Effect of increased left ventricle mass on ischemia assessment in electrocardiographic signals: rabbit isolated heart study

Abstract

BackgroundDetailed quantitative analysis of the effect of left ventricle (LV) hypertrophy on myocardial ischemia manifestation in ECG is still missing. The associations between both phenomena can be studied in animal models. In this study, rabbit isolated hearts with spontaneously increased LV mass were used to evaluate the effect of such LV alteration on ischemia detection criteria and performance.MethodsElectrophysiological effects of increased LV mass were evaluated on sixteen New Zealand rabbit isolated hearts under non-ischemic and ischemic conditions by analysis of various electrogram (EG) parameters. To reveal hearts with increased LV mass, LV weight/heart weight ratio was proposed. Standard paired and unpaired statistical tests and receiver operating characteristics analysis were used to compare data derived from different groups of animals, monitor EG parameters during global ischemia and evaluate their ability to discriminate between unchanged and increased LV as well as non-ischemic and ischemic state.ResultsSuccessful evaluation of both increased LV mass and ischemia is lead-dependent. Particularly, maximal deviation of QRS and area under QRS associated with anterolateral heart wall respond significantly to even early phase (the 1st-3rd min) of ischemia. Besides ischemia, these parameters reflect increased LV mass as well (with sensitivity reaching approx. 80%). However, the sensitivity of the parameters to both phenomena may lead to misinterpretations, when inappropriate criteria for ischemia detection are selected. Particularly, use of cut-off-based criteria defined from control group for ischemia detection in hearts with increased LV mass may result in dramatic reduction (approx. 15%) of detection specificity due to increased number of false positives. Nevertheless, criteria adjusted to particular experimental group allow achieving ischemia detection sensitivity of 89–100% and specificity of 94–100%, respectively.ConclusionsIt was shown that response of the heart to myocardial ischemia can be successfully evaluated only when taking into account heart-related factors (such as LV mass) and other methodological aspects (such as recording electrodes position, selected EG parameters, cut-off criteria, etc.). Results of this study might be helpful for developing new clinical diagnostic strategies in order to improve myocardial ischemia detection in patients with LV hypertrophy.

Analysis of Hemodynamic Related Changes in High Frequency Content of QRS Complex in Working Isolated Rabbit Heart

“…Due to a limited space, only results for single pseudo-ECG lead are presented. The lead sensing the electrical activity of the lateral LV wall was chosen as it showed the highest sensitivity to electrical changes in the LV of isolated rabbit hearts in our previous experiments [8]. Identical results were observed within all remaining channels.…”

Di-4-ANEPPS Modulates Electrical Activity and Progress of Myocardial Ischemia in Rabbit Isolated Heart

“…Reduced severity of myocardial ischemia in the stained hearts is reflected on EG as attenuated ischemic patterns. It further leads to late and inaccurate ischemia detection, even when QRS A and T A are used ( Ronzhina et al, 2017 ). In the control group, both parameters seem to be appropriate for discrimination between the non-ischemic state and earlier (namely, the 3rd minute of ischemia in case of QRS A ) or later (namely, the 7th minute of ischemia in case of T A ) phase of the ischemia.…”

“…QT D and its corrected value QT C were used to detect possible arrhythmogenic effect of the dye. QRS A and T A were previously considered as the most suitable for early ischemia assessment in the present animal model and recording setup ( Ronzhina, 2017 ; Ronzhina et al, 2017 ). Cardiac electrical activity under variable experimental conditions was represented by averaged values of parameters calculated in each minute of the experiment.…”

Golden Standard or Obsolete Method? Review of ECG Applications in Clinical and Experimental Context

“…Then, an EG is recorded contact-less by electrodes placed on the inner surface of the bath ( Figure 1A ). Various numbers and positions of electrodes may be used including a two-dimensional lead system ( Ronzhina et al, 2017 ) or three-dimensional orthogonal lead system ( Janousek et al, 2010 ). Such approach minimizes mechanical irritation of the heart and allows to record more than one EG lead.…”