‘Opioidergic postconditioning’ of heart muscle during ischemia/reperfusion injury

  Background: Ischemic preconditioning and postconditioning are the novel strategies of attaining cardioprotection against ischemia/reperfusion (I/R) injury. Previous studies suggested the role of opioid pathway, however the class of opioid receptors responsible for this effect in humans remains unknown. The aim of the study was to assess the influence of opioids on simulated I/R injury outcomes in the hu­man myocardium. Methods: Trabeculae of the human right atrium were electrically driven in organ bath and subjected to simulated I/R injury. Morphine (10–4M, 10–5M, 10–6M) or d-opioid receptor agonist DADLE (10–8M, 10–7M, 10–6M) was used at the time of re-oxygenation. Additional trabecula was subjected to hypoxia protocol only (Control). Contractive force of the myocardium was assessed as the maximal force of a contraction (Amax), the rate of rise of the force of a contraction (Slope L) and relaxation as the rate of decay of the force of a contraction (Slope T). Results: Application of morphine 10–4M resulted in increase of Amax, Slope L and Slope T during re-oxygenation period as compared to Control (77.99 ± 1.5% vs. 68.8 ± 2.2%, p < 0.05; 45.72 ± 2.9% vs. 34.12 ± 5.1%, p < 0.05; 40.95 ± 2.5% vs. 32.37 ± 4.3%, p < 0.05). Parameters were not significantly different in the lower morphine concentrations. Application of DADLE 10–6M resulted in decrease of Amax and Slope L as compared to Control (68.13 ± 5.5% vs. 76.62 ± 6.6%, p < 0.05; 28.29 ± 2.2 vs. 34.80 ± 3.9%, p < 0.05). Conclusions: At re-oxygenation, morphine improves systolic and diastolic function of the human myo­cardium in the dose-dependent manner. Delta-opioid receptor stimulation attenuates systolic function of human heart muscle which remains in contrast to previous reports with animal models of I/R injury. (Cardiol J 2017; 24, 4: 419–425

Implantable cardioverter-defibrillators — is defibrillation efficacy testing still necessary?

Test defibrylacji (DT) od ponad 20 lat stanowił integralną część procedury implantacji wszczepialnych kardiowerterów- -defibrylatorów (ICD). Indukcja migotania komór w czasie DT ma na celu potwierdzenie adekwatnego marginesu bezpieczeństwa pomiędzy maksymalną energią generowaną przez ICD, a energią defibrylacji wymaganą dla przerwania zagrażających życiu arytmii komorowych. Aktualnie postęp technologiczny sprawił, że skuteczność kliniczna terapii antyarytmicznej ICD sięga 90% co wpływa na stały trend do rezygnacji z wykonywania DT. Tematem artykułu są aktualne pytania związane z problemem podwyższonego progu defibrylacji (DFT) oraz koniecznością i bezpieczeństwem dalszego rutynowego wykonywania DT.Defibrillation testing (DT) has been an integral component of implantable cardioverter-defibrillator (ICD) implantation procedure for over the last 20 years. The induction of ventricular fibrillation (VF) during the DT is the accepted method to determine a sufficient safety margin between the maximum shock energy of the ICD and the shock energy required for defibrillation life threatening ventricular arrhythmias. Nowadays, ICD technology has evolved and the likelihood of successful VF defibrillation achieved 90%, which determines a trend toward ICD implantation without DT. The topic of this article are questions and answers concerning the problems with elevated defibrillation threshold and the appropriateness and safety of routine intraoperative DT

Visualisation of the oblique vein of the left atrium (vein of Marshall) using cardiac computed tomography: is the game worth the candle?

Background: The vein of Marshall (VoM) is a small vessel that descends obliquely on the back of the left atrium and ends in the coronary sinus near the area where the great cardiac vein continues into the coronary sinus.Aim: The aim of the study was to examine the frequency of occurrence and anatomical aspects as well as the possibility of visualising the VoM, including an evaluation of the quality of the visualisation, on computed tomography (CT).Methods: Three hundred patients aged 58.8 ± 11.5 years (111 women) were included into this single-centre study. Cardiac CT was performed in all patients. The search for the VoM was performed by two experienced researchers using two- and three-dimensional techniques. A dedicated Likert-based scale was used to evaluate the quality of the visualisations.Results: The VoM was found in 61 (20.33%) of 300 patients. Its average diameter was 1.72 ± 0.69 mm with no sex-related differences (men: 1.71 ± 0.69 mm; women: 1.73 ± 0.57 mm; p = 0.91). The average length of the vessel was 9.24 ± 7.58 mm. The VoM was more frequently (p = 0.01) visualised in the systolic phases (68.85% of cases) compared to the diastolic phases (27.86% of cases). Occasionally it was visualised in other phases (3.29%).Conclusions: Although it was possible to visualise the VoM using cardiac CT in about 20% of the population, this method of visualisation requires that special attention be paid to the quality of the images, especially in the systolic phases. Visualisation may be useful before certain electrophysiology procedures

The co-application of hypoxic preconditioning and postconditioning abolishes their own protective effect on systolic function in human myocardium

Background: Ischemic preconditioning (IPC) and postconditioning (POC) are well documented to trigger cardioprotection against ischemia/reperfusion (I/R) injury, but the effect oftheir both co-application remains unclear in human heart. The present study sought to assessthe co-application of IPC and POC on fragments of human myocardium in vitro.Methods: Muscular trabeculae of the human right atrial were electrically driven in the organbath and subjected to simulated I/R injury – hypoxia/re-oxygenation injury in vitro. To achieveIPC of trabeculae the single brief hypoxia period preceded the applied lethal hypoxia, and to achieve POC triple brief hypoxia periods followed the lethal hypoxia. Additional muscular trabeculae were exposed only to the hypoxic stimulation (Control) or were subjected to the non-hypoxic stimulation (Sham). 10 μM norepinephrine (NE) application ended every experiment to assess viability of trabeculae. The contraction force of the myocardium assessed as a maximal amplitude of systolic peak (%Amax) was obtained during the whole experiment’s period.Results: Co-application of IPC and POC resulted in decrease in %Amax during the re-oxygentaionperiod and after NE application, as compared to Control (30.35 ± 2.25 vs. 41.89 ± 2.25, 56.26 ± 7.73 vs. 65.98 ± 5.39, respectively). This was in contrary to the effects observed when IPC and POC were applied separately.Conclusions: The co-application of IPC and POC abolishes the cardioprotection of either intervention alone against simulated I/R injury in fragments of the human right heart atria