Thoracoscopic epicardial left atrial ablation in symptomatic patients with atrial fibrillation.

AIMS: The low efficacy rates reported for conventional catheter ablation of longstanding persistent atrial fibrillation (LPAF) have led to the development of alternative techniques such as minimal invasive surgical ablation, aiming for durable and contiguous transmural lesions. The aim was to evaluate the efficacy and safety of total thoracoscopic epicardial left atrial ablation (TELA-AF) procedures in a prospective study of severely symptomatic patients with either drug-resistant AF and/or failed attempts of catheter ablation. METHODS AND RESULTS: The TELA-AF surgical technique includes pulmonary vein isolation, left atrial (LA) 'box lesion', and partial vagal denervation. The LA appendage was excluded if deemed safe. Patients were followed with clinical evaluations and 12-lead electrocardiograms at 3, 6, and 12 months after the surgical intervention, complemented with a 7-day Holter monitoring after 6 and 12 months. Sixty patients, of whom 38 (63%) suffered from LPAF, underwent TELA-AF between November 2008 and December 2010. One patient with LPAF was lost to follow-up. At 12-month follow-up, 55/59 patients (93%) were free from atrial fibrillation (AF), while 7/59 patients (12%) suffered from recurrent LA tachycardia. Among patients with LPAF, 32/37 (86%) maintained sinus rhythm after 12 months. Adverse events included four perioperative bleedings requiring conversion to sternotomy in three cases, two ischaemic strokes and one transient ischaemic attack. CONCLUSION: The total thoracoscopic surgical ablation procedure is highly effective even in patients with LPAF, and it seems safe. The high rate of iatrogenic LA re-entrant tachycardia, however, warrants further improvement of the technique.

Dissecting ventricular pseudoaneurysm after perimyocarditis-a case report.

BACKGROUND: The current case describes the fast development of a pseudoaneurysm in a patient that presented with signs of systemic inflammation and generally deranged blood work. CASE PRESENTATION: The pseudoaneurysm appeared within one week of disease onset. The anatomic extent of the pseudoaneurysm was unusual, as it dissected intramurally beneath the septum, inferior to the right ventricle and had effect on the RV filling. The etiology could not be definitely defined, since in adults the most common cause for pseudoaneurysm development is recent myocardial infarction, but in this patient the coronary arteries were healthy. Instead it could have been a consequence of an aggressive perimyocarditis. CONCLUSIONS: Due to the unpredictable nature of pseudoaneurysms we advocate early contact with a center with cardiothoracic surgery expertise for rapid surgical intervention.

Influence of blood/tissue differences in contrast agent relaxivity on tracer-based MR perfusion measurements.

PURPOSE: Perfusion assessment by monitoring the transport of a tracer bolus depends critically on conversion of signal intensity into tracer concentration. Two main assumptions are generally applied for this conversion; (1) contrast agent relaxivity is identical in blood and tissue, (2) change in signal intensity depends only on the primary relaxation effect. The purpose of the study was to assess the validity and influence of these assumptions. MATERIALS AND METHODS: Blood and cerebral tissue relaxivities r1, r2, and r2* for gadodiamide were measured in four pigs at 1.5 T. Gadolinium concentration was determined by inductively coupled plasma atomic emission spectroscopy. Influence of the relaxivities, secondary relaxation effects and choice of singular value decomposition (SVD) regularization threshold was studied by simulations. RESULTS: In vivo relaxivities relative to blood concentration [in s(-1) mM(-1) for blood, gray matter (GM), white matter (WM)] were for r1 (2.614 ± 1.061, 0.010 ± 0.001, 0.004 ± 0.002), r2 (5.088 ± 0.952, 0.091 ± 0.008, 0.059 ± 0.014), and r2* (13.292 ± 3.928, 1.696 ± 0.157, 0.910 ± 0.139). Although substantial, by a nonparametric test for paired samples, the differences were not statistically significant. The GM to WM blood volume ratio was estimated to 2.6 ± 0.9 by r1, 1.6 ± 0.3 by r2, and 1.9 ± 0.2 by r2*. Secondary relaxation was found to reduce the tissue blood flow, as did the SVD regularization threshold. CONCLUSION: Contrast agent relaxivity is not identical in blood and tissue leading to substantial errors. Further errors are introduced by secondary relaxation effects and the SVD regularization.

Experimental treatment of superior venous congestion during cardiopulmonary bypass.

OBJECTIVES: Superior venous outflow obstruction affects cerebral perfusion negatively by reducing cerebral perfusion pressure (CPP). We present a randomized study designed to compare two alternative strategies to preserve the CPP during superior vena cava (SVC) congestion and cardiopulmonary bypass (CPB). METHODS: Fourteen pigs on bi-caval CPB were subjected to 75% occlusion of the SVC flow. CPP was restored either by vasopressor treatment (VP, n = 7) or by partial relief (PR) of the congestion (n = 7). The cerebral effects of the interventions were studied for 60 min with intracranial pressure (ICP) monitoring, cerebral blood flow measurement, the near-infrared light spectroscopy tissue oxygen saturation index (StO2), arterial and venous blood gas analyses and serial measurements of the glial cell damage marker protein S100ß. RESULTS: Both strategies restored the CPP to baseline levels and no signs of severe ischaemia were observed. In the PR group, the venous and ICPs were normalized in response to the intervention, while in the VP group those parameters remained elevated throughout the experiment. The haemoglobin oxygen saturation in the sagittal sinus (SsagO2) was increased by both VP and PR, while significant improvement in the StO2 was observed only in the PR group. The S100ß concentrations were similar in the two groups. CONCLUSIONS: Experimental SVC obstruction during CPB may reduce the CPP, resulting in impaired cerebral perfusion. Both vasopressor treatment and improved venous drainage can, in the short term, individually restore the CPP during these circumstances.

Even small aneurysms can bleed: a ruptured small idiopathic aneurysm of the internal thoracic artery.

Internal thoracic artery (ITA) aneurysms are rare, but a rupture is potentially fatal. Most cases of ITA aneurysms are iatrogenic, caused by, for instance, previous sternotomy or pacemaker implantation. Other known aetiologies are vasculopathies, either of inflammatory origin or as part of connective tissue disorders like Marfan's syndrome, Ehler-Dahnlos syndrome or neurofibromatosis Type 1. Idiopathic ITA aneurysms are exceedingly scarce. The present case illustrates an unusual scenario, which posed diagnostic challenges, where spontaneous rupture of an idiopathic or possibly very late post-traumatic aneurysm of the left ITA led to a life-threatening bleeding, successfully treated by endovascular coiling with standby preparation for conversion to open surgery. This case demonstrates the importance of the careful interpretation of radiological findings and the significance of multidisciplinary collaboration between radiologist and clinician.

Minimal safe arterial blood flow during selective antegrade cerebral perfusion at 20° centigrade.

BACKGROUND: Selective antegrade cerebral perfusion (SACP) enables surgery on the aortic arch, where cerebral ischemia may cause neurologic sequels. This study aims to identify the minimum arterial flow level to maintain adequate cerebral perfusion during SACP in deep hypothermia in the pig. METHODS: Two groups of pigs were subjected to SACP at 20(°)C α-stat. In group 1 (n = 6), flow was stepwise adjusted from 8-6-4-2-8 mL · kg(-1) · min(-1) and in group 2 (n = 5), flow was kept constant at 6 mL · kg(-1) · min(-1). Magnetic resonance imaging and spectroscopy were performed at each flow level together with hemodynamic monitoring and blood gas analysis. The biochemical marker of cerebral damage protein S100ß was measured in peripheral blood. RESULTS: Decreased mixed venous oxygen saturation and increased lactate in magnetic resonance spectroscopy was seen as a sign of anaerobic metabolism below 6 mL · kg(-1) · min(-1). No ischemic damage was seen on diffusion-weighted imaging, but the concentrations of S100ß were significantly elevated in group 1 compared with group 2 at the end of the experiment (p < 0.05). Perfusion-weighted imaging showed coherence between flow setting and cerebral perfusion, increase of blood volume across time, and regional differences in perfusion during SACP. CONCLUSIONS: The findings suggest an ischemic threshold close to 6 mL · kg(-1) · min(-1) in the present model. Regional differences in perfusion during SACP may be of pathogenic importance to focal cerebral ischemia.

Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass.

To investigate the effects on cerebral perfusion by experimental venous congestion of the superior vena cava (SVC) during bicaval cardiopulmonary bypass (CPB) at 34 °C, pigs were subjected to SVC obstruction at levels of 75%, 50%, 25% and 0% of baseline SVC flow at two arterial flow levels (low, LQ, high, HQ). The cerebral perfusion was examined with near-infrared spectroscopy (NIRS), cerebral microdialysis and blood gas analysis. SVC obstruction caused significant decreases in the NIRS tissue oxygenation index (TOI) and in SVC oxygen saturations (P<0.05, both groups), while the mixed venous saturation was decreased only in the LQ group. Sagittal sinus venous saturations were measured in the HQ group and found significantly reduced in response to venous congestion (P<0.05). No microdialysis changes were seen at the group level, however, individual ischemic patterns in terms of concomitant venous desaturation, decreased TOI and increased lactate/pyruvate occurred in both groups. The total venous drainage remained stabile throughout the experiment, indicating increased flow in the inferior vena cava cannula. The results indicate that SVC congestion may impair cerebral perfusion especially in the case of compromised arterial flow during CPB. Reduced SVC cannula flow may pass undetected during bicaval CPB, if SVC flow is not specifically monitored.

Selective antegrade cerebral perfusion at two different temperatures compared to hypothermic circulatory arrest--an experimental study in the pig with microdialysis.

Hypothermic arrest and selective antegrade cerebral perfusion (SACP) is widely used during aortic arch surgery. The microdialysis technique monitors biomarkers of cellular metabolism and cellular integrity over time. In this study, the cerebral changes during hypothermic circulatory arrest (HCA) at 20 degrees C and HCA with SACP at two different temperatures, 20 and 28 degrees C, were monitored. Twenty-three pigs were divided into three groups. A microdialysis probe was fixated into the forebrain. Circulatory arrest started at a brain and body temperature of 20 degrees C or 28 degrees C. Arrest with/without cerebral perfusion (flow 10 ml/kg, max carotid artery pressure 70 mmHg) lasted for 80 min followed by reperfusion and rewarming during 40 min and an observation period of 120 min. The microdialysis markers were registered at six time-points. The lactate/pyruvate ratio (L/P ratio) and the lactate/glucose ratio (L/G ratio) increased significantly (P<0.05), during arrest, in the HCA group. The largest increase of glycerol was found in the group with tepid cerebral perfusion (28 degrees C) and the HCA group (P<0.05). This study supports the use of SACP over arrest. It also suggests that cerebral metabolism and cellular membrane integrity may be better preserved with SACP at 20 degrees C compared to 28 degrees C.

In vivo h-VEGF165 gene transfer improves early endothelialisation and patency in synthetic vascular grafts.

OBJECTIVES: Small-diameter synthetic vascular graft performance is inferior to autologous vein grafts. This study tested the hypotheses that local in vivo administration of plasmids encoding for human vascular endothelial growth factor (VEGF), or co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2 in the tissues surrounding a porous synthetic vascular graft would enhance graft endothelialisation and, consecutively, graft patency. METHODS: First, optimal gene for small-diameter synthetic graft endothelialisation was studied in rat abdominal aorta model (n=132): plasmids encoding for human vascular endothelial growth factor; co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2; or control plasmids were injected around 60 microm ePTFE graft. Second, optimal small-diameter synthetic graft design for endothelialisation was explored in rabbit abdominal aorta model (n=90). Various ePTFE grafts or pre-clotted polyester grafts were used with/without plasmids encoding for human vascular endothelial growth factor. Third, clinically used medium-size synthetic grafts were investigated with/without plasmids encoding for human vascular endothelial growth factor in dog carotid (n=20) and femoral arteries (n=15). Endothelialisation was assessed in midgraft area with scanning electron microscopy. RESULTS: In rats, plasmids encoding for human vascular endothelial growth factor enhanced endothelialisation; whereas co-administration of plasmids encoding for human vascular endothelial growth factor/plasmids encoding for fibroblast growth factor-2 had worst outcome at 1 week (NS), 2 weeks (P=0.01) and 4 weeks (P=0.02). In rabbits, pre-clotted polyester grafts had a trend for faster endothelialisation than ePTFE grafts (P=0.08); whereas plasmids encoding for human vascular endothelial growth factor enhanced endothelialisation compared to controls at 2 weeks (P=0.06), however, the effect reversed at 4 weeks (P=0.03). In dogs, synthetic graft patency was improved by plasmids encoding for human vascular endothelial growth factor in femoral position (P=0.103); whereas all carotid grafts were patent at 6 weeks. CONCLUSIONS: Thus, these data suggested that endothelialisation was fastest in pre-clotted polyester grafts; and that local application of plasmids encoding for human vascular endothelial growth factor had a potential to improve early endothelialisation and patency in synthetic vascular grafts.