Zero-fluoroscopy ablation of the cavotricuspid isthmus guided by intracardiac echocardiography in patients with typical atrial flutter

Introduction

In previous studies we have demonstrated the advantages of electrophysiology catheter navigation by intracardiac echocardiography (ICE). In this prospective study we investigated ICE-guided zero-fluoroscopy ablation of the cavotricuspid isthmus (CTI) involving a decapolar diagnostic and an irrigated radiofrequency (RF) ablation catheter in patients with typical atrial flutter (AFL).

Methods and results

Twenty-seven consecutive patients (mean age 73.4±11.6 years, 18 male) with ECG-recordings suggesting ongoing (n=19) or recent CTI-dependent AFL underwent an electrophysiological study (EPS) utilizing solely ICE for catheter navigation. All EPS could be successfully accomplished without the need for fluoroscopy. CTI-dependent AFL was confirmed by entrainment manoeuvre in all patients with ongoing AFL. Mean EPS duration was 44.0±20.3 minutes and mean ablation procedure duration was 22.3±16.4 minutes. RF ablation was applied for 6.3±3.1 minutes (50 Watts, irrigated RF-ablation in all patients). After the last RF application, bidirectional CTI-Block was confirmed by differential pacing in all patients. Echocardiographic parameters such as CTI-length, prominence of the eustachian ridge (ER), and depth of the CTI-pouch on the ablation plane (Figure 1) were assessed to analyse their correlation with EPS- or ablation procedure duration. CTI-pouch was shallower in patients with ablation procedure duration above median (4,9±1.09mm vs. 6.3±0.9mm, p=0.048), suggesting a more laterally ablation plane in these patients, where the CTI musculature is stronger. CTI-length or ER-prominence above the respective median did not correlated with longer EPS duration. However, in some cases with prominent ER inversion of the ablation catheter was needed to achieve contact of catheter-tip to the tissue. An asymptomatic intramural hematoma was diagnosed by ICE after successful ablation in one patient, no other major or minor complications were documented in this study.

Conclusions

Zero-fluoroscopy CTI ablation guided solely by intracardiac echocardiography in patients with CTI-dependent AFL is feasible and safe. ICE visualisation may help to localize the optimal ablation plane, to detect and correct poor tissue contact of the catheter tip and recognise early potential complications during the ablation procedure.

Funding Acknowledgement

Type of funding sources: None.

P4687Relevance of TAPSE and FAC, and their relationship to PASP as echo-derived measures for RV-PA coupling in heart failure: a comparative analysis with invasive RV-pressure volume loop data

Background

Right ventricular (RV) to pulmonary artery (PA) coupling (C), quantified by pressure volume (PV) loop analysis, predicts RV function, and is independently associated with long term survival in systolic heart failure (HFrEF). However, the PV loop technique is invasive and complex to carry out, especially when used to do RV functional analyses. Different echo-surrogate parameters are proposed to measure RV-PA-C, such as the tricuspid annular plane systolic excursion, TAPSE/PAsystolic pressure (SP) and FAC (fractional area change)/PASP as the most promising parameters. However, up to now, no validation of these non-invasive coupling indices with the invasive gold standard method of RV-PV-loops has been done.

Methods

In 111 patients with advanced HFrEF (Post-hoc analysis of Magdeburger CRT Responder Trial, DRKS00011133), echo-derived TAPSE and FAC, and their relationship to PASP were related to the RV PV-loop-derived parameters of intrinsic RV contractility (Ees), pulmonary load (Ea), and the RV-PA-C efficiency (Ees/Ea) by linear regression analysis. Within a MRI substudy (n=49 patients) we examined the relationship of pure longitudinal contraction (MRI-TAPSE) and radial free wall to septum contraction (area change of 5 RV segments from tricuspid valve to apex in the short axis view) to the invasive RV-PA-C.

Results

The MRI analysis demonstrated that radial RV contraction (R2=0.77, p<0.001) correlated better to invasive RV-PA-C than pure longitudinal shortening (R2=0.37, p<0.001) (radial vs. longitudinal: p<0.00). Echo data for the entire patient cohort confirmed the MRI data. The FAC (R2=0.8, p<0.001) was significantly better associated with RV-PA-C than TAPSE (R2=0.57, p<0.001) (TAPSE vs FAC, p<0.001). Placing TAPSE or FAC into a quotient with PASP did not at all (TAPSE vs. TAPSE/PASP, p=0.1) or significantly attenuated (FAC vs. FAC/PASP R2=0.8 vs 0.58, p<0.001) their association to RV-PA-C. However, FAC/PASP and TAPSE/PASP correlated significantly better with global afterload (Eea), PA compliance, and pressure volume area (PVA), (p<0.001). In ROC analysis for all-cause mortality, all 4 tested parameters were prognostic relevant, however, with higher AUC values for FAC/PASP (AUC=0.74, p<0.001) and TAPSE/PASP (AUC=0.74, p<0.001) than for single TAPSE (AUC= 0.71, p=0.001) or FAC (AUC=0.7, p=0.001). Within a multivariate Cox regression analysis, only the FAC/PASP remained an independent predictor for long term survival.

Conclusion

FAC, an echo parameter that includes a predominant radial with a smaller part of longitudinal contraction, correlated significantly better to the invasively derived RV-PA-C-ratio than pure longitudinal RV shortening (TAPSE). Combining FAC or TAPSE with PASP did not improve the non-invasive RV-PA coupling information. However, it provided more comprehensive information on pulmonary vascular load and RV oxygen consumption, which seems to be translated into a higher prognostic power.

Acknowledgement/Funding

scientific grant from Boston Scientific

Isolation and intravenous injection of murine bone marrow derived monocytes

As a subtype of leukocytes and progenitors of macrophages, monocytes are involved in many important processes of organisms and are often the subject of various fields in biomedical science. The method described below is a simple and effective way to isolate murine monocytes from heterogeneous bone marrow. Bone marrow from the femur and tibia of Balb/c mice is harvested by flushing with phosphate buffered saline (PBS). Cell suspension is supplemented with macrophage-colony stimulating factor (M-CSF) and cultured on ultra-low attachment surfaces to avoid adhesion-triggered differentiation of monocytes. The properties and differentiation of monocytes are characterized at various intervals. Fluorescence activated cell sorting (FACS), with markers like CD11b, CD115, and F4/80, is used for phenotyping. At the end of cultivation, the suspension consists of 45%± 12% monocytes. By removing adhesive macrophages, the purity can be raised up to 86%± 6%. After the isolation, monocytes can be utilized in various ways, and one of the most effective and common methods for in vivo delivery is intravenous tail vein injection. This technique of isolation and application is important for mouse model studies, especially in the fields of inflammation or immunology. Monocytes can also be used therapeutically in mouse disease models.

Treatment with aliskiren/amlodipine combination in patients with moderate-to-severe hypertension: a randomised, double-blind, active comparator trial

AIMS

To assess the extent of reduction in blood pressure (BP) of aliskiren/amlodipine combination therapy compared with amlodipine monotherapy in moderate-to-severe hypertensive patients.

METHODS

This was an 8-week multicentre, randomised, double-blind study. After a 1-to 4-week washout period, eligible patients [mean sitting systolic blood pressure (msSBP) ≥ 160 to < 200 mmHg] were randomised to receive a once-daily dose of aliskiren/amlodipine 150/5mg (n = 244) or amlodipine 5 mg (n = 241) for 1 week, followed by up-titration to aliskiren/amlodipine 300/10 mg or amlodipine 10 mg for 7 weeks. Efficacy outcome measures included change from baseline to week 8 endpoint in msSBP (primary endpoint), mean sitting diastolic blood pressure (msDBP), and BP control rate (< 140/90 mmHg). Safety was assessed by monitoring and recording all adverse events (AEs) and laboratory abnormalities.

RESULTS

Patients' demographic characteristics were balanced between the two groups, mean baseline BP being 171.0/94.3 mmHg for aliskiren/amlodipine and 171.8/95.6 mmHg for amlodipine. Of 485 randomised patients, 433 (89.3%) completed the study. At week 8 endpoint, combination therapy resulted in significantly greater msSBP/msDBP reductions and BP control rate, compared with monotherapy (all: p ≤ 0.0001). The overall incidence of AEs was similar between the two groups. The most commonly reported AE was peripheral oedema with the incidence lower for combination therapy (14.4%) than for monotherapy (18.3%).

CONCLUSION

In this population with considerably elevated BP, use of aliskiren/amlodipine combination showed significantly greater BP reductions and allowed more patients to achieve BP control compared with amlodipine monotherapy, with no additional safety concerns.

Ultrasound guided thrombin injection of pseudoaneurysm of the radial artery after percutaneous coronary intervention

Thrombin injection is frequently used to occlude iatrogenic pseudoaneurysms in larger vessels, but has never successfully been used in the radial artery location. Here we report the use of this treatment in a patient with radial artery pseudoaneurysm following coronary intervention. After Doppler sonographic visualization of the pseudoaneurysm cavity and its neck, an ultrasound-guided transcutaneous injection of thrombin was carried out. Immediately after the injection, the pseudoaneurysm was completely clotted and Doppler measurement confirmed the stop of blood flow. The result suggests that ultrasound-guided injection of thrombin into a radial artery pseudoaneurysm following coronary intervention is a feasible alternative to surgical intervention.

Deazaadenosine prevents leukozyte evasion during acute cardiac allograft rejection by suppression of adhesion molecule expression

BACKGROUND

In the initial phase after cardiac transplantation, mononuclear cells infiltrate the graft initiating a relevant impulse for rejection. 3-Deazaadenosin (c3Ado), an analog of adenosine, has demonstrated in vitro anti-inflammatory properties. Furthermore, in vivo studies on arteriosclerosis development and septic myocardial dysfunction c3Ado revealed reduced cellular infiltration. In addition ischemia and reperfusion injury could be diminished in a pulmonary animal model. The aim of our study was to investigate the properties of c3Ado to reduce adhesion molecule expression and cellular infiltration in a fully allogeneic cardiac transplant model.

METHODS AND RESULTS

Lewis rats were challenged with Wistar-Furth cardiac allografts. Untreated grafts were rejected within 7 days (group 1). In group 2, animals received 2 x 5 mg c3Ado SC per day. Grafts were harvested on days 1, 3, and 6 after transplantation for further examination (n = 4 per group and time point). Immunohistochemical examination revealed significant reduction of graft-infiltrating MHC II positive cells, T-cell receptor positive cells (R73), as well as ED1-positive monocytes and macrophages (P < .01) at days 3 and 6 after transplantation. Adhesion molecule (ICAM-1, VCAM-1) expression on days 1 and 3 after transplantation was almost completely diminished in c3Ado-treated grafts.

CONCLUSION

Thus, c3Ado is able to reduce graft infiltration by preventing leukocyte evasion through the suppression of adhesion molecule expression. This may be a novel strategy to protect transplanted organs from early damage after transplantation and extend organ survival after transplantation.

Neurokinin-1 receptor activation induces reactive oxygen species and epithelial damage in allergic airway inflammation

BACKGROUND

An induction of reactive oxygen species (ROS) is characteristic for inflammation but the exact pathways have not been identified for allergic airway diseases so far.

OBJECTIVE

The aim of this study was to characterize the role of the tachykinin NK-1 receptor on ROS production during allergen challenge and subsequent inflammation and remodelling.

METHODS

Precision-cut lung slices of ovalbumin (OVA)-sensitized mice were cultivated and ROS-generation in response to OVA challenge (10 microg/mL) was examined by the 2',7'-dichloroflourescein-diacetate method. Long-term ROS effects on epithelial proliferation were investigated by 5-bromo-2'-deoxyuridine incorporation (72 h). In vivo, the results were validated in OVA-sensitized animals which were treated intra-nasally with either placebo, the tachykinin neurokinin 1 (NK-1) receptor antagonist SR 140333 or the anti-oxidant N-acetylcystein (NAC) before allergen challenge. Inflammatory infiltration and remodelling were assessed 48 h after allergen challenge.

RESULTS

ROS generation was increased by 3.7-fold, which was inhibited by SR 140333. [Sar(9),Met(11)(O(2))]-Substance P (5 nM) caused a tachykinin NK-1 receptor-dependent fourfold increase in ROS generation. Epithelial proliferation was decreased by 68% by incubation with [Sar(9),Met(11)(O(2))]-SP over 72 h. In-vivo, treatment with SR 140333 and NAC reduced epithelial damage (91.4% and 76.8% vs. placebo, respectively, P<0.01) and goblet cell hyperplasia (67.4% and 50.1% vs. placebo, respectively, P<0.05), and decreased inflammatory cell influx (65.3% and 45.3% vs. placebo, respectively, P<0.01).

CONCLUSION

Allergen challenge induces ROS in a tachykinin NK-1 receptor-dependent manner. Inhibition of the tachykinin NK-1 receptor reduces epithelial damage and subsequent remodelling in vivo. Therefore, patients may possibly benefit from treatment regime that includes radical scavengers or tachykinin NK-1 receptor antagonists.

Apoptosis of human macrophages by Flt-4 signaling: implications for atherosclerotic plaque pathology

BACKGROUND

Neointimal inflammation and angiogenesis are important contributors of progression and destabilization of the atherosclerotic plaque. While the role of vascular endothelial growth factor (VEGF) and its receptors VEGF-R1 (Flt-1) and VEGF-R2 (Flk-1) in this process has clearly been defined, expression of the VEGF-R3 (Flt-4) has only been documented on lymphatic and tumor endothelium. This study examined Flt-4 expression in human atherosclerotic plaque and explored its implications for atherosclerotic disease.

METHODS AND RESULTS

Carotid artery thrombendartherectomy specimens from 10 patients with unstable plaque were stained for Flt-4 and its specific growth factors VEGF-C and VEGF-D. Microvascular endothelial cells (MVEC) stained positive for VEGF-C and -D, but not for Flt-4. Interestingly, macrophages within inflammatory perivascular regions coexpressed Flt-4, VEGF-C and VEGF-D. In vitro studies confirmed the expression of Flt-4, VEGF-C and VEGF-D in human monocytes and cultured macrophages. Treatment of macrophages with VEGF-D induced apoptosis as determined by annexin V staining, by immunoblotting of activated caspase 3, and by the ratio of Bcl-2/Bax as well as by DNA fragmentation. Immunohistochemical studies of advanced human carotid atherosclerotic plaque confirmed the coexpression of Flt-4 with activated caspase 3 and TUNEL staining in macrophages, indicating an ongoing apoptotic process.

CONCLUSION

Human monocytes/macrophages express VEGF-C and -D and their receptor Flt-4 in vitro and in vivo within advanced atherosclerotic lesions. Flt-4, in turn, mediates monocyte/macrophage apoptosis and may this way alter plaque stability.

Cell cycle protein expression in vascular smooth muscle cells in vitro and in vivo is regulated through phosphatidylinositol 3-kinase and mammalian target of rapamycin

Cell cycle progression represents a key event in vascular proliferative diseases, one that depends on an increased rate of protein synthesis. An increase in phosphatidylinositol 3-kinase (PI 3-kinase) activity is associated with vascular smooth muscle cell proliferation, and rapamycin, which blocks the activity of the mammalian target of rapamycin, inhibits this proliferation in vitro and in vivo. We hypothesized that these 2 molecules converge on a critical pathway of translational regulation that is essential for successful upregulation of cell cycle-regulatory proteins in activated smooth muscle cells. p70(S6) kinase, a target of PI 3-kinase and the mammalian target of rapamycin, was rapidly activated on growth factor stimulation of quiescent coronary artery smooth muscle cells and after balloon injury of rat carotid arteries. The translational repressor protein 4E-binding protein 1 was similarly hyperphosphorylated under these conditions. These events were associated with increases in the protein levels of cyclin B1, cyclin D1, cyclin E, cyclin-dependent kinase 1, cyclin-dependent kinase 2, proliferating cell nuclear antigen, and p21(Cip1) in vivo and in vitro, whereas inhibition of the PI 3-kinase signaling pathway with either rapamycin or wortmannin blocked the upregulation of these cell cycle proteins, but not mRNA, and arrested the cells in vitro before S phase. In contrast to findings in other cell types, growth factor- or balloon injury-induced downregulation of the cell cycle inhibitor p27(Kip1) was not affected by rapamycin treatment. These data suggest that cell cycle progression in vascular cells in vitro and in vivo depends on the integrity of the PI 3-kinase signaling pathway in allowing posttranscriptional accumulation of cell cycle proteins.

3-deazaadenosine prevents adhesion molecule expression and atherosclerotic lesion formation in the aortas of C57BL/6J mice

Adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) play an important role during the development of atherosclerosis. 3-Deazaadenosine (c(3)Ado), an adenosine analogue, inhibits endothelial-leukocyte adhesion and ICAM-1-expression in vitro. We hypothesized that c(3)Ado is able to prevent the expression of adhesion molecules and atherosclerotic lesion formation in female C57BL/6J mice. The animals were placed on an atherogenic diet with or without c(3)Ado for 9 weeks. Frozen cross sections of the proximal ascending aorta just beyond the aortic sinus were stained with oil red O, hematoxylin, and elastic van Gieson's stains and were analyzed by computer-aided planimetry for fatty plaque formation and neointimal proliferation. Monoclonal antibodies against CD11b (macrophages), VCAM-1, and ICAM-1 were used for immunohistochemistry. Mice on the atherogenic diet demonstrated multiple (5.4+/-1.6 per animal) lesions covering 3.4+/-2.8% of the endothelium and a marked neointima when compared with control mice (4501+/-775 versus 160+/-38 microm(2), P<0.001). Mice on the cholesterol-rich diet without c(3)Ado showed strong endothelial coexpression of ICAM-1 and VCAM-1. Moreover, there was a 10-fold increase in monocyte accumulation on the endothelial surface (33. 3+/-4.9 versus 3.8+/-1.2, P<0.004). In contrast, in mice treated with c(3)Ado, expression of ICAM-1 and VCAM-1 as well as monocyte adhesion and infiltration were almost completely inhibited. Furthermore, these mice did not show any fatty streak formation or neointima formation (125+/-32 microm(2)). Our results demonstrate that c(3)Ado can inhibit diet-induced fatty streak formation and the expression of endothelial ICAM-1 and VCAM-1 in C57BL/6J mice. This may provide a novel pharmacological approach in the prevention and treatment of atherosclerosis.

A novel role for the cyclin-dependent kinase inhibitor p27(Kip1) in angiotensin II-stimulated vascular smooth muscle cell hypertrophy

Angiotensin II (Ang II) has been shown to stimulate either hypertrophy or hyperplasia. We postulated that the differential response of vascular smooth muscle cells (VSMCs) to Ang II is mediated by the cyclin-dependent kinase (Cdk) inhibitor p27(Kip1), which is abundant in quiescent cells and drops after serum stimulation. Ang II treatment (100 nM) of quiescent VSMCs led to upregulation of the cell-cycle regulatory proteins cyclin D1, Cdk2, proliferating cell nuclear antigen, and Cdk1. p27(Kip1) levels, however, remained high, and the activation of the G1-phase Cdk2 was inhibited as the cells underwent hypertrophy. Overexpression of p27(Kip1) cDNA inhibited serum-stimulated [(3)H]thymidine incorporation compared with control-transfected cells. This cell-cycle inhibition was associated with cellular hypertrophy, as reflected by an increase in the [(3)H]leucine/[(3)H]thymidine incorporation ratio and by an increase in forward-angle light scatter during flow cytometry at 48 hours after transfection. The role of p27(Kip1) in modulating the hypertrophic response of VSMCs to Ang II was further tested by antisense oligodeoxynucleotide (ODN) inhibition of p27(Kip1) expression. Ang II stimulated an increase in [(3)H]thymidine incorporation and the percentage of S-phase cells in antisense ODN-transfected cells but not in control ODN-transfected cells. We conclude that p27(Kip1) plays a role in mediating VSMC hypertrophy. Ang II stimulation of quiescent cells in which p27(Kip1) levels are high results in hypertrophy but promotes hyperplasia when levels of p27(Kip1) are low, as in the presence of other growth factors.

Cyclosporine-induced coronary artery constriction--dissociation between thromboxane release and coronary vasospasm

Cyclosporine influences vascular tone, including that of coronary arteries. But its effect on myocardial prostanoid release, which may contribute to a drug-induced coronary and/or myocardial dysfunction, remains unknown. We used the isolated perfused rat heart to study the effect of cyclosporine on both the mechanical function parameters and myocardial prostanoid release into the effluent by ELISA. Cyclosporine (5 microM) induced an increase of perfusion pressure from 40 +/- 3 to 73 +/- 4 mm Hg within 60 minutes (p < 0.001), reflecting an increase of coronary tone. Cyclosporine did not affect heart rate but contractility (+dp/dtmax) tended to decrease, although not significantly. The drug's effect on coronary tone was rapidly reversible upon withdrawal. Cyclosporine perfusion resulted in an increase of thromboxane B2 liberation from 236 +/- 150 to 1321 +/- 354 pg/ml effluent (p < 0.001), whereas the 6-keto-prostaglandin F1 alpha release was unaffected. The vehicle cremophor did not change any of these parameters. Neither inhibition of myocardial prostanoid formation with acetylsalicylic acid nor thromboxane receptor blockade prevented the cyclosporine-induced increase of perfusion pressure. However, perfusion with nitroglycerin or the voltage-sensitive calcium channel antagonist nifedipine in addition to cyclosporine were able to prevent the increase of perfusion pressure. This is the first time it has been demonstrated that cyclosporine induces an acute release of the prostanoid thromboxane within the myocardium. Despite the resulting imbalance in favor of the vasoconstrictive prostanoid, a dependency of the cyclosporine-induced increase of coronary tone on this imbalance was excluded. Conversely, nitric oxide donation or calcium channel blockade were able to prevent the negative effect of the drug on coronary tone, supporting the concept of endothelium-dependent and/or myogenic mechanism of cyclosporine toxicity on the coronary vascular bed.

Cell cycle progression: new therapeutic target for vascular proliferative disease

Entry into and progression of vascular cells through the cell cycle is considered a key event in vascular proliferative diseases. Multiple growth factors and cytokines have been found to regulate vascular cell proliferation. However, the machinery regulating cell cycle represents the "final common pathway" of these signaling cascades and thus provides an attractive therapeutic target for the prevention of vascular proliferative diseases. This review focuses on the current understanding of the regulation of the cell cycle machinery especially as it relates to vascular cell biology and the feasibility of targeting cell cycle for the prevention of restenosis after balloon angioplasty and bypass vein graft disease.

Comparison of in vitro cardiovascular function with in vivo echocardiographic assessment after long-term administration of cyclosporine to rats

Clinical reports indicate that cyclosporine is able to induce heart failure without rejection after heart transplantation. This supposition is supported by ex vivo animal studies, yet ex vivo studies do not account for the potential of counter-regulatory mechanisms, and the clinical observations seem rare in comparison with the number of patients treated with cyclosporine. We hypothesized that cyclosporine administration to rats would fail to exhibit any effect on myocardial contractility in vivo notwithstanding a negative influence ex vivo. Transthoracic echocardiographic examinations (two-dimensional targeted M-mode tracings) were done in a blinded fashion before and after 1-week treatment of rats (10 or 20 mg/kg/day cyclosporine i.p. vs. vehicle). After excision of the hearts, contractility and changes in coronary tone were determined ex vivo during flow-constant perfusion. Neither cyclosporine nor vehicle treatment resulted in changes of echocardiographic parameters (left ventricular diameter, fractional shortening). The heart rate was significantly increased in the high-dose cyclosporine group. This group showed a significant 38% reduction of contractility during the subsequent perfusion ex vivo, whereas low-dose cyclosporine or vehicle had no effect on myocardial performance. Vasoconstriction did not account for this impairment, because coronary tone was unaltered. Cyclosporine, given in doses used in animal studies, impairs myocardial contractility ex vivo but fails to exhibit any effect on myocardial performance in vivo, possibly because of an increase in sympathetic tone. Considering that the denervated transplanted heart in humans is even sensitized to adrenergic stimuli, our finding makes unlikely a clinical contribution of cyclosporine to failure after orthotopic heart transplantation.