Abnormal P-waves found in patients with sleep-disordered breathing are associated with triggered pro-arrhythmic activity

Background

Sleep-disordered breathing (SDB) is frequently associated with atrial arrhythmias, but diagnostic markers that predict the propensity for atrial arrhythmias are missing. Abnormal P-wave terminal force in lead V1 (PTFV1) has been associated with atrial structural/electrical remodeling and arrhythmias.

Purpose

Here we investigate the association of triggered pro-arrhythmic activity with abnormal PTFV1 in human right atrial appendage biopsies of patients without and with SDB.

Methods

30 patients undergoing elective coronary artery bypass grafting were screened for SDB by polygraphy. An apnoea-hypopnea index (AHI) of ≥15/h defined SDB. PTFV1 was measured as product of negative P-wave amplitude and duration in lead V1 and was defined as abnormal if >4000 ms*μV. Ca/Calmodulin-dependent protein kinase II (CaMKII) activity was measured in human right atrial appendage biopsies by a specific HDAC4 pull-down assay. Premature atrial contractions (PACs) were triggered by exposure to 100 nM isoproterenol (at 3.5 mM [Ca]o) in human atrial trabeculae. PACs severity was classified by a score from 0 points (no arrhythmias) to 5 points (salve). In addition, atrial fibrosis was quantified by Masson's trichrome stain in cryo-sectioned atrial tissue. Multivariate linear regression analyses were performed accounting for age, sex, BMI, existing AF, heart failure, diabetes, and creatinine.

Results

Interestingly, the AHI was independently associated with the magnitude of PTFV1 (fig. A+B, B=57.47±21.03, R2=0.48, P=0.01). Importantly, patients with an abnormal PTFV1 had a significantly increased CaMKII activity (fig. C, P=0.04) and showed significantly more severe triggered PACs (fig. D, P=0.02). Moreover, the magnitude of PTFV1 correlated significantly and independently with PAC severity (fig. D, B=0.0005±0.0002, R2=0.50, P=0.03). Consistently, these arrhythmias could be significantly reduced by acute CaMKII inhibition (5 μM KN93, P<0.01), which abolished the correlation between PTFV1 and PAC severity (P=N.S.). Surprisingly, atrial fibrosis was significantly decreased in patients with an abnormal PTFV1 (fig. E, P=0.02), suggesting that abnormal PTFV1 is a marker of proarrhythmic atrial electrical remodeling of functional cardiomyocytes but not of fibrotic tissue.

Conclusion

The severity of sleep-disordered breathing (AHI) is independently associated with an abnormal PTFV1. Intriguingly, this abnormality is associated with an increased CaMKII activity and with CaMKII-dependent arrhythmias, suggesting PTFV1 to be a potential tool to evaluate the pro-arrhythmic risk of patients with SDB.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Part of this study was funded by Philips Respironics.

Dangerous surgical scavenger hunt: the complicated course of a patient with left ventricular assist device and end-stage renal disease undergoing reconstructive flap surgery

Patients with left ventricular assist devices (LVADs) who develop stage IV sacral pressure sores (SPS) have an increased procedural risk. We present the complications, including severe intra- and postoperative bleeding, diarrhea with metabolic acidosis, volume loss and acute on chronic renal failure, flap dehiscence and late LVAD outflow cannula thrombosis, in a 54-year-old male who underwent diverting ileostomy (DI) and subsequent fasciocutaneous flap (FCF) surgery for stage IV SPS while supported with an LVAD. Our experience suggests that, despite continuous heparinization, life-threatening thrombotic complications, such as device clotting, can occur. Therefore, the benefit of intervention has to outweigh the risk of bleeding, which should be managed with meticulous surgical technique and substitution of red blood cells rather than the reversal of heparinization or the substitution of clotting factors. Continuation of double anti-platelet therapy should also be considered.

Everolimus versus mycophenolate mofetil in heart transplantation: a randomized, multicenter trial

In an open-label, 24-month trial, 721 de novo heart transplant recipients were randomized to everolimus 1.5 mg or 3.0 mg with reduced-dose cyclosporine, or mycophenolate mofetil (MMF) 3 g/day with standard-dose cyclosporine (plus corticosteroids ± induction). Primary efficacy endpoint was the 12-month composite incidence of biopsy-proven acute rejection, acute rejection associated with hemodynamic compromise, graft loss/retransplant, death or loss to follow-up. Everolimus 1.5 mg was noninferior to MMF for this endpoint at month 12 (35.1% vs. 33.6%; difference 1.5% [97.5% CI: -7.5%, 10.6%]) and month 24. Mortality to month 3 was higher with everolimus 1.5 mg versus MMF in patients receiving rabbit antithymocyte globulin (rATG) induction, mainly due to infection, but 24-month mortality was similar (everolimus 1.5 mg 10.6% [30/282], MMF 9.2% [25/271]). Everolimus 3.0 mg was terminated prematurely due to higher mortality. The mean (SD) 12-month increase in maximal intimal thickness was 0.03 (0.05) mm with everolimus 1.5 mg versus 0.07 (0.11) mm with MMF (p < 0.001). Everolimus 1.5 mg was inferior to MMF for renal function but comparable in patients achieving predefined reduced cyclosporine trough concentrations. Nonfatal serious adverse events were more frequent with everolimus 1.5 mg versus MMF. Everolimus 1.5 mg with reduced-dose cyclosporine offers similar efficacy to MMF with standard-dose cyclosporine and reduces intimal proliferation at 12 months in de novo heart transplant recipients.

Minimized extracorporeal circulation in coronary artery bypass surgery is equivalent to standard extracorporeal circulation in patients with reduced left ventricular function

BACKGROUND

Minimized extracorporeal circulation (MECC) is a promising alternative to standard extracorporeal circulation (ECC) and its use is increasing in routine coronary bypass surgery. We analyzed the clinical outcome of patients with reduced left ventricular function who underwent coronary artery bypass surgery with MECC or with standard ECC.

METHODS

From January 2003 to September 2008, 238 patients with a left ventricular function < 30 % underwent bypass surgery with ECC or MECC. The primary end point of our retrospective observational study was 30-day mortality. Secondary endpoints were the transfusion requirements, as well as intensive care and the in-hospital course.

RESULTS

Demographic data, comorbidities and left ventricular function were similar in the study groups. MECC patients had a tendency towards a lower 30-day mortality rate, a better postoperative renal function and reduced ventilation times. Extracorporeal circulation time and postoperative high-dose inotropic support were significantly lower in the MECC group, while the stays in the intensive care unit and in hospital were comparable between the two groups. In our study, age in the ECC group, and previous infarction and New York Heart Association grade IV in the MECC group were preoperative risk factors associated with a higher mortality.

CONCLUSION

Coronary bypass surgery using MECC is feasible and safe for patients with severely impaired left ventricular function. It is a promising alternative to ECC with a low mortality rate and a more favorable postoperative course.

[Mutation in factor II and factor V gene in patients with peripheral arterial occlusive disease]

Mutations in factor-V- and factor-II-genes are correlated with an increased risk for venous thrombosis according to the literature. The significance of the mutations in factor- II- and factor-V-genes for the development of the peripheral arterial occlusive disease is not known. Therefore, we investigated the presence of these mutations in 152 patients with documented peripheral arterial occlusive disease and 318 controls without peripheral arterial occlusive disease with polymerase chain reaction (PCR). There was no association between factor-II-mutation and peripheral arterial occlusive disease. The factor-V-mutation, however, was increased in patients with peripheral arterial occlusive disease double fold (12 positive cases in 318 controls, 12 positive cases in 152 patients with peripheral arterial occlusive disease). The significance level was reached (p = 0.05) in statistical analysis but the result did not fall below the significance level as necessary to reach statistical significance (odds ratio 2.19). Nevertheless, from these data we have to discuss a biological relevance of factor-V-mutation in the pathogenesis of peripheral arterial occlusive disease.

Chronisch-arterielle Verschlusskrankheit der Beine im Stadium IIb-IV

Die Faktor-V- und Faktor-II-Mutationen sind nach der Literatur mit einem erhöhten Risiko für venöse Thrombosen verbunden. Die Bedeutung der Mutationen im Faktor-IIund -V-Gen für die Entstehung und das Fortschreiten der arteriellen Verschlusskrankheit ist bislang nicht geklärt. Wir untersuchten das Vorhandensein dieser Mutationen bei 152 Patienten mit dokumentierter pAVK und 318 Kontrollen (ohne pAVK) mittels Polymerase-Kettenreaktion (PCR) und RFLP-Analyse. Die Ergebnisse erbrachten keinen Hinweis auf eine Assoziation zwischen einer Faktor-II-Mutation und der Entstehung einer pAVK. Dagegen waren Faktor- V-Mutationen bei pAVK-Patienten doppelt so häufig zu beobachten wie bei Gesunden (in der Kontrollgruppe ergaben sich 12 positive Fälle bei 318 Probanden, in der Patientengruppe ergaben sich 12 positive Fälle bei 152 Patienten). In der statistischen Analyse wurde das Signifikanzniveau (p = 0,05) zwar erreicht, aber nicht unterschritten. Das Chancenverhältnis (Odds-Ratio) betrug 2,19 (Konfidenzintervall 0,96-4,99). Schlussfolgerung: Die biologische Relevanz der Faktor-V-Mutation in der Pathogenese der pAVK kann aufgrund unserer Daten diskutiert werden.

Matrix metalloproteinase-9 in bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome (BOS) is a severe complication after lung transplantation (LTX). In a retrospective cohort study 12 stable healthy recipients (non-BOS) and eight patients with BOS were enrolled after LTX and matrix metalloproteinases (MMP)-9, TIMP-1 and cell characteristics in bronchoalveolar lavage (BAL) samples (n = 145) were analysed. BALs from patients with BOS were further divided according to whether they were obtained before (pre-BOS) or after manifestation of BOS (BOS group). The MMP-9/TIMP-1 ratio was significantly increased in the BOS group compared with non-BOS or pre-BOS; furthermore, the ratio was negatively correlated with forced expiratory volume in one second. In zymography, the active form of MMP-9 was detected predominantly in the BOS group. In addition, zymography showed the banding pattern of neutrophil-derived MMP-9, indicating that polymorphonuclear neutrophils (PMNs) were the main source of MMP-9. According to that, MMP-9 was significantly correlated with the number of PMN. In immunocytochemistry, MMP-9 was also associated predominantly with PMN. This is the first study to evaluate the expression of matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases-1 over time during manifestation of a fibroproliferative lung disease in patients. It demonstrates development of bronchiolitis obliterans syndrome after lung transplantation is associated with an imbalance of matrix metalloproteinases-9/tissue inhibitors of metalloproteinase-1 ratio.