Monophasic action potentials at discontinuation of cardiopulmonary bypass: evidence for contraction-excitation feedback in man.

Taggart, Peter; Sutton, Peter; Treasure, Tom; Lab, Max J.; O’Brien, William H.; Runnalls, M.; Swanton, R. H.; Emanuel, Richard

doi:10.1161/01.cir.77.6.1266

Cited by 78 publications

(26 citation statements)

References 50 publications

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“…We observed a reduction in temperature of less than 0.50°C during the initial minute and no consistent further changes during a second minute. 40 In the present studies, we found no evidence of a systematic difference in DF between anterior and posterior epicardium that would have potentially indicated cooling of the anterior epicardium. We also found no significant differences between patients with coronary artery disease and patients with valve disease, but the power of this statistical comparison was limited because of the small number of patients in each group.…”

Section: Study Limitationscontrasting

confidence: 68%

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Bradley

Clayton

Nash

et al. 2011

Circ: Arrhythmia and Electrophysiology

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Background-Ischemic ventricular fibrillation in experimental models has been shown to progress through a series of stages. Progression of ischemic VF in the in vivo human heart has not been determined. Methods and Results-We studied 10 patients undergoing cardiac surgery. Ventricular fibrillation was induced by burst pacing.After 30 seconds, global myocardial ischemia was induced by aortic cross-clamp and maintained for 2.5 minutes, followed by coronary reflow. Epicardial activity was sampled (1 kHz) with a sock that contained 256 unipolar contact electrodes. Dominant frequencies were calculated with a fast Fourier transform with a moving window. The locations of phase singularities and activation wavefronts were identified at 10-ms intervals. Preischemic (perfused) ventricular fibrillation was maintained by a disorganized mix of large and small wavefronts. During global myocardial ischemia, mean dominant frequencies decreased from 6.4 to 4.7 Hz at a rate of Ϫ0.011Ϯ0.002 Hz s Ϫ1 (PϽ0.001) and then increased rapidly to 7.4 Hz within 30 seconds of reflow. In contrast, the average number of epicardial phase singularities increased during ischemia from 7.7 to 9.7 at a rate of 0.013Ϯ0.005 phase singularities per second (PϽ0.01) and remained unchanged during reflow, at 10.3. The number of wavefronts showed a similar time course to the number of phase singularities. Conclusions-In human ventricular fibrillation, we found an increase in complexity of electric activation patterns during global myocardial ischemia, and this was not reversed during reflow despite an increase in activation rate. (Circ Arrhythm Electrophysiol. 2011;4:684-691.)

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Section: Study Limitationscontrasting

confidence: 68%

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Bradley

Clayton

Nash

et al. 2011

Circ: Arrhythmia and Electrophysiology

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“…16 Similar phenomena have been described in man. [17][18][19] The observation, in the current study, that ventricular events are correlated with patient-specific changes in intracardiac pressure, and not absolute pressure, is consistent with observations in the above studies that show that acute chamber dilatation shortens myocardial refractoriness, whereas chronic dilatation does not.…”

Section: Mechanisms Linking Elevated Ventricular Pressures and Ventrisupporting

confidence: 91%

Influence of Intracardiac Pressure on Spontaneous Ventricular Arrhythmias in Patients With Systolic Heart Failure

Reiter¹,

Stromberg

Whitman

et al. 2013

Circ: Arrhythmia and Electrophysiology

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Background— The implantation of a combination hemodynamic monitor-cardioverter-defibrillator in the Reducing Decompensation Events Utilizing Intracardiac Pressures in Patients with Chronic Heart Failure (REDUCEhf) study allowed assessment of the relationship between daily intracardiac pressure and occurrence of ventricular arrhythmic (VT/VF) events. Methods and Results— Median estimated pulmonary artery diastolic pressures (ePAD) were calculated every 24 hours in 378 subjects with New York Heart Association functional class II-III heart failure who had at least 60 days of hemodynamic data. Forty-six subjects experienced 140 VT/VF events on 80 unique study days in which daily median ePAD was available. The incidence of days with VT/VF events was significantly higher when the daily median ePAD for a subject was elevated, defined as >1 SD above that subject’s average median ePAD for the whole study: (2.8 episode days per patient-year compared with 1.7 episode days per patient-year; P =0.040). However, the incidence of days with VT/VF events was not significantly different on days when ePAD was >25 mm Hg compared with days when ePAD was <25 mm Hg. For all 378 subjects, the risk of VT/VF increased with average median ePAD calculated over the whole follow-up period (odds ratio, 1.072 for a 1-mm Hg increase; 95% confidence interval, 1.023–1.124; P =0.003). Conclusions— There is significant positive association between average daily median ePAD and risk for VT/VF. Among patients with VT/VF, elevated intracardiac pressures are associated with higher VT/VF risk only when the definition of increased pressure is subject specific.

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“…Also, the patients were on cardiopulmonary bypass and therefore the hearts were in a non-working state. This would have reduced the ischaemic burden and the influence of mechanoelectric feedback 31. As anticipated from the small heterogeneity, no arrhythmias occurred during ischaemia in these hearts.…”

Section: Discussionmentioning

confidence: 73%

Repolarisation and refractoriness during early ischaemia in humans

Sutton

Taggart²,

Opthof³

et al. 2000

Heart

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Objectives-To determine whether eVective refractory period (ERP) shortens or lengthens in the first minutes of ischaemia in humans, and the relation between ERP changes and action potential duration (APD). Methods-ERP and monophasic action potential duration (MAPD) were measured from a single left ventricular epicardial site in 26 patients undergoing coronary artery surgery. Cardiopulmonary bypass was instituted and normothermia maintained. Refractory period was determined by the extrastimulus technique at a basic cycle length of 500 ms, at four times (group 1, 15 patients) or two times (group 2, 11 patients) the preischaemic diastolic threshold. A three minute period of ischaemia was instituted by aortic cross clamping between the input from the pump oxygenator and the heart. Results-After three minutes of ischaemia, mean (SEM) ERP lengthened from 232 (5) ms (control) to 246 (7) ms (p < 0.005) in group 1, and from 256 (10) ms (control) to 348 (25) ms (p < 0.005) in group 2. In the same time MAPD shortened from 256 (5) ms (control) to 189 (9) ms (p < 0.001) with no diVerence between groups. Thus postrepolarisation refractoriness developed during ischaemia. Before ischaemia, ERP showed a good correlation with APD (R 2 = 0.64) but by one minute of ischaemia the correlation was poor (R 2 = 0.29). Conclusions-These results show that during the first three minutes of global ischaemia in patients with coronary artery disease: (1) ERP lengthened in response to both a low and a high stimulus strength; and (2) there was a good correlation between ERP and APD before ischaemia, which was lost by one minute as APD decreased and ERP increased. These findings may have important implications in arrhythmogenesis. (Heart 2000;84:365-369)

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Monophasic action potentials at discontinuation of cardiopulmonary bypass: evidence for contraction-excitation feedback in man.

Cited by 78 publications

References 50 publications

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Influence of Intracardiac Pressure on Spontaneous Ventricular Arrhythmias in Patients With Systolic Heart Failure

Repolarisation and refractoriness during early ischaemia in humans

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