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2) Bulgarian Academy of Sciences, Centre of Biomedical Engineering,Sofia, Bulgaria VARIATION OF THE TRANSTHORACIC IMPEDANCE.

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Presentation on theme: "2) Bulgarian Academy of Sciences, Centre of Biomedical Engineering,Sofia, Bulgaria VARIATION OF THE TRANSTHORACIC IMPEDANCE."— Presentation transcript:

1 2) Bulgarian Academy of Sciences, Centre of Biomedical Engineering,Sofia, Bulgaria VARIATION OF THE TRANSTHORACIC IMPEDANCE IN A SEQUENCE OF CARDIOVERSION SHOCKS E. Trendafilova 1, V. Krasteva 2, TS. Mudrov 2, JP. Didon 3 3) Schiller Médical SAS, Wissembourg, France ACUTE CARDIAC CARE )National Heart Hospital, Sofia, Bulgaria Methods Included 96 patients according standard hospital procedures and written informed consent Escalating E protocol is adopted 1) 120  200  200 J for atrial fibrillation (AFIB) 2) 30  120  200 J for atrial flutter (AFL). The number of processed shocks is: 62/26/11 (AFIB) and 34/17/3 (AFL). During each shock, voltage and current waveforms are recorded and TTI is deduced. Before each shock, Z is measured as the attenuation of a low-intensity, high-frequency (30kHz) current. Baseline parameters of patients Significant correlation is found for the TTI percentage change in function of E (r = 0.65, p<0.001). Post-shock elevation of TnI above ULN was recorded in 2 pts (360 J monophasic shocks were applied in both pts). Post-shock elevation of CK and proportional elevation of CK-MB were recorded only when 360 J monophasic shocks were applied. Post-shock arrhythmias Post-shock cardiac damage Key elements of CVS Transthoracic impedance Z,TTI percentage change vs. Z before shock 1 Stable impedance Z with variation of less than 1% is measured before first, second and third shocks with up to 6-fold energy escalation. This finding supports the hypothesis that the high-frequency Z is not influenced by the shock sequence and cannot be used to explain the success of repeating defibrillation. Conversely TTI during shock, changes significantly from 110% down to 95% and is related to the energy setting. Before each shock, Z is measured as the attenuation of a low-intensity, high-frequency (30kHz) current: 90.03±18.9  (from 52.9 to  ). Measurement of Z before Sh1 is stated as 100% basis value. For the sequence of shocks, the percentage change of TTI and Z is evaluated (Figure 2). The t-test shows no significant variation of Z relative to E and shock number (p>0.05). In contrast, TTI is significantly higher at 30J (AFL, p<0.001) and respectively lower at 200J (AFIB, p<0.01). Р № Age59,36 (± 10,28) Female31 (32,3 %) ВМІ29,24 (± 4, 64) Body Surface Area (m 2 )2,02 (± 0,18) Structural heart diseases86 (89,6 %) Hypertension64 (66,7 %) Oral anticoagulants96 (100 %) Amiodarone61 (63,5 %) Beta-blockers23 (24 %) Dual Antiarrhythmic therapy34 (35,4 %) LA (mm)49,84 (± 7,29) EF (%)55,89 (± 9,9) AFIB62 (64,6 %) Duration of arrhythmia (days)108,02 (± 130,08) Number of shocks1,64 (± 0,83) Starting En (J) 87,19 (± 43,55) Max. En (J) 135,31 (± 72,75) Commulative En (J) 206,35 (± 193) Efficacy93 (96,9 %) Monophasic shock applied4 (4,2 %) Efficacy of Mono shock2 (2,1 %) HR before CVS (bts/min) 93,75 (± 19,98) HR after CVS (bts/min) 66,36 (± 13,37) Mean blood pressure before CVS (mmHg) 100,03 (± 13,51) Mean blood pressure after CVS (mmHg) 86,68 (± 13,08) Post-shock arrhythmias35 (36,5 %) Post-shock premature beats17 (48,6 %) Post-shock SV arrhythmias18 (51,4 %) Post-shock arrhythmias requiring AAD13 (37,1%) Post-shock bradycardia ≤ 50/min9 (9,38 %) Temporary pacemaker1 (1,04 %) Atropine after CVS1 (1,04 %) Post-shock ECG changes5 (5,2 %) ST depression3 (3,12 %) T wave inversion2 (2,08 %) СК before CVS117 (± 123,05) СК after CVS189,9 (± 456,63) СК-МВ before CVS13,7 (± 7,04) СК-МВ after CVS27,71 (± 42,36) TnI before CVS0,044 (± 0,13) TnI after CVS0,056 (± 0,13) Results Hypothesis This study provides evidences that escalating energy protocol does not affect the pre-shock impedance (Z) but only the impedance during the shock (TTI) which is correlated to the energy setting (E). Background Transthoracic impedance in defibrillation/cardioversion has been referred as a predictor of the shock outcome suggesting that sequence of shocks with escalating energies affect the impedance thus improving the success rate. CONCLUSIONS


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