 with DDDR pacing, which was not noted in the lung disease group (Table 4). However, those patients with lung disease showed a statistically significant improvement at all levels of exercise in the ventilatory equivalent for oxygen (Table 5). This correlated with an improvement in AT (though it did not attain statistical significance).
Table 1—Patient Population
Patient No./Age, yr/Sex | Diagnosis |
1/69/F | NLF, Cl, PS, SSS |
2/68/M | NLF, Cl, PS, SSS |
3/78/M | NLF, Cl, PS, SSS, 1° |
4/68/F | NLF, Cl, PS, SSS |
5/67/M | NLF, Cl, PS, SSS |
6/69/M | NLF, Cl, 3°, SSS |
7/72/M | NLF, Cl, SSS, 1° |
8/72/M | NLF, SSS, 1° |
9/76/M | LD, Cl, PS, SSS, 1° |
10/75/F | LD, Cl, SSS, 1° |
11/81/F | LD, Cl, PS, SSS, 1° |
12/79/F | LD, SSS, 3° |
13/68/M | LD, Cl, PS, SSS, 2° |
14/71/F | LD, SSS, 1° |
15/73/M | LD, SSS, 3° |
16/72/M | LD, SSS, 3° |
Table 2—Pulmonary Function Data
PatientNo. | DX | FVC | FEV, | FEF25/75 | PatientNo. | DX | FVC | FEV, | FEF25/75 |
2 | NLF | 94 | 90 | 74 | 9 | LD | 73 | 61 | 50 |
3 | NLF | 91 | 90 | 77 | 10 | LD | 83 | 46 | 26 |
4 | NLF | 104 | 98 | 81 | 11 | LD | 63 | 65 | 61 |
1 | NLF | 90 | 94 | 107 | 12 | LD | 76 | 66 | 55 |
5 | NLF | 116 | 122 | 132 | 13 | LD | 70 | 64 | 52 |
6 | NLF | 94 | 96 | 92 | 14 | LD | 42 | 53 | 45 |
7 | NLF | 84 | 91 | 101 | 15 | LD | 69 | 67 | 55 |
8 | NLF | 105 | 96 | 69 | 16 | LD | 40 | 39 | аз |
Average | NLF | 97 | 97 | 92 | Average | LD | 65 | 58 | 47 |
Table 3—Exercise Data: Cardiac Output and Exercise Duration
Ex Dur, min | CO Max, L/M | CO Diff, L/M | |
LD/DDDR | 8.01 | 6.92 | 3.04 |
LD/WIR | 6.80 | 5.07 | 1.88 |
P | (0.01) | (0.01) | (0.02) |
NLF/DDDR | 12.53 | 12.17 | 6.38 |
NLF/WIR | 11.63 | 7.00 | 3.24 |
P | (0.02) | (0.001) | (0.019) |
Table 4—Exercise Data: Anaerobic Threshold and Vcot max
AT Time, min | Vco2max,L/M | |
LD/DDDR | 6.9 | 1.01 |
LD/WIR | 6.25 | 0.89 |
P | NS | NS |
NLF/DDDR | 9.29 | 2.09 |
NLF/WIR | 8.19 | 1.77 |
P | (0.0015) | (0.0045) |
Table 5—Ventilatory Equivalent for Oxygen During Exercise
Ve/Vo2.50% | Ve/Vo2 75% | VE/Vo2max | |
LD/DDDR | 34.2 | 37.3 | 41.9 |
LD/WIR | 37.1 | 39.5 | 45.5 |
P | (0.002) | (0.011) | (0.02) |
NLF/DDDR | 26.7 | 28.7 | 36.6 |
NLF/WIR | 28.3 | 29.7 | 38.4 |
P | (0.04) | NS | NS |