Kp. Anderson et al., Distinctive RR dynamics preceding two modes of onset of spontaneous sustained ventricular tachycardia, J CARD ELEC, 10(7), 1999, pp. 897-904
Citations number
26
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Introduction: We hypothesized that autonomic activity preceding spontaneous
sustained monomorphic ventricular tachycardia (VTsm) as assessed by heart
rate (HR) and RR interval variability (RRV) differs between type 1 VTsm whi
ch is initiated by morphologically distinct, early cycle, possibly triggeri
ng premature ventricular complexes (PVCs) and type 2 VTsm in which the init
ial complex has a QRS waveform identical to subsequent complexes.
Methods and Results: Baseline Holter tapes (1,646) from a clinical trial we
re scanned for VTsm. QRS complexes of VTsm were compared by two-lead cross-
correlation to distinguish type 1 and type 2 VTsm. Frequency domain RRV ind
ex were estimated over 5 minutes, 15 minutes, and 24 hours. Type 1 and type
2 VTsm were present in 15 (group 1) and 33 (group 2) of 48 patients, respe
ctively; HR did not change in group 1 (88.4 +/- 15.2 to 89.7 +/- 13.0 beats
/min, P = 0.89), but increased before the onset of VTsm in group 2 (74.3 +/
- 16.3 to 81.2 +/- 18.0 beats/min, P < 0.001). RRV index were Severely depr
essed in both groups. No RRV index changed significantly before the onset o
f type 1 VTsm, whereas significant changes occurred before type 2 VTsm from
24-hour average to 30 minutes before VTsm in very low (very low-frequency
power [VLFP]: 6.62 +/- 1.53 to 6.20 +/- 2.07 In msec(2), P = 0.036), low (l
ow-frequency power [LFP]: 5.61 +/- 1.43 to 5.28 +/- 1.59 In msec(2), P = 0.
004), normalized low (normalized low-frequency power [LFPn]: -0.48 +/- 0.58
to -0.55 +/- 0.64 normalized units [nu], P = 0.05) and the ratio of LFP to
high-frequency power (HFP) (LFP/HFP: 4.20 +/- 3.47 to 3.45 +/- 2.53, P = 0
.017). Declines in RRV index between 2 hours to the 30-minute period before
VTsm occurred in group 2 but not group 1 in LFP (5.85 +/- 1.42 to 5.28 +/-
1.59 In msec, P = 0.043) and HFP (4.94 +/- 5.14 to 3.46 +/- 2.52 In msec(2
), P = 0.008), with a downward trend in LFP/HFP (4.94 +/- 5.14 to 3.45 +/-
2.53, P = 0.127) and LFPn (-0.38 +/- 0.36 to -0.55 +/- 0.64, P = 0.15), whi
le HFPn tended to rise (-1.47 +/- 0.65 to -1.27 +/- 0.64, P = 0.15).
Conclusions: HR and RRV did not change before type 1 VTsm, suggesting that
short-term changes in autonomic activity were not essential to initiation o
f apparent PVC-triggered VTsm. In contrast, RR interval dynamics before typ
e 2 VTsm suggested that short-term changes in neurohormonal activity contri
buted to arrhythmia initiation. Heterogeneities in arrhythmia onset may ref
lect distinct triggers and substrate properties that could provide a basis
for effective therapeutic targets.