Impact of vessel volume on thermodilution measurements in patients with coronary microvascular dysfunction

BACKGROUND

Two invasive methods are available to estimate microvascular resistance: bolus and continuous thermodilution. Comparative studies have revealed a lack of concordance between measurements of microvascular resistance obtained through these techniques.

AIMS

This study aimed to examine the influence of vessel volume on bolus thermodilution measurements.

METHODS

We prospectively included patients with angina with non-obstructive coronary arteries (ANOCA) undergoing bolus and continuous thermodilution assessments. All patients underwent coronary CT angiography to extract vessel volume. Coronary microvascular dysfunction was defined as coronary flow reserve (CFR) < 2.0. Measurements of absolute microvascular resistance (in Woods units) and index of microvascular resistance (IMR) were compared before and after volumetric adjustment.

RESULTS

Overall, 94 patients with ANOCA were included in this study. The mean age was 64.7 ± 10.8 years, 48% were female, and 19% had diabetes. The prevalence of CMD was 16% based on bolus thermodilution, while continuous thermodilution yielded a prevalence of 27% (Cohen's Kappa 0.44, 95% CI 0.23-0.65). There was no correlation in microvascular resistance between techniques (r = 0.17, 95% CI -0.04 to 0.36, p = 0.104). The adjustment of IMR by vessel volume significantly increased the agreement with absolute microvascular resistance derived from continuous thermodilution (r = 0.48, 95% CI 0.31-0.63, p < 0.001).

CONCLUSIONS

In patients with ANOCA, invasive methods based on coronary thermodilution yielded conflicting results for the assessment of CMD. Adjusting IMR with vessel volume improved the agreement with continuous thermodilution for the assessment of microvascular resistance. These findings strongly suggest the importance of considering vessel volume when interpreting bolus thermodilution assessment.

Historic characteristics and mortality of patients in the Swiss Amyloidosis Registry

AIMS OF THE STUDY

Systemic amyloidoses are rare protein-folding diseases with heterogeneous, often nonspecific clinical presentations. To better understand systemic amyloidoses and to apply state-of-the-art diagnostic pathways and treatment, the interdisciplinary Amyloidosis Network was founded in 2013 at University Hospital Zurich. In this respect, a registry was implemented to study the characteristics and life expectancy of patients with amyloidosis within the area covered by the network. Patient data were collected retrospectively for the period 2005-2014 and prospectively from 2015 onwards.

METHODS

Patients aged 18 years or older diagnosed with any subtype of systemic amyloidosis were eligible for inclusion if they were treated in one of the four referring centres (Zurich, Chur, St Gallen, Bellinzona). Baseline data were captured at the time of diagnosis. Follow-up data were assessed half-yearly for the first two years, then annually.

RESULTS

Between January 2005 and March 2020, 247 patients were screened, and 155 patients with confirmed systemic amyloidosis were included in the present analysis. The most common amyloidosis type was light-chain (49.7%, n = 77), followed by transthyretin amyloidosis (40%, n = 62) and amyloid A amyloidosis (5.2%, n = 8). Most patients (61.9%, n = 96) presented with multiorgan involvement. Nevertheless, single organ involvement was seen in all types of amyloidosis, most commonly in amyloid A amyloidosis (75%, n = 6). The median observation time of the surviving patients was calculated by the reverse Kaplan-Meier method and was 3.29 years (95% confidence interval [CI] 2.33-4.87); it was 4.87 years (95% CI 3.14-7.22) in light-chain amyloidosis patients and 1.85 years (95% CI 1.48-3.66) in transthyretin amyloidosis patients, respectively. The 1-, 3- and 5-year survival rates were 87.0% (95% CI 79.4-95.3%), 68.5% (95% CI 57.4-81.7%) and 66.0% (95% CI 54.6-79.9%) respectively for light-chain amyloidosis patients and 91.2% (95% CI 83.2-99.8%), 77.0% (95% CI 63.4-93.7%) and 50.6% (95% CI 31.8-80.3%) respectively for transthyretin amyloidosis patients. There was no significant difference between the two groups (p = 0.81).

CONCLUSION

During registry set-up, a more comprehensive work-up of our patients suffering mainly from light-chain amyloidosis and transthyretin amyloidosis was implemented. Survival rates were remarkably high and similar between light-chain amyloidosis and transthyretin amyloidosis, a finding which was noted in similar historic registries of international centres. However, further studies are needed to depict morbidity and mortality as the amyloidosis landscape is changing rapidly.

Addressing global disparities in blood pressure control: perspectives of the International Society of Hypertension

ABSTRACT

Raised blood pressure (BP) is the leading cause of preventable death in the world. Yet, its global prevalence is increasing, and it remains poorly detected, treated, and controlled in both high- and low-resource settings. From the perspective of members of the International Society of Hypertension based in all regions, we reflect on the past, present, and future of hypertension care, highlighting key challenges and opportunities, which are often region-specific. We report that most countries failed to show sufficient improvements in BP control rates over the past three decades, with greater improvements mainly seen in some high-income countries, also reflected in substantial reductions in the burden of cardiovascular disease and deaths. Globally, there are significant inequities and disparities based on resources, sociodemographic environment, and race with subsequent disproportionate hypertension-related outcomes. Additional unique challenges in specific regions include conflict, wars, migration, unemployment, rapid urbanization, extremely limited funding, pollution, COVID-19-related restrictions and inequalities, obesity, and excessive salt and alcohol intake. Immediate action is needed to address suboptimal hypertension care and related disparities on a global scale. We propose a Global Hypertension Care Taskforce including multiple stakeholders and societies to identify and implement actions in reducing inequities, addressing social, commercial, and environmental determinants, and strengthening health systems implement a well-designed customized quality-of-care improvement framework.

Outcomes in patients with moderate and asymptomatic severe aortic stenosis followed up in heart valve clinics

BACKGROUND

Heart valve clinics (HVC) have been introduced to manage patients with valvular heart disease within a multidisciplinary team.

OBJECTIVE

To determine the outcome benefit of HVC approach compared with standard of care (SOC) for patients with moderate and asymptomatic severe aortic stenosis (mAS and asAS).

METHODS

Single-centre, observational registry of patients with mAS and asAS with at least one cardiac ambulatory consultation at our Cardiovascular Centre. Based on the outpatient strategy, patients were divided into HVC group, if receiving at least one visit at HVC, and SOC group, if followed by routine cardiac consultations.

RESULTS

2129 patients with mAS and asAS were divided into those followed in HVC (n=251) versus SOC group (n=1878). The mean age was 76.5±12.4 years; 919 (43.2%) had asAS. During a follow-up of 4.8±1.8 years, 822 patients (38.6%) died, 307 (14.4%) were hospitalised for heart failure and 596 (28%) underwent aortic valve replacement (AVR). After propensity score matching, the number of consultations per year, exercise stress tests, brain natriuretic peptide (BNP) determinations and CTs were higher in the HVC cohort (p<0.05 for all). A shorter time between indication of AVR and less advanced New York Heart Association class was reported in the HVC cohort (p<0.001 and p=0.032). Compared with SOC, the HVC approach was associated with reduced all-cause mortality (HR=0.63, 95% CI 0.40 to 0.98, p=0.038) and cardiovascular death (p=0.030). At multivariable analysis, the HVC remained an independent predictor of all-cause mortality (HR=0.54, 95% CI 0.34 to 0.85, p=0.007).

CONCLUSIONS

In patients with mAS and asAS, the HVC approach was associated with more efficient management and outcome benefit compared with SOC.

Renal denervation in the management of hypertension in adults. A clinical consensus statement of the ESC Council on Hypertension and the European Association of Percutaneous Cardiovascular Interventions (EAPCI)

Since the publication of the 2018 European Society of Cardiology/European Society of Hypertension (ESC/ESH) Guidelines for the Management of Arterial Hypertension, several high-quality studies, including randomised, sham-controlled trials on catheter-based renal denervation (RDN) were published, confirming both the blood pressure (BP)-lowering efficacy and safety of radiofrequency and ultrasound RDN in a broad range of patients with hypertension, including resistant hypertension. A clinical consensus document by the ESC Council on Hypertension and the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on RDN in the management of hypertension was considered necessary to inform clinical practice. This expert group proposes that RDN is an adjunct treatment option in uncontrolled resistant hypertension, confirmed by ambulatory BP measurements, despite best efforts at lifestyle and pharmacological interventions. RDN may also be used in patients who are unable to tolerate antihypertensive medications in the long term. A shared decision-making process is a key feature and preferably includes a patient who is well informed on the benefits and limitations of the procedure. The decision-making process should take (i) the patient's global cardiovascular (CV) risk and/or (ii) the presence of hypertension-mediated organ damage or CV complications into account. Multidisciplinary hypertension teams involving hypertension experts and interventionalists evaluate the indication and facilitate the RDN procedure. Interventionalists require expertise in renal interventions and specific training in RDN procedures. Centres performing these procedures require the skills and resources to deal with potential complications. Future research is needed to address open questions and investigate the impact of BP-lowering with RDN on clinical outcomes and potential clinical indications beyond hypertension.

Renal denervation in the management of hypertension in adults. A clinical consensus statement of the ESC Council on Hypertension and the European Association of Percutaneous Cardiovascular Interventions (EAPCI)

Since the publication of the 2018 European Society of Cardiology/European Society of Hypertension (ESC/ESH) Guidelines for the Management of Arterial Hypertension, several high-quality studies, including randomised, sham-controlled trials on catheter-based renal denervation (RDN) were published, confirming both the blood pressure (BP)-lowering efficacy and safety of radiofrequency and ultrasound RDN in a broad range of patients with hypertension, including resistant hypertension. A clinical consensus document by the ESC Council on Hypertension and the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on RDN in the management of hypertension was considered necessary to inform clinical practice. This expert group proposes that RDN is an adjunct treatment option in uncontrolled resistant hypertension, confirmed by ambulatory BP measurements, despite best efforts at lifestyle and pharmacological interventions. RDN may also be used in patients who are unable to tolerate antihypertensive medications in the long term. A shared decision-making process is a key feature and preferably includes a patient who is well informed on the benefits and limitations of the procedure. The decision-making process should take (i) the patient's global cardiovascular (CV) risk and/or (ii) the presence of hypertension-mediated organ damage or CV complications into account. Multidisciplinary hypertension teams involving hypertension experts and interventionalists evaluate the indication and facilitate the RDN procedure. Interventionalists require expertise in renal interventions and specific training in RDN procedures. Centres performing these procedures require the skills and resources to deal with potential complications. Future research is needed to address open questions and investigate the impact of BP-lowering with RDN on clinical outcomes and potential clinical indications beyond hypertension.

Diagnostic performance of exercise stress tests for detection of epicardial and microvascular coronary artery disease: the UZ Clear study

BACKGROUND

Cardiac stress tests remain the cornerstone for evaluating patients suspected of having obstructive coronary artery disease (CAD). Coronary microvascular dysfunction (CMD) can lead to abnormal non-invasive tests.

AIMS

We sought to assess the diagnostic performance of exercise stress tests with indexes of epicardial and microvascular resistance as reference.

METHODS

This was a prospective, single-arm, multicentre study of patients with an intermediate pretest probability of CAD and positive exercise stress tests who were referred for invasive angiography. Patients underwent an invasive diagnostic procedure (IDP) with measurement of fractional flow reserve (FFR) and index of microvascular resistance (IMR) in at least one coronary vessel. Obstructive CAD was defined as diameter stenosis (DS) >50% by quantitative coronary angiography (QCA). The objective was to determine the false discovery rate (FDR) of cardiac exercise stress tests with both FFR and IMR as references.

RESULTS

One hundred and seven patients (137 vessels) were studied. The mean age was 62.1±8.7, and 27.1% were female. The mean diameter stenosis was 37.2±27.5%, FFR was 0.84±0.10, coronary flow reserve was 2.74±2.07, and IMR 20.3±11.9. Obstructive CAD was present in 39.3%, whereas CMD was detected in 20.6%. The FDR was 60.7% and 62.6% with QCA and FFR as references (p-value=0.803). The combination of FFR and IMR as clinical reference reduced the FDR by 25% compared to QCA (45.8% vs 60.7%; p-value=0.006).

CONCLUSIONS

In patients with evidence of ischaemia, an invasive functional assessment accounting for the epicardial and microvascular compartments led to an improvement in the diagnostic performance of exercise tests, driven by a significant FDR reduction.

Outcomes benefit in asymptomatic patients with moderate aortic valve stenosis followed up in heart valve clinics

Background

The management of patients with asymptomatic moderate aortic stenosis (AS), particularly the follow-up and the choice between early intervention vs watchful waiting, remains debated. A progressively increasing number of patients with valvular heart disease (VHD) were diagnosed and followed in an ambulatory setting with a dedicated cardiologist and cardiac imaging specialist: the Heart Valve Clinics (HVC). However, the number of patients with VHD is that high, that these patients are also followed by routine cardiac care consultations (standard-of-care).

Purpose

To determine the benefit of a HVC approach and outcomes compared to standard-of-care for patients with moderate asymptomatic AS.

Methods

From November 2014 a HVC environment was introduced at our Cardiovascular Center, to follow patients with moderate and severe VHD by an imaging and valve specialist. Patients who received at least one visit in the Ambulatory HVC were included in a prospective registry. All consecutive patients with aortic valve velocity max&gt;3 cm/sec diagnosed with 2-D echocardiography according to the ESC Guidelines were included in this study. Exclusion criteria included more than moderate aortic regurgitation and prior aortic valve replacement (AVR). Natural history, need for AVR, and survival of patients with baseline moderate AS were assessed at follow up. Cox proportional hazard model, Kaplan-Meier survival curves and propensity score matching where used to assess the HVC approach effect on the mortality.

Results

A total of 2130 patients were included (1879 in the standard-of-care group and 251 in the Ambulatory HVC group). 1187 (55.7%) were male, and the mean (SD) age was 77.2±12.2 years. A total of 919 patients (43.1%) had severe AS (aortic valve area &lt;1.0 cm2). Mean clinical follow-up was 1.2±2.4 years. A total of 822 patients (38.6%) died during the follow up and 114 patients (55.6%) underwent AVR during the study period. After using 1:1, nearest neighbour, without replacement propensity score matching, baseline characteristics between the two groups were balanced. The introduction of Ambulatory HVC was associated with a reduction of adjusted all-cause mortality compared to the standard-of-care group (HR=0.53, 95% CI 0.35–0.82, p=0.004) (Figure1). At multivariable analysis, the Ambulatory HVC pathway was a significant predictor of reduced all-cause of death (HR=0.46, 95% CI 0.33–0.65, p&lt;0.001), together with younger age and higher GFR, independently of AVA, tricuspid regurgitation gradient, LVEF and chronic obstructive pulmonary disease.

Conclusions

Patients with moderate AS followed up in HVC had lower rate of all-cause of death compared to the standard-of-care group. The Ambulatory HVC was a significant predictor of reduced all-cause of death and was associated with more efficient patient management and lower mortality. Dedicated HVC have the potential to improve patient care and clinical outcomes.

Funding Acknowledgement

Type of funding sources: None.

Sex differences in arterial hypertension

There is strong evidence that sex chromosomes and sex hormones influence blood pressure (BP) regulation, distribution of cardiovascular (CV) risk factors and co-morbidities differentially in females and males with essential arterial hypertension. The risk for CV disease increases at a lower BP level in females than in males, suggesting that sex-specific thresholds for diagnosis of hypertension may be reasonable. However, due to paucity of data, in particularly from specifically designed clinical trials, it is not yet known whether hypertension should be differently managed in females and males, including treatment goals and choice and dosages of antihypertensive drugs. Accordingly, this consensus document was conceived to provide a comprehensive overview of current knowledge on sex differences in essential hypertension including BP development over the life course, development of hypertension, pathophysiologic mechanisms regulating BP, interaction of BP with CV risk factors and co-morbidities, hypertension-mediated organ damage in the heart and the arteries, impact on incident CV disease, and differences in the effect of antihypertensive treatment. The consensus document also highlights areas where focused research is needed to advance sex-specific prevention and management of hypertension.

Assessment of Artificial Intelligence in Echocardiography Diagnostics in Differentiating Takotsubo Syndrome From Myocardial Infarction

Importance

Machine learning algorithms enable the automatic classification of cardiovascular diseases based on raw cardiac ultrasound imaging data. However, the utility of machine learning in distinguishing between takotsubo syndrome (TTS) and acute myocardial infarction (AMI) has not been studied.

Objectives

To assess the utility of machine learning systems for automatic discrimination of TTS and AMI.

Design, Settings, and Participants

This cohort study included clinical data and transthoracic echocardiogram results of patients with AMI from the Zurich Acute Coronary Syndrome Registry and patients with TTS obtained from 7 cardiovascular centers in the International Takotsubo Registry. Data from the validation cohort were obtained from April 2011 to February 2017. Data from the training cohort were obtained from March 2017 to May 2019. Data were analyzed from September 2019 to June 2021.

Exposure

Transthoracic echocardiograms of 224 patients with TTS and 224 patients with AMI were analyzed.

Main Outcomes and Measures

Area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity of the machine learning system evaluated on an independent data set and 4 practicing cardiologists for comparison. Echocardiography videos of 228 patients were used in the development and training of a deep learning model. The performance of the automated echocardiogram video analysis method was evaluated on an independent data set consisting of 220 patients. Data were matched according to age, sex, and ST-segment elevation/non-ST-segment elevation (1 patient with AMI for each patient with TTS). Predictions were compared with echocardiographic-based interpretations from 4 practicing cardiologists in terms of sensitivity, specificity, and AUC calculated from confidence scores concerning their binary diagnosis.

Results

In this cohort study, apical 2-chamber and 4-chamber echocardiographic views of 110 patients with TTS (mean [SD] age, 68.4 [12.1] years; 103 [90.4%] were female) and 110 patients with AMI (mean [SD] age, 69.1 [12.2] years; 103 [90.4%] were female) from an independent data set were evaluated. This approach achieved a mean (SD) AUC of 0.79 (0.01) with an overall accuracy of 74.8 (0.7%). In comparison, cardiologists achieved a mean (SD) AUC of 0.71 (0.03) and accuracy of 64.4 (3.5%) on the same data set. In a subanalysis based on 61 patients with apical TTS and 56 patients with AMI due to occlusion of the left anterior descending coronary artery, the model achieved a mean (SD) AUC score of 0.84 (0.01) and an accuracy of 78.6 (1.6%), outperforming the 4 practicing cardiologists (mean [SD] AUC, 0.72 [0.02]) and accuracy of 66.9 (2.8%).

Conclusions and Relevance

In this cohort study, a real-time system for fully automated interpretation of echocardiogram videos was established and trained to differentiate TTS from AMI. While this system was more accurate than cardiologists in echocardiography-based disease classification, further studies are warranted for clinical application.

Arterial hypertension

Arterial hypertension is the most important contributor to the global burden of disease; however, disease control remains poor. Although the diagnosis of hypertension is still based on office blood pressure, confirmation with out-of-office blood pressure measurements (ie, ambulatory or home monitoring) is strongly recommended. The definition of hypertension differs throughout various guidelines, but the indications for antihypertensive therapy are relatively similar. Lifestyle adaptation is absolutely key in non-pharmacological treatment. Pharmacologically, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, calcium channel blockers, and diuretics are the first-line agents, with advice for the use of single-pill combination therapy by most guidelines. As a fourth-line agent, spironolactone should be considered. The rapidly evolving field of device-based therapy, especially renal denervation, will further broaden therapeutic options. Despite being a largely controllable condition, the actual rates of awareness, treatment, and control of hypertension are disappointingly low. Further improvements throughout the process of patient screening, diagnosis, treatment, and follow-up need to be urgently addressed.

The Use and Perceived Usefulness of an Online Toolbox Targeted at Employers (MiLES Intervention) for Enhancing Successful Return to Work of Cancer Survivors

PURPOSE

The MiLES intervention is a web-based intervention targeted at employers with the objective of enhancing successful return to work (RTW) of cancer survivors. The aim of this study is to gain insight into the employers' use and perceived usefulness of the MiLES intervention.

METHODS

Employer representatives (e.g. Human Resource managers and supervisors) were given access to the MiLES intervention, which contains, among others, interactive videos, conversation checklists and tailored tips. After six weeks, an online questionnaire gathered data on employers' use and the perceived usefulness of the intervention. In-depth qualitative data on these topics were gathered during semi-structured interviews, which were analyzed using a content analysis.

RESULTS

Thirty-one eligible employers were included. Twenty-two of them filled out the questionnaire and twenty were interviewed. Typically, employers used the intervention 2-3 times, for 26 min per visit. The usefulness of the intervention scored 7.6 out of 10 points, and all employers would recommend it to colleagues. Employers' use decreased when support needs were low and when the intervention did not correspond with their specific situation (e.g. complex reintegration trajectories). Employers perceived the intervention to be supporting and practically oriented. They appreciated the fact that the intervention was web-based and combined visual and textual content. The possibility of consulting specialized services for complex situations would further enhance its usefulness.

CONCLUSION

The MiLES intervention provides employers with a useful tool in their daily practice. Its effectiveness for enhancing employers' managerial skills and cancer survivors' successful RTW is subject for further research.

Reviewing imaging modalities for the assessment of plaque erosion

Plaque rupture followed by intracoronary thrombus formation is recognized as the most common pathophysiological mechanism in acute coronary syndromes (ACS). The second most common underlying substrate for ACS is plaque erosion whose hallmark is thrombus formation without cap disruption. Invasive and non-invasive methods have emerged as a promising tool for evaluation of plaque features that either predict or detect plaque erosion. Optical coherence tomography (OCT), high-definition intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and near-infrared autofluorescence (NIRF) have been used to study plaque erosion. The detection of plaque erosion in the clinical setting, mainly facilitated by OCT, has shed light upon the complex pathophysiology underlying ACS not related to plaque rupture. Coronary computed tomography angiography (CCTA), which is to date the most commonly used non-invasive technique for coronary plaque evaluation, may also have a role in the evaluation of patients predisposed to erosion. Also, computational models enabling quantification of endothelial shear stress may pave the way to new research in coronary plaque pathophysiology. This review focuses on the recent imaging techniques for the evaluation of plaque erosion including invasive and non-invasive assessment.

Impact of non-invasive anatomical testing on optimal medical prescription in patients with suspected coronary artery disease

Background

Compared to functional testing, coronary computed tomography angiography (CTA) improves clinical outcomes in patients with suspected coronary artery disease (CAD). This is thought to be the result of an increased prescription of preventive medical therapy (statins and aspirin) when relying on a CTA imaging strategy. We compared the rate of statins prescription in a patient cohort assessed either with coronary CTA or exercise testing, and evaluated the agreement on medication prescriptions.

Methods

Consecutive patients who underwent coronary CTA and exercise test for suspected CAD were included. Four clinical cardiologists independently analysed each case based on clinical information and the result of either coronary CTA or exercise test. For each case, treatment strategy and prescription were recorded while blinded to the results of the other cardiac test. Treatment strategy was reassessed using the alternative imaging modality three weeks after the first evaluation.

Results

A total of 113 patients were included. Mean age was 56.7±11.5 years, 52% were males and diabetes were present in 6%. Coronary CTA showed an obstructive epicardial stenosis in 21.4% and any type of atherosclerotic plaque in 54.2%. Functional testing identified ischemia in 9.1%. The use of coronary CTA resulted in higher number of statin (64.9% vs. 44.5%, P<0.001) and aspirin (21.4% vs. 4.3%, P<0.001) prescriptions. There was a substantial agreement on the prescription of statins (mean Cohen's κ coefficient of 0.79±0.07).

Conclusions

Epicardial atherosclerotic disease was found in half of patients with suspected CAD as assessed by coronary CTA. Compared to functional testing, coronary CTA evaluation by coronary was associated with an increase in the rate preventive therapy prescription.

Hypotensive Response to Angiotensin II Type 2 Receptor Stimulation in the Rostral Ventrolateral Medulla Requires Functional GABA-A Receptors

Objectives: Angiotensin II, glutamate and gamma-aminobutyric acid (GABA) interact within the rostral ventrolateral medulla (RVLM) and the paraventricular nucleus (PVN) modulating the central regulation of blood pressure and sympathetic tone. Our aim was to assess the effects of local angiotensin II type 2 receptor stimulation within the RVLM and the PVN on neurotransmitter concentrations and mean arterial pressure (MAP).

Methods:In vivo microdialysis was used for measurement of extracellular glutamate and GABA levels and for local infusion of the angiotensin II type 2 receptor agonist Compound 21 in the RVLM and the PVN of conscious normotensive Wistar rats. The MAP response to local Compound 21 was monitored with a pressure transducer under anaesthesia. Angiotensin II type 2 receptor selectivity was assessed using the angiotensin II type 2 receptor antagonist PD123319; the GABA-A receptor antagonist bicuculline was used to assess the involvement of GABA-A receptors.

Results: Infusion of Compound 21 (0.05 μg/μl/h) in the RVLM significantly increased GABA levels and lowered blood pressure. These effects were abolished by co-infusion with PD123319. No changes in neurotransmitter levels or effects on blood pressure were seen with PD123319 infusion alone. Co-infusion of bicuculline abolished the Compound 21 evoked decrease in MAP. Infusion of Compound 21 within the PVN did not change extracellular neurotransmitter levels nor MAP.

Conclusion: Selective stimulation of angiotensin II type 2 receptor within the RVLM by local Compound 21 infusion reduces blood pressure and increases local GABA levels in normotensive rats. This hypotensive response requires functional GABA-A receptors, suggesting that GABAergic neurons are involved in the sympatho-inhibitory action underlying this hypotensive response.

Abstract 305: Activation of Central Angiotensin II type 2 Receptors Attenuates Neurogenic Hypertension

Aim: The role of the angiotensin II type-2 receptor (AT2R) in hypertension is under debate and the expression can be modulated in different pathological states. In hypertension AT2R are upregulated, therefore we hypothesize that central AT2R stimulation will lower blood pressure in conscious spontaneously hypertensive rats (SHR).

Methods: SHR were implanted with a radio-telemetry device and an icv cannula connected to a miniosmotic pump delivering saline vehicle, AT2R agonist Compound 21 (C21) (0.002μg/μl/hr) alone or in combination with AT2R antagonist PD123319. MAP was assessed for 21 days: 7 days baseline (saline), 14 days treatment (e.g. C21). To assess the role of the angiotensin II type-1 receptor (AT1R) and NO in these responses, AT1R blocker losartan or NO synthase inhibitor L-NAME were administered centrally with C21. (n=5-7/group).

Results: Icv C21-infusion blocked the increase in MAP seen in the vehicle group (MAP (mmHg): baseline: vehicle 153±5 vs C21 157±4; day 21 (D21): vehicle 164±5 vs C21 155±5;p<0.05). PD123319 abolished this blood pressure lowering effect (MAP (mmHg): baseline 154±5; D21 163±5;p<0.05). Co-infusion of C21 and losartan did not reinforce the MAP lowering effect seen with C21 alone (MAP (mmHg): baseline 157±2; D21 153±1;p<0.05). Simultaneous L-NAME administration abolished the effects of C21 (MAP (mmHg): baseline 156±4; D21 190±5;p<0.05).

Mechanistically, an improved parasympathetic control of HR was seen in the C21-treated group (change in HR after i.p. propranolol (bpm): vehicle -68.2±2.4 vs C21 -36.3±4.1;p<0.05). Impaired baroreflex sensitivity (BRS) also improved under C21-infusion (BRS (ms/mmHg) D21: vehicle 1.81±0.16 vs C21 3.15±0.07;p<0.05)

Conclusion: Selective central AT2R stimulation with C21 attenuates hypertension and corrects autonomic dysfunction in SHR. These effects are mediated through a NO-dependent mechanism. In contrast to an enhanced peripheral AT2R effect following AT1R blockade, concomitant central AT1R blockade did not enhance these responses to central AT2R stimulation. These findings suggest activation of the central AT2R represent a possible new therapeutic target for the treatment of neurogenic hypertension.

Creation of an iliac arteriovenous shunt lowers blood pressure in chronic obstructive pulmonary disease patients with hypertension

OBJECTIVE

Vasodilators are used with caution in patients with chronic obstructive pulmonary disease (COPD). We have developed a device for percutaneous arteriovenous shunt creation in the iliac region to increase cardiac output and oxygen delivery for patients with COPD. Although this device does not cause significant blood pressure changes in normotensive patients with COPD, we hypothesized that arteriovenous shunt creation might cause vasodilator effects in hypertensive patients because of a reduction in vascular resistance.

METHODS

Twenty-four patients with COPD and hypertension enrolled in an open label study of arteriovenous shunt creation for COPD. We performed cardiac catheterization at baseline and again 3 to 6 months after the procedure. As a safety measure we also recorded office blood pressure at baseline and again after 3, 6, 9, and 12 months.

RESULTS

The procedure increased oxygen delivery (1.1-1.4 L.min(-1)) and cardiac output (6-8.2 L.min(-1)) (P < .001) and lowered both the systemic vascular resistance (P < .001) and the pulmonary vascular resistance (P < .01). After 12 months, however, the average systolic blood pressure was reduced from 145 to 132 mm Hg (P < .0001), and the average diastolic blood pressure was reduced from 86 to 67 mm Hg (P < .0001).

CONCLUSIONS

Percutaneous iliac arteriovenous fistula creation for COPD causes a significant and persistent lowering of blood pressure in patients with co-existing hypertension.

Angiotensin II type 2 receptor-mediated and nitric oxide-dependent renal vasodilator response to compound 21 unmasked by angiotensin-converting enzyme inhibition in spontaneously hypertensive rats in vivo

Angiotensin II type 2 receptor (AT2R)-mediated vasodilation has been demonstrated in different vascular beds in vitro and in perfused organs. In vivo studies, however, consistently failed to disclose renal vasodilator responses to compound 21, a selective AT2R agonist, even after angiotensin II type 1 receptor blockade. Here, we investigated in vivo whether angiotensin-converting enzyme inhibition, reducing endogenous angiotensin II levels, could unmask the effects of selective AT2R stimulation on blood pressure and renal hemodynamics in normotensive and hypertensive rats. After pretreatment with the angiotensin-converting enzyme inhibitor captopril, intravenous administration of compound 21 did not affect blood pressure and induced dose-dependent renal vasodilator responses in spontaneously hypertensive but not in normotensive rats. The D1 receptor agonist fenoldopam, used as positive control, reduced blood pressure and renal vascular resistance in both strains. The AT2R antagonist PD123319 and the nitric oxide synthase inhibitor L-NMMA (N(G)-monomethyl-L-arginine acetate) abolished the renal vasodilator response to compound 21 without affecting responses to fenoldopam. The cyclooxygenase inhibitor indomethacin partially inhibited the renal vascular response to compound 21, whereas the bradykinin B2 receptor antagonist icatibant was without effect. Angiotensin-converting enzyme inhibition unmasked a renal vasodilator response to selective AT2R stimulation in vivo, mediated by nitric oxide and partially by prostaglandins. AT2R may have a pathophysiological role to modulate renal hemodynamic effects of angiotensin II in the hypertensive state.

Ets1 is a common element in directing transcription of the alpha and beta genes of human protein kinase CK2

Protein kinase CK2 is a conserved and vital Ser/Thr phosphotransferase with various links to malignant diseases, occurring as a tetramer composed of two catalytically active (CK2alpha and/or CK2alpha') and two regulatory subunits (CK2beta). There is balanced availability of CK2alpha and CK2beta transcripts in proliferating and differentiating cultured cells. Examination of the human CK2beta gene for transcriptionally active regions by systematic deletions and reporter gene assays indicates strong promoter activity at positions -42 to 14 and 12 to 72 containing transcription start sites 1 and 2 of the gene (positions +1 and 33), respectively, an upstream and a downstream enhancer activity at positions -241 to -168 and 123 to 677, respectively, and silencer activity at positions -241 to -261. Of the various transcription factor binding motifs present in those regions, Ets1 and CAAT-related motifs turned out to be of particular importance, Ets1 for promoter activation and CAAT-related motifs for enhancer activation. In addition, there are contributions by Sp1. Most strikingly, the Ets1 region representing two adjoining consensus motifs also occurs with complete identity in the recently characterized promoter of the CK2alpha gene [Krehan, A., Ansuini, H., Böcher, O., Grein, S., Wirkner, U. & Pyerin, W. (2001) J. Biol. Chem. 275, 18327-18336], and affects comparably, when assayed in parallel, the promoters of both CK2 genes, both by motif mutations and by Ets1 overexpression. The data strongly support the hypothesis that Ets1 acts as a common regulatory element of the CK2alpha and CK2beta genes involved in directing coordinate transcription and contributing to the balanced availability of transcripts.