Impossibility Results on Stability of Phylogenetic Consensus Methods.

We answer two questions raised by Bryant, Francis, and Steel in their work on consensus methods in phylogenetics. Consensus methods apply to every practical instance where it is desired to aggregate a set of given phylogenetic trees (say, gene evolution trees) into a resulting, "consensus" tree (say, a species tree). Various stability criteria have been explored in this context, seeking to model desirable consistency properties of consensus methods as the experimental data are updated (e.g., more taxa, or more trees, are mapped). However, such stability conditions can be incompatible with some basic regularity properties that are widely accepted to be essential in any meaningful consensus method. Here, we prove that such an incompatibility does arise in the case of extension stability on binary trees and in the case of associative stability. Our methods combine general theoretical considerations with the use of computer programs tailored to the given stability requirements. [Associative stability; consensus; extension stability; phylogeny.].

Incidence of perioperative stroke in clampless aortic anastomosis during off-pump coronary artery bypass grafting.

This study aimed to assess if clampless off-pump coronary artery bypass grafting (OPCAB) decreases the incidence of perioperative stroke (POS) rate and in-hospital mortality. The secondary aim was to evaluate 12-year rates of overall mortality. Between January 2003 to December 2015, data of 645 consecutive patients undergoing isolated CABG were retrospectively collected. 363 underwent aortic no-touch OPCAB (No-touch group) and 282 underwent OPCAB with the Heartstring device (HS group). In-hospital mortality and perioperative stroke rate as primary endpoint, as well as long-term follow-up outcome were analysed. In-hospital mortality was lower into No-touch group compared with HS group but without significant statistical difference (1.7 vs. 3.2%, p = 0.19, respectively); the rate of postoperative stroke was higher in No-touch group compared with HS group, although this difference did not reach statistically significance. Delirium was reported with higher presentation rate in HS group (3.9 vs. 0.8%, p = 0.01). Blood transfusions rate was higher in HS subjects (23.4 vs. 16.1%, p = 0.01). Intubation time, ICU, and hospital length of stay were increased in the HS group (p = 0.008, p = 0.001 and p = 0.003, respectively). Over a 12-year follow-up period, survival probabilities at 1, 5, and 10 years were 93.6 ± 1.3 vs. 93.2 ± 1.5, 80.4 ± 2.6 vs. 80.3 ± 2.2, and 57.9 ± 5 vs. 58.4 ± 3.8% in the No-touch and HS group, respectively (p = 0.97). In this retrospective study, clampless off-pump CABG lowers perioperative stroke rate whose incidence is, however, not inferior compared with No-touch technique, and no statistically significance was detected. Delirium has a higher presentation rate in clampless off-pump CABG.

Postinfarction left ventricular free wall rupture: a 17-year single-centre experience.

OBJECTIVES: Left ventricular free wall rupture (LVFWR) is a catastrophic complication following acute myocardial infarction with an estimated incidence of 0.2-7.6% and mortality can be as high as 60%. This study aimed to identify the risk factors for morbidity and mortality in patients affected by LVFWR. METHODS: This is a retrospective study of 35 patients who underwent surgery for LVFWR between January 2000 and December 2016 at our institution. RESULTS: The mean age of patients was 68.3 years. The in-hospital survival was 65.7% (n = 23), and 13% of survived patients presented with cardiac arrest. The following characteristics were associated with in-hospital mortality at univariable analysis: pre-existing hypertension (P = 0.02), need for inotropes (P = 0.02) and cardiac arrest (P < 0.0001) at presentation, cardiopulmonary resuscitation (P = 0.004), preoperative extracorporeal membrane oxygenation (P = 0.004), technique of LVFWR repair (P = 0.013), operation on extracorporeal membrane oxygenation (P = 0.005) and postoperative extracorporeal membrane oxygenation (P = 0.001). In the multivariable analysis, cardiac arrest at presentation was an independent predictor of in-hospital mortality (odds ratio 11.7, 95% confidence interval 2.352-59.063; P = 0.003). The overall mean postoperative follow-up was 8.3 ± 1.3 years. Overall survival rates at 5 and 10 years were 53.2 ± 8.6% and 49.1 ± 8.9%, respectively. Among the survivors, only 6 (26.1%) patients died during follow-up with a 5-year and 10-year overall survival rate of 80.9 ± 8.7% and 74.7 ± 10%, respectively. CONCLUSIONS: These data suggest a trend towards long-term benefit in patients surviving high-risk surgery for LVFWR repair. Considering the high lethality of LVFWR, the urgency and complexity of the primary surgical intervention early diagnosis and prompt surgery play a key role in the management of this complication.

Implantation of the Jarvik 2000® left ventricular assist device using the miniaturized extracorporeal circulation system - a case report.

Myocardial failure is generally considered to be a progressive, irreversible medical condition with characteristic ventricular enlargement, spatial alteration of the heart chambers, diminished cardiac inotropy and resultant dysfunctional, mechanically inefficient heart.The Jarvik 2000®, similar to the mechanical pump, is an electrically powered, axial-flow left ventricular assist device (LVAD) designed to enhance the function of the chronically failing heart and, consequently, normalize the cardiac output for a long period of time.We report the case of 70-year-old man with congestive dilated cardiomyopathy and bioprosthetic mitral valve who underwent surgical implantation of the Jarvik 2000® LVAD, using the miniaturized extracorporeal circulation (MECC) system.The LVAD was implanted through a left thoracotomy and the MECC system was used to avoid intraoperative spontaneous hemodynamic instability and/or malignant ventricular arrhythmia. The circulatory support with the MECC system was optimal and no complication in terms of hemodynamic instability and perioperative bleeding was recorded. The MECC system obliterated the adverse effects associated with conventional extracorporeal circulation, which are often fatal in critically-ill patients.

Early vascular complications after percutaneous cannulation for extracorporeal membrane oxygenation for cardiac assist.

BACKGROUND: Extracorporeal membrane oxygenation (VA ECMO) demonstrated an advantage in survival and neurological outcome in patients with cardiogenic shock and, in selected population, in victims of refractory cardiac arrest. The incidence of vascular complications ranges in recent series from 10 to 70% including both early and late complications. The aim of the present study was to determine the incidence of early vascular complications and the effectiveness of the prevention of limb ischemia by the insertion of a catheter for distal perfusion. METHODS: Data from our registry of 100 patients treated with VA ECMO implanted via percutaneous femoral approach for cardiogenic shock or refractory cardiac arrest were analyzed. If the leg perfusion was inadequate, an additional 7-9 Fr percutaneous catheter distal to the ECMO arterial cannula was placed into the femoral artery to prevent limb ischemia. RESULTS: Thirty-five patients had early vascular complications. Thirty patients with early ischemia were cannulated with a small reperfusion cannula to obtain antegrade perfusion of the limb. Twenty-six had an effective reperfusion. Seven patients developed a compartment syndrome of the leg requiring urgent fasciotomy that led to clinical improvement and recovery in five, while the other two patients progressed to irreversible ischemia requiring amputation of the limb. CONCLUSION: The majority of ischemic episodes were resolved with the insertion of a distal perfusion catheter. We did not observe any mortal vascular complication, nor any of the observed complications was related to increased mortality.

Post-valvular surgery multi-vessel coronary artery spasm - A literature review.

Coronary artery spasm (CAS) refers to the spontaneous or stimuli-induced transient, often localized and intense subtotal or total constriction/occlusion of the epicardial coronary artery, usually concomitant with angina pectoris with associated elevation of the ST segment on electrocardiogram (ECG). In this article, we present a literature review on post-valvular surgery CAS and report the clinical case of a 77 year-old man who experienced severe early post-aortic surgery chest pain and hemodynamic instability. Emergent coronary angiography revealed severe occlusion of multiple branches of both coronary arteries. The CAS was alleviated with intracoronary infusion of nitroglycerin.

St. Jude Medical Trifecta aortic valve: results from a prospective regional multicentre registry.

BACKGROUND: The Trifecta aortic bioprosthesis (St. Jude Medical, Inc., St. Paul, MN, USA) is a stented pericardial heart valve with excellent preliminary results. Aim of the study was to evaluate its early clinical and hemodynamic performances in a multicenter regional registry. METHODS: Between January 2011 and June 2012, 178 consecutive patients undergoing aortic valve replacement with the Trifecta bioprosthesis were prospectively enrolled at 9 Italian centers. Clinical and echocardiographic data were collectedat discharge, 6-months and at 1-year postoperatively. RESULTS: The average age was 75.4 ± 7.7 years,and 95 (53 %) were men. Indication for valve replacement included stenosis in 123 patients (69 %), mixed lesions in 25 (14 %), and regurgitation in 30 (17 %). Ninety-three (52 %) patients were in NYHA functional class III/ IV. Hospital mortality accounted for 5 (2.8 %) patients. No valve-related perioperative complications were encountered. Median follow-up was 20.5 months (range: 1-34). Early (≤6 months) complications included one thromboembolic event, one major bleeding, and 3 endocarditis (2 explants). Two late (>6 months) thromboembolic events and two endocarditis (1 explant) were registered. No valve thrombosis or structural deterioration were observed after discharge. At 30-months, freedom from all-cause mortality was 87 %, freedom from valve-related mortality 99.4 %, freedom from endocarditis 97.5 %, and freedom from valve explants 98 %. At 1-year, mean gradients ranged from 8 to 16 mmHg, and effective orifice area indexes from 1.0 to 1.2 cm(2)/m(2) for valve sizes from 19 to 27 mm, respectively. No patients had severe prosthesis-patient mismatch. CONCLUSIONS: Trifecta bioprosthesis provided favourable clinical and hemodynamic results over time.

A rare case of ALCAPA and rheumatic mitral valve regurgitation in an adult patient.

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital coronary artery defect leading to sudden cardiac death. Diagnosis is made after the onset of symptoms, mainly in the pediatric population. We describe an uncommon presentation of ALCAPA and rheumatic mitral valve regurgitation, diagnosed by a coronary 64-CT scan performed before a planned mitral valve repair operation.

Cardiovascular variability is similarly altered in coronary patients with normal left ventricular function and in heart failure patients.

OBJECTIVE: After myocardial infarction (MI), baroreflex function is impaired and heart rate (HR) variability is reduced. An impaired baroreflex has been observed also in coronary patients with no previous MI, leading to hypothesize alterations of HR variability also in these patients. The aim of the present work was, therefore, to study whether and to what extent cardiovascular variability is altered in coronary patients with no previous MI. METHODS: Thirty-two individuals were studied: eleven patients with coronary artery disease but no previous MI [coronary artery disease (CAD)], eleven patients with a reduced left ventricular ejection fraction [congestive heart failure (CHF)] and ten age-matched controls (CNT). RESULTS: Overall HR variability was significantly and similarly reduced in CAD (630 ±â€Š272 ms) and CHF patients (594 ±â€Š395 ms) with respect to CNT (1405 ±â€Š837 ms), this being the case also for the low and high frequency spectral components. Low-frequency oscillations of blood pressure (BP) were also significantly and similarly less pronounced in CAD (0.7 ±â€Š0.7 mmHg) and CHF patients (0.7 ±â€Š0.7 mmHg) compared with CNT (1.8 ±â€Š1.4 mmHg). Moreover, both CAD and CHF patients showed a significantly reduced baroreflex function and an increased pulse-wave velocity with respect to CNT. CONCLUSION: Our study shows that in coronary patients with no MI and no left ventricular dysfunction, there is a profound alteration of both HR and BP variability as in CHF patients, presumably because of a marked impairment of the autonomic modulation of the heart and blood vessels.

Late driveline left ventricular assist device infection treated with frozen-and-thawed allogeneic platelet gel.

In this case report, we report the application of frozen-and-thawed allogeneic platelet gel (PLT-gel) to treat a late driveline exit site infection in a 56-year old patient supported by a Heartware-HVAD left ventricular assist device. The treatment duration was 4 weeks and at the follow-up the skin around the exit site was free from further infection. PLT-gel can be used to treat local infection of the driveline exit site and to prevent further high-risk infections.

Systemic and myocardial inflammatory response in coronary artery bypass graft surgery with miniaturized extracorporeal circulation: differences with a standard circuit and off-pump technique in a randomized clinical trial.

Inflammatory response and hemodilution are the main drawbacks of extracorporeal circulation. We hypothesize that the use of miniaturized extracorporeal circulation (MECC) might lower the systemic and myocardial inflammatory patterns compared with a standard system (SECC) and off-pump coronary artery bypass grafting (OPCABG). Sixty-one patients undergoing isolated coronary artery bypass graft were prospectively randomized to MECC (n = 19), SECC (n = 20), or OPCABG (n = 22). Blood samples were collected from radial artery and coronary sinus to analyze blood lactate, hemodilution, and markers for inflammation and endothelial activation such as tumor necrosis factor (TNF)-α, interleukin-6, monocyte chemotactic protein-1, and E-selectin. No differences were observed in early clinical outcome. Interleukin -6 levels increased in every group during and after cardiac surgery, whereas TNF-α values grew in the SECC group (p = 0.05). E-selectin systemic values decreased during and after operation (p = 0.001) in every group. Monocyte chemotactic protein-1 systemic and cardiac levels raised only in SECC group (p = 0.014). In conclusion, MECC is comparable to SECC and OPCABG in the clinical outcome of low-risk patients, and it might be extensively used with no additional intraoperative risk. The analysis of the inflammatory patterns of endothelial activation shows MECC as effective as OPCABG, suggesting further studies to clarify MECC recommendation in high-risk patients.

Infusion of Escherichia coli lipopolysaccharide toxin in rats produces an early and severe impairment of baroreflex function in absence of blood pressure changes.

The assessment of baroreflex function since the first appearance of endotoxemia is important because the arterial baroreflex should exert a protective role during sepsis. Nevertheless, contrasting results were previously reported. This could be due to the hemodynamic instability characterizing this condition that may per se interfere with reflex cardiovascular adjustments. The aim of our study was therefore to study the baroreflex function (a) since the very beginning of infusion of Escherichia coli lipopolysaccharide (LPS) toxin and (b) in absence of the unloading effect produced by a decrease in blood pressure. Lipopolysaccharide was infused in 10 rats for 20 min at the infusion rate of 0.05 mg · kg · min. Blood pressure was continuously measured before, during, and after infusion, and the baroreflex function was evaluated analyzing spontaneous fluctuations of systolic blood pressure and pulse interval by the sequence and transfer-function techniques. Plasma concentrations of inflammatory (interleukin 6, tumor necrosis factor α) and anti-inflammatory (interleukin 10) cytokines were measured in other eight rats, similarly instrumented, four of which receiving the same LPS infusion. We found that blood pressure levels did not change with the infusion of LPS, whereas inflammatory cytokines increased significantly. The baroreflex sensitivity was significantly reduced 10 min after the beginning of LPS infusion, reached values about half those at baseline within 15 min after the start of infusion, and remained significantly low after the end of infusion. In conclusion, we documented that septic shock inducing LPS infusion is responsible for a very rapid impairment of the baroreflex function, independent from the level of blood pressure.

Fatal huge left free wall ventricular rupture after acute posterior myocardial infarction.

A 77-year-old man, with a recent history of an acute inferior myocardial infarction, was referred to our hospital with echocardiographic and clinical signs of left ventricular free wall rupture (LVFWR). The intraoperative finding demonstrated a huge double LVFWR. The inferoposterior wall was dramatically destroyed without any possibility to repair.

Simultaneous management of renal carcinoma with caval vein thrombosis and double coronary artery disease.

INTRODUCTION: Recent advances in surgical and anesthesiology techniques allow simultaneous thoracic and abdominal operations to be performed for severe heart disease and benignant or malignant abdominal diseases. CASE REPORT: The simultaneous surgical management in a 75-year-old patient suffering from severe double coronary artery disease and a renal cell carcinoma with extended intravascular growth into the inferior vena cava is reported. CONCLUSION: The postoperative course was uneventful. Simultaneous surgery proved to be beneficial and safe, showing optimal results in our patient.

Type 2 diabetes mellitus is associated with faster degeneration of bioprosthetic valve: results from a propensity score-matched Italian multicenter study.

BACKGROUND: The present study was aimed at determining the impact of type 2 diabetes mellitus (DM) on postoperative bioprosthetic structural valve degeneration. METHODS AND RESULTS: Twelve Italian centers participated in the study. Patient data refer to bioprosthetic implantations performed from November 1988 to December 2009, which resulted in 6184 patients (mean age 71.3±5.4 years, 60.1% male) being enrolled. Of these patients, 1731 (27.9%) had type 2 DM. The propensity score-matching algorithm successfully matched 1113 patients with type 2 DM with the same number of no-DM patients. The postmatching standard differences were less than 0.1 for each of the covariates, and 64.2% of DM patients were matched. The early (30 days) mortality rate was 7.8% (n=87) versus 2.9% (n=33) in patients with or without type 2 DM (P<0.001), respectively. Seven-year freedom from valve deterioration was significantly lower in patients with DM (73.2% [95% confidence interval, 61.6-85.5] versus 95.4% [95% confidence interval, 83.9-100], P<0.001). In Cox regression models with robust SEs that accounted for the clustering of matched pairs, DM was the strongest predictor of structural valve degeneration (hazard ratio 2.39 [95% confidence interval 2.28-3.52]). When we allowed for interaction between type 2 DM and other key risk factors, DM remained a significant predictor beyond any potentially associated variable. CONCLUSIONS: Patients with type 2 DM undergoing bioprosthetic valve implantation are at high risk of early and long-term mortality, as well as of structural valve degeneration.

Persistence of arterial functional abnormalities after successful coronary revascularization.

BACKGROUND: In patients with myocardial ischemia and coronary atherosclerosis, arterial stiffness and endothelial function are impaired. Whether these alterations can be favorably affected by successful coronary revascularization is debated. METHODS: We studied 39 hospitalized patients 59.3 ± 3.2 years old (mean ± SEM). In 21 patients with angiographic evidence of significant coronary artery stenosis, revascularization procedures were performed (stenting n = 11 and bypass surgery n = 10). The remaining patients had no significant stenosis and thus served as controls. Prerevascularization measurements included carotido-femoral pulse wave velocity (PWV), radial artery flow-mediated vasodilatation and a complete echocardiographic examination. The same measurements were performed 6 months later. Pharmacological treatment consisted of different cardiovascular drugs and remained substantially unchanged over the 6-month follow-up period. RESULTS: With the exception of an increased left ventricular mass index (LVMI; 130 ± 5.3 versus 105.8 ± 7.2 g/m(2), P < 0.05) and a lower Em/Am (0.6 ± 0.01 and 0.8 ± 0.01 respectively, P < 0.05) observed in patients with coronary stenosis, all other hemodynamic, cardiac and vascular variables were similar in the two groups. Following the 6-month follow-up period, all variables remained substantially unchanged, with the exception, in revascularized patients, of a significant reduction in LVMI (-12%, P < 0.05) and an improvement in Tissue Doppler Imaging-measured diastolic function (Em/Am + 30%, P < 0.05). This was not associated, however, with any significant change in PWV and in flow-mediated vasodilatation. CONCLUSION: Cardiac revascularization has no effect on arterial function, assessed either as arterial stiffness or as flow-mediated vasodilatation. On the contrary, the improvement in coronary blood flow triggers local cardiac changes, namely, a reduction in LVMI and an improvement in diastolic function.

Increased pulse wave velocity and not reduced ejection fraction is associated with impaired baroreflex control of heart rate in congestive heart failure.

BACKGROUND: It is known that baroreflex sensitivity (BRS) is impaired in cardiac patients with myocardial infarction (MI). Nevertheless, it is unknown whether factors other than a reduced ejection fraction play a role in the baroreflex impairment of these patients. METHODS AND RESULTS: Heart failure patients [congestive heart failure (CHF), n = 31, age 63 +/- 1.2 years, mean +/- SEM)], age-matched controls (n = 29) and coronary artery disease (CAD) patients without MI (n = 29) had RR interval and arterial blood pressure (BP) continuously monitored. Baroreflex function was assessed by the slope of the regression of RR interval, and BP responses to graded (-10, -20 and -40 mmHg) neck suction stimulation, the slope of bradycardic or tachycardic responses to spontaneous increases or reductions of SBP (sequence analysis) and the baroreflex efficiency index. Pulse wave velocity (PWV) was also measured.Compared with controls, CHF patients had RR interval and BP reflex responses to neck suction reduced by -36 and -54%, respectively (P < 0.01). By contrast, no differences were found between CHF and CAD patients. Similar reductions were observed for the sequence analysis (P < 0.01) in both CHF and CAD patients. Multiple regression analysis showed that in CHF and CAD patients, PWV and SBP and not ejection fraction were correlated with BRS. CONCLUSION: The baroreflex function is impaired in CHF patients, the extent and the degree of baroreflex impairment being similar to that of CAD patients without MI. In CHF and CAD patients, the baroreflex impairment correlates significantly with the increased PWV and not with ejection fraction.