A comprehensive neuromonitoring approach in a large animal model of cardiac arrest

Background

Anoxic brain injuries represent the main determinant of poor outcome after cardiac arrest (CA). Large animal models have been described to investigate new treatments during CA and post‐resuscitation phase, but a detailed model that includes extensive neuromonitoring is lacking.

Method

Before an electrically‐induced 10‐minute CA and resuscitation, 46 adult pigs underwent neurosurgery for placement of a multifunctional probe (intracranial pressure or ICP, tissue oxygen tension or PbtO₂ and cerebral temperature) and a bolt‐based technique for the placement and securing of a regional blood flow probe and two sEEG electrodes; two modified cerebral microdialysis (CMD) probes were also inserted in the frontal lobes and accidental misplacement was prevented using a perforated head support.

Result

42 animals underwent the CA procedure and 41 achieved the return of spontaneous circulation (ROSC). In 4 cases (8.6%) an adverse event took place during preparation, but only in two cases (4.3%) this was related to the neurosurgery. In 6 animals (13.3%) the minor complications that occurred resolved after probe repositioning.

Conclusion

Herein we provide a detailed comprehensive neuromonitoring approach in a large animal model of CA that might help future research.

Early Hyperdynamic Sepsis Alters Coronary Blood Flow Regulation in Porcine Fecal Peritonitis

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis.

Methods: Fourteen pigs were randomized to sham (n = 7) or fecal peritonitis-induced sepsis (n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation.

Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I₂ receptor, and prostaglandin F_2α receptor.

Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved.

Quantification of Cardiac Kinetic Energy and Its Changes During Transmural Myocardial Infarction Assessed by Multi-Dimensional Seismocardiography

Introduction: Seismocardiography (SCG) records cardiac and blood-induced motions transmitted to the chest surface as vibratory phenomena. Evidences demonstrate that acute myocardial ischemia (AMI) profoundly affects the SCG signals. Multidimensional SCG records cardiac vibrations in linear and rotational dimensions, and scalar parameters of kinetic energy can be computed. We speculate that AMI and revascularization profoundly modify cardiac kinetic energy as recorded by SCG.

Methods: Under general anesthesia, 21 swine underwent 90 min of myocardial ischemia induced by percutaneous sub-occlusion of the proximal left anterior descending (LAD) coronary artery and subsequent revascularization. Invasive hemodynamic parameters were continuously recorded. SCG was recorded during baseline, immediately and 80 min after LAD sub-occlusion, and immediately and 60 min after LAD reperfusion. iK was automatically computed for each cardiac cycle (iK^CC) in linear (iK_Lin) and rotational (iK_Rot) dimensions. iK was calculated as well during systole and diastole (iK^Sys and iK^Dia, respectively). Echocardiography was performed at baseline and after revascularization, and the left ventricle ejection fraction (LVEF) along with regional left ventricle (LV) wall abnormalities were evaluated.

Results: Upon LAD sub-occlusion, 77% of STEMI and 24% of NSTEMI were observed. Compared to baseline, troponins increased from 13.0 (6.5; 21.3) ng/dl to 170.5 (102.5; 475.0) ng/dl, and LVEF dropped from 65.0 ± 0.0 to 30.6 ± 5.7% at the end of revascularization (both p < 0.0001). Regional LV wall abnormalities were observed as follows: anterior MI, 17.6% (three out of 17); septal MI, 5.8% (one out of 17); antero-septal MI, 47.1% (eight out of 17); and infero-septal MI, 29.4% (five out of 17). In the linear dimension, iKLinCC, iKLinSys, and iKLinDia dropped by 43, 52, and 53%, respectively (p < 0.0001, p < 0.0001, and p = 0.03, respectively) from baseline to the end of reperfusion. In the rotational dimension, iKRotCC and iKRotSys dropped by 30 and 36%, respectively (p = 0.0006 and p < 0.0001, respectively), but iKRotDia did not change (p = 0.41). All the hemodynamic parameters, except the pulmonary artery pulse pressure, were significantly correlated with the parameters of iK, except for the diastolic component.

Conclusions: In this very context of experimental AMI with acute LV regional dysfunction and no concomitant AMI-related heart valve disease, linear and rotational iK parameters, in particular, systolic ones, provide reliable information on LV contractile dysfunction and its effects on the downstream circulation. Multidimensional SCG may provide information on the cardiac contractile status expressed in terms of iK during AMI and reperfusion. This automatic system may empower health care providers and patients to remotely monitor cardiovascular status in the near future.

Quantification of cardiac kinetic energy and its changes during transmural myocardial ischemia assessed by multi-dimensional seismocardiography

Background

The third law of Newton implies that if one body exerts a force on a second body, the latter exerts a force equal in magnitude and opposite in direction on the first body. This reaction to heart and blood motion elicits low frequency vibrations transmitted to the chest surface. Multi-dimensional seismocardiography (SCG) assesses these linear and rotational accelerations by means of micro-accelerometers and micro-gyroscopes. From the linear and rotational acceleration signals, kinetic energy (KE) and its temporal integration (iK) can be computed as scalar parameters, both in a linear (iKLin) and in a rotational (iKRot) dimension. Evidence demonstrate that acute myocardial ischemia (AMI) profoundly affects the SCG waveform amplitude and that unidimensional SCG is accurate for the determination of acute coronary syndrome (ACS). Whether and how AMI affects multidimensional SCG signals is unknwon.

Purpose

AMI upon left anterior descendent coronary artery (LAD) occlusion markedly depresses iKLin and iKRot.

Methods

The protocol was in accordance with the principles of laboratory animal care. After 20 minutes of steady-state, anesthetized Landrance pigs underwent a percutaneous mid-LAD occlusion by means of intra-coronary balloon inflation for 90 min., followed by deflation and reperfusion (RE). SCG was recorded at baseline (BSL), upon LAD occlusion (AMIt0), after 60 min of occlusion (AMIt60), at the onset of LAD reperfusion (REt0) and after 60 min of recovery (REt60). iKLin and iKRot were computed from the amplitudes of SCG waveforms. iKLin and iKRot were calculated during the systolic and diastolic phases of the cardiac cycle (iKSys and iKDia, respectively). Firedman's ANOVA was used to test the trend of the above variables throughout the protocol, followed by Wilcoxon paired tests. Data are presented as median [IR].

Results

Of the 21 investigated pigs, 3 died before protocol termination as a result of AMI complications and 4 had ruled out during the signal processing because of technical reasons. Considering the rotational variables, when compared to baseline, iKRot_Sys decreased by 17% both at AMIt0 (p=0.05) and AMIt60 (p=0.02); by 38% and 49% at REt0 and t60 (respectively, p&lt;0.001). Similarly, iKRot_Dia decreased by 64% and 59% at AMIt0 and AMIt60 (respectively, p&lt;0.02), and by 74% at REt0 and REt60 (both p=0.002). Considering the linear variables, iKLin_Sys decreased by 19% and 34% at AMIt0 and AMIt60 (respectively, p&lt;0.04), by 39% and 53% at REt0 and REt60 (respectively, p&lt;0.02). iKLin_Dia decreased by 42% at AMIt60 (p=0.03) and by 67% at REt60 (p=0.005) compared to baseline but did not change at the other time points (figure 1).

Conclusions

AMI depresses profoundly cardiac kinetic energy as recorded by multidimensional SCG. Thus, this nonintrusive and operator independent tool may prove useful in the detection of AMI and provide considerable opportunities for remote non-intrusive monitoring of cardiac functions.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Fonds Erasme, FNRS_Fonds National Recherche Scientifique, Fonds pour la Chirurgie Cardiaque, PRODEXA

Mesp1 controls the speed, polarity, and directionality of cardiovascular progenitor migration

During embryonic development, Mesp1 marks the earliest cardiovascular progenitors (CPs) and promotes their specification, epithelial-mesenchymal transition (EMT), and cardiovascular differentiation. However, Mesp1 deletion in mice does not impair initial CP specification and early cardiac differentiation but induces cardiac malformations thought to arise from a defect of CP migration. Using inducible gain-of-function experiments during embryonic stem cell differentiation, we found that Mesp2, its closest homolog, was as efficient as Mesp1 at promoting CP specification, EMT, and cardiovascular differentiation. However, only Mesp1 stimulated polarity and directional cell migration through a cell-autonomous mechanism. Transcriptional analysis and chromatin immunoprecipitation experiments revealed that Mesp1 and Mesp2 activate common target genes that promote CP specification and differentiation. We identified two direct Mesp1 target genes, Prickle1 and RasGRP3, that are strongly induced by Mesp1 and not by Mesp2 and that control the polarity and the speed of cell migration. Altogether, our results identify the molecular interface controlled by Mesp1 that links CP specification and cell migration.