Outcomes of Atrioventricular Node Ablation and Pacing in Patients with Heart Failure and Atrial Fibrillation: From Cardiac Resynchronization Therapy to His Bundle Pacing.

Objective: To review the relevant literature on the use of atrioventricular node ablation and pacing in patients with heart failure and atrial fibrillation. Methods: APubMed/MEDLINE and SCOPUS search was performed in order to assess the clinical outcomes of atrioventricular node ablation and pacemaker implantation, as well as the complications that may occur. Results: Several clinical trials, observational analyses and meta-analyses have shown that the "pace and ablate" strategy not only improves symptoms but also can enhance cardiac performance in patients with heart failure and atrial fibrillation. Although this procedure is effective and safe, some complications may occur including worsening of heart failure, permanent fibrillation, arrhythmias and sudden death. Regarding pacemaker implantation, cardiac resynchronization therapy is shown to be the optimal choice compared to right ventricle apical pacing. His bundle pacing is a promising alternative to cardiac resynchronization therapy and has shown beneficial effects, while left bundle branch pacing is an innovative modality. Conclusions: Atrioventricular node ablation and pacemaker implantation is shown to have beneficial effects on clinical outcomes of patients with atrial fibrillation ± heart failure who do not respond or are intolerant to medical treatment. Cardiac resynchronization therapy is the treatment of choice and His bundle pacing seems to be an effective alternative way of pacing in these patients.

Biomarkers in the clinical management of patients with atrial fibrillation and heart failure.

Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.

The effect of 1.5 T cardiac magnetic resonance on human circulating leucocytes.

Aims: Investigators have proposed that cardiovascular magnetic resonance (CMR) should have restrictions similar to those of ionizing imaging techniques. We aimed to investigate the acute effect of 1.5 T CMR on leucocyte DNA integrity, cell counts, and function in vitro, and in a large cohort of patients in vivo. Methods and results: In vitro study: peripheral blood mononuclear cells (PBMCs) were isolated from healthy volunteers, and histone H2AX phosphorylation (γ-H2AX) expression, leucocyte counts, and functional parameters were quantified using flow cytometry under the following conditions: (i) immediately following PBMC isolation, (ii) after standing on the benchside as a temperature and time control, (iii) after a standard CMR scan. In vivo study: blood samples were taken from 64 consecutive consenting patients immediately before and after a standard clinical scan. Samples were analysed for γ-H2AX expression and leucocyte counts. CMR was not associated with a significant change in γ-H2AX expression in vitro or in vivo, although there were significant inter-patient variations. In vitro cell integrity and function did not change with CMR. There was a significant reduction in circulating T cells in vivo following CMR. Conclusion: 1.5 T CMR was not associated with DNA damage in vitro or in vivo. Histone H2AX phosphorylation expression varied markedly between individuals; therefore, small studies using γ-H2AX as a marker of DNA damage should be interpreted with caution. Cardiovascular magnetic resonance was not associated with loss of leucocyte viability or function in vitro. Cardiovascular magnetic resonance was associated with a statistically significant reduction in viable leucocytes in vivo.

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation.

BACKGROUND AND OBJECTIVE: Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection. METHODS: A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days. RESULTS: Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01). CONCLUSIONS: A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.

The MindfulBreather: Motion Guided Mindfulness.

For millennia, humans have focused their attention on the breath to develop mindfulness, but finding a scientific way to harness mindful breathing has proven elusive. Existing attempts to objectively measure and feedback on mindfulness have relied on specialist external hardware including electroencephalograms or respirometers that have been impractical for the majority of people learning to meditate. Consequently, training in the key skill of breath-awareness has lacked practical objective measures and guidance to enhance training. Here, we provide a brief technology report on an invention, The MindfulBreather® that addresses these issues. The technology is available to download embedded in a smartphone app that targets, measures and feedbacks on mindfulness of breathing in realtime to enhance training. The current article outlines only the technological concept with future studies quantifying efficacy, validity and reliability to be reported elsewhere. The MindfulBreather works by generating Motion Guided Mindfulness through interacting gyroscopic and touchscreen sensors in a three phase process: Mindfulness Induction (Phase I) gives standardized instruction to users to place their smartphone on their abdomen, breathe mindfully and to tap only at the peak of their inhalation. The smartphone's gyroscope detects periodic tilts during breathing to generate sinusoidal waveforms. Waveform-tap patterns are analyzed to determine whether the user is mindfully tapping only at the correct phase of the breathing cycle, indicating psychobiological synchronization. Mindfulness Maintenance (Phase II) provides reinforcing pleasant feedback sounds each time a breath is mindfully tapped at the right time, and the App records a mindful breath. Lastly, data-driven Insights are fed back to the user (Phase III), including the number of mindful breaths tapped and breathing rate reductions associated with parasympathetic engagement during meditation. The new MGM technology is then evaluated and contrasted with traditional mindfulness approaches and a novel Psychobiological Synchronization Model is proposed. In summary, unlike existing technology, the MindfulBreather requires no external hardware and repurposes regular smartphones to deliver app-embedded Motion-Guided Mindfulness. Technological applications include reducing mindwandering and down-regulation of the brain's default mode through enhanced mindful awareness. By objectively harnessing breath awareness, The MindfulBreather aims to realize the ancient human endeavor of mindfulness for the 21st century.

Republished: Cardiac MRI of patients with implanted electrical cardiac devices.

Implantable pulse generators and defibrillators have traditionally been considered contraindications to MRI. However, recent data have challenged this paradigm and demonstrated that patients with newer generation devices can safely undergo MRI, including cardiac MRI, provided basic precautions are taken. Indeed, the introduction of MRI conditional systems has led to a conceptual shift in clinical decision making-'can this patient undergo MRI safely?' is being superseded by 'should this patient be implanted with an MRI conditional device?'. This review outlines the risks associated with MRI in patients with implanted cardiac devices, and discusses practical measures to minimise risks and facilitate safe and diagnostic scanning.

Multiparametric cardiovascular magnetic resonance surveillance of acute cardiac allograft rejection and characterisation of transplantation-associated myocardial injury: a pilot study.

BACKGROUND: Serial surveillance endomyocardial biopsies are performed in patients who have recently undergone heart transplantation in order to detect acute cardiac allograft rejection (ACAR) before symptoms occur, however the biopsy process is associated with a number of limitations. This study aimed to prospectively and longitudinally evaluate the performance of multiparametric cardiovascular magnetic resonance (CMR) for detecting and monitoring ACAR in the early phase post-transplant, and characterize graft recovery following transplantation. METHODS: All patients receiving a heart transplant at a single UK centre over a period of 25 months were approached within one month of transplantation. Multiparametric CMR was prospectively performed on the same day as biopsy on four separate occasions (6 weeks, 10 weeks, 15 weeks and 20 weeks post-transplant). CMR included assessment of global and regional ventricular function, myocardial tissue characterization (T1 mapping, T2 mapping, extracellular volume, LGE) and pixel-wise absolute myocardial blood flow quantification. CMR parameters were compared with biopsy findings. As is standard, grade 2R or higher ACAR was considered significant. RESULTS: 88 CMR-matched biopsies were performed in 22 patients. Eight (9%) biopsies in 5 patients demonstrated significant ACAR. Significant ACAR was associated with a reduction in circumferential strain (-12.7±2.5% vs. -13.7±3.6%, p=0.047) but there was considerable overlap between groups. Whilst trends were observed between ACAR and proposed CMR markers of oedema, particularly after adjusting for primary graft dysfunction, differences were not significant. Significant improvements were seen in markers of graft structure and contractility, oedema and microvascular function over the period studied, although few parameters normalised. CONCLUSIONS: This study provides novel insight into the myocardial injury associated with transplantation, and its recovery, however multiparametric CMR was not able to accurately detect ACAR during the early phase post-transplantation.

Voxel-wise quantification of myocardial blood flow with cardiovascular magnetic resonance: effect of variations in methodology and validation with positron emission tomography.

BACKGROUND: Quantitative assessment of myocardial blood flow (MBF) from cardiovascular magnetic resonance (CMR) perfusion images appears to offer advantages over qualitative assessment. Currently however, clinical translation is lacking, at least in part due to considerable disparity in quantification methodology. The aim of this study was to evaluate the effect of common methodological differences in CMR voxel-wise measurement of MBF, using position emission tomography (PET) as external validation. METHODS: Eighteen subjects, including 9 with significant coronary artery disease (CAD) and 9 healthy volunteers prospectively underwent perfusion CMR. Comparison was made between MBF quantified using: 1. Calculated contrast agent concentration curves (to correct for signal saturation) versus raw signal intensity curves; 2. Mid-ventricular versus basal-ventricular short-axis arterial input function (AIF) extraction; 3. Three different deconvolution approaches; Fermi function parameterization, truncated singular value decomposition (TSVD) and first-order Tikhonov regularization with b-splines. CAD patients also prospectively underwent rubidium-82 PET (median interval 7 days). RESULTS: MBF was significantly higher when calculated using signal intensity compared to contrast agent concentration curves, and when the AIF was extracted from mid- compared to basal-ventricular images. MBF did not differ significantly between Fermi and Tikhonov, or between Fermi and TVSD deconvolution methods although there was a small difference between TSVD and Tikhonov (0.06 mL/min/g). Agreement between all deconvolution methods was high. MBF derived using each CMR deconvolution method showed a significant linear relationship (p<0.001) with PET-derived MBF however each method underestimated MBF compared to PET (by 0.19 to 0.35 mL/min/g). CONCLUSIONS: Variations in more complex methodological factors such as deconvolution method have no greater effect on estimated MBF than simple factors such as AIF location and observer variability. Standardization of the quantification process will aid comparison between studies and may help CMR MBF quantification enter clinical use.

Cardiac MRI of patients with implanted electrical cardiac devices.

Implantable pulse generators and defibrillators have traditionally been considered contraindications to MRI. However, recent data have challenged this paradigm and demonstrated that patients with newer generation devices can safely undergo MRI, including cardiac MRI, provided basic precautions are taken. Indeed, the introduction of MRI conditional systems has led to a conceptual shift in clinical decision making-'can this patient undergo MRI safely?' is being superseded by 'should this patient be implanted with an MRI conditional device?'. This review outlines the risks associated with MRI in patients with implanted cardiac devices, and discusses practical measures to minimise risks and facilitate safe and diagnostic scanning.

Acute hepatic failure following intravenous amiodarone.

A 73-year-old gentleman presented to the hospital after an episode of loss of consciousness. He had a defibrillator in situ, which on interrogation was found to have fired for an episode of ventricular fibrillation. As an inpatient he developed frequent episodes of self-terminating ventricular tachycardia, treated initially with oral amiodarone. A 24 h amiodarone infusion was started on day 3 of admission, following which the patient developed hyperventilation. Investigations revealed that this was secondary to acute hepatic and renal failure, requiring haemofiltration on the intensive care unit. Cessation of amiodarone was associated with normalisation of liver function over 48 h. The patient had normal blood and jugular venous pressures throughout days 1-4 of admission. We discuss the role of amiodarone as the predominant factor in the deterioration of this patient's liver function, versus the differential diagnosis of ischaemia-induced hepatotoxicity, citing recent research regarding this subject.

A pain in the leg following angiography.

This case illustrates a complication following deployment of the Angioseal® vascular closure device after routine angiography. The AngioSeal device is a percutaneous, bioabsorbable, collagen-based hemostatic plug deployed to seal the arterial puncture. We describe a 69-year-old gentleman who presented with unilateral leg cramps 1 week post-procedure. When seen in the cardiology clinic, a magnetic resonance imaging angiogram was requested, which showed a filling defect in the right popliteal artery. The collagen seal had embolized and was subsequently removed by the vascular surgeons.

Decompensated heart failure secondary to hypocalcaemia post coronary artery bypass grafting.

A man presented with an exacerbation of heart failure following coronary artery bypass grafting. He was found to be severely hypocalcaemic secondary to a combination of decreased parathyroid reserve and severe vitamin D deficiency. On treatment of his hypocalcaemia, all symptoms resolved. This case highlights the importance of recognising that metabolic derangement can affect cardiac function.

Shortness of breath in a CF patient: not always the chest.

The authors report the case of an adult with cystic fibrosis (CF) presenting with an episode of acute shortness of breath during an inpatient stay for infective exacerbation of CF. The treatment of bronchodilators and steroids for presumed airways disease was not effective and on review of the chest x-ray, it showed some evidence of pulmonary oedema. An echo showed a dilated left ventricle and globally reduced function. Serology came back positive for enterovirus which was in keeping with a diagnosis of myocarditis.