Sanjay Chaubey

Electrophysiological abnormalities precede overt structural changes in arrhythmogenic right ventricular cardiomyopathy due to mutations in desmoplakin-A combined murine and human study

Aims Anecdotal observations suggest that sub-clinical electrophysiological manifestations of arrhythmogenic right ventricular cardiomyopathy (ARVC) develop before detectable structural changes ensue on cardiac imaging. To test this hypothesis, we investigated a murine model with conditional cardiac genetic deletion of one desmoplakin allele (DSP ±) and compared the findings to patients with non-diagnostic features of ARVC who carried mutations in desmoplakin. Methods and results Murine: the DSP (±) mice underwent electrophysiological, echocardiographic, and immunohistochemical studies. They had normal echocardiograms but delayed conduction and inducible ventricular tachycardia associated with mislocalization and reduced intercalated disc expression of Cx43. Sodium current density and myocardial histology were normal at 2 months of age. Human: ten patients with heterozygous mutations in DSP without overt structural heart disease (DSP+) and 12 controls with supraventricular tachycardia were studied by high-density electrophysiological mapping of the right ventricle. Using a standard S1–S2 protocol, restitution curves of local conduction and repolarization parameters were constructed. Significantly greater mean increases in delay were identified particularly in the outflow tract vs. controls (P< 0.01) coupled with more uniform wavefront progression. The odds of a segment with a maximal activation–repolarization interval restitution slope >1 was 99% higher (95% CI: 13%; 351%, P= 0.017) in DSP+ vs. controls. Immunostaining revealed Cx43 mislocalization and variable Na channel distribution. Conclusion Desmoplakin disease causes connexin mislocalization in the mouse and man preceding any overt histological abnormalities resulting in significant alterations in conduction–repolarization kinetics prior to morphological changes detectable on conventional cardiac imaging. Haploinsufficiency of desmoplakin is sufficient to cause significant Cx43 mislocalization. Changes in sodium current density and histological abnormalities may contribute to a worsening phenotype or disease but are not necessary to generate an arrhythmogenic substrate. This has important implications for the earlier diagnosis of ARVC and risk stratification.

Endothelial NADPH oxidase-2 promotes interstitial cardiac fibrosis and diastolic dysfunction through proinflammatory effects and endothelial-mesenchymal transition

OBJECTIVES This study sought to investigate the effect of endothelial dysfunction on the development of cardiac hypertrophy and fibrosis. BACKGROUND Endothelial dysfunction accompanies cardiac hypertrophy and fibrosis, but its contribution to these conditions is unclear. Increased nicotinamide adenine dinucleotide phosphate oxidase-2 (NOX2) activation causes endothelial dysfunction. METHODS Transgenic mice with endothelial-specific NOX2 overexpression (TG mice) and wild-type littermates received long-term angiotensin II (AngII) infusion (1.1 mg/kg/day, 2 weeks) to induce hypertrophy and fibrosis. RESULTS TG mice had systolic hypertension and hypertrophy similar to those seen in wild-type mice but developed greater cardiac fibrosis and evidence of isolated left ventricular diastolic dysfunction (p < 0.05). TG myocardium had more inflammatory cells and VCAM-1-positive vessels than did wild-type myocardium after AngII treatment (both p < 0.05). TG microvascular endothelial cells (ECs) treated with AngII recruited 2-fold more leukocytes than did wild-type ECs in an in vitro adhesion assay (p < 0.05). However, inflammatory cell NOX2 per se was not essential for the profibrotic effects of AngII. TG showed a higher level of endothelial-mesenchymal transition (EMT) than did wild-type mice after AngII infusion. In cultured ECs treated with AngII, NOX2 enhanced EMT as assessed by the relative expression of fibroblast versus endothelial-specific markers. CONCLUSIONS AngII-induced endothelial NOX2 activation has profound profibrotic effects in the heart in vivo that lead to a diastolic dysfunction phenotype. Endothelial NOX2 enhances EMT and has proinflammatory effects. This may be an important mechanism underlying cardiac fibrosis and diastolic dysfunction during increased renin-angiotensin activation.

The effect of cyclosporin-A on peri-operative myocardial injury in adult patients undergoing coronary artery bypass graft surgery: a randomised controlled clinical trial

Objective Cyclosporin-A (CsA) has been reported to reduce myocardial infarct size in both the experimental and clinical settings. This protective effect is dependent on its ability to prevent the opening of the mitochondrial permeability transition pore, a critical determinant of cell death in the setting of acute ischaemia-reperfusion injury. Whether CsA can reduce the extent of peri-operative myocardial injury (PMI) in patients undergoing coronary artery bypass graft (CABG) surgery is unknown, and is investigated in this randomised controlled clinical trial. Methods 78 adult patients undergoing elective CABG surgery were randomised to receive either an intravenous bolus of CsA (2.5 mg/kg) or placebo administered after induction of anaesthesia and prior to sternotomy. PMI was assessed by measuring serum cardiac enzymes, troponin T (cTnT) and CK-MB at 0, 6, 12, 24, 48 and 72 h after surgery. Results There was no significant difference in mean peak cTnT levels between control (n=43) and CsA treatment (n=40) patients (0.56±0.06 ng/mL with control vs 0.35±0.05 ng/mL with CsA; p=0.07). However, in higher-risk patients with longer cardiopulmonary bypass times, there was a significant reduction in PMI with CsA therapy (p=0.049), with a reduced postoperative cTnT rise by 0.03 ng/mL for every 10 min, when compared with control. Conclusions In patients with longer cardiopulmonary bypass times, a single intravenous bolus of CsA administered prior to CABG surgery reduced the extent of PMI.

Nox2 Is Required for Macrophage Chemotaxis towards CSF-1

Macrophage migration and infiltration is an important first step in many pathophysiological processes, in particular inflammatory diseases. Redox modulation of the migratory signalling processes has been reported in endothelial cells, vascular smooth muscle cells and fibroblasts. However the redox modulation of the migratory process in macrophages and in particular that from the NADPH oxidase-2 (Nox2) dependent ROS has not been established. To investigate the potential role of Nox2 in the migratory response of macrophages, bone marrow derived macrophages were obtained from WT and NOX2 knockout mice (Nox2KO) and subjected to CSF-1 stimulation. We report here that loss of Nox2 expression in BMM resulted in a significant reduction in the CSF-1 induced spreading response suggesting that Nox2 can modulate cytoskeletal events. Moreover, Nox2KO BMMs were deficient in cellular displacement in the presence of CSF-1. More significantly, when challenged with a gradient of CSF-1, Nox2KO BMMs showed a complete loss of chemotaxis accompanied by a reduction in cell migration speed and directional migration persistence. These results point to a specific role for Nox2KO downstream of CSF-1 during the BMM migratory response. Indeed, we have further found that Nox2KO BMMs display a significant reduction in the levels of ERK1/2 phosphorylation following stimulation with CSF-1.Thus Nox2 is important in BMM cellular motion to CSF-1 stimulation and necessary for their directed migration towards a CSF-1 gradient, highlighting Nox2 dependent signalling as a potential anti-inflammatory target.

Differing effect of modifiable cardiovascular risk factors on intima-media thickening and plaque formation at different sites of the arterial vasculature

Objective The effects of cardiovascular risk factors on the vascular anatomy at differing sites of the arterial vasculature have not been well described. The aim of this study was to compare the effect of cardiovascular risk factors on the intima media thickness (IMT) of the wall of the right and left common carotid artery (CCA) at their bifurcation and proximal from their bifurcation, and the effects on the presence of plaque at carotid and femoral arteries. Design Cross-sectional population-based study. Setting/participants Random samples of men (n=425) and women (n=367) aged 56–77 years were recruited from two general practices participating in the British Regional Heart Study. Main outcome measures Ultrasound examination ascertained IMT and the presence of atheromatous plaque. A model for correlated outcomes was used to simultaneously model all risk factor on all measured vascular sites. Results All cardiovascular risk factors (HbA1c, waist-to-hip ratio, hypertension, LDL and smoking) showed a larger association with IMT thickening at the wall of the CCA at its bifurcation than proximal to its bifurcation. The IMT was greater on the left wall of the CCA than on the right. The association between hypertension with the wall of the CCA depended on age. Smoking was the only risk factor that demonstrated an increased odds (45%, 95% CI 14% to 65%) of the presence of plaque at the femoral arteries when compared with the CCA. Conclusions The associations of cardiovascular risk factors with the vascular anatomy are not uniform for IMT thickening or the presence of plaque. These differences in local arterial anatomy may result in differences between trial outcomes that investigate surrogate endpoints such as IMT.

An 8-year single-centre experience of cardiac resynchronisation therapy: procedural success, early and late complications, and left ventricular lead performance.

AIMS Despite the increasing number of device implants worldwide, little is known about the early and late complications of cardiac resynchronisation therapy (CRT) or the incidence of these complications in patients with different heart failure aetiologies. We aim to determine procedural success and early and late complications in CRT patients. METHODS AND RESULTS All early (<90 days) and late (>90 days) complications occurring over 490 consecutive CRT procedures in 402 patients, from a large single-centre registry between 2000 and 2009 were analysed. Mean follow-up duration was 1012 ± 610 days. In addition, procedural data and long-term left ventricular (LV) lead performance were examined. The mean age of patients was 65 ± 15 years, 31% were female. The majority of devices (70%) were CRT-defibrillators. Left ventricular lead implantation was achieved after one or more than one attempt in 96.7% of patients (first procedure was successful in 95.1%). The incidence of early and late complications was 9.4% and 6.1% respectively. Infection and lead displacement were the most common complications. Dilated cardiomyopathy (DCM) was associated with significantly more complications than ischaemic cardiomyopathy (P = 0.01) and these occurred later in the DCM population. Long-term LV lead performance was comparable with that of right atrial and ventricular leads. CONCLUSION Transvenous implantation of the LV lead is safe and achievable for CRT with high procedural success rates. For the first time we describe the late complications from CRT in different heart failure populations. This group of patients must be kept under surveillance, not only for heart failure events but also for device-related issues. The reasons for higher complication rates in DCM patients require further evaluation.

Calcified amorphous tumour of the heart: presentation of a rare case operated using minimal access cardiac surgery

Calcified amorphous tumour (CAT) of the heart is a rarely reported non-neoplastic cardiac mass. The authors report a 69-year-old female with long-standing severe asthma and on home oxygen, who presented with a 2 cm mobile mass in the left ventricular outflow tract and symptoms of left heart failure and stroke. During minimal access cardiac surgery, a CAT was found attached to the base of the mitral valve. The tumour was removed and the patient had an uneventful postoperative course. The authors present their experience with this patient and review the current literature on this rare kind of tumour.

Using the Dunn Chemotaxis Chamber to Analyze Primary Cell Migration in Real Time

The directed migration of cells (chemotaxis) occurs not only during wound healing and inflammatory responses but also during embryonic development. However, the intracellular signaling pathways that enable a cell to detect a chemoattractant and subsequently migrate toward the source are not clearly defined. The Dunn chemotaxis chamber in conjunction with time-lapse microscopy is a powerful tool that enables the user to observe directly the morphological response of cells to a chemoattractant in real time. Here, using the Dunn chemotaxis chamber, we describe the response of murine bone marrow-derived macrophages to colony stimulating factor-1. This is a particularly useful protocol as it can be adapted to study bone marrow-derived macrophages isolated from genetically modified mice and thus study the requirement of a specific protein in cell migration and chemotaxis.

Aggregation of marginal gains in cardiac surgery: feasibility of a perioperative care bundle for enhanced recovery in cardiac surgical patients

OBJECTIVES The aim of this pilot study was to assess the feasibility of a perioperative care bundle for enhanced recovery after cardiac surgery (ERACS). DESIGN A prospective, observational study. SETTING A major urban teaching and university hospital and tertiary referral center. PARTICIPANTS The study included 53 patients undergoing cardiac surgery before implementation of an ERACS protocol (pre-ERACS group) and 52 patients undergoing cardiac surgery after implementation of an ERACS protocol (ERACS group). INTERVENTIONS Based on recommendations from a consensus review in colorectal surgery, the following enhanced recovery perioperative care bundle was applied: detailed preoperative information, avoidance of prolonged fasting periods preoperatively, preoperative carbohydrate beverages, optimization of analgesia with avoidance of long-acting opioids, prevention of postoperative nausea and vomiting, early enteral nutrition postoperatively, and early mobilization. MEASUREMENTS AND MAIN RESULTS The authors hypothesized that length of hospital stay would be reduced with ERACS. Secondary outcome variables included a composite of postoperative complications and pain scores. Whereas the length of stay in the group of patients receiving the bundle of enhanced recovery interventions remained unchanged compared with the non-ERACS group, there was a statistically significant reduction in the number of patients in the ERACS group presenting with one or more postoperative complications (including hospital-acquired infections, acute kidney injury, atrial fibrillation, respiratory failure, postoperative myocardial infarction, and death). In addition, postoperative pain scores were improved significantly in the ERACS group. CONCLUSIONS This pilot study demonstrated that ERACS is feasible and has the potential for improved postoperative morbidity after cardiac surgery. A larger multicenter quality improvement study implementing perioperative care bundles would be the next step to further assess outcomes in ERACS patients.

Assessment of inflammation with a very small iron-oxide particle in a murine model of reperfused myocardial infarction

To investigate a very small iron‐oxide particle (VSOP) in a mouse model of acute ischemia‐reperfusion to access the mechanism of such particles in areas of myocardial inflammation.