Multidisciplinary Approach to Sedation and Early Mobility of Intubated Critically Ill Neurologic Patients Improves Mobility at Discharge

Background and Purpose

Over-sedation may confound neurologic assessment in critically ill neurologic patients and prolong duration of mechanical ventilation (MV). Decreased sedative use may facilitate early functional independence when combined with early mobility. The objective of this study was to evaluate the impact of a stepwise, multidisciplinary analgesia-first sedation pathway and early mobility protocol on medication use and mobility in the neuroscience intensive care unit (ICU).

Methods

We performed a single-center prospective cohort study with adult patients admitted to a neuroscience ICU between March and June 2016-2018 who required MV for greater than 48 hours. Patients were included from three separate phases of the study: Phase I - historical controls (2016); Phase II - analgesia-first pathway (2017); Phase III - early mobility protocol (2018). Primary outcomes included propofol requirements during MV, total rehabilitation therapy provided, and functional mobility during ICU admission.

Results

156 patients were included in the analysis. Decreasing propofol exposure was observed during Phase I, II, and III (median 2243.7 mg/day vs 2065.6 mg/day vs 1360.8 mg/day, respectively; P = .04 between Phase I and III). Early mobility was provided in 59.7%, 40%, and 81.6% of patients while admitted to the ICU in Phase I, II, and III, respectively (P < .01). An increased proportion of patients in Phase III were walking or ambulating at ICU discharge (26.7%; 8/30) compared to Phase I (7.9%, 3/38, P = .05).

Conclusions

An interdisciplinary approach with an analgesia-first sedation pathway with early mobility protocol was associated with less sedative use, increased rehabilitation therapy, and improved functional mobility status at ICU discharge.

LXR-beta signalling is a key mediator in the pathogenesis of aortic valve stenosis and its prevention by saringosterol

Background

Cholesterol metabolism contributes as a risk factor for aortic valve stenosis (AS), but pharmacological approaches remained unsatisfying. The liver-X-receptor (LXR) is a key regulator in cholesterol metabolism, though its clinical use is limited due to unwanted side effects. The seaweed-derived oxysterol saringosterol is an agonist of the LXRβ, promising a more favourable tolerability.

Purpose

This study aimed to better understand the pathophysiology of aortic valve stenosis and to assess the potential of saringosterol as a targeted pharmacotherapy.

Methods

Tissue samples from aortic valves were collected from patients with AS or aortic valve regurgitation (AR). Transcriptomics were performed and gene ontology (GO) analysis was used to determine pathways and genes that are relevant to AS, and then validated using qPCR.

In vivo, mice received a wire-induced aortic valve stenosis and were either fed a diet supplemented with saringosterol or control diet. Haemodynamic characteristics were assessed using echocardiography. Additionally, hepatic concentrations of saringosterol, expression of LXRβ regulated genes as well as aortic valve thickness and composition were assessed.

In vitro, human aortic valve interstitial cells (VIC) were cultured in a procalcifing medium and stimulated with saringosterol to investigate the underlying molecular mechanisms.

Results

Transcriptomic analysis of AS samples revealed the regulation of several GO-terms related to cholesterol- or lipid metabolism. Many of the genes identified were regulated by LXRβ, suggesting its pathophysiological relevance in AS. We validated this assumption by performing qPCR from aortic valves for the most prominent downstream targets of LXRβ, ABCA1 and ABCG1, with both being differentially regulated.

In vivo, treatment with saringosterol for six weeks resulted in a significant accumulation of saringosterol in liver tissue as well as induction of LXRβ-regulated genes. Furthermore, treatment with saringosterol strikingly reduced the development of AS after wire injury as assessed by echocardiographic and histological measurements.

In vitro, the differentiation of VIC into osteoblastic and myofibroblastic phenotypes was abolished by saringosterol, which reduced the expression of the procalcifying mediators RUNX-2 and ACTA-2 in a dose-dependent manner.

Conclusion

We identified LXRβ-signalling as a key regulator in the pathophysiology of AS. Transcriptomic analyses revealed that cholesterol metabolism was altered in human AS, and many of the genes involved were linked to the LXRβ. In a murine model, we demonstrated that oral application of saringosterol induced LXRβ-activity and mitigated the development of AS. In vitro experiments demonstrated that saringosterol prevents adverse cell differentiation of VIC, which provides a mechanistic explanation.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): BONFOR Universität Bonn

Parameters predicting COVID-19-induced myocardial injury and mortality

Clinical manifestations of COVID-19 affect many organs, including the heart. Cardiovascular disease is a dominant comorbidity and prognostic factors predicting risk for critical courses are highly needed. Moreover, immunomechanisms underlying COVID-induced myocardial damage are poorly understood.

OBJECTIVE

To elucidate prognostic markers to identify patients at risk.

RESULTS

Only patients with pericardial effusion (PE) developed a severe disease course, and those who died could be identified by a high CD8/Treg/monocyte ratio. Ten out of 19 COVID-19 patients presented with PE, 7 (78%) of these had elevated APACHE-II mortality risk-score, requiring mechanical ventilation. At admission, PE patients showed signs of systemic and cardiac inflammation in NMR and impaired cardiac function as detected by transthoracic echocardiography (TTE), whereas parameters of myocardial injury e.g. high sensitive troponin-t (hs-TnT) were not yet increased. During the course of disease, hs-TnT rose in 8 of the PE-patients above 16 ng/l, 7 had to undergo ventilatory therapy and 4 of them died. FACS at admission showed in PE patients elevated frequencies of CD3⁺CD8⁺ T cells among all CD3+ T-cells, and lower frequencies of Tregs and CD14⁺HLA^-DR⁺-monocytes. A high CD8/Treg/monocyte ratio predicted a severe disease course in PE patients, and was associated with high serum levels of antiviral cytokines. By contrast, patients without PE and PE patients with a low CD8/Treg/monocyte ratio neither had to be intubated, nor died.

CONCLUSIONS

PE predicts cardiac injury in COVID-19 patients. Therefore, TTE should be performed at admission. Immunological parameters for dysfunctional antiviral immunity, such as the CD8/Treg/monocyte ratio used here, supports risk assessment by predicting poor prognosis.

Mechanisms of endothelial cell activation by endocannabinoid 2-arachidonoylglycerol

Background

Endothelial dysfunction promotes atherogenesis, vascular inflammation, and thrombus formation. Reendothelialization after angioplasty is required in order to restore vascular function and to prevent stent thrombosis. The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation. Earlier studies have demonstrated the relevance of this endocannabinoid in human pathophysiology during coronary artery disease and in murine experimental atherogenesis. However, evidence on the impact of 2-AG on endothelial cell function remains scarce.

Methods

Endothelial repair was studied in two treatment groups of wildtype mice following electrical denudation of the common carotid artery. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184, which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received DMSO. The residual endothelial gap at five days was visualized by Evan's blue staining in either group. In vitro, the effect of 2-AG on human coronary artery endothelial cell (HCAEC) viability was assessed by an XTT-based assay. Endothelial activation was studied by an adhesion assay of THP-1 monocytes to 2-AG-preconditioned HCAEC. Activation of HCAEC adhesion molecules was characterized by flow cytometry.

Results

Elevated 2-AG levels significantly impaired reendothelialization in wildtype mice following electrical injury of the common carotid artery, resulting in a residual denudation at 5 days of 2291±286 μm vs. 1505±223 μm (n=18–19; p&lt;0.05). In vitro, 2-AG significantly reduced viability of HCAEC at 24 hours (0.31±0.10 vs. 1.00±0.08; n=3; p&lt;0.01). Finally, 2-AG promoted HCAEC activation resulting in a significant increase in THP-1 monocyte adhesion to HCAEC following pre-treatment of HCAEC with 2-AG (0.17±0.03 THP-1 cells per HCAEC vs. 0.07±0.01 THP-1 cells per HCAEC; n=3; p&lt;0.05). Adhesion molecules E-selectin, ICAM-1 and VCAM-1, that are known to be regulated by 2-AG in the venous endothelium, remained unchanged in arterial endothelial cells. Besides, HCAEC migration, ROS-production, expression of NADPH oxidases and secretion of inflammatory cytokines were unaffected by 2-AG.

Conclusion

Elevated 2-AG levels hamper endothelial repair and impair HCAEC proliferation while facilitating adhesion of monocytes. Intriguingly, the underlying mechanisms in the arterial vascular bed appear distinct from venous endothelium. Given that 2-AG is elevated during coronary artery disease in humans, 2-AG might impair reendothelialization after angioplasty and thus impact on clinical outcomes.

Funding Acknowledgement

Type of funding source: None

Parameters predicting COVID-19-induced myocardial injury and mortality

Clinical manifestations of COVID-19 affect many organs, including the heart. Cardiovascular disease is a dominant comorbidity and prognostic factors predicting risk for critical courses are highly needed. Moreover, immunomechanisms underlying COVID-induced myocardial damage are poorly understood.

OBJECTIVE

To elucidate prognostic markers to identify patients at risk.

RESULTS

Only patients with pericardial effusion (PE) developed a severe disease course, and those who died could be identified by a high CD8/Treg/monocyte ratio. Ten out of 19 COVID-19 patients presented with PE, 7 (78%) of these had elevated APACHE-II mortality risk-score, requiring mechanical ventilation. At admission, PE patients showed signs of systemic and cardiac inflammation in NMR and impaired cardiac function as detected by transthoracic echocardiography (TTE), whereas parameters of myocardial injury e.g. high sensitive troponin-t (hs-TnT) were not yet increased. During the course of disease, hs-TnT rose in 8 of the PE-patients above 16 ng/l, 7 had to undergo ventilatory therapy and 4 of them died. FACS at admission showed in PE patients elevated frequencies of CD3⁺CD8⁺ T cells among all CD3+ T-cells, and lower frequencies of Tregs and CD14⁺HLA^-DR⁺-monocytes. A high CD8/Treg/monocyte ratio predicted a severe disease course in PE patients, and was associated with high serum levels of antiviral cytokines. By contrast, patients without PE and PE patients with a low CD8/Treg/monocyte ratio neither had to be intubated, nor died.

CONCLUSIONS

PE predicts cardiac injury in COVID-19 patients. Therefore, TTE should be performed at admission. Immunological parameters for dysfunctional antiviral immunity, such as the CD8/Treg/monocyte ratio used here, supports risk assessment by predicting poor prognosis.

P988Implantable cardioverter defibrillators in patients with electrical heart disease and hypertrophic cardiomyopathy - data from the German device Registry

Background

Implantable cardioverter- defibrillator (ICD) therapy is established for prevention of sudden cardiac death (SCD) in different entities. However, data from large patient cohorts on patients with electrical heart disease of hypertrophic cardiomyopathy (HCM) is rare. Therefore, we investigated these patients by analysing registry data from a multi-center “real-life” registry.

Methods

The German Device Registry (DEVICE) is a nationwide, prospective registry with one-year follow-up investigating 5450 patients receiving device implantations in 50 German centres. The present analysis of DEVICE focussed on patients with electrical heart disease or HCM who received an ICD for primary or secondary prevention.

Results

174 patients with HCM and 112 patients with electrical heart disease were compared with 5164 other ICD patients. Median follow-up was 17.0 months. Patients in the control group were significantly older. Of note, overall mortality after one year was 1.8% in HCM patients, 6.6% in patients with electrical heart disease and 7.3% in the control group. Patients in the control group presented significantly more severe comorbidities. In contrast to HCM patients and the control group where primary prevention was the major indication for ICD implantation 77.5% of patients with electrical heart disease received an ICD for secondary prevention. The number of surgical revisions was higher in patients with electrical heart disease.

Conclusion

Data from the present registry display a surprisingly high mortality in patients with electrical heart disease equivalent to the control group. A high proportion of patients who received an ICD for secondary prevention may be regarded as a major determinant for these results while severe comorbidities such as diabetes, hypertension and renal failure are major determinants for mortality in the control cohort.

P7142-AG impacts on endothelial cell activation and endothelial cell viability in vitro and impairs endothelial repair in vivo

Background

The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation and few studies have addressed its influence on myeloid cells in the context of atherogenesis. However, the impact of 2-AG on endothelial cell function has not been studied before.

Methods

Endothelial repair was studied in two treatment groups of wildtype mice following electrical denudation of the common carotid artery at a length of 3000 μm. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184 [5 mg/kg i.p.], which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received vehicle. The residual endothelial gap at five days in either group was visualized by Evan's blue staining. In vitro, the effect of 2-AG on human coronary artery endothelial cell (HCAEC) viability was assessed by an XTT-based assay. Endothelial activation was studied by an adhesion assay of THP-1 monocytes to 2-AG-preconditioned HCAEC. HCAEC migration, ROS-production, expression of NADPH oxidases, and secretion of inflammatory cytokines were assessed by Boyden chamber, qPCR, and colorimetric assays.

Results

Treatment with JZL184 produced a significant increase in 2-AG levels and impaired reendothelialisation in wildtype mice following electrical injury of the common carotid artery. The residual denudation at 5 days yielded 2291±286 μm in JZL184-treated animals vs. 1505±223 μm in vehicle treated controls (n=18–19; p<0.05). In vitro, JZL184 significantly reduced viability of HCAEC at 24 hours (0.31±0.10 vs. 1.00±0.08; n=3; p<0.01). Finally, 2-AG promoted HCAEC activation resulting in a significant increase in THP-1 monocyte adhesion to HCAEC following pre-treatment of HCAEC with 2-AG (0.17±0.03 THP-1 cells per HCAEC vs. 0.07±0.01 THP-1 cells per HCAEC; n=3; p<0.05). Besides, HCAEC migration, ROS-production, expression of NADPH oxidases and secretion of inflammatory cytokines were unaffected by 2-AG.

Conclusion

Elevated 2-AG levels appear to hamper endothelial repair and to promote HCAEC activation and cell death. Our data suggest that besides its influence on myeloid cells, 2-AG is also adverse to endothelial integrity which might promote early atherosclerotic lesion formation. Thus, decreasing vascular 2-AG levels might represent a promising therapeutic strategy for the prevention of atherosclerosis and coronary heart disease.

P720Atheroprotective effects of 17beta-estradiol are mediated by PPARgamma in human coronary artery smooth muscle cells

Background

17β-estradiol (E2) mediates vasculoprotection in various preclinical and clinical models of atherosclerosis and neointimal hyperplasia. However, the molecular mechanisms underlying these effects are still not fully elucidated. Previous studies have demonstrated the essential role of the peroxisome-proliferator-activated-receptor-γ (PPARγ) in mediating vasculoprotective effects of E2 in vivo. The aim of the current study was to investigate whether PPARγ is implicated in mediating vasculoprotective mechanisms of E2 in human coronary artery smooth muscle cells (HCASMC).

Methods

Primary HCASMC were purchased and stimulated with E2 [10 nM], the selective estrogen receptor α (ERα) agonist propylpyrazole triol (PPT) [50 nM] and the selective ERα antagonist methyl-piperidino-pyrazole (MPP) [1 μM], respectively. Changes in PPARγ mRNA and protein expression upon stimulation of ERα were assessed by qPCR and Western blot analyses. Nuclear PPARγ protein expression and DNA binding affinity was assessed after the isolation of the nuclear protein fraction. Hereafter, HCASMC were incubated with E2, PPARγ-antagonist GW9662 [1 μM – 30 μM], or both. HCASMC proliferation was assessed by nuclear BrdU staining and reactive oxygen species (ROS) formation was assessed by L-012- and DCF-DA assays.

Results

E2 significantly increased PPARγ expression in HCASMC (1.95±0.41 –fold; n=5; p=0.0335). This effect was mimicked by ERα agonist PPT (1.63±0.27 –fold; n=7; p=0.0489) and was abrogated by co-incubation with ERα antagonist MPP (1.17±0.18 –fold; n=3; pvs. control >0.05). Nuclear PPARγ expression was enhanced by E2 (1.53±0.16 –fold; n=4; pvs. control = 0.0074; Fig. 2A) whereas PPARγ's DNA binding activity to PPRE remained unchanged upon stimulation with E2 (0.94±0.11 –fold; n=4; pvs. control >0.05). Pharmacological inhibition of PI3K/Akt by LY294002 abrogated E2-induced expression of PPARγ (0.24±0.09 –fold; n=3; pvs. E2 = 0.0017), arguing for a PI3K/Akt-dependent activation by E2. The role of PPARγ in mediating vasculoprotective effects of E2 was assessed in functional assays using PPARγ-antagonist GW9662. E2 diminished HCASMC proliferation which was restored by GW9662. While E2 only slightly decreased ROS production by HCASMC, GW9662 significantly increased ROS levels (1,036±169 RLU x s–1 x cell–1 versus 561±99 RLU x s–1 x cell–1; n=5–6; p=0.0287).

Conclusion

In summary, the present study identifies PPARγ as a downstream mediator of E2-related atheroprotective effects in HCASMC. 17β-estradiol regulates vascular PPARγ-expression in HCASMC via the ERα receptor and the PI3K/Akt pathway. PPARγ agonism might be a promising therapeutic strategy to prevent cardiovascular events in postmenopausal women with depleted E2 plasma levels.

Acknowledgement/Funding

This work was supported by the Bonfor program of the University of Bonn [grant number O-109.0057 to JJ].

P4145Endothelial NLRP3-Inflammasome impairs vascular function via microparticles

Background

In recent years inflammation has emerged to the centre of attention of cardiovascular research. One of its key figures is the NLRP3-inflammasome a multimeric protein complex that stimulates inflammatory responses in atherogenesis through proinflammatory cytokines like caspases IL-1β and -18. It is activated by danger signals such as cholesterol crystals, oxidized LDL, ATP or uric acids. Microparticles (MP) are extracellular vesicles that are released by activated or apoptotic cells. They are known as a vector for the intercellular transfer of biological information. The body of evidence indicates that endothelial microparticles contribute to the development and complications in atherosclerosis. With this study we sought to elucidate the effects microparticles, that are discharged by inflammasome activated endothelial cells, exert on arterial vascular cells.

Methods and results

RTPCR experiments showed that activation of human coronary artery endothelial cells (HCAEC) with LPS and Nigericin leads to NLRP3-inflammasome-specific upregulation of NLRP3 and IL1β. Analysis of the supernatant of aforementioned cells via westernblot revealed release of cleaved caspase-1 while donorcells undergo pyroptosis. FACS and electronmicroscopy experiments revealed time dependent release of endothelial microparticles (EMP) by inflammasome activated HCAEC, while western blot demonstrated that EMP enclose active caspase-1. Fluorescence microscopic imaging illustrated time dependent incorporation of EMP by HCAEC. Stimulation of HCAEC with EMP revealed detrimental biological effects on recipient cells as viability assay and scratch assay showed decreased viability and proliferation/ migration, cytotoxity assay showed increased cytotoxity and RT-PCR experiments showed increased expression of NALP3, IL-1b, VCAM and ICAM. The fact that treatment of recipient cells with the NLRP3-Inhibitor isoliquiritigenin (ILG), heat-inactivation of EMP and rupturing the EMP-membrane by freezing is able to diminish harmful effects EMP exert on recipient cells shown by viability assay, scratch assay and microscopic imaging underlines detrimental effects being exerted by EMP-encapsuled inflamasome-components.

Conclusion

Our findings verify that MP released from inflammasome-activated endothelial cells are incorporated by vascular cells which in turn sustain a reduction of cell viability, migration and proliferation. EMP effectuate activation of the NLRP3-inflammasme in their target cells. The cytotoxic effects of EMP are suppressed by inhibitors of the NLRP3-inflammasome and affection of EMP-membrane. Our results emphasize the immunological role of endothelial cells and indicate that inflammasome activation is transferable through microparticle-associated communication. This in turn facilitates cell death and possibly initiates a vicious cycle of inflammation suggesting a role in the advancement of atherosclerosis.

Acknowledgement/Funding

Else Kröner Scholarship

P4140Myeloid but not endothelial expression of the CB2 receptor promotes atherogenesis in the context of elevated levels of the endocannabinoid 2-arachidonoylglycerol

Background

The endocannabinoid 2-arachidonoylglycerol (2-AG) is an inflammatory mediator and ligand to the cannabinoid receptors CB1 and CB2, which are expressed on myeloid and endothelial cells. 2-AG has recently been described to promote atherogenesis in ApoE-deficient mice. While the CB2 receptor has previously been considered to solely exert anti-inflammatory and atheroprotective effects, newer data have raised the notion, that CB2 might exert atherogenic effects in the context of elevated 2-AG plasma levels. In the present study, we investigated the atherogenic mechanisms of 2-AG and the role of the CB2 receptor on myeloid and endothelial cells in atherogenesis using cell-specific knockout mouse models.

Methods

Two mouse models with atherogenic background and distinct cell-specific knockouts of the CB2 receptor on myeloid (ApoE−/−LysMcreCB2fl/fl) or endothelial cells (ApoE−/−Tie2creCB2fl/fl) were created. Mice were treated with JZL184, which inhibits 2-AG-degrading enzyme monoacylglycerol lipase, and thereby elevates 2-AG plasma levels, or with vehicle (DMSO), while being fed a high-fat diet for four weeks. Plaque volume and plaque composition were analyzed. In vitro, macrophages were treated with 2-AG and mRNA levels of adhesion molecules, scavenger receptors and chemokines, the production of reactive oxygen species (ROS) and the release of myeloperoxidase (MPO) were determined using qPCR, fluorometric assays and ELISA respectively.

Results

Elevated levels of 2-AG promote atherogenesis in ApoE-deficient mice (JZL184 vs. DMSO: 39.6±2.1% vs. 32.6±2.4%; n=14; p<0.05). The atherogenic effect of 2-AG is abrogated in mice lacking myeloid CB2 receptor expression (35.0±2.0% vs. 34.0±2.5%; n=14–16; p>0.05) but not in mice lacking endothelial CB2 receptor expression (37.1±3.1% vs. 20.9±2.6%; n=10–12; p<0.01). In vitro, 2-AG significantly increases transcription of adhesion molecule ICAM-1 (2.09±0.42 –fold; n=5–6; p<0.05), chemokine receptor CCR-1 (2.04±0.46 -fold; n=10–11; p<0.05) and scavenger receptor CD36 (8.02±1.89-fold; n=3; p<0.05) in 2-AG-treated macrophages. These effects are mitigated by pharmacological inhibition of CB2. Furthermore, 2-AG significantly increases myeloperoxidase (MPO) release in monocytes in a CB receptor-dependent fashion (451±23 pg/ml vs. 151±8.3 pg/ml; n=3–4; p<0.01) and promotes ROS production (2698±24 pdu vs. 1981±27 pdu; n=8; p<0.01).

Conclusion

Elevated 2-AG levels show an atherogenic effect in vivo which is dependent on the presence of the CB2 receptor on myeloid cells. Our in vitro data reveal 2-AG to promote pro-inflammatory signaling in macrophages and elucidate a previously unrecognized link between the endocannabinoid system and MPO in monocytes. In summary, cell-specific effects of the endocannabinoid system will have to be taken into account to facilitate its exploitation as an anti-atherosclerotic drug target.

Acknowledgement/Funding

This work was supported by the Bonfor program of the University of Bonn [grant number O-109.0057 to JJ].

Mechanisms of zolpidem-induced long QT syndrome: acute inhibition of recombinant hERG K(+) channels and action potential prolongation in human cardiomyocytes derived from induced pluripotent stem cells

BACKGROUND AND PURPOSE

Zolpidem, a short-acting hypnotic drug prescribed to treat insomnia, has been clinically associated with acquired long QT syndrome (LQTS) and torsade de pointes (TdP) tachyarrhythmia. LQTS is primarily attributed to reduction of cardiac human ether-a-go-go-related gene (hERG)/I(Kr) currents. We hypothesized that zolpidem prolongs the cardiac action potential through inhibition of hERG K(+) channels.

EXPERIMENTAL APPROACH

Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record hERG currents from Xenopus oocytes and from HEK 293 cells. In addition, hERG protein trafficking was evaluated in HEK 293 cells by Western blot analysis, and action potential duration (APD) was assessed in human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes.

KEY RESULTS

Zolpidem caused acute hERG channel blockade in oocytes (IC(50) = 61.5 μM) and in HEK 293 cells (IC(50) = 65.5 μM). Mutation of residues Y652 and F656 attenuated hERG inhibition, suggesting drug binding to a receptor site inside the channel pore. Channels were blocked in open and inactivated states in a voltage- and frequency-independent manner. Zolpidem accelerated hERG channel inactivation but did not affect I-V relationships of steady-state activation and inactivation. In contrast to the majority of hERG inhibitors, hERG cell surface trafficking was not impaired by zolpidem. Finally, acute zolpidem exposure resulted in APD prolongation in hiPSC-derived cardiomyocytes.

CONCLUSIONS AND IMPLICATIONS

Zolpidem inhibits cardiac hERG K(+) channels. Despite a relatively low affinity of zolpidem to hERG channels, APD prolongation may lead to acquired LQTS and TdP in cases of reduced repolarization reserve or zolpidem overdose.

Regulation of apoptosis in HL-1 cardiomyocytes by phosphorylation of the receptor tyrosine kinase EphA2 and protection by lithocholic acid

BACKGROUND AND PURPOSE

Heart failure and atrial fibrillation are associated with apoptosis of cardiomyocytes, suggesting common abnormalities in pro-apoptotic cardiac molecules. Activation of the receptor tyrosine kinase EphA2 causes apoptosis in vitro, and dysregulation of EphA2-dependent signalling is implicated in LEOPARD and Noonan syndromes associated with cardiomyopathy. Molecular pathways and regulation of EphA2 signalling in the heart are poorly understood. Here we elucidated the pathways of EphA2-dependent apoptosis and evaluated a therapeutic strategy to prevent EphA2 activation and cardiac cell death.

EXPERIMENTAL APPROACH

EphA2 signalling was studied in an established model of doxazosin-induced apoptosis in HL-1 cells. Apoptosis was measured with TUNEL assays and as cell viability using a formazan method. Western blotting and siRNA for EphA2 were also used.

KEY RESULTS

Apoptosis induced by doxazosin (EC(50) = 17.3 μM) was associated with EphA2 activation through enhanced phosphorylation (2.2-fold). Activation of pro-apoptotic downstream factors, phospho-SHP-2 (3.9-fold), phospho-p38 MAPK (2.3-fold) and GADD153 (1.6-fold) resulted in cleavage of caspase 3. Furthermore, two anti-apoptotic enzymes were suppressed (focal adhesion kinase, by 41%; phospho-Akt, by 78%). Inactivation of EphA2 with appropriate siRNA mimicked pro-apoptotic effects of doxazosin. Finally, administration of lithocholic acid (LCA) protected against apoptosis by increasing EphA2 protein levels and decreasing EphA2 phosphorylation.

CONCLUSIONS AND IMPLICATIONS

EphA2 phosphorylation and activation of SHP-2 are critical steps in apoptosis. Reduction of EphA2 phosphorylation by LCA may represent a novel approach for future anti-apoptotic treatment of heart failure and atrial fibrillation.

Effects of anesthesia on functional activation of cerebral blood flow and metabolism

Functional brain mapping based on changes in local cerebral blood flow (lCBF) or glucose utilization (lCMR(glc)) induced by functional activation is generally carried out in animals under anesthesia, usually alpha-chloralose because of its lesser effects on cardiovascular, respiratory, and reflex functions. Results of studies on the role of nitric oxide (NO) in the mechanism of functional activation of lCBF have differed in unanesthetized and anesthetized animals. NO synthase inhibition markedly attenuates or eliminates the lCBF responses in anesthetized animals but not in unanesthetized animals. The present study examines in conscious rats and rats anesthetized with alpha-chloralose the effects of vibrissal stimulation on lCMR(glc) and lCBF in the whisker-to-barrel cortex pathway and on the effects of NO synthase inhibition with N(G)-nitro-L-arginine methyl ester (L-NAME) on the magnitude of the responses. Anesthesia markedly reduced the lCBF and lCMR(glc) responses in the ventral posteromedial thalamic nucleus and barrel cortex but not in the spinal and principal trigeminal nuclei. L-NAME did not alter the lCBF responses in any of the structures of the pathway in the unanesthetized rats and also not in the trigeminal nuclei of the anesthetized rats. In the thalamus and sensory cortex of the anesthetized rats, where the lCBF responses to stimulation had already been drastically diminished by the anesthesia, L-NAME treatment resulted in loss of statistically significant activation of lCBF by vibrissal stimulation. These results indicate that NO does not mediate functional activation of lCBF under physiological conditions.

[Circular hemorrhagic subendocardial necrosis after heart arrest and resuscitation]

A 19 year old boy, previously healthy suffered a cardiac arrest by getting up. Ten minutes afterwards the general practitioner commenced cardiopulmonary resuscitation, 15 minutes later ventricular fibrillation developed and the emergency physician carried out intubation and repeated defibrillation. During the next few hours a stabilization of the circulatory system was achieved. Five days after the cardiac arrest brain death occurred. The postmortem findings on the heart (only a heart section was performed) showed extensive circular hemorrhagic subendocardial necrosis with initial organization of the left ventricular wall and the septum with a well-preserved subendocardial area. In the right ventricular wall only a few small areas of organization were observed. All lesions were consistent with the cardiac arrest suffered 5 days previously. The morphological changes differ from those of a usual hemorrhagic infarction and of the sequences of a cardiopulmonary resuscitation. The circular subendocardial necroses occur after a cardiac arrest which exceeds the resuscitation time of the heart. They do not respect the area of coronary distribution and their hemorrhagic component develops after successful reanimation within the necrotic myocardium.

Direct percutaneous transluminal coronary angioplasty in acute myocardial infarction. Predictors of short-term outcome and the impact of coronary stenting. Study Group of The Arbeitsgemeinschaft Leitender Kardiologischer Krankenhausärzte (ALKK)

BACKGROUND

Direct percutaneous transluminal coronary angioplasty (PTCA) is widely accepted in the treatment of acute myocardial infarction since excellent results had been reported from several small randomized trials. Less favourable results were observed in large-scale registries. In particular, the use of stents in acute myocardial infarction has become common practice without documented evidence of clinical efficacy.

METHODS

Data were analysed from a registry of all consecutive percutaneous transluminal coronary angioplasty procedures from 62 centres in Germany, including 2331 direct percutaneous transluminal coronary angioplasty in acute myocardial infarction from July 1994 to April 1997.

RESULTS

The overall angiographic success rate of percutaneous transluminal coronary angioplasty, defined as complete antegrade perfusion of the infarct vessel, was 87%. In-hospital mortality was 11.2%. The most important predictor of death was the presence of cardiogenic shock in 15% of patients, of whom 52% died. Mortality in patients without shock was 3.9%. Failed percutaneous transluminal coronary angioplasty was associated with a mortality of 36%. Further independent predictors of death were older age, multivessel disease, and anterior myocardial infarction. Stents were used in 4.1% of the procedures in 1994, increasing to 53% in 1997. However, this was not accompanied by improved clinical outcome. Mortality with coronary stenting was 9.9% vs 11.6% without stents (ns).

CONCLUSIONS

Direct percutaneous transluminal coronary angioplasty is a valuable treatment strategy in acute myocardial infarction, although the results are less exceptional than reported from some highly specialized centres. Failed percutaneous transluminal coronary angioplasty seems to be harmful, thus outweighing much of the benefit from successful procedures. Stents did not improve the clinical outcome significantly, despite technically successful placement in 98%. Mortality from cardiogenic shock continues to be excessively high despite direct PTCA.

Blockade of cerebral blood flow response to insulin-induced hypoglycemia by caffeine and glibenclamide in conscious rats

The possibility that adenosine and ATP-sensitive potassium channels (KATP) might be involved in the mechanisms of the increases in cerebral blood flow (CBF) that occur in insulin-induced hypoglycemia was examined. Cerebral blood flow was measured by the [14C]iodoantipyrine method in conscious rats during insulin-induced, moderate hypoglycemia (2 to 3 mmol/L glucose in arterial plasma) after intravenous injections of 10 to 20 mg/kg of caffeine, an adenosine receptor antagonist, or intracisternal infusion of 1 to 2 mumol/L glibenclamide, a KATP channel inhibitor. Cerebral blood flow was also measured in corresponding normoglycemic and drug-free control groups. Cerebral blood flow was 51% higher in untreated hypoglycemic than in untreated normoglycemic rats (P < 0.01). Caffeine had a small, statistically insignificant effect on CBF in normoglycemic rats, but reduced the CBF response to hypoglycemia in a dose-dependent manner, i.e., 27% increase with 10 mg/kg and complete elimination with 20 mg/kg. Chemical determinations by HPLC in extracts of freeze-blown brains showed significant increases in the levels of adenosine and its degradation products, inosine and hypoxanthine, during hypoglycemia (P < 0.05). Intracisternal glibenclamide had little effect on CBF in normoglycemia, but, like caffeine, produced dose-dependent reductions in the magnitude of the increases in CBF during hypoglycemia, i.e., +66% with glibenclamide-free artificial CSF administration, +25% with 1 mumol/L glibenclamide, and almost complete blockade (+5%) with 2 mumol/L glibenclamide. These results suggest that adenosine and KATP channels may play a role in the increases in CBF during hypoglycemia.

Examination of potential mechanisms in the enhancement of cerebral blood flow by hypoglycemia and pharmacological doses of deoxyglucose

Cerebral blood flow (CBF) rises when the glucose supply to the brain is limited by hypoglycemia or glucose metabolism is inhibited by pharmacological doses of 2-deoxyglucose (DG). The present studies in unanesthetized rats with insulin-induced hypoglycemia show that the increases in CBF, measured with the [14C]iodoantipyrine method, are relatively small until arterial plasma glucose levels fall to 2.5 to 3.0 mM, at which point CBF rises sharply. A direct effect of insulin on CBF was excluded; insulin administered under euglycemic conditions maintained by glucose injections had no effects on CBF. Insulin administration raised plasma lactate levels and decreased plasma K+ and HCO3- concentrations and arterial pH. These could not, however, be related to the increased CBF because insulin under euglycemic conditions had similar effects without affecting CBF; furthermore, the inhibition of brain glucose metabolism with pharmacological doses (200 mg/kg intravenously) of DG increased CBF, just like insulin hypoglycemia, without altering plasma lactate and K+ levels and arterial blood gas tensions and pH. Nitric oxide also does not appear to mediate the increases in CBF. Chronic blockade of nitric oxide synthase activity by twice daily i.p. injections of NG-nitro-L-arginine methyl ester for 4 days or acutely by a single i.v. injection raised arterial blood pressure and lowered CBF in normoglycemic, hypoglycemic, and DG-treated rats but did not significantly reduce the increases in CBF due to insulin-induced hypoglycemia (arterial plasma glucose levels, 2.5-3 mM) or pharmacological doses of deoxyglucose.

Lack of effects of inhibition of nitric oxide synthesis on local glucose utilization in the rat brain

The effects of chronic treatment with NG-nitro-L-arginine methyl ester, a potent inhibitor of nitric oxide synthase activity, on local cerebral glucose utilization were examined in conscious rats. Intraperitoneal injections of 50 mg/kg of the nitroarginine twice daily for 4 days have been found to result in almost complete inhibition of nitric oxide synthase activity in brain. Local cerebral glucose utilization was determined by means of the quantitative autoradiographic [14C]deoxyglucose method in an experimental group (n = 7) of rats that were treated with the nitroarginine according to this schedule and in a normal control group (n = 7) treated similarly with saline. The rats were conscious but partially restrained during the determinations of local cerebral glucose utilization. The nitroarginine treatment raised mean arterial blood pressure statistically significantly to 147 +/- 3 mm Hg (mean +/- SEM) from a level of 120 +/- 5 mm Hg in the saline controls (p < 0.001 by grouped t test), but there were no statistically significant effects on glucose utilization in any of 39 brain structures examined. It is concluded that nitric oxide normally exerts no significant influence on energy metabolism in the rat brain.

Preservation of autoregulatory cerebral vasodilator responses to hypotension after inhibition of nitric oxide synthesis

Effects of inhibition of nitric oxide (NO) synthesis on the cerebrovascular autoregulatory vasodilator response to hypotension were studied in conscious rats. Cerebral blood flow (CBF) was determined with [14C]iodoantipyrine in a saline-treated control group and in three groups following inhibition of NO synthase activity by twice daily intraperitoneal injections of 50 mg/kg of NG-nitro-L-arginine methyl ester (L-NAME) for four days. In the saline-control group (n = 8) and in the L-NAME-treated Group (a) (n = 8) CBF was determined while systemic mean arterial blood pressure (MABP) remained at its resting level (means +/- S.D., 128 +/- 6 and 151 +/- 11 mmHg, respectively). In the other groups CBF was determined after MABP was reduced by blood withdrawal to 118 +/- 9 and 88 +/- 8 mmHg in Groups (b) (n = 8) and (c) (n = 8), respectively. Despite the elevated MABP, global CBF was significantly lower in L-NAME-treated Group (a) than in the saline-controls (P < 0.005), indicating cerebral vasoconstriction resulting from inhibition of NO synthesis. Global CBF was not significantly reduced further in the two groups with hypotension. Local CBF in the hypotensive rats showed no significant reductions below values in L-NAME-treated control rats (Group (a)) in 31 of 32 brain structures; the only exception was in the auditory cortex of the severely hypotensive rats (Group (c)). The autoregulatory mechanism for cerebral vasodilatation to compensate for reduced arterial blood pressure is maintained following inhibition of NO synthesis.

Rates of local cerebral protein synthesis in the rat during normal postnatal development

The degree of recycling of leucine derived from protein breakdown into the precursor pool for protein synthesis was measured in rat brain at different postnatal ages, and age-specific values were used in the calculation of regional (local) rates of cerebral leucine incorporation into protein (lCPSleu) in 44 brain regions and the brain as a whole. Early in development, a greater fraction of the precursor leucine pool is derived from protein breakdown, indicating that protein degradation is higher in young rats compared with adults. In whole brain and in most regions, values for lCPSleu were highest at 10 days and gradually decreased with age. By 60 days of age, values in cortex were approximately 60% of those at 10 days of age. In the paraventricular and supraoptic nuclei of the hypothalamus, however, lCPSleu increased during development, reaching peak values in adults. In white matter of the cerebellum and the cerebrum, peaks of lCPSleu were reached at 14 and 21 days, respectively, approximately at the times of maximum rates of myelination.

Role of the cerebellar fastigial nucleus in the physiological regulation of cerebral blood flow

Local cerebral blood flow (ICBF) was measured with [14C]iodoantipyrine in conscious, unrestrained rats during electrical stimulation of the fastigial nucleus (FN). Electrode position in the FN was determined by blood pressure (MABP) responses to stimulation under anesthesia. In nine rats in which MABP responses had been variable under anesthesia, bipolar stimulation (50 Hz, 0.5 ms, 1 s on/1 s off) with currents of 30-100 microA after recovery from anesthesia produced stereotypic behavior but little effect on MABP and ICBF. In seven other conscious rats currents could be raised to 75-200 microA without inducing seizures, resulting in sustained MABP elevations during the ICBF measurement and significantly increased ICBF in the sensory-motor (+45%), parietal (+31%), and frontal cortices (+56%) and the caudate-putamen (+27%) above control values (n = 9). Glucose utilization, measured with [14C]deoxyglucose, in rats similarly stimulated was significantly increased in six structures, including some of the above, indicating increases in ICBF due to metabolic activation. Unilateral or bilateral electrolytic lesions of the FN, placed 6-7 days before ICBF measurement, had negligible effects on resting ICBF and on autoregulation in conscious rats. These results fail to support a specific role for the FN in physiological regulation of cerebral blood flow in unanesthetized rats.

[Correlations between arrhythmias and left ventricular function at rest and during stress in patients with postinfarct aneurysm]

The results (clinical, hemodynamic, and angiographic data) of 197 patients with left ventricular anterior wall aneurysm were evaluated at rest and during exercise (bicycle ergometer) 6 months after the acute infarction. Using the technique of digital subtraction angiography, left ventricular volumes were estimated after injection of contrast medium into the pulmonary artery and measuring of pulmonary artery pressure. In 136 patients a programmed right ventricular stimulation was performed additionally. The patients were divided into the following groups: patients with (VT+) and without (VT-) ventricular arrhythmias in history. Group VT- was subdivided in patients with positive (RV+) or negative (RV-) result of right ventricular stimulation. In group VT+ chamber volumes were greater and ejection fraction was smaller than in group VT-. At rest the results of subgroup RV+ were similar to group VT+, but during exercise similar to group RV-. These results show that left ventricular function at rest and during exercise is much more impaired in patients with spontaneous and by stimulation-induced arrhythmias than in patients without these arrhythmias. The conclusions for clinical practice of these findings are not yet clear, concerning, for example, the prophylactic use of antiarrhythmic measurements in patients without spontaneous but with induced arrhythmias. Further investigations (long-term follow-ups of these patients) will be necessary.

[Malignant hemangioendotheliosarcoma in the area of the right coronary artery: imaging by selective coronary angiography]

We report on a case of a malignant hemangioendotheliosarcoma in the right coronary artery. The first manifestation was a pericardial tamponade from a hemorrhagic pericardial effusion. The diagnosis was established only by selective coronary angiography of the right coronary artery, other imaging procedures did not lead to the diagnosis. During follow-up, multiple angiosarcoma developed in the liver, the spleen and, finally, in the lungs. Despite multichemotherapy, the patient died 7 months after the first manifestation.

[The determination of myocardial perfusion parameters from coronary angiograms by analysing the passage of contrast media through the myocardium]

Digital subtraction angiography allows to record the passage of contrast material through the myocardium as a time-intensity curve, the so-called densogram. Temporal changes of contrast material in a region of interest are described by a differential equation. The free parameters of this model equation are determined by a curve-fitting procedure. Four parameters of the model equation are expected to be connected with myocardial perfusion. We intended to verify this assumption by comparing changes in coronary blood flow (CBF) with changes of the different parameters. The angiograms of 9 patients without coronary artery disease were studied before and after intravenous application of dipyridamole. Changes in CBF were assessed by a videodensitometric method. Linear regressions between changes of CBF and the parameters of the differential equation show the following results: one parameter of the model equation--the ratio of regional blood flow and regional volume--remarkably underestimated CBF changes. This can be explained by an increase of regional blood volume after increased CBF due to dipyridamole. However, a close correlation was found between CBF changes and the remaining parameters. This study suggests that digital measurements from coronary angiograms using the presented model equation provide a means of assessing myocardial perfusion.

[The reliability of angiographic volume determination of the left ventricle using digital image subtraction--significance in stress tests]

Using the technique of digital subtraction angiography (DSA), left ventricular volumes can be determined after intravenous injection of contrast medium at rest and during exercise. The significance of the well known errors of angiographic determination of left ventricular volumes was investigated in 22 patients before and during a bicycle exercise test. Before and after exercise 40 ml of contrast medium were injected (18 ml/s) intravenously to calculate left ventricular volumes. Enddiastolic and endsystolic contours of the left ventricle were traced by two investigators (A and B) on five different days. Using these contours, volumes were calculated by a computer system. The first calculation of both investigators (single measurement) and the mean value of all five calculations (repetitive measurements) were compared. In the same procedure left ventricular contours of six patients were calculated after conventional contrast ventriculography (40 ml of contrast medium). No systematic deviations were found in comparing the results of both investigators using the single or repetitive method by means of DSA: (VolB = 0.86 VolA + 12.2, r = 0.97 versus VolB = 0.96 VolA + 9.1, r = 0.99). Compared to single method the residuals (Syx) of the repetitive method were significantly smaller: Syx = +/- 16.3 ml vs +/- 8.9 ml (p less than 0.01). Similar results were found in conventional ventriculography: single method Syx = +/- 18.7 ml and repetitive method Syx = +/- 8.8 ml (p less than 0.01). Comparing the volumes determined by DSA and by conventional ventriculography, respectively, no significant differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of local cerebral blood flow with [14C]iodoantipyrine in the mouse

Local cerebral blood flow was measured in the mouse by means of the [14C]iodoantipyrine method. This method has been previously used in the monkey, dog, cat, and rat, but its application to small mammals such as the mouse requires special attention to potential sources of error. The small size of the mouse brain requires special attention to the rapid removal and freezing of the brain to minimize effects of postmortem diffusion of tracer in the tissue. Because of the relatively low diameter/length ratios of the catheters needed for arterial sampling in small animals, substantial errors can occur in the determination of the time course of the [14C]iodoantipyrine concentration in the arterial blood unless corrections for lag time and dead space washout in the catheter are properly applied. Local cerebral blood flow was measured in seven awake mice with appropriate care to minimize these sources of error. The values were found to vary from 48 ml/100 g/min in the corpus callosum to 198 ml/100 g/min in the inferior colliculus. The results demonstrate that the [14C]iodoantipyrine method can be used to measure local cerebral blood flow in the mouse and that the values in that species are, in general, somewhat higher than those in the rat.

[Indications for coronary angiography in patients with acquired heart valve diseases with reference to risk factors]

The aims of the study were to examine the frequency of coronary artery disease (CAD) in patients with acquired valvular heart disease and to investigate the parameters by which significant coronary artery stenosis can be identified without invasive measures in these patients. For this reason 266 consecutive patients with acquired valvular heart disease (aortic, mitral or combined lesions) were examined retrospectively. In 24 patients (9%) a significant (50% or more reduction of the diameter) coronary artery stenosis was found. The prevalence of CAD increased with age: only one patient younger than 50 years, but 23 patients (13%) older than 50 years revealed significant CAD (19% men, 7% women). Increased levels of cholesterol and/or triglycerides were found more frequently in patients with CAD (33% and 29%, respectively) than in those without (6% and 12%, respectively). No differences were found in patients with aortic and mitral valve disease. Patients with typical chest pain revealed CAD in 30% of cases, whereas only 5% of the patients without angina pectoris (or 4% with atypical chest pain) showed a significant coronary artery stenosis. A high percentage (62%) of patients with typical chest pain and mitral valve disease revealed CAD. None of the 77 female patients without typical angina pectoris had significant coronary artery stenosis, whereas 11% of the male patients showed significant CAD even without typical symptoms. In 51 patients without typical angina pectoris and with no risk factors, no CAD was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

[Systolic and diastolic blood flow velocities in the left coronary artery before and following i.v. dipyridamole. Comparative measurements using a digital image processing in 2 unstenosed vessel branches]

The hemodynamic significance of coronary artery stenoses cannot be assessed by presently-used methods. Especially stenoses of small and moderate degree only reveal hemodynamic relevance during augmentation of coronary flow. It can be expected that the increase in flow is limited in a stenotic branch, compared with an unstenosed branch of the same vessel. The increase in coronary blood flow in two unstenosed branches of the same vessel, however, should be nearly identical. To prove this hypothesis, the relative increase in coronary flow was measured in two unstenosed branches of the left coronary artery by means of digital subtraction angiocardiography. Ten patients were examined before and after intravenous administration of 20 mg (on average 0.29 mg/kg body weight) dipyridamole. Dipyridamole resulted in an increase in the diameter of the left anterior descending branch (LAD) of 11% (p less than 0.005) and of the circumflex artery (RCx) of 13% (p less than 0.005). The increase in flow velocity during systole amounted to 49% in the LAD (p less than 0.001) and to 58% in the RCx (p less than 0.005); during diastole to 60% in the LAD (p less than 0.005) and 83% in the RCx (p less than 0.005). The increase in volume flow during systole amounted to 78% in the LAD (p less than 0.005) and to 89% in the RCx (p less than 0.005), during diastole to 84% in the LAD (p less than 0.005) and to 113% in the RCx (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

[Results of coronary revascularization in occluded coronary arteries]

In a total of 82 patients (age 37-71 years) with an occluded left anterior descending artery (LAD) the results of coronary revascularization were evaluated 7 months postoperatively on average. In all patients the indications for revascularization was given by clinical symptoms (angina pectoris) or by prognostic reasons. In patients with multivessel disease. In patients with anterior wall infarction viable myocardium was proven by thallium-scintigram at rest and during exercise. 29 patients were evaluated by coronary angiography postoperatively, in 19 patients the angiograms of the left ventricle could be assessed quantitatively. Total patency rate was 76%, for the LAD 69%, for the circumflex artery 73% and for the right coronary artery 83%. The relatively low patency rate for the LAD was caused by an increased collateral flow to the occluded LAD and therefore by a significantly lower bypass flowrate measured during surgery. Angina pectoris improved markedly, 55% of patients had angina pectoris class III or IV versus 10% postoperatively. These changes were observed in all patients irrespectively of patency rate or occluded grafts to the LAD. Left ventricular volumes and ejection fraction did not change on average after revascularization. Only end-diastolic volume increased significantly in patients with an occluded graft to the LAD. There was a tendency of the end-systolic volume to decrease postoperatively in patients with complete revascularization or at least an open graft to the LAD. The results show a similar clinical improvement in these patients with occluded LAD as shown after "usual" revascularization in other patients. Preoperative coronary angiograms are helpful in judging the postoperative outcome of grafts to the occluded LAD.

[Percutaneous transluminal coronary angioplasty: determination of left ventricular function in physical stress using intravenous digital subtraction angiocardiography]

24 patients with coronary artery disease underwent intravenous digital subtraction angiocardiography at rest and during exercise before and after percutaneous transluminal coronary angioplasty (PTCA). Before PTCA mean pulmonary artery pressure increased pathologically in 20 patients (on average from 22 +/- 4 to 40 +/- 9 mm Hg, p less than 0.001). The increase in cardiac index from 4.2 +/- 1.3 to 6.2 +/- 2.01 I X min-1 X m-2 (p less than 0.01) was achieved by an increase in heart rate from 77 +/- 13 to 119 +/- 16 min-1 (p less than 0.001) as stroke volume remained unchanged during exercise (52 +/- 14 ml X m-2, resting value: 53 +/- 13 ml X m-2). Though end-systolic volume increased from 32 +/- 11 to 41 +/- 13 ml X m-2 (p less than 0.001) and ejection fraction fell from 63 +/- 8% to 56 +/- 10% (p less than 0.005), stroke volume remained unchanged due to an enhanced diastolic filling (EDVI: 86 +/- 19 ml X m-2 at rest, 92 +/- 18 ml X m-2 during exercise, p less than 0.001). After angiographically successful PTCA in 21 of 24 patients average mean pulmonary artery pressure during exercise remained pathologically elevated (36 +/- 9 mm Hg, no significant difference from value before PTCA). It normalized in only 6 of 17 patients. On the other hand there was a marked improvement of left ventricular systolic performance. Ejection fraction during exercise (65 +/- 11%) was higher than before PTCA (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Evaluation of myocardial perfusion based on digital subtraction angiocardiography measured contrast medium flow times]

The purpose of this study was to discover whether myocardial perfusion can be determined quantitatively by digital subtraction angiocardiography from the passage of contrast medium through the myocardium. Cineangiograms (duration 20 s) were obtained during routine coronary angiography and analyzed by means of a computerized image processing system. Regional myocardial contrast intensity was plotted versus time as a densogram for quantitative assessment. The parameter "medium rise time" showed a good reproducibility (r = 0.92). The average of medium rise time was 2.9 s in well-perfused areas, 3.7 s in less perfused areas, 5.2 s in areas with markedly reduced perfusion and 5.8 s for perfusion defects or scars using Tl-201 scintigrams as reference. The differences between the four groups were significant except between areas of markedly reduced perfusion and perfusion defects or scars (p less than 0.05). The correlation of medium rise time to the extent of the stenosis of the coronary vessel supplying the corresponding myocardial region revealed that the medium rise time on an average was 3.2 s distal to unstenosed vessels, 3.2 s distal to slightly stenosed vessels, 5.4 s distal to highly stenosed vessels and 4.7 s distal to vessel occlusion. The differences between the groups were not significant except between the groups of patients with low and high-grade coronary stenoses. These results indicate that the parameter "medium rise time" of the intensity-time curves determined by digital image processing provides a quantitative assessment of myocardial perfusion from cineangiograms.

[Transprosthetic catheterization of a Björk-Shiley aortic prosthesis with fatal outcome]

Retrograde transprosthetic catheterization of a Björk-Shiley aortic prosthesis (type ABP) using a Sones catheter resulted in sticking of the tilting disc. Every attempt to withdraw the catheter failed and the patient died before he could be transferred for emergency reoperation. We advise against transprosthetic catheterization of tilting or bileaflet prostheses, which has been reported to be easily to perform without apparent risk. If left ventricular catheterization is mandatory after aortic valve replacement, the transseptal approach should be used. This is the only procedure which permits accurate evaluation of the functioning of the prosthesis or a concomitant mitral valve disease.

[Qualitative evaluation of myocardial perfusion using digital subtraction angiocardiography]

The purpose of this study was to discover whether the passage of contrast medium through the myocardium can be visualized by digital subtraction angiocardiography and whether myocardial perfusion can be determined qualitatively from the difference images. Cineangiograms (duration 20 s) were obtained during routine coronary angiography and analyzed by means of a computerized image processing system. The results show that the passage of contrast medium through the coronary artery system, myocardium and coronary veins can be visualized. In 10 patients myocardial perfusion at rest was classified qualitatively into four categories (well perfused, slightly reduced perfusion, markedly reduced perfusion and perfusion defect) from local contrast intensity and the time dependent wash-in phase of the contrast medium. Intra- and interobserver comparison of the qualitative estimation of myocardial perfusion showed a close correlation (p less than 0.001 to p less than 0.0001). In the same 10 patients myocardial perfusion at rest was evaluated from Tl-201 scintiscans by two independent observers. A comparison between the qualitative classification of local myocardial perfusion assessed by both methods revealed a close correlation (p +/- 0.049). These results indicate that myocardial perfusion at rest can be visualized by digital image processing and evaluated qualitatively from cineangiograms.

[Left ventricular function at rest and by stress in patients with aortic valve diseases. Study using digital subtraction angiocardiography]

Using digital subtraction angiocardiography left ventricular (LV) function and mean pulmonary artery pressure (PPA) at rest and during exercise were examined in 49 patients with aortic valve disease, 23 patients with aortic stenosis (AS), 12 patients with combined aortic valve lesions (kAV) and 14 patients with aortic regurgitation (AI). Muscular hypertrophy was present in all patients. LV-mass-to-volume ratio was significantly higher in patients with AS and kAV than in patients with AI. There was no significant difference in heart rate at rest or during exercise among the three groups. During exercise PPA increased significantly in all groups. The increase was significantly higher in patients with AS than in those with AI. End-diastolic and end-systolic volumes increased significantly in patients with AS and kAV on the average, showing no change in patients with AI. Ejection fraction decreased significantly in patients with AS and kAV and remained unchanged in patients with AI. Due to the increase in heart rate cardiac index increased significantly during exercise in all groups. In patients with pressure overloaded left ventricles (AS and kAV) the increase in filling pressure partly results in a decrease of compliance caused by hypertrophy. Thus in these ventricles LV function cannot be judged by LV filling pressures alone. In those patients in whom the indication for valve replacement was given without knowing the results of the exercise test, the changes of LV volumes and ejection fraction were abnormal during exercise on the average.(ABSTRACT TRUNCATED AT 250 WORDS)