Independency of myocardial stunning of endothelial stunning?

Clinical management of postcardiotomy shock in adults

Postcardiotomy cardiogenic shock represents the most serious expression of low cardiac output syndrome after cardiac surgery. Although infrequent, it is a relevant condition due to its specific and complex pathophysiology and important morbidity-mortality. The diagnosis requires a high index of suspicion and multimodal hemodynamic monitoring, where echocardiography and the pulmonary arterial catheter play a main role. Early and multidisciplinary management should focus on the management of postoperative or mechanical complications and the optimization of determinants of cardiac output through fluid therapy or diuretic treatments, inotropic drugs and vasopressors/vasodilators and, in the absence of a response, early mechanical circulatory support. The aim of this paper is to review and update the pathophysiology, diagnosis and management of postcardiotomy cardiogenic shock.

Gradual Versus Abrupt Reperfusion During Primary Percutaneous Coronary Interventions in ST‐Segment–Elevation Myocardial Infarction (GUARD)

Background

Intramyocardial edema and hemorrhage are key pathological mechanisms in the development of reperfusion‐related microvascular damage in ST‐segment–elevation myocardial infarction. These processes may be facilitated by abrupt restoration of intracoronary pressure and flow triggered by primary percutaneous coronary intervention. We investigated whether pressure‐controlled reperfusion via gradual reopening of the infarct‐related artery may limit microvascular injury in patients undergoing primary percutaneous coronary intervention.

Methods and Results

A total of 83 patients with ST‐segment–elevation myocardial infarction were assessed for eligibility and 53 who did not meet inclusion criteria were excluded. The remaining 30 patients with totally occluded infarct‐related artery were randomized to the pressure‐controlled reperfusion with delayed stenting (PCRDS) group (n=15) or standard primary percutaneous coronary intervention with immediate stenting (IS) group (n=15) (intention‐to‐treat population). Data from 5 patients in each arm were unsuitable to be included in the final analysis. Finally, 20 patients undergoing primary percutaneous coronary intervention who were randomly assigned to either IS (n=10) or PCRDS (n=10) were included. In the PCRDS arm, a 1.5‐mm balloon was used to achieve initial reperfusion with thrombolysis in myocardial infarction grade 3 flow and, subsequently, to control distal intracoronary pressure over a 30‐minute monitoring period (MP) until stenting was performed. In both study groups, continuous assessment of coronary hemodynamics with intracoronary pressure and Doppler flow velocity was performed, with a final measurement of zero flow pressure (primary end point of the study) at the end of a 60‐minute MP. There were no complications associated with IS or PCRDS. PCRDS effectively led to lower distal intracoronary pressures than IS over 30 minutes after reperfusion (71.2±9.37 mm Hg versus 90.13±12.09 mm Hg, P =0.001). Significant differences were noted between study arms in the microcirculatory response over MP. Microvascular perfusion progressively deteriorated in the IS group and at the end of MP, and hyperemic microvascular resistance was significantly higher in the IS arm as compared with the PCDRS arm (2.83±0.56 mm Hg.s.cm −1 versus 1.83±0.53 mm Hg.s.cm −1 , P =0.001). The primary end point (zero flow pressure) was significantly lower in the PCRDS group than in the IS group (41.46±17.85 mm Hg versus 76.87±21.34 mm Hg, P =0.001). In the whole study group (n=20), reperfusion pressures measured at predefined stages in the early reperfusion period showed robust associations with zero flow pressure values measured at the end of the 1‐hour MP (immediately after reperfusion: r =0.782, P <0.001; at the 10th minute: r =0.796, P <0.001; and at the 20th minute: r =0.702, P =0.001) and peak creatine kinase MB level (immediately after reperfusion: r =0.653, P =0.002; at the 10th minute: r =0.597, P =0.007; and at the 20th minute: r =0.538, P =0.017). Enzymatic myocardial infarction size was lower in the PCRDS group than in the IS group with peak troponin T (5395±2991 ng/mL versus 8874±1927 ng/mL, P =0.006) and creatine kinase MB (163.6±93.4 IU/L versus 542.2±227.4 IU/L, P <0.001).

Conclusions

In patients with ST‐segment–elevation myocardial infarction, pressure‐controlled reperfusion of the culprit vessel by means of gradual reopening of the occluded infarct‐related artery (PCRDS) led to better‐preserved coronary microvascular integrity and smaller myocardial infarction size, without an increase in procedural complications, compared with IS.

Registration

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02732080.

No evidence of cardiac stunning or decoupling immediately after cardiopulmonary bypass for elective coronary surgery

BACKGROUND

There is significant uncertainty regarding the timing of onset of cardiovascular stunning after cardiac surgery. Cardiovascular stunning is affecting both contractility (Ees) and arterial load. Arterial load may be represented by arterial elastance (Ea) and participates in ventriculo-arterial coupling through the Ea/Ees ratio, giving information on efficiency and performance. An alternative approach to ventriculo-arterial interaction is oscillatory power fraction (OPF). The aim of this study was to investigate the immediate beat-to-beat effects of on-pump coronary artery bypass graft (CABG) surgery on contractility, cardiac power parameters, arterial load and ventriculo-arterial coupling as well as classical haemodynamic parameters.

METHODS

We included 41 patients scheduled for fast-track CABG surgery. Measurements were taken before and after cardiopulmonary bypass. A flow and pressure curve were recorded from transoesophageal pulsed wave Doppler and a radial artery catheter, respectively. This enabled the calculation of stroke work, total cardiac energy delivery, OPF and Ea/Ees ratio. Routine haemodynamic monitoring provided the classical haemodynamic parameters.

RESULTS

Immediately after cardiopulmonary bypass there was no firm evidence for alterations in contractility, stroke work, stroke volume or arterial elastance. Ea/Ees ratio and OPF remained unchanged.

CONCLUSIONS

There was no evidence for clinically relevant cardiac stunning or altered arterial load immediately after cardiopulmonary bypass for CABG surgery. The unchanged Ea/Ees ratio and OPF are indicating unchanged cardiac efficiency before and after cardiopulmonary bypass. This indicates that in elective CABG patients cardiovascular stunning is perhaps a phenomenon of inflammation and not immediate ischaemia-reperfusion injury or mechanical handling.

Early Graft Loss after Kidney Transplantation: Endothelial Dysfunction of Renal Microvasculature

Decision process about the acceptance of the deceased donor kidney for transplantation might be challenging. Although histological evaluation of pretransplant donor kidney biopsy provides reliable information regarding cortical necrosis, vascular thrombosis, extensive global glomerulosclerosis, and interstitial fibrosis/tubular atrophy, only electron microscopy enables thorough and reliable insights into microvasculature changes of kidney graft. The aim of the present paper is to briefly present two cases of early kidney graft loss. In one case, the donor was exposed to long-term extracorporeal membrane oxygenation (ECMO); in the other case, the donor experienced Takotsubo cardiomyopathy. In both cases, light microscopy of pretransplant biopsy found no pathology or significant discrepancy in morphology of kidney graft, while electron microscopy revealed severe endothelial dysfunction of renal microvasculature. Our results suggest that severe injury of renal microvasculature with relatively preserved tubular epithelium may be associated with some conditions of deceased kidney donors leading to early kidney graft nonfunction and loss. Further studies are needed to determine prognostic significance of severe ultrastructural microvasculature lesions and to evaluate disease states and conditions that could be associated with severe endothelial dysfunction of kidney graft.

Impact of age on cardiovascular function, inflammation, and oxidative stress in experimental asphyxial cardiac arrest

BACKGROUND

Advanced age is an independent predictor of poor outcome after cardiac arrest (CA). From experimental studies of regional ischemia-reperfusion injury, advanced age is associated with larger infarct size, reduced organ function, and augmented oxidative stress. The objective of this study was to investigate the effect of age on cardiovascular function, oxidative stress, inflammation, and endothelial activation after CA representing global ischemia-reperfusion.

METHODS

Aged (26 months) and young (5 months) rats were subjected to 8 min of asphyxia induced CA, resuscitated and observed for 360 min. Left ventricular pressure-derived cardiac function was measured at baseline and 360 min after CA. Blood samples obtained at baseline, 120 min, and 360 min after CA were analyzed for IL-1β, IL-6, IL-10, TNF-α, elastase, sE-selectin, sL-selectin, sI-CAM1, hemeoxygenase-1 (HO-1) and protein carbonyl. Tissue samples of brain, heart, kidney, and lung were analyzed for HO-1.

RESULTS

Cardiac function, evaluated by dP/dt_max and dP/dt_min , was decreased after CA in both young and aged rats, with no group differences. Mean arterial pressure increased after CA in young, but not old rats. Aged rats showed significantly higher plasma levels of elastase and sE-selectin after CA, and there was a significant different development over time between groups for IL-6 and IL-10. Young rats showed higher levels of HO-1 in plasma and renal tissue after CA.

CONCLUSION

In a rat model of asphyxial CA, advanced age is associated with an attenuated hyperdynamic blood pressure response and increased endothelial activation.

Impaired NO-mediated vasodilatation in rat coronary arteries after asphyxial cardiac arrest

BACKGROUND

Cardiovascular dysfunction after cardiac arrest is a common finding. It is unknown whether altered endothelium-mediated vasoreactivity contributes to this dysfunction. We hypothesised that cardiac arrest and resuscitation results in impaired endothelial function. This was addressed by measurements of inflammatory and endothelial plasma markers and of endothelium-dependent vasodilatation in coronary and mesenteric arteries in rats after cardiac arrest and resuscitation.

METHODS

Male Sprague Dawley rats underwent either asphyxia-induced cardiac arrest for 5 min and subsequent resuscitation (n = 30) or a sham procedure (control animals, n = 39). Animals were euthanised after 30 min or 2 h. Blood was analysed for TNF-α, IL-1β, IL-6, IL-10, sE-selectin, sP-selectin, sVCAM-1, ICAM-1, VEGF-α and vWF. Arterial rings of the left anterior descending coronary artery and mesenteric resistance arteries were mounted in microvascular myographs, and concentration-response curves were constructed.

RESULTS

The plasma levels of the endothelial markers, sP-selectin and vWF increased following cardiac arrest at both 30 min and 2 h. Acetylcholine-induced endothelium-dependent and mainly nitric oxide (NO)-mediated vasodilatation was impaired in the coronary arteries at 30 min, but not 2 h after resuscitation. Endothelium-derived hyperpolarisation (EDH)-type vasodilatation induced by NS309 and vasodilatation induced by the NO donor sodium nitroprusside was unaltered. In parallel with systemic hypotension, mesenteric arteries exhibited a larger response to NS309 2 h after resuscitation.

CONCLUSION

The present results show marked endothelial alterations after cardiac arrest and resuscitation reflected by increased endothelial plasma markers, impaired NO-mediated coronary vasodilatation in the early post-resuscitation phase and enhanced EDH-type vasodilatation in mesenteric arteries later in the post-resuscitation phase.

Cardiodynamics and infarct size in regional and global ischemic isolated heart model: comparison of 1 hour and 2 hours reperfusion

Background and Objectives

We investigated whether 1 hour reperfusion is enough to assess cardiodynamics and infarct size in both regional ischemia (RI) and global ischemia (GI) in isolated rat heart models.

Materials and Methods

Hearts were randomly assigned to one of the following groups (each n=14): 1) Sham hearts for 1 hour; 2) Sham hearts for 2 hours; 3) 30 minutes RI followed by 1 hour reperfusion; 4) 30 minutes of RI followed by 2 hours reperfusion; 5) 30 minutes GI followed by 1 hour reperfusion; and 6) 30 minutes GI followed by 2 hours reperfusion.

Results

There were no significant differences in infarct size between 1 hour and 2 hours reperfusion in both RI and GI. Left ventricular developed pressure was significantly decreased at both 1 hour and 2 hours reperfusion in groups of RI and GI compared to baseline (p<0.01). Rate-pressure product and +dP/dt_max also significantly decreased compared to baseline level at both 1 hour and 2 hours reperfusion in groups of RI and GI (p<0.05).

Conclusion

There was no significant difference in infarct size between 1 hour and 2 hours reperfusion in groups of RI and GI. Cardiodynamic variables measured at 1 hour and 2 hours reperfusion significantly decreased compared to baseline level. Our data suggests that reperfusion of 1 hour is sufficient to assess cardiodynamics in both regional and global ischemic isolated hearts model.

Direct relationship between levels of TNF-alpha expression and endothelial dysfunction in reperfusion injury

We previously found that myocardial ischemia/reperfusion (I/R) initiates expression of tumor necrosis factor-alpha (TNF) leading to coronary endothelial dysfunction. However, it is not clear whether there is a direct relationship between levels of TNF expression and endothelial dysfunction in reperfusion injury. We studied levels of TNF expression by using different transgenic animals expressing varying amounts of TNF in I/R. We crossed TNF overexpression (TNF(++/++)) with TNF knockout (TNF(-/-)) mice; thus we have a heterozygote population of mice with the expression of TNF "in between" the TNF(-/-) and TNF(++/++) mice. Mouse hearts were subjected to 30 min of global ischemia followed by 90 min of reperfusion and their vasoactivity before and after I/R was examined in wild type (WT), TNF(-/-), TNF(++/++) and TNF heterozygote (TNF(-/++), cross between TNF(-/-) and TNF(++/++)) mice. In heterozygote TNF(-/++) mice with intermediate cardiac-specific expression of TNF, acetylcholine-induced or flow-induced endothelial-dependent vasodilation following I/R was between TNF(++/++) and TNF(-/-) following I/R. Neutralizing antibodies to TNF administered immediately before the onset of reperfusion-preserved endothelial-dependent dilation following I/R in WT, TNF(-/++) and TNF(++/++) mice. In WT, TNF(-/++) and TNF(++/++) mice, I/R-induced endothelial dysfunction was progressively lessened by administration of free-radical scavenger TEMPOL immediately before initiating reperfusion. During I/R, production of superoxide (O(2) (.-)) was greatest in TNF(++/++) mice as compared to WT, TNF(-/++) and TNF(-/-) mice. Following I/R, arginase mRNA expression was elevated in the WT, substantially elevated in the TNF(-/++) and TNF(++/++) mice and not affected in the TNF(-/-) mice. These results suggest that the level of TNF expression determines arginase expression in endothelial cells during myocardial I/R, which is one of the mechanisms by which TNF compromises coronary endothelial function in reperfusion injury.

Cardiac stunning in the clinic: the full picture

Cardiac stunning refers to different dysfunctional levels occurring after an episode of acute ischemia, despite blood flow is near normal or normal. The phenomenon was initially identified in animal models, where it has been very well characterized. After being established in the experimental setting, it remained unclear, whether a similar syndrome occurs in humans. In addition, it remained controversial, whether stunning was of any clinical relevance as it is spontaneously reversible. Hence, many studies continue to focus on the properties and mechanisms of stunning, although therapies seem more relevant for attenuating and treating myocardial ischemia/reperfusion (I/R) injury, i.e. to bridge until recovery. This article reviews the different facets of cardiac stunning, i.e. myocardial, vascular/microvascular/endothelial, metabolic, neural/neuronal, and electrical stunning. This review also displays where these facets exist and which clinical relevance they might have. Particular attention is directed to the different therapeutic interventions that the various facets of this I/R-induced cardiac injury might require. A final outlook considers possible alternatives to further reduce the detrimental consequences of brief episodes of ischemia and reperfusion.

Vascular control in humans: focus on the coronary microcirculation

Myocardial perfusion is regulated by a variety of factors that influence arteriolar vasomotor tone. An understanding of the physiological and pathophysiological factors that modulate coronary blood flow provides the basis for the judicious use of medications for the treatment of patients with coronary artery disease. Vasomotor properties of the coronary circulation vary among species. This review highlights the results of recent studies that examine the mechanisms by which the human coronary microcirculation is regulated in normal and disease states, focusing on diabetes. Multiple pathways responsible for myogenic constriction and flow-mediated dilation in human coronary arterioles are addressed. The important role of endothelium-derived hyperpolarizing factors, their interactions in mediating dilation, as well as speculation regarding the clinical significance are emphasized. Unique properties of coronary arterioles in human vs. other species are discussed.

Oxidative stress induces myeloperoxidase expression in endocardial endothelial cells from patients with chronic heart failure

Increased oxidative stress has been implicated in the pathogenesis of a number of cardiovascular diseases. Recent findings suggest that myeloperoxidase (MPO) may play a key role in the initiation and maintenance of chronic heart failure (CHF) by contributing to the depletion of the intracellular reservoir of nitric oxide (NO). NO consumption through MPO activity may lead to protein chlorination or nitration, leading to tissue damage. Primary cultures of human endocardial endothelial cells (EEC) obtained at heart transplantation of patients with CHF and human umbilical vein endothelial cells (HUVEC) were subjected to oxidative stress by incubation with hydrogen peroxide at non lethal (60 microM) dose for different exposure times (3 and 6 h). Treated and control cells were tested by immunohistochemistry and RT-PCR for MPO and 3-chlorotyrosine expression. Both endothelial cell types expressed myeloperoxidase following oxidative stress, with higher levels in EEC. Moreover, 3-chlorotyrosine accumulation in treated cells alone indicated the presence of MPO-derived hypochlorous acid. Immunohistochemistry on sections from post-infarcted heart confirmed in vivo the endothelial positivity to MPO, 3-chlorotyrosine and, to a minor extent, nitrotyrosine. Immunohistochemical observations were confirmed by detection of MPO mRNA in both stimulated EEC and HUVEC cells. This study demonstrates for the first time that EEC can express MPO after oxidative stress, both in vitro and in vivo, followed by accumulation of 3-chlorotyrosine, an end product of oxidative stress. Deregulation of endothelial functions may contribute to the development of a number of cardiovascular diseases, including CHF. The results also highlight the notion that endothelium is not only a target but also a key player in oxidative-driven cardiovascular stress.

The role of inflammatory cytokines in endothelial dysfunction

Clinical and experimental data support a link between endothelial dysfunction and inflammation. Inflammatory cytokines are important protagonists in formation of atherosclerotic plaque, eliciting effects throughout the atherosclerotic vessel. Importantly, the development of atherosclerotic lesions, regardless of the risk factor, e.g., diabetes, hypertension, obesity, is characterized by disruption in normal function of the endothelial cells. Endothelial cells, which line the internal lumen of the vasculature, are part of a complex system that regulates vasodilation and vasoconstriction, growth of vascular smooth muscle cells, inflammation, and hemostasis, maintaining a proper blood supply to tissues and regulating inflammation and coagulation. Current concepts suggest that the earliest event in atherogenesis is endothelial dysfunction, manifested by deficiencies in the production of nitric oxide (NO) and prostacyclin. The focus of this review is to summarize recent evidence showing the effects of inflammation on vascular dysfunction in ischemic-heart disease, which may prompt new directions for targeting inflammation in future therapies.

Inhibiting matrix metalloproteinase-2 reduces protein release into coronary effluent from isolated rat hearts during ischemia-reperfusion

BACKGROUND

Previous studies have shown that the disruption of the coronary endothelium and the increase in its permeability during ischemia-reperfusion (I/R), are linked to matrix metalloproteinase-2 (MMP-2) activity. Studies from our group have shown that during I/R, activity of MMP-2 in the coronary effluent increases and this increase is associated with cardiac dysfunction, which in turn, can be prevented by MMP inhibitors. Therefore, we hypothesize that inhibiting MMPs reduces the MMP-2 dependent disruption of the coronary endothelium and subsequent protein release during I/R.

METHODS

Isolated rat hearts were perfused in the Langendorff mode at a constant pressure and subjected to 15, 20 or 30 min no-flow ischemia followed by 30 min of reperfusion. The MMP inhibitors, o-phenanthroline (Phen, 100 microM) or doxycycline (Doxy, 30 microM) an inhibitors of MMPs, were added to the perfusion solution 10 min before ischemia and for the first 10 min of reperfusion. The coronary effluents were collected during perfusion for protein analysis. Creatine kinase was measured as an index of cellular damage. Endothelial integrity was assessed by measuring coronary flow and by measuring the levels of serotransferrin and interstitial albumin in the coronary effluent. Additionally, damage to the endothelium was assessed histologically by light microscopy analysis of the cellular structure of the myocardium. MMP-2 activity was measured by zymography in hearts subjected to 15, 20 and 30 min of ischemia without reperfusion.

RESULTS

MMP-2 activity was increased in heart tissue at the end of ischemia and was correlated with duration of ischemia. The post-ischemia decrease in coronary flow, and the increase in the release of serotransferrin and albumin were attenuated by Phen. Edema (another indirect marker of endothelial damage) was observed in I/R heart and the edema was abolished in I/R heart treated with MMP inhibitors.

CONCLUSION

MMP inhibition not only reduces cardiac mechanical dysfunction but also reduces endothelial damage resulting from cardiac I/R injury.

The association of coronary flow changes and inflammatory indices to ischaemia-reperfusion microvascular damage and left ventricular remodelling

BACKGROUND

The aim of this study was to investigate the effect of coronary flow (CF) changes and inflammatory indices on myocardial microcirculation--assessed by myocardial contrast echocardiography (MCE)--and on left ventricular remodelling, in an experimental ischaemia-reperfusion model.

METHODS

In 15 pigs, weighing 30 +/- 5 kg, ligation of the left anterior descending (LAD) coronary artery was performed, followed by reperfusion for 120 min. Peak, mean, duration and volume of systolic and diastolic components of CF distal to the LAD ligation were measured using a butterfly flowmeter and their ratio was calculated. The following two-dimensional echocardiography indices of LV geometry/function were measured from the apical four-chamber view: LV end-systolic (ESD) and end-diastolic (EDD) dimension long- (Ls, Ld) and short-axis (Ss, Sd) and their ratio (Ld/Sd, Ls/Ss, defined as the sphericity index). Interleukin (IL) 1beta, 6, 10 and tumour necrosis factor (TNF) were measured in samples obtained from the LV cavity and coronary sinus. A 0.5 ml/min injection slow bolus over 30 s of SonoVue was made into the left ventricle (LV) in order to assess myocardial perfusion by MCE. Standard apical four-chamber views were digitally acquired and stored for off-line analysis using the Echofit system. The peak intensity (Ac) of the microbubbles at the apex, distally to ligation, was normalised with respect to the peak intensity of the microbubbles in the LV cavity. All parameters were recorded at baseline, immediately after ligation and at 5, 15, 30, 60, 120 min during reperfusion. The percentage changes of CF indices, echocardiographic parameters, interleukins and Ac between baseline and reperfusion were calculated.

RESULTS

Mean systolic CF, systolic volume, peak and mean diastolic flow (MDF) changes and epicardial mean CF, Ld/Sd, Ls/Ss changes and coronary sinus IL-6 (IL-6 cs) were inversely correlated with Ac changes during reperfusion. At 5 and 15 min of reperfusion (hyperaemic phase), the greatest median increase of mean diastolic (172% and 86%), and mean systolic CF (713% and 344%) and the greatest reduction of Ac (-41% at 5 min) compared to baseline (P < 0.05) were observed. The maximum increase of IL-6 cs (40%) was detected at 120 min. ROC analysis showed that of all examined echocardiography indices an increase of mean diastolic CF > 22% was the best predictor of a >25% reduction of Ac with 76% sensitivity and 65% specificity (area 71%, CI 54%-85%, P = 0.02). In addition an >32% increase of IL-6 at 120 min of reperfusion predicted a >25% reduction of Ac with a 76% sensitivity and 65% specificity (area 71% CI 61%-97%, P = 0.01).

CONCLUSION

Changes of mean diastolic CF and IL-6 cs are associated with alterations in myocardial microvascular integrity after ischaemia-reperfusion and may be used as a predictor of myocardial dysfunction.