Left ventricular venting during extracorporeal membrane oxygenation; the effects on cardiac performance in a porcine model of critical post-cardiotomy failure.

Introduction: Left ventricular distension is a major concern with postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO) supporting a critical heart failure after cardiac surgery. This porcine study evaluates the effects of left ventricular venting on cardiac function during ECMO-supported circulation and after weaning from ECMO.

Methods: Twenty anaesthetised open-chest pigs were put on cardiopulmonary bypass with aortic cross-clamping and suboptimal cardioplegic arrest for 40 min.

An experimental study on intraoperative recovery of recurrent laryngeal nerve function.

Objective: If bilateral thyroid surgery is planned and staged thyroidectomy considered in case of loss of neuromonitoring signal (LOS), a waiting time of 20 minutes is suggested for evaluation of early nerve recovery. This recommendation is based on clinical observations and has not been thoroughly validated experimentally.

Methods: Sixteen pigs were randomly studied, and electromyogram (EMG) was continuously recorded during traction injury until an amplitude decrease of 70% from baseline (BL) (16 nerves) or LOS (16 nerves), and further during 40-minute recovery time.

Vocal cord function during recurrent laryngeal nerve injury assessed by accelerometry and EMG.

Objective: Gradual impairment of nerve conduction is expected to be tightly associated with simultaneous gradual loss of vocal cord contractility, related to the fact that injured axons are connected to a defined number of muscle cells. In clinical studies, there is a time gap between observed adverse electromyographic (EMG) changes and examination of vocal cord function. This study evaluates the impact of intraoperative EMG changes on synchronous vocal cord contractility by simultaneous use of continuous intraoperative neuromonitoring (C-IONM) and accelerometry for registration of actual vocal cord function at a given change of EMG amplitude.

How do I get an emergency civilian walking blood bank running?

The shift toward using a transfusion strategy in a ratio to mimic whole blood (WB) functionality has revitalized WB as a viable option to replace severe blood loss in civilian health care. A military-civilian collaboration has contributed to the reintroduction of WB at Haukeland University Hospital in Bergen, Norway. WB has logistical and hemostatic advantages in both the pre- and in-hospital settings where the goal is a perfectly timed balanced transfusion strategy.

Left ventricular dysfunction after two hours of polarizing or depolarizing cardioplegic arrest in a porcine model.

Introduction: This experimental study compares myocardial function after prolonged arrest by St. Thomas' Hospital polarizing cardioplegic solution (esmolol, adenosine, Mg) with depolarizing (hyperkalaemic) St. Thomas' Hospital No 2, both administered as cold oxygenated blood cardioplegia.

Carvedilol-Enriched Cold Oxygenated Blood Cardioplegia Improves Left Ventricular Diastolic Function After Weaning From Cardiopulmonary Bypass.

Objectives: To investigate whether adding carvedilol, a nonselective β- and selective α1-receptor blocking agent with antioxidant properties, to oxygenated blood cardioplegia improves myocardial function after weaning from bypass.

Design: A randomized controlled study.

Setting: A university laboratory.

Insulin Postconditioning Reduces Infarct Size in the Porcine Heart in a Dose-Dependent Manner.

Aim: Insulin and glucose may have opposite effects when used to reduce ischemia-reperfusion injury. When insulin is administered alone, feeding state determines tolerance and further induces metabolic and hormonal changes. Higher insulin doses are needed for similar activation of cardioprotective Akt signaling in the fed compared to the fasted pig heart.

The influence of acute unloading on left ventricular strain and strain rate by speckle tracking echocardiography in a porcine model.

Noninvasive measurements of myocardial strain and strain rate by speckle tracking echocardiography correlate to cardiac contractile state but also to load, which may weaken their value as indices of inotropy. In a porcine model, we investigated the influence of acute dynamic preload reductions on left ventricular strain and strain rate and their relation to the pressure-conductance catheter-derived preload recruitable stroke work (PRSW) and peak positive first derivative of left ventricular pressure (LV-dP/dtmax). Speckle tracking strain and strain rate in the longitudinal, circumferential, and radial directions were measured during acute dynamic reductions of end-diastolic volume during three different myocardial inotropic states.

Myocardial function after polarizing versus depolarizing cardiac arrest with blood cardioplegia in a porcine model of cardiopulmonary bypass.

Objectives: Potassium-based depolarizing St Thomas' Hospital cardioplegic solution No 2 administered as intermittent, oxygenated blood is considered as a gold standard for myocardial protection during cardiac surgery. However, the alternative concept of polarizing arrest may have beneficial protective effects. We hypothesize that polarized arrest with esmolol/adenosine/magnesium (St Thomas' Hospital Polarizing cardioplegic solution) in cold, intermittent oxygenated blood offers comparable myocardial protection in a clinically relevant animal model.

Esmolol added in repeated, cold, oxygenated blood cardioplegia improves myocardial function after cardiopulmonary bypass.

Objective: This study investigated if the β-receptor blocking agent esmolol, added to standard oxygenated blood cardioplegia, improved myocardial function after weaning from bypass.

Design: A block-randomized, blinded study.

Setting: A university laboratory.

Intracoronary insulin administered at reperfusion in a porcine model of acute coronary syndrome.

Background: Experimental studies have demonstrated that insulin elicits cardioprotection in coronary occlusion-reperfusion models. We studied the effects of intracoronary insulin on regional cardiac function in a porcine model with reperfusion after a critical coronary artery stenosis.

Methods: In 20 anaesthetized pigs with an extracorporeal shunt from the brachiocephalic to the left anterior descending coronary artery, a fixed stenosis was applied, obtaining 50% reduction of shunt flow for 60 min.

Haemodynamic differences between pancuronium and vecuronium in an experimental pig model.

Objective: To compare baseline cardiovascular function in anesthetised pigs using either pancuronium or vecuronium as a neuromuscular blocker.

Study Design: Retrospective, non-randomized comparison.

Animals: Norwegian Land Race pigs (Sus scrofa domesticus) weighing mean 42 ± SD 3 kg.

Reperfusion therapy with low-dose insulin or insulin-like growth factor 2; myocardial function and infarct size in a porcine model of ischaemia and reperfusion.

In an open-chest porcine model, we examined whether myocardial pharmacological conditioning at the time of reperfusion with low-dose insulin or insulin-like growth factor 2 (IGF2), not affecting serum glucose levels, could reduce infarct size and improve functional recovery. Two groups of anaesthetized pigs with either 60 or 40 min. of left anterior descending artery occlusion (total n = 42) were randomized to receive either 0.

Is strain by Speckle Tracking Echocardiography dependent on user controlled spatial and temporal smoothing? An experimental porcine study.

Background: Speckle Tracking Echocardiography (STE) strain analysis relies on both spatial and temporal smoothing. The user is often allowed to adjust these smoothing parameters during analysis. This experimental study investigates how different degrees of user controllable spatial and temporal smoothing affect global and regional STE strain values in recordings obtained from normal and ischemic myocardium.

Multi-layer radial systolic strain vs. one-layer strain for confirming reperfusion from a significant non-occlusive coronary stenosis.

Aims: The aim of this study was to investigate whether multi-layer radial strain and strain rate analysis is superior to one-layer strain analysis for confirming reperfusion following a non-occlusive coronary stenosis.

Methods And Results: In 10 anaesthetized pigs, an extracorporeal shunt was inserted from the brachiocephalic to the left anterior descending coronary artery. Microspheres were injected and left ventricular (LV) short- and long-axis echocardiographic views were recorded with the open shunt, during the 120 min of severe stenosis and 20 min (early) and 100 min (late) after reperfusion.

Multidose cold oxygenated blood is superior to a single dose of Bretschneider HTK-cardioplegia in the pig.

Background: A single-dose strategy for cardioplegia is desired in minimal invasive approaches to valve surgery and aortic arch repairs. We hypothesized that a single infusion of Bretschneider HTK solution offers myocardial protection comparable to repeated cold oxygenated blood.

Methods: Sixteen pigs on bypass with 60 minutes of aortic cross-clamping were randomized to a single dose of Custodiol (HTK group) or repeated oxygenated blood cardioplegia (CBC group).

Esmolol before 80 min of cardiac arrest with oxygenated cold blood cardioplegia alleviates systolic dysfunction. An experimental study in pigs.

Objective: Myocardial dysfunction after reperfusion can be a clinical problem in the early postoperative phase after on-pump cardiac surgery. The aim was, in an experimental setting, to investigate if administration of the beta-adrenergic receptor blocker esmolol prior to cross-clamping for 80 min with cold oxygenated blood cardioplegia would improve myocardial protection and early postoperative function.

Methods: Twenty-four anaesthetised pigs were randomly allocated into one of two equally sized groups and put on mild hypothermic cardiopulmonary bypass.

Multilayer radial systolic strain can identify subendocardial ischemia: an experimental tissue Doppler imaging study of the porcine left ventricular wall.

Aims: This study investigates whether subendocardial ischemia can be detected by measuring multilayer radial systolic strain from epicardial tissue Doppler imaging.

Methods: In 10 anesthetized open-chest pigs an extracorporeal shunt from the proximal brachiocephalic to the left anterior descending coronary artery was constricted in steps. Color microsphere injections and short axis Tissue Velocity Imaging (TVI) recordings were performed with open shunt, with a non-significant stenosis, and with 2 steps of shunt flow reduction.

Radial strain gradient across the normal myocardial wall in open-chest pigs measured with doppler strain rate imaging.

Background: One of the reasons for the large variation in radial strain measured with Doppler strain rate imaging in normal myocardium might be the different strain length (SL) used during analyses. The aim of this study was to evaluate the effect of different SL settings on strain recordings and the method's ability to detect transmural radial strain gradients.

Methods: In 8 anesthetized pigs (mean weight 54 kg) epicardial echocardiography was performed.