Cerebral hemodynamics during atrial fibrillation: Computational fluid dynamics analysis of lenticulostriate arteries using 7 T high-resolution magnetic resonance imaging.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, inducing irregular and faster heart beating. Aside from disabling symptoms-such as palpitations, chest discomfort, and reduced exercise capacity-there is growing evidence that AF increases the risk of dementia and cognitive decline, even in the absence of clinical strokes. Among the possible mechanisms, the alteration of deep cerebral hemodynamics during AF is one of the most fascinating and least investigated hypotheses. Lenticulostriate arteries (LSAs)-small perforating arteries perpendicularly departing from the anterior and middle cerebral arteries and supplying blood flow to basal ganglia-are especially involved in silent strokes and cerebral small vessel diseases, which are considered among the main vascular drivers of dementia. We propose for the first time a computational fluid dynamics analysis to investigate the AF effects on the LSAs hemodynamics by using 7 T high-resolution magnetic resonance imaging (MRI). We explored different heart rates (HRs)-from 50 to 130 bpm-in sinus rhythm and AF, exploiting MRI data from a healthy young male and internal carotid artery data from validated 0D cardiovascular-cerebral modeling as inflow condition. Our results reveal that AF induces a marked reduction of wall shear stress and flow velocity fields. This study suggests that AF at higher HR leads to a more hazardous hemodynamic scenario by increasing the atheromatosis and thrombogenesis risks in the LSAs region.

Long-term (≥15 years) Follow-up of Percutaneous Coronary Intervention of Unprotected Left Main (From the GRAVITY Registry).

Long term survival and its determinants after Percutaneous Coronary Intervention (PCI) on Unprotected Left Main Coronary Artery (ULMCA) remain to be appraised. In 9 European Centers 470 consecutive patients performing PCI on ULMCA between 2002 and 2005 were retrospectively enrolled. Survival from all cause and cardiovascular (CV) death were the primary end points, while their predictors at multivariate analysis the secondary ones. Among the overall cohort 81.5% of patients were male and mean age was 66 ± 12 years. After 15 years (IQR 13 to 16), 223 patients (47%) died, 81 (17.2%) due to CV etiology. At multivariable analysis, older age (HR 1.06, 95%CI 1.02 to 1.11), LVEF < 35% (HR 2.97, 95%CI 1.24 to 7.15) and number of vessels treated during the index PCI (HR 1.75, 95%CI 1.12 to 2.72) were related to all-cause mortality, while only LVEF <35% (HR 4.71, 95%CI 1.90 to 11.66) to CV death. Repeated PCI on ULMCA occurred in 91 (28%) patients during the course of follow up and did not significantly impact on freedom from all-cause or CV mortality. In conclusion, in a large, unselected population treated with PCI on ULMCA, 47% died after 15 years, 17% due to CV causes. Age, number of vessels treated during index PCI and depressed LVEF increased risk of all cause death, while re-PCI on ULMCA did not impact survival.

Hypertriglyceridemia and omega-3 fatty acids: Their often overlooked role in cardiovascular disease prevention.

AIMS: This review aims to describe the pathogenic role of triglycerides in cardiometabolic risk, and the potential role of omega-3 fatty acids in the management of hypertriglyceridemia and cardiovascular disease. DATA SYNTHESIS: In epidemiological studies, hypertriglyceridemia correlates with an increased risk of cardiovascular disease, even after adjustment for low density lipoprotein cholesterol (LDL-C) levels. This has been further supported by Mendelian randomization studies where triglyceride-raising common single nucleotide polymorphisms confer an increased risk of developing cardiovascular disease. Although guidelines vary in their definition of hypertriglyceridemia, they consistently define a normal triglyceride level as <150 mg/dL (or <1.7 mmol/L). For patients with moderately elevated triglyceride levels, LDL-C remains the primary target for treatment in both European and US guidelines. However, since any triglyceride level in excess of normal increases the risk of cardiovascular disease, even in patients with optimally managed LDL-C levels, triglycerides are an important secondary target in both assessment and treatment. Dietary changes are a key element of first-line lifestyle intervention, but pharmacological treatment including omega-3 fatty acids may be indicated in people with persistently high triglyceride levels. Moreover, in patients with pre-existing cardiovascular disease, omega-3 supplements significantly reduce the risk of sudden death, cardiac death and myocardial infarction and are generally well tolerated. CONCLUSIONS: Targeting resistant hypertriglyceridemia should be considered as a part of clinical management of cardiovascular risk. Omega-3 fatty acids may represent a valuable resource to this aim.

Hospital survival and long term quality of life after emergency institution of venoarterial ECMO for refractory circulatory collapse.

BACKGROUND: Thanks to significant technical improvements, VA-ECMO is increasingly used to reverse circulatory collapse refractory to standard treatments. METHODS: We studied patients who underwent VA-ECMO due to primary cardiogenic shock or cardiac arrest between January 2008 and June 2011 at our institution. Variables related to hospital survival were analyzed. Long-term survival and health-related quality of life were checked. RESULTS: VA-ECMO was instituted in 23 patients: 17 outpatients and 6 inpatients. Seven of the outpatients were admitted to hospital under ongoing CPR. In these pts, time to CPR was 7 min (6-8) and time to ECMO 93 min (74-107); after 20 hours (16-22), all these pts died. Among remaining 16 pts, 6 were bridged to heart transplant and 4 to heart recovery, 8 survived to hospital discharge and 7 were alive with high health-related quality of life after 46 months (36-54). Ongoing CPR, inotropic score and lactates at cannulation did not differ between survivors and non-survivors; duration of shock, SOFA score and serum creatinine at ECMO institution, and lactates and fluid balance after 36 hours were higher in non-survivors. Patients could be kept on spontaneous breathing for >30% of time while on VA-ECMO. CONCLUSION: Emergency VA-ECMO institution can reverse refractory acute cardiovascular collapse, provided it is carried out before significant organ dysfunction occurs. Light sedation and spontaneous breathing while on VA-ECMO can be well tolerated by patients, but related clinical benefits should be proved. Patients successfully bridged to heart recovery or transplant are candidates for long-term good quality of life.

Donor-to-recipient decremental conduction of atrial fibrillation following orthotopic heart transplantation: insights into the mechanism of atrioatrial conduction.

We describe the unique case of a heart transplant patient with type I atrial fibrillation that arose in the donor atrium during a late acute rejection episode and conducted to the recipient atrium with second-degree type I local block. After internal cardioversion, programmed stimulation showed bidirectional decremental conduction across the suture line with nearly equal atrioatrial interval, whereas the recipient atrium showed progressively delayed intra-atrial conduction. These findings strongly suggest that the mechanism of atrioatrial conduction may be electrical propagation along viable myocardium bridging the surgical scar and that the electrophysiologic characteristics of the recipient atrium are involved in decremental conduction across the suture line.

Thromboembolism after atrioventricular node ablation and pacing: long term follow up.

OBJECTIVE: To assess the incidence of arterial embolic events in patients with high rate, drug resistant, severely symptomatic paroxysmal and chronic atrial fibrillation who have undergone atrioventricular (AV) node ablation and permanent pacing. DESIGN: Multicentre retrospective cohort study. PATIENTS AND MANAGEMENT: From May 1987 to January 1997, AV node ablation was performed in 585 severely symptomatic patients (mean (SD) age 66 (11) years) with high rate, drug resistant paroxysmal atrial fibrillation (308) or chronic atrial fibrillation (277). Lone atrial fibrillation was present in 133 patients, while the remaining 452 suffered from dilated, ischaemic, or valvar heart disease. Patients underwent VVIR (454) or DDDR (131) pacemaker implantation, after AV node ablation. Antiplatelet agents were given to 202 patients, warfarin to 187 patients. RESULTS: During a follow up of 33.6 (24.2) months, thromboembolic events were observed in 17 patients (3%); the actuarial occurrence rates of thromboembolism were 1.1%, 3%, 4.2%, and 7.4% after one, three, five, and seven years, respectively. Among five variables, univariate analysis showed that only the presence of chronic atrial fibrillation at the time of ablation (relative risk (RR) = 1.8, 95% confidence interval (CI) = 1.02 to 3. 20, p = 0.04) and the need for warfarin treatment (RR = 1.6, 95% CI 1.00 to 2.71, p = 0.048) were associated with a significantly higher risk of occurrence of thromboembolic events. On multivariate analysis the only predictor of embolic events during the follow up was the presence of chronic atrial fibrillation. CONCLUSIONS: Data from this large cohort of patients indicate a fairly low incidence (1.04% per year) of thromboembolic events after AV node ablation and pacing for drug refractory, high rate atrial fibrillation.

Two-to-one AV block associated with the congenital long QT syndrome.

INTRODUCTION: Conduction abnormalities associated with long QT syndrome (LQTS) have been reported as "pseudo 2:1 AV block" due to sinus intervals shorter than ventricular refractoriness. METHOD AND RESULTS: We report the electrophysiologic characteristics of a patient suffering from congenital LQTS with episodes of true 2:1 AV block. Induction of 2:1 infra-Hisian blocks and return to 1:1 conduction were observed using single atrial and ventricular extrastimuli. The block was located in the Purkinje network but not in the myocardium. CONCLUSION: The His-Purkinje system of our LQTS patient displayed dynamic properties with a strong increase in refractoriness for short-long sequences and a decrease for long-short sequences that triggered intermittent 2:1 AV blocks.

Impaired baroreflex sensitivity is correlated with hemodynamic deterioration of sustained ventricular tachycardia.

OBJECTIVES: The goal of this study was to evaluate clinical and autonomic variables (heart rate variability and baroreflex sensitivity) related to hemodynamic tolerability of VT in patients with sustained monomorphic VT and a healed myocardial infarction. BACKGROUND: Sustained ventricular tachycardia (VT) with hemodynamic deterioration is associated with a worse prognosis than that of well tolerated VT. The causes of hemodynamic deterioration of VT are incompletely understood. METHODS: Twenty-four consecutive patients with sustained monomorphic VT and a healed myocardial infarction (mean age +/- SD 66 +/- 8 years, left ventricular [LV] ejection fraction 37 +/- 11%) were assigned to group 1 if the VT was well tolerated (n = 11) or to group 2 if faintness or syncope occurred or if systolic blood pressure was < 90 mm Hg with clinical signs of shock (n = 13). RESULTS: No difference was found between the two groups in age, LV function, rate and duration of the VT or heart rate variability. However, patients in group 2 had a significantly lower baroreflex sensitivity (3.4 +/- 1.1 vs. 7.1 +/- 3.7 ms/mm Hg, p = 0.003). Multiple logistic regression analysis showed that only the value of baroreflex sensitivity (p = 0.0003)-but not age, LV ejection fraction, VT cycle length or SD of the RR interval (all p > 0.25)-correlated with the tolerability of the VT. Finally, LV ejection fraction (p = 0.0001) and baroreflex sensitivity (p = 0.0003)-but not age, cycle length of the tachycardia or SD of the RR interval-predicted cardiac death or unstable VT during follow-up. CONCLUSIONS: These data suggest that an impaired cardiovascular reflex response may play a key role in the hemodynamic deterioration of sustained VT and that the evaluation of baroreflex sensitivity in patients at high risk for sustained VT may become useful both in risk stratification and in the individualization of treatment.

Left cardiac sympathetic denervation in long QT syndrome patients.

The idiopathic long QT syndrome (LQTS) is an unusual clinical disorder characterized by a prolongation of the QT interval and by syncopal episodes occurring among young subjects, most often during exercise, stress, or other conditions of increased sympathetic activity. Both an imbalance in sympathetic innervation and an intracardiac defect in membrane currents have been proposed as pathogenetic mechanisms. The latter appears substantiated by recent advances in molecular genetics showing a linkage on chromosomes 11, 3, 7, and 4, with identification of the genes for chromosomes 3 and 7. For symptomatic patients with the long QT syndrome, beta-adrenergic blockade, with efficacy in approximately 80% of patients, currently remains the therapy of first choice. For the patients who continue to suffer syncope or cardiac arrest despite beta blockade, evidence has been provided that left cardiac sympathetic denervation represents a very effective treatment. The improvement in the understanding of the molecular mechanisms involved may soon lead to gene specific therapy in most long QT patients.