73790
document
Rate-modulated cardiac pacing based on transthoracic impedance measurements of minute ventilation : correlation with exercise gas exchange . The relation of pacing rate to physiologic variables of metabolic demand was examined in 10 consecutive patients with a minute ventilation-sensing , rate-modulating ventricular pacemaker implanted for complete heart block . All patients had paroxysmal ( seven patients ) or chronic ( three patients ) atrial fibrillation and were referred for catheter ablation of the atrioventricular junction . Treadmill exercise testing with measurement of expired gas exchange and respiratory flow was performed before ablation and 4 weeks after pacemaker implantation , with the pacemaker programmed to both the fixed-rate VVI and rate-modulating minute ventilation VVIR pacing modes in random sequence . The relation of pacing rate to oxygen consumption ( VO2 ) , expired carbon dioxide concentration ( VCO2 ) , respiratory quotient , tidal volume , respiratory rate and minute ventilation was determined during exercise in the rate-modulating minute ventilation pacing mode . Pacing rate was highly correlated with minute ventilation ( r = 0.89 ) , respiratory quotient ( r = 0.89 ) , VCO2 ( r = 0.87 ) , tidal volume ( r = 0.87 ) , VO2 ( r = 0.84 ) and respiratory rate ( r = 0.84 ) . The mean exercise duration increased from 8.3 +/- 2.8 min in the fixed rate pacing mode to 10.2 +/- 3.4 min in the rate-modulating , minute ventilation mode ( p = 0.0001 ) . The maximal VO2 increased from 13.4 +/- 3.4 to 16.3 +/- 4.1 cc/kg per min ( p = 0.0004 ) . The maximal heart rate achieved in the minute ventilation pacing mode was 136 +/- 9.7 beats/min , similar to that observed in the patient 's intrinsic cardiac rhythm before ablation ( 134.9 +/- 30.1 beats/min , p = NS ) . ( ABSTRACT TRUNCATED AT 250 WORDS )
73791
Intervention_Surgical
catheter ablation of the atrioventricular junction
73792
Intervention_Physical
Treadmill exercise testing
73793
Outcome_Physical
expired gas exchange and respiratory flow
73794
Outcome_Physical
relation of pacing rate to oxygen consumption ( VO2 )
73795
Outcome_Physical
expired carbon dioxide concentration ( VCO2 )
73796
Outcome_Physical
respiratory quotient
73797
Outcome_Physical
tidal volume
73798
Outcome_Physical
respiratory rate and minute ventilation
73799
Outcome_Physical
Pacing rate
73800
Outcome_Other
minute ventilation
73801
Outcome_Physical
respiratory quotient
73802
Outcome_Physical
VCO2
73803
Outcome_Physical
tidal volume
73804
Outcome_Physical
VO2
73805
Outcome_Physical
respiratory rate
73806
Outcome_Physical
mean exercise duration
73807
Outcome_Physical
maximal VO2
73808
Participant_Sample-size
10
73809
Participant_Condition
paroxysmal
73810
Participant_Sample-size
seven
73811
Participant_Sample-size
three
73812
Participant_Condition
atrial fibrillation