{
  "abstract": "Introduction Sudden cardiac death (SCD) is a significant cause of mortality due to malignant arrhythmias like ventricular fibrillation (VF). There is no effective preventative treatment for SCD, making further understanding of cardiac electrophysiology crucial. The electrical restitution properties of the heart during VF were investigated to determine if cardiac memory impacts restitution in addition to the effect of pacing location on ventricular electrophysiology.Methods New Zealand White Male Rabbits (3–3.5 kg) n=8 for an Isolated Langendorff heart preparation. Two left ventricular epicardial sites were used (Apex and Base) to record Monophasic Action Potentials (MAPs). The five pacing sites were right ventricle (RV) apex endocardium, RV apex epicardium (epi), RV base epi, left ventricle (LV) apex epi and LV base epi. The order locations of pacing via hook electrodes were randomised. Pacing stimulation protocols were used for effective refractory period (ERP), S1 delay, S2 delay, action potential duration (APD), standard restitution and VF threshold were conducted.Results No significant difference was found in ERP, APD restitution (APDR) max or conduction velocity restitution (CVR) max when pacing at different locations. Significant differences were found between pacing sites when considering S1and S2 delay from Apex MAP between LV Apex Epi and RV Base Epi (p≤0.005) and from Base MAP between LV Base epi and RV Apex epi (p≤0.01). The S1 and S2 delay data shows that when stimulating closer to the recording site the delay is shorter. As the stimulation location moves further away from the recording location (apex or base) there is a clear increase in S1 and S2 delay. A link between APD and diastolic interval (DI) during VF was identified within the first 30 beats. However, this negative relationship between APD and preceding DI begins to deteriorate post 30 beats (Apex R value = -0.45) with no distinct relationship being found at 90 beats (Apex R value = -0.05) post VF initiation. The same deterioration is seen in the positive relationship between APD and preceding APD with an average decrease in R value of 0.3. This indicates that restitution may be important in determining VF properties within the first 30 beats as VF may not be entirely random.Conclusions This study found that a linear relationship between APD and DI is maintained within the first 30 beats during VF. It also found that there is a significant effect on S1 and S2 delay when altering pacing stimulation location but no significant effect of pacing site on other aspects of ventricular electrophysiology.",
  "authors": [
    {
      "affiliations": [
        "Department of Cardiovascular Sciences, University of Leicester, Leicester LE3 9QP, UK"
      ],
      "name": "Bethan Roper-Jones"
    },
    {
      "affiliations": [
        "Department of Cardiovascular Sciences, University of Leicester, Leicester LE3 9QP, UK"
      ],
      "name": "Rachel L Sutcliffe"
    },
    {
      "affiliations": [
        "Department of Cardiovascular Sciences, University of Leicester, Leicester LE3 9QP, UK"
      ],
      "name": "Emily Allen"
    },
    {
      "affiliations": [
        "Department of Cardiovascular Sciences, University of Leicester, Leicester LE3 9QP, UK"
      ],
      "name": "Reshma A Chauhan"
    },
    {
      "affiliations": [
        "Department of Cardiovascular Sciences, University of Leicester, Leicester LE3 9QP, UK"
      ],
      "name": "G André Ng"
    }
  ],
  "title": "BS37 Restitution properties during ventricular fibrillation and the effects of cardiac pacing location on ventricular electrophysiology in the rabbit heart",
  "uid": "2e95e9f0-12c4-5def-81fb-8a3d5b39aa62"
}