Effects of Renal Denervation vs Sham in Resistant Hypertension After Medication Escalation: Prespecified Analysis at 6 Months of the RADIANCE-HTN TRIO Randomized Clinical Trial

Importance

Although early trials of endovascular renal denervation (RDN) for patients with resistant hypertension (RHTN) reported inconsistent results, ultrasound RDN (uRDN) was found to decrease blood pressure (BP) vs sham at 2 months in patients with RHTN taking stable background medications in the Study of the ReCor Medical Paradise System in Clinical Hypertension (RADIANCE-HTN TRIO) trial.

Objectives

To report the prespecified analysis of the persistence of the BP effects and safety of uRDN vs sham at 6 months in conjunction with escalating antihypertensive medications.

Design, Setting, and Participants

This randomized, sham-controlled, clinical trial with outcome assessors and patients blinded to treatment assignment, enrolled patients from March 11, 2016, to March 13, 2020. This was an international, multicenter study conducted in the US and Europe. Participants with daytime ambulatory BP of 135/85 mm Hg or higher after 4 weeks of single-pill triple-combination treatment (angiotensin-receptor blocker, calcium channel blocker, and thiazide diuretic) with estimated glomerular filtration rate (eGFR) of 40 mL/min/1.73 m2 or greater were randomly assigned to uRDN or sham with medications unchanged through 2 months. From 2 to 5 months, if monthly home BP was 135/85 mm Hg or higher, standardized stepped-care antihypertensive treatment starting with aldosterone antagonists was initiated under blinding to treatment assignment.

Interventions

uRDN vs sham procedure in conjunction with added medications to target BP control.

Main Outcomes and Measures

Six-month change in medications, change in daytime ambulatory systolic BP, change in home systolic BP adjusted for baseline BP and medications, and safety.

Results

A total of 65 of 69 participants in the uRDN group and 64 of 67 participants in the sham group (mean [SD] age, 52.4 [8.3] years; 104 male [80.6%]) with a mean (SD) eGFR of 81.5 (22.8) mL/min/1.73 m2 had 6-month daytime ambulatory BP measurements. Fewer medications were added in the uRDN group (mean [SD], 0.7 [1.0] medications) vs sham (mean [SD], 1.1 [1.1] medications; P = .045) and fewer patients in the uRDN group received aldosterone antagonists at 6 months (26 of 65 [40.0%] vs 39 of 64 [60.9%]; P = .02). Despite less intensive standardized stepped-care antihypertensive treatment, mean (SD) daytime ambulatory BP at 6 months was 138.3 (15.1) mm Hg with uRDN vs 139.0 (14.3) mm Hg with sham (additional decreases of -2.4 [16.6] vs -7.0 [16.7] mm Hg from month 2, respectively), whereas home SBP was lowered to a greater extent with uRDN by 4.3 mm Hg (95% CI, 0.5-8.1 mm Hg; P = .03) in a mixed model adjusting for baseline and number of medications. Adverse events were infrequent and similar between groups.

Conclusions and Relevance

In this study, in patients with RHTN initially randomly assigned to uRDN or a sham procedure and who had persistent elevation of BP at 2 months after the procedure, standardized stepped-care antihypertensive treatment escalation resulted in similar BP reduction in both groups at 6 months, with fewer additional medications required in the uRDN group.

Trial Registration

ClinicalTrials.gov Identifier: NCT02649426.

Outpatient management of heart valve disease following the COVID-19 pandemic: implications for present and future care

The established processes for ensuring safe outpatient surveillance of patients with known heart valve disease (HVD), echocardiography for patients referred with new murmurs and timely delivery of surgical or transcatheter treatment for patients with severe disease have all been significantly impacted by the novel coronavirus pandemic. This has created a large backlog of work and upstaging of disease with consequent increases in risk and cost of treatment and potential for worse long-term outcomes. As countries emerge from lockdown but with COVID-19 endemic in society, precautions remain that restrict 'normal' practice. In this article, we propose a methodology for restructuring services for patients with HVD and provide recommendations pertaining to frequency of follow-up and use of echocardiography at present. It will be almost impossible to practice exactly as we did prior to the pandemic; thus, it is essential to prioritise patients with the greatest clinical need, such as those with symptomatic severe HVD. Local procedural waiting times will need to be considered, in addition to usual clinical characteristics in determining whether patients requiring intervention would be better suited having surgical or transcatheter treatment. We present guidance on the identification of stable patients with HVD that could have follow-up deferred safely and suggest certain patients that could be discharged from follow-up if waiting lists are triaged with appropriate clinical input. Finally, we propose that novel models of working enforced by the pandemic-such as increased use of virtual clinics-should be further developed and evaluated.

Six-Month Results of Treatment-Blinded Medication Titration for Hypertension Control After Randomization to Endovascular Ultrasound Renal Denervation or a Sham Procedure in the RADIANCE-HTN SOLO Trial

BACKGROUND

The multicenter, international, randomized, blinded, sham-controlled RADIANCE-HTN SOLO trial (A Study of the ReCor Medical Paradise System in Clinical Hypertension) demonstrated a 6.3 mm Hg greater reduction in daytime ambulatory systolic blood pressure (BP) at 2 months by endovascular ultrasound renal denervation (RDN) compared with a sham procedure among patients not treated with antihypertensive medications. We report 6-month results after the addition of a recommended standardized stepped-care antihypertensive treatment to the randomized endovascular procedure under continued blinding to initial treatment.

METHODS

Patients with a daytime ambulatory BP ≥135/85 mm Hg and <170/105 mm Hg after a 4-week discontinuation of up to 2 antihypertensive medications, and a suitable renal artery anatomy, were randomized to RDN (n=74) or sham (n=72). Patients were to remain off antihypertensive medications throughout the first 2 months of follow-up unless safety BP criteria were exceeded. Between 2 and 5 months, if monthly measured home BP was ≥135/85 mm Hg, a standardized stepped-care antihypertensive treatment was recommended consisting of the sequential addition of amlodipine (5 mg/d), a standard dose of an angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, and hydrochlorothiazide (12.5 mg/d), followed by the sequential uptitration of hydrochlorothiazide (25 mg/d) and amlodipine (10 mg/d). Outcomes included the 6-month (1) change in daytime ambulatory systolic BP adjusted for medications and baseline systolic BP, (2) medication burden, and (3) safety.

RESULTS

A total of 69/74 RDN patients and 71/72 sham patients completed the 6-month ambulatory BP measurement. At 6 months, 65.2% of patients in the RDN group were treated with the standardized stepped-care antihypertensive treatment versus 84.5% in the sham group (P=0.008), and the average number of antihypertensive medications and defined daily dose were less in the RDN group than in the sham group (0.9±0.9 versus 1.3±0.9, P=0.010 and 1.4±1.5 versus 2.0±1.8, P=0.018; respectively). Despite less intensive standardized stepped-care antihypertensive treatment, RDN reduced daytime ambulatory systolic BP to a greater extent than sham (-18.1±12.2 versus -15.6±13.2 mm Hg, respectively; difference adjusted for baseline BP and number of medications: -4.3 mm Hg, 95% confidence interval, -7.9 to -0.6, P=0.024). There were no major adverse events in either group through 6 months.

CONCLUSIONS

The BP-lowering effect of endovascular ultrasound RDN was maintained at 6 months with less prescribed antihypertensive medications compared with a sham control.

CLINICAL TRIAL REGISTRATION

URL: https://www.

CLINICALTRIALS

gov. Unique identifier: NCT02649426.

Abstract P5-07-02: Not presented

This abstract was not presented at the conference.

Citation Format: Chatterjee S, Berdnikov A, Buchel E, Safneck J, Marshall AJ, Murphy LC, Raouf A. Not presented [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-02.

Gefitinib targets ZAP-70-expressing chronic lymphocytic leukemia cells and inhibits B-cell receptor signaling

Chronic lymphocytic leukemia (CLL) can be divided into groups based on biomarkers of poor prognosis. The expression of the tyrosine kinase ZAP-70 (member of the Syk tyrosine kinase family) in CLL cells is associated with shorter overall survival in CLL patients. Currently, there is a lack of targeted therapies for patients with ZAP-70 expression in CLL cells. The tyrosine kinase inhibitor gefitinib has been shown to be effective at induce apoptosis in acute myeloid leukemia through inhibition of Syk. In this study, we sought to test the efficacy of gefitinib in primary human ZAP-70+ CLL cells. We demonstrate that gefitinib preferentially induces cell death in ZAP-70-expressing CLL cells with a median IC₅₀ of 4.5 μM. In addition, gefitinib decreases the viability of ZAP-70+ Jurkat T leukemia cells but fails to affect T cells from CLL patients. Western blot analysis shows gefitinib reduces both basal and B-cell receptor (BCR)-stimulated phosphorylation of Syk/ZAP-70, ERK, and Akt in ZAP-70+ CLL cells. Moreover, gefitinib inhibits the pro-survival response from BCR stimulation and decreases pro-survival proteins such as Mcl-1. Finally, ZAP-70 expression sensitizes Raji cells to gefitinib treatment. These results demonstrate that gefitinib specifically targets ZAP-70+ CLL cells and inhibits the BCR cell survival pathway leading to apoptosis. This represents the likelihood of tyrosine kinase inhibitors being effective targeted treatments for ZAP-70+ CLL cells.

Follicular dendritic cell secreted protein FDC-SP controls IgA production

Follicular dendritic cell secreted protein (FDC-SP) is a secreted peptide predominantly expressed in mucosal tissues. We previously reported that FDC-SP transgenic mice have altered B-cell responses to systemic immunization; however, the role of FDC-SP in mucosal immunity is unknown. Here, we report that FDC-SP functions in regulating immunoglobulin A production. FDC-SP transgenic mice show decreased IgA levels in serum, saliva, and bronchoalveolar lavage fluid. Reciprocally, FDC-SP-deficient mice show significantly increased IgA levels in serum and intestinal lavage, associated with accumulation of IgA+ cells in blood, bone marrow, Peyer's patches, and lymph nodes. FDC-SP-deficient mice generated higher titers of antigen-specific IgA but normal IgG1 responses upon immunization. Purified FDC-SP transgenic B cells generated decreased IgA responses to transforming growth factor β (TGFβ)+interleukin 5 (IL5) stimulation. Consistent with a direct effect of FDC-SP on B cells, recombinant FDC-SP suppressed B-cell IgA production in vitro. Six- to 14-month-old FDC-SP-deficient mice show IgA deposition in kidney glomeruli, which was associated with proteinuria and pathology consistent with mild IgA nephropathy (IgAN). Our results demonstrate a novel biological activity of FDC-SP in controlling B-cell IgA production and identify FDC-SP-deficient mice as a novel mouse model of IgAN.

Epidermal and dermal integration into sphere-templated porous poly(2-hydroxyethyl methacrylate) implants in mice

Percutaneous medical devices remain susceptible to infection and failure. We hypothesize that healing of the skin into the percutaneous device will provide a seal, preventing bacterial attachment, biofilm formation, and subsequent device failure. Porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] with sphere-templated pores (40 microm) and interconnecting throats (16 microm) were implanted in normal C57BL/6 mice for 7, 14, and 28 days. Poly(HEMA) was either untreated, keeping the surface nonadhesive for cells and proteins, or modified with carbonyldiimidazole (CDI) or CDI reacted with laminin 332 to enhance adhesion. No clinical signs of infection were observed. Epidermal and dermal response within the poly(HEMA) pores was evaluated using light and transmission electron microscopy. Cells (keratinocytes, fibroblasts, endothelial cells, inflammatory cells) and basement membrane proteins (laminin 332, beta4 integrin, type VII collagen) could be demonstrated within the poly(HEMA) pores of all implants. Blood vessels and dermal collagen bundles were evident in all of the 14- and 28-day implants. Fibrous capsule formation and permigration were not observed. Sphere-templated polymers with 40 microm pores demonstrate an ability to recapitulate key elements of both the dermal and the epidermal layers of skin. Our morphological findings indicate that the implant model can be used to study the effects of biomaterial pore size, pore interconnect (throat) size, and surface treatments on cutaneous biointegration. Further, this model may be used for bacterial challenge studies.

A mouse model to evaluate the interface between skin and a percutaneous device

Percutaneous medical devices are integral in the management and treatment of disease. The space created between the skin and the device becomes a haven for bacterial invasion and biofilm formation and results in infection. We hypothesize that sealing this space via integration of the skin into the device will create a barrier against bacterial invasion. The purpose of this study was to develop an animal model in which the interaction between skin and biomaterials can be evaluated. Porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] rods were implanted for 7 days in the dorsal skin of C57 BL/6 mice. The porous poly(HEMA) rods were surface-modified with carbonyldiimidazole (CDI) or CDI plus laminin 5; unmodified rods served as control. Implant sites were sealed with 2-octyl cyanoacrylate; corn pads and adhesive dressings were tested for stabilization of implants. All rods remained intact for the duration of the study. There was histological evidence of both epidermal and dermal integration into all poly(HEMA) rods regardless of treatment. This in vivo model permits examination of the implant/skin interface and will be useful for future studies designed to facilitate skin cell attachment where percutaneous devices penetrate the skin.

Evaluating orangutan census techniques using nest decay rates: implications for population estimates

An accurate estimate for orangutan nest decay time is a crucial factor in commonly used methods for estimating orangutan population size. Decay rates are known to vary, but the decay process and, thus, the temporal and spatial variation in decay time are poorly understood. We used established line-transect methodology to survey orangutan nests in a lowland forest in East Kalimantan, Indonesia, and monitored the decay of 663 nests over 20 months. Using Markov chain analysis we calculated a decay time of 602 days, which is significantly longer than times found in other studies. Based on this, we recalculated the orangutan density estimate for a site in East Kalimantan; the resulting density is much lower than previous estimates (previous estimates were 3-8 times higher than our recalculated density). Our data suggest that short-term studies where decay times are determined using matrix mathematics may produce unreliable decay times. Our findings have implications for other parts of the orangutan range where population estimates are based on potentially unreliable nest decay rate estimates, and we recommend that for various parts of the orangutan range census estimates be reexamined. Considering the high variation in decay rates there is a need to move away from using single-number decay time estimates and, preferably, to test methods that do not rely on nest decay times as alternatives for rapid assessments of orangutan habitat for conservation in Borneo.

Regulation of B-lymphocyte activation by the PH domain adaptor protein Bam32/DAPP1

PI3Ks (phosphoinositide 3-kinases) play critical roles in BCR (B-cell receptor) signalling via the generation of 3-phosphoinositide second messengers. Recruitment of PH domain (pleckstrin homology domain)-containing signal transduction proteins to the plasma membrane through binding to 3-phosphoinositide second messengers represents a major effector mechanism for PI3Ks. Here, we review data on the PH domain-containing adaptor protein Bam32 (B-cell adaptor molecule of 32 kDa)/DAPP1 (dual adaptor for phosphotyrosine and 3-phosphoinositides 1), focusing on its functions in B-lymphocyte activation. Present results support the view that Bam32/DAPP1 mediates multiple PI3K-dependent responses in B-cells through membrane-proximal mechanisms involving Src kinases, Rac1, F-actin and mitogen-activated protein kinases, resulting in selective effects on BCR-mediated proliferation, antigen presentation and generation of antibody responses.

Multi-detector row CT coronary angiography in patients with cardiomyopathy -- initial single-centre experience

AIMS

To evaluate the diagnostic accuracy of computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients with cardiomyopathy (CM).

SUBJECTS AND METHODS

Eighteen patients with CM were approached to undergo CT coronary angiography to evaluate the use of this technique for investigating the presence of significant coronary artery disease (CAD), and also to compare the findings with catheter angiography.

RESULTS

On a segment-by-segment analysis the sensitivity, specificity, positive and negative predictive values in the CM group were 66.7, 96.5, 40 and 98.8%, respectively, with 100% accuracy in "whole-patient terms".

CONCLUSION

Non-invasive, 16-detector row CT coronary angiography in patients with presumed CM would seem to be a useful clinical tool for the exclusion of significant coronary artery disease. However, the presence of suboptimal contrast opacification in this patient group means that the implication of these results must be interpreted with caution.

16-Detector row computed tomographic coronary angiography in patients undergoing evaluation for aortic valve replacement: comparison with catheter angiography

AIM

To evaluate the diagnostic accuracy of 16-detector row computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients under evaluation for aortic stenosis pre-aortic valve replacement.

SUBJECTS AND METHODS

Forty consecutive patients under evaluation for severe aortic stenosis and listed for cardiac catheterization before potential aortic valve replacement underwent coronary artery calcium (CAC) scoring and retrospective electrocardiogram (ECG)-gated multi-detector row computed tomographic coronary angiography (MDCTA) using a GE Lightspeed 16-detector row CT within 1 month of invasive coronary angiography (ICA) for comparative purposes. All 13 major coronary artery segments of the American Heart Association model were evaluated for the presence of > or =50% stenosis and compared to the reference standard. Data were analysed on a segment-by-segment basis and also in "whole patient" terms.

RESULTS

A total of 412/450 segments from 35 patients were suitable for analysis. The overall accuracy of MDCTA for detection of segments with > or =50% stenosis was high, with a sensitivity of 81.3%, specificity 95.0%, positive predictive value (PPV) 57.8%, and negative predictive value (NPV) 98.4%. On a "whole-patient" basis, 100% (19/19) of patients with significant coronary disease were correctly identified and there were no false-negatives. Excluding patients with CAC >1000 from the analysis improved the accuracy of MDCTA to: sensitivity 90%, specificity 98.1%, PPV 60%, NPV 99.7%.

CONCLUSION

Non-invasive 16-detector row MDCTA accurately excludes significant coronary disease in patients with severe aortic stenosis undergoing evaluation before aortic valve replacement and in whom ICA can therefore be avoided. Its segment-by-segment accuracy is improved further if CAC>1000 is used as a gatekeeper to MDCTA.

Multidetector row computed tomography: imaging congenital coronary artery anomalies in adults

The quality of the imaging of the main coronary arteries and side branches provided by multidetector row computed tomography (MDCT) may have importance when assessing congenital coronary artery anomalies. This review discusses the rationale for using MDCT for this indication and examines the advantages and disadvantages of the technique. Examples of MDCT imaging of congenital coronary artery anomalies are presented. These images provide persuasive evidence to support clinical use of MDCT cardiac imaging in the context of suspected congenital coronary artery anomalies as a first line investigation.

Multi-detector row computed tomography: imaging the coronary arteries

Over the last 2 years, multi-detector row computed tomographic (MDCT) cardiac imaging has continued to rapidly develop and evolve from the experimental research setting to become a useful clinical tool. The increasing availability of MDCT presents today's clinicians with an additional non-invasive diagnostic cardiac imaging method, in particular for the coronary arteries. With the advent and increasing clinical use of 16-detector row machines, and now with the imminent clinical emergence of 64-channel machines, the improvements in spatial and temporal resolution and sophisticated ECG-gating are allowing motion-free, fast, accurate, detailed, contrast-enhanced cardiac imaging that begins to approach the accuracy of traditional invasive diagnostic techniques. Additional diagnostic information may also be provided.

Highly accurate coronary angiography with submillimetre, 16 slice computed tomography

OBJECTIVE

To assess submillimetre coronary computed tomographic angiography (CTA) in comparison with invasive quantitative coronary angiography as the gold standard and to examine the effect of significant coronary artery calcification (CAC), which is known to impede lumen visualisation, on the accuracy of the examination.

METHODS

After invasive coronary angiography, 58 patients underwent coronary imaging with a GE Lightspeed 16 computed tomography (CT) system. CAC was quantified after an ECG triggered acquisition with a low tube current. Coronary CTA was performed with retrospective ECG gating and a 16 x 0.63 mm collimation and was reconstructed with an effective 65-250 ms temporal resolution. All 13 major coronary artery segments were evaluated for the presence of > or = 50% stenosis, and compared with the gold standard.

RESULTS

One patient moved and could not be evaluated. All segments (except occluded segments) were evaluated for 57 patients. Overall the accuracy of coronary CTA for detection of > or = 50% stenosis was: sensitivity 83%, specificity 97%, positive predictive value 80%, and negative predictive value 97%. The number of diseased coronary arteries was correctly diagnosed in 34 of 38 (89%) patients overall. Altogether 21 of 57 (37%) patients had a CAC score > or = 400, which was predefined as representing significant CAC. Excluding these patients from the analysis improved the accuracy of coronary CTA to a sensitivity of 89%, specificity 98%, positive predictive value 79%, and negative predictive value 99%.

CONCLUSIONS

Non-invasive coronary angiography with submillimetre CT is reliable and accurate. It appears that a subgroup of patients may be selected based on CAC score in whom the investigation has even higher accuracy. Coronary CTA has reached the stage where it should be considered for a clinical role. Further research is required to define this role.

Glucose-sensitive holographic sensors

Holographic sensors for monitoring glucose were fabricated from hydrogel films containing chemical ligands based on phenylboronic acid. The films were transformed into reflection holograms using a diffusion method coupled with exposure to laser light. The diffraction wavelength of the holograms was used to monitor the swelling of the hydrogel film in the presence of glucose. Fully reversible changes in diffraction wavelength were demonstrated, highlighting the potential for using these holograms as glucose sensors.

Three dimensional volume quantification of aortic valve calcification using multislice computed tomography

OBJECTIVE

To assess a new multislice computed tomography (CT) technique for three dimensional quantification of aortic valve calcification volume (3D AVCV) and to study the relation between stenosis and calcification of the aortic valve.

METHODS

50 patients with echocardiographic calcification of the aortic valve underwent two separate ECG triggered multislice CT for quantification of 3D AVCV. The agreement between the two 3D AVCV scores was assessed and 3D AVCV was compared with echocardiographic markers of severity of aortic stenosis.

RESULTS

Overall the level of agreement between the two 3D AVCV scores was excellent (median interscan variability 7.9% (interquartile range 10.1); correlation coefficient, r = 0.99; repeatability coefficient 237.8 mm3 (limits of agreement -393 to 559 mm3)). However, the magnitude of the 3D AVCV did influence the interscan variability. The 3D AVCV correlated closely with the maximal predicted transvalvar gradient (r2 = 0.77) and aortic valve area (r2 = 0.73).

CONCLUSIONS

Multislice CT provides a technique for quantifying 3D AVCV that has good reproducibility. There is a close non-linear relation between echocardiographic parameters of severity of valve stenosis and 3D AVCV scores.

Refined computed tomography of the thoracic aorta: the impact of electrocardiographic assistance

There have been a number of advances in helical computed tomography (CT) in recent years, which have had a beneficial impact on the quality of imaging of the thoracic aorta. These advances include sub-second gantry rotation, multislice acquisition, and the use of electrocardiographic (ECG) assistance. We examine these techniques with emphasis on the principles behind ECG assistance and its use to reduce aortic motion artefact. We highlight examples of ECG-assisted multislice CT in a spectrum of pathologies of the thoracic aorta.

Multislice computed tomographic coronary angiography: experience in a UK centre

AIM

To evaluate the technique of coronary angiography with retrospectively electrocardiogram (ECG)-gated four-slice helical computed tomography (CT).

MATERIALS AND METHODS

Within 1 month of undergoing routine day-case diagnostic coronary angiography, 30 consecutive patients also underwent retrospectively ECG-gated multislice CT coronary angiography. This enabled direct comparison of seven segments of proximal and mid-coronary artery for each patient by two blinded assessors. Each segment of coronary artery from the multislice CT image was evaluated initially for "assessability" and those segments deemed assessable were subsequently investigated for the presence or absence of a significantly (n=70%) stenotic lesion.

RESULTS

Overall 68% of proximal and mid-coronary artery segments were assessable. The sensitivity and specificity of four-slice CT coronary angiography in assessable segments for detecting the presence or absence (n=70%) of stenoses were 72 and 86%, respectively. These results correspond to a positive predictive value of 53% and a 93% negative predictive value. If the 32% of non-assessable segments are added into the calculation then the sensitivity and specificity fall to 49 and 66%, respectively.

CONCLUSION

Although multislice CT coronary angiography is a promising technique, the overall assessability and diagnostic accuracy of four-slice CT acquisition is not sufficient to justify routine clinical use. Further, evaluation should investigate the benefit of the reduction in temporal and spatial resolution offered by 16 and 32 slice acquisition.

New insights into onset mechanisms of atrial fibrillation and flutter after coronary artery bypass graft surgery

OBJECTIVE

To determine by means of a monitoring study the onset mechanisms of atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG).

PATIENTS AND DESIGN

During elective CABG, 81 patients had one bipolar atrial and one ventricular epicardial electrode attached. These were connected to a Vitatron 900E external pacing device, which monitored the patients for four consecutive days. 12 lead ECGs were obtained if AF was clinically detected and Holter ECGs were obtained in 8 (33%) of these patients.

RESULTS

24 patients (30%) developed paroxysmal AF (50%), atrial flutter (17%), or both (33%). The number of AF episodes varied from 1-169 a day (median 5) and were usually of short duration (median 2.25 minutes). Pacemaker diagnostics showed much intrapatient and interpatient variability in onset mechanisms but the majority of AF onsets (71%) were preceded by either short runs of AF or multiple atrial extrasystoles. The final trigger was a conducted atrial extrasystole in 72% of cases. There were no bradycardic triggers. The Holter ECGs confirmed the device's data.

CONCLUSIONS

The onset mechanisms of post-CABG AF are dominated by atrial extrasystoles with multiple atrial extrasystoles and short runs of AF preceding the main AF onset in the majority of cases. These results have major implications for the development of new preventive pacing algorithms.

Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation

BACKGROUND

One third of chronic heart failure patients have major intraventricular conduction and uncoordinated ventricular contraction. Non-controlled studies suggest that biventricular pacing may improve haemodynamics and well-being by reducing ventricular asynchrony. The aim of this trial was to assess the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation.

METHODS

Fifty nine NYHA class III patients with left ventricular systolic dysfunction, chronic atrial fibrillation, slow ventricular rate necessitating permanent ventricular pacing, and a wide QRS complex (paced width >or=200 ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, crossover study compared the patients' parameters, as monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. The primary end-point was the 6-min walked distance, secondary end-points were peak oxygen uptake, quality-of-life, hospitalizations, patients' preferred study period and mortality.

RESULTS

Because of a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, we did not observe a significant difference. However, in the patients with effective therapy the mean walked distance increased by 9.3% with biventricular pacing (374+/-108 vs 342+/-103 m in univentricular;P =0.05). Peak oxygen uptake increased by 13% (P=0.04). Hospitalizations decreased by 70% and 85% of the patients preferred the biventricular pacing period (P<0.001).

CONCLUSION

As compared with conventional VVIR pacing, effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes. Further randomized controlled studies are required to definitively validate this therapy in such patients.

Multislice computed tomography cardiac imaging: current status

Non-invasive CT coronary artery imaging has previously had little relevance to most UK radiologists due to the limited availability of electron beam CT scanners. Major advances in CT technology have promoted new applications for helical CT, which include cardiac imaging. Widespread installation of 'multislice' helical CT scanners will make CT coronary artery imaging available for the first time in many UK hospitals. The technical advances and early clinical trial data are reviewed and multislice helical CT cardiac imaging in general is discussed.

Aortic valve imaging with computed tomography: a review

The finding of aortic valve calcification is of clinical relevance. Thickening and calcification of the aortic valve ('aortic sclerosis') may progress over time to calcific aortic stenosis, and calcification of the aortic valve has prognostic importance even in the absence of valve obstruction. Aortic valve calcification may also have effects on the conduction system. There is progressive awareness of the need for an imaging technique that can accurately and reproducibly quantify calcification of native and prosthetic aortic valves. Through adaptation of techniques from electron beam computed tomography (CT) coronary calcium scoring, CT has been proposed as the appropriate imaging modality. Although originally described as a method of comparing the calcification of different aortic valve bioprostheses, the major role suggested for CT aortic valve calcium quantification is now in the field of preventive medicine. This has stemmed from the recognition that traditional vascular risk factors also have a role in the etiology of calcific aortic stenosis. Subsequently, the realization that pharmacological modification of lipid profiles may result in slowing of progression or even regression of aortic valve calcification has led to a need to quantify aortic valve calcification for follow up purposes. Echocardiography has been used to estimate aortic valve calcification in studies of the natural history of aortic stenosis, but it does not accurately quantify calcium. CT appears able to fulfil this requirement, though the technique is still relatively novel. This review examines the need for aortic valve calcium quantification and the evolution of imaging to the current status. Future directions and the promise of new helical CT technologies with respect to cardiac imaging are explored.

Idiopathic dilatation of the pulmonary artery

Idiopathic dilatation of the pulmonary artery is an uncommon cause of a large main pulmonary artery whose diagnosis is dependent on the exclusion of other causes of central pulmonary artery dilatation. We present four new cases who have been known to have large central pulmonary arteries for many years, and suggest that a long period of observation should be considered to be a further criterion for diagnosis as, in some patients who appear to have this condition, an underlying pathology will become apparent.

Churg-Strauss syndrome with critical endomyocardial fibrosis: 10 year survival after combined surgical and medical management

A case is presented of the Churg-Strauss syndrome with hypereosinophilia and severe cardiac involvement, namely biventricular endomyocardial fibrosis and gross encroachment of the right ventricular cavity. The clinical picture was similar to Loeffler's syndrome and the idiopathic hypereosinophilic syndrome. Combined aggressive surgical and medical management led to full recovery and survival at 10 years. The good long term outcome is attributed to strict control of peripheral eosinophil count by oral corticosteroids. This case illustrates the damaging effects of hypereosinophilia on the heart.

Massive pericardial effusion with left-to-right intracardiac shunt

We describe a 31-year-old man with Down's syndrome who presented with severe chronic hypothyroidism and a massive pericardial effusion. Following partial aspiration of this effusion, he rapidly deteriorated and died. Findings at autopsy revealed him to have an atrioventricular septal defect with shunting at the atrial level. We postulate that, by releasing extrinsic pressure on his right heart by the aspiration, there was sudden shunting of blood from left-to-right, resulting in hypotension, shock, and subsequent death. We highlight the difficulties in management of such a case, and suggest alternative strategies.

Osteoprotegerin, a crucial regulator of bone metabolism, also regulates B cell development and function

Osteoprotegerin (OPG) is a CD40-regulated gene in B cells and dendritic cells (DCs). We investigated the role of OPG in the immune system by generating opg(-/-) mice. Like its role as a regulator of bone metabolism, OPG also influences processes in the immune system, notably in B cell development. Ex vivo, opg(-/-) pro-B cells have enhanced proliferation to IL-7, and in opg(-/-) spleen, there is an accumulation of type 1 transitional B cells. Furthermore, opg(-/-) bone marrow-derived DCs are more effective in stimulating allogeneic T cells than control DCs. When challenged with a T-dependent Ag, opg(-/-) mice had a compromised ability to sustain an IgG3 Ag-specific response. Thus, in the immune system, OPG regulates B cell maturation and development of efficient Ab responses.

Regulation of B-cell activation and differentiation by the phosphatidylinositol 3-kinase and phospholipase Cgamma pathway

Signal transduction through the B-cell antigen receptor (BCR) determines the fate of B lymphocytes during their development and during immune responses. A multitude of signal transduction events are known to be activated by ligation of the BCR; however, the critical parameters determining the biological outcome of the signal transduction cascade are only just beginning to be understood. Two enzymes which act on plasma membrane phospholipids, phosphatidylinositol 3-kinase (PI3K) and phospholipase Cgamma (PLCgamma), have been implicated as critical mediators of B-cell activation and differentiation signals. Activation of these ubiquitous enzymes is regulated by B-lymphocyte-specific signal transduction proteins, such as CD 19 and B-cell linker protein. These enzymes function by generating both membrane-anchored and soluble second messenger molecules which regulate the activity of downstream signal transduction proteins. Active PI3K produces phosphatidylinositol-3,4-bisphosphate (PI(3,4)P2) and phosphatidylinositol-3,4-trisphosphate (PI(3,4,5)P3) which can bind to signaling proteins such as Btk or Akt via their pleckstrin homology domains, resulting in their membrane recruitment and activation. The lipid phosphatases SHIP and PTEN negatively regulate production of PI(3,4)P2 and PI(3,4,S)P3 and therefore function to put a "brake" on the PI3K pathway. Active PLCgamma produces inositol-1,4,5-trisphosphate, which regulates Ca2+ mobilization, and diacylglycerol, which binds to a subset of protein kinase C enzymes leading to their membrane localization and activation. Recent evidence has indicated that PLCgamma activation is partially dependent on the PI(3,4,5)P3 production by activated PI3K. Since PI3K and PLCgamma also share common downstream targets such as the NF-AT and NF-kappaB transcription factors, it is becoming clear that these two pathways are interconnected at several levels. Studies of mice deficient in components of the PI3K and PLCgamma pathways demonstrate that these pathways play critical roles in both pre-BCR and BCR-dependent selection events during B-cell differentiation. Taken together, the present data clearly indicate that PI3K and PLCgamma play critical and indispensable roles in the signal transduction cascades leading to multiple biological responses downstream of the BCR.

A novel B lymphocyte-associated adaptor protein, Bam32, regulates antigen receptor signaling downstream of phosphatidylinositol 3-kinase

We have identified and characterized a novel src homology 2 (SH2) and pleckstrin homology (PH) domain-containing adaptor protein, designated Bam32 (for B cell adaptor molecule of 32 kD). cDNAs encoding the human and mouse Bam32 coding sequences were isolated and the human bam32 gene was mapped to chromosome 4q25-q27. Bam32 is expressed by B lymphocytes, but not T lymphocytes or nonhematopoietic cells. Human germinal center B cells show increased Bam32 expression, and resting B cells rapidly upregulate expression of Bam32 after ligation of CD40, but not immunoglobulin M. Bam32 is tyrosine-phosphorylated upon B cell antigen receptor (BCR) ligation or pervanadate stimulation and associates with phospholipase Cgamma2. After BCR ligation, Bam32 is recruited to the plasma membrane through its PH domain. Membrane recruitment requires phosphatidylinositol 3-kinase (PI3K) activity and an intact PI(3,4, 5)P(3)-binding motif, suggesting that membrane association occurs through binding to 3-phosphoinositides. Expression of Bam32 in B cells leads to a dose-dependent inhibition of BCR-induced activation of nuclear factor of activated T cells (NF-AT), which is blocked by deletion of the PH domain or mutation of the PI(3,4,5)P(3)-binding motif. Thus, Bam32 represents a novel B cell-associated adaptor that regulates BCR signaling downstream of PI3K.

Does learning affect the structure of vocalizations in chimpanzees?

We recorded 'pant-hoot' vocalizations from male chimpanzees, Pan troglodytes, housed in two captive facilities in the U.S.A., Lion Country Safari and North Carolina Zoological Park. Acoustic analysis revealed significant differences between the two groups in the temporal patterning of the calls. Because the captive males within each group are from diverse origins, within-group similarity in pant-hoot structure could not have resulted from genetic similarity of the callers. In addition, there were no obvious differences in housing conditions that could have caused the between-group differences. Instead, the results suggest that the calls in each group converged in structure as a consequence of vocal learning. Within-group variation in call structure of the captive groups was similar to that found in a group of wild Ugandan chimpanzees (Kanyawara study group, Kibale National Park), suggesting the presence of species-specific constraints on this call within which different populations can converge on local variants. In addition, an acoustically novel pant-hoot variant that was introduced by one male to the Lion County Safari colony spread to five other males in the same colony. This suggests that chimpanzees may also be able to modify the frequency parameters of their calls through learning. Copyright 1999 The Association for the Study of Animal Behaviour.

Switching to statins: a challenge for primary care

In 1997, doctors in England received official guidelines on the use of statins (3-hydroxy-3-methylglutaryl coenzyme A inhibitors) for primary and secondary prevention of coronary heart disease (CHD). Six months later we determined the status of patients who had been discharged from a specialist lipid clinic in 1989. 195 patients received questionnaires, with the consent of their general practitioners, regarding morbidity in, the subsequent decade and present medication, and were asked to have their cholesterol checked. Analysis was confined to the 86 with a current cholesterol measurement. Of 61 patients who had been discharged on a regimen of dietary advice and/or medication for primary prevention of CHD, 8 had been changed to a statin and 6 had been started on one. According to the new guidelines, none of these qualified for treatment. Of 25 patients who had been discharged on drugs for secondary prevention, all qualified for a statin but only 14 were receiving one--in 6 cases without achieving the recommended reductions in cholesterol. In many of the patients reviewed, treatment had not been altered to conform with the new guidelines. If hyperlipidaemic patients are to benefit promptly from advances in treatment, one solution might be a central registry that arranged regular tests and reported back to general practitioners. However, since many patients at risk do not have very high cholesterol levels, a coordinated approach to CHD risk factors would be preferable.

Toxoplasma gondii and Schistosoma mansoni synergize to promote hepatocyte dysfunction associated with high levels of plasma TNF-alpha and early death in C57BL/6 mice

To address the question of how the murine host responds to a prototypic type 1 cytokine inducer while concurrently undergoing a helminth-induced type 2 cytokine response, C57BL/6 strain animals with patent schistosomiasis mansoni were orally infected with the cystogenic Toxoplasma gondii strain ME49. Schistosoma mansoni infection resulted in a significantly higher mortality rate when mice were subsequently orally infected with ME49, and these animals displayed a defective IFN-gamma and NO response relative to animals infected with T. gondii alone. Plasma levels of TNF-alpha and aspartate transaminase in double-infected mice were greatly elevated relative to mice infected with either parasite alone. Consistent with the latter observation, these animals exhibited severe liver pathology, with regions of coagulative necrosis and hepatocyte vacuolization unapparent in mice carrying either infection alone. Interestingly, mean egg granuloma size was approximately 50% of that in mice with S. mansoni infection alone. The exacerbated liver pathology in coinfected mice did not appear to be a result of uncontrolled tachyzoite replication, because both parasite-specific RT-PCR analysis and immunohistochemical staining demonstrated a low number of tachyzoites in the liver. We hypothesize that mortality in these animals results from the high level of systemic TNF-alpha, which mediates a severe liver pathology culminating in death of the animal.