A customized technique for confluent aortic annular and selective sinus of Valsalva endocarditis.

We describe a novel technical modification for reoperative aortic valve replacement in destructive recurrent prosthetic aortic valve endocarditis. We encountered complex anatomy in a previously operated aortic root wherein the aortic annulus and the right coronary sinus of Valsalva were destroyed. This precluded secure suture placement. We modified a composite mechanical Valsalva conduit to create a separate sinus of Valsalva left in continuity with the mechanical valve. This approach allowed us to exclude the infected right sinus of Valsalva and the corresponding aortic annulus.

Bayesian networks identify determinants of outcomes following cardiac surgery in a UK population.

BACKGROUND: Traditional risk stratification tools do not describe the complex principle determinant relationships that exist amongst pre-operative and peri-operative factors and their influence on cardiac surgical outcomes. This paper reports on the use of Bayesian networks to investigate such outcomes. METHODS: Data were prospectively collected from 4776 adult patients undergoing cardiac surgery at a single UK institute between April 2012 and May 2019. Machine learning techniques were used to construct Bayesian networks for four key short-term outcomes including death, stroke and renal failure. RESULTS: Duration of operation was the most important determinant of death irrespective of EuroSCORE. Duration of cardiopulmonary bypass was the most important determinant of re-operation for bleeding. EuroSCORE was predictive of new renal replacement therapy but not mortality. CONCLUSIONS: Machine-learning algorithms have allowed us to analyse the significance of dynamic processes that occur between pre-operative and peri-operative elements. Length of procedure and duration of cardiopulmonary bypass predicted mortality and morbidity in patients undergoing cardiac surgery in the UK. Bayesian networks can be used to explore potential principle determinant mechanisms underlying outcomes and be used to help develop future risk models.

Interventricular septal mass with coronary artery disease-An unusual presentation in a septuagenarian patient.

A 79-year-old male with a history of syncope attack was found to have a mass in the interventricular septum. The tumor was surgically removed, and the histological diagnosis was ectopic thyroid tissue. The outcome of the surgery was expected to be successful, however, the patient died from multiorgan failure.

Infective endocarditis as a complication of longstanding ventriculoatrial (VA) shunt: the importance of suspicion and early investigation in patients with VA shunt and pyrexia of unknown origin.

Ventriculoatrial (VA) shunts are a method of cerebrospinal fluid diversion, which nowadays are infrequently seen in medical practice. Infective endocarditis (IE) can occur as rare complications of VA shunts, through the introduction of a foreign body close to the tricuspid valve. We report a case of infective endocarditis, that is, in a patient with VA shunt for congenital hydrocephalus. We present the case to highlight the importance of early investigation for IE in patients with fever of unknown origin and shunt in situ, as rapid deterioration can occur and be fatal. We also discuss past experience reported in the literature on the role of cardiothoracic intervention. Prompt diagnosis and early cardiothoracic referral for surgery are crucial, there may only be a narrow window of opportunity for intervention before patients develop fulminant sepsis.

Zooplankton dynamics in a highly eutrophic microtidal estuary.

Mesozooplankton was sampled seasonally in a large microtidal estuary (Peel-Harvey) suffering from massive macroalgal growths and cyanobacterial blooms. Comparisons with other estuaries indicate that eutrophication led to copepod abundance declining and macroalgal-associated species increasing. Mesozooplankton species are almost exclusively autochthonous, i.e. spend entire life cycle within the estuary. Meroplanktonic species are virtually absent because main benthic macroinvertebrate species undergo direct benthic rather than planktotrophic development. There are also few abundant holoplanktonic species. Most species are tychoplanktonic, i.e. benthic and transported into plankton through physical disturbance of sediment. Species number, concentration and Simpson's Index are greater during night than day. Annual cyclical changes in species composition are related closely to changes in salinity. At the most degraded site, nematode concentrations were high and the species number and concentration changed markedly during extreme eutrophication, when oxygen concentrations were low, disrupting annual cyclical changes in species composition.

Microtidal estuaries warrant special management measures that recognise their critical vulnerability to pollution and climate change.

Not all estuaries are equally susceptible to anthropogenic perturbation. Microtidal estuaries with long residence times are intrinsically less robust than well-flushed macrotidal estuaries, facilitating the accumulation of contaminants. This promotes development of blooms of non-toxic and toxic phytoplankton, and hypoxia and anoxia may occur in deeper sections of the typically stratified water column. In Mediterranean and arid climates, high temperatures and low and/or seasonal rainfall can result in marked hypersalinity. Thus, any increase in anthropogenic perturbation will further decrease the health of a system in which the biota already experiences natural stress. Microtidal estuaries are also more susceptible to climate change, the detrimental longer-term effects of which are becoming manifestly obvious. Numerous attempts have been made to develop novel solutions to problems caused by eutrophication, phytoplankton blooms, hypoxia and hypersalinity, which have met with various levels of success, but the need for such measures and effective legislation is increasingly critical.

Virchow's triad and intestinal ischemia post cardiac surgery.

BACKGROUND: Intestinal ischemia is associated with a very high mortality rate. We combined the principles of Virchow's triad to produce preoperative and postoperative models for the development of intestinal ischemia. METHODS: A single institutional study was undertaken involving 18,325 consecutive patients from April 1997 to March 2012. Univariate and multivariate analysis was performed. RESULTS: Mortality was 87% in 91 patients who developed bowel ischemia. Multivariate logistic regression demonstrated that age, peripheral vascular disease, intraaortic balloon pump support, female sex, and preexisting renal failure were significant determinates of intestinal ischemia preoperatively. Logistic regression demonstrated that age, peripheral vascular disease, creatine kinase-MB level, reoperation for bleeding, and blood product usage were significant determinates of intestinal ischemia postoperatively. CONCLUSIONS: Potentially remedial causes of intestinal ischemia include blood product usage, reoperation for bleeding, and creatine kinase-MB release. Age, female sex, peripheral vascular disease, intraaortic balloon pump usage, and preexisting renal failure are fixed risk factors. Despite the continuing trend of reduced blood product usage in the field of cardiac surgery, the increase in patients' risk factors will mean that incidences of intestinal ischemia may increase in the future.

Pneumonectomy: risk factor or innocent bystander?

BACKGROUND: Pneumonectomy is associated with a higher operative mortality rate and worse 5-year survival after resection for non-small-cell lung cancer, compared to lobectomy. We investigated whether pneumonectomy is an independent risk factor for hospital mortality and poor long-term survival, after risk factor adjustment. METHODS: We analyzed a prospectively validated thoracic surgery database. Kaplan-Meier survival curves were constructed for patients who had undergone lobectomy (n = 1484) or pneumonectomy (n = 266). Logistic and Cox multivariate regression analysis and propensity matching were performed on hospital mortality and long-term survival data. RESULTS: Univariate analysis demonstrated that pneumonectomy was a significant risk factor for hospital death (p = 0.02) and long-term survival (p < 0.001). Logistic regression failed to demonstrate pneumonectomy as a risk factor for hospital mortality. Cox regression analysis failed to identify pneumonectomy as a statistically significant risk factor. Propensity analysis (n = 266 in each group with 1:1 matching) demonstrated that pneumonectomy was not associated with hospital mortality (p = 0.37) or poorer long-term survival (p = 0.19) compared to lobectomy. CONCLUSION: Pneumonectomy is not an independent risk factor for hospital mortality or long-term survival, after adjustment for confounding factors.

Long-term survival of non-smokers undergoing coronary artery bypass surgery.

OBJECTIVES: We sought to investigate long-term survival of non-smokers undergoing coronary artery bypass surgery (CABG). METHODS: A prospective database of consecutive patients was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Univariate, multivariate and a propensity analyses were performed. RESULTS: We analysed 13 337 primary CABG procedures. Median follow-up was 7 years. Kaplan-Meier survival curves demonstrate that non-smokers have a significantly improved long-term survival compared with ex- and current smokers, P < 0.0001. Cox regression analysis identified smoking status, age, diabetes, ejection fraction (EF), body mass index, cerebrovascular disease, dialysis, left internal mammary artery (LIMA) non-usage, postoperative creatinine kinase muscle-brain isoenzyme (CKMB), radial artery usage, preoperative rhythm, forced vital capacity (FVC) and logistic EuroSCORE as significant risk factors determining long-term survival. Propensity matching resulted in 3575 non-smokers being matched 1:1, with ex-smokers. After matching, univariate analysis demonstrated the significantly worse long-term survival of ex-smokers compared with non-smokers, P < 0.0001. Cox regression analysis identified smoking status, age, postoperative CKMB, cerebrovascular disease, dialysis, diabetes, EF, FVC, LIMA non-usage, radial artery used, sinus rhythm and logistic EuroSCORE as significant risk factors determining long-term survival. Survival by smoking status plotted at the mean of the covariates, prepropensity matching, demonstrated that non-smokers had a significantly better long-term survival than ex-smokers, P < 0.0001; however, after propensity matching, non-smokers under 65 years of age had a significantly worse long-term survival compared with ex-smokers, P < 0.0001. CONCLUSIONS: Non-smokers under the age of 65 years of age have significantly worse long-term survival compared with ex-smokers after risk factor adjustment. We speculate that this is because ex-smokers have had the causative factor, smoking, removed, but non-smokers have not.

Preoperative red cell distribution width in patients undergoing pulmonary resections for non-small-cell lung cancer.

OBJECTIVES: Red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with cardiac disease. We sought to investigate the association of RDW in patients undergoing lung resections for non-small-cell lung cancer with respect to in-hospital morbidity, mortality and long-term survival. METHODS: Analysis of consecutive patients on a validated prospective thoracic surgery database was performed for those undergoing potentially curative resections at a single institution. Univariate and multivariate analyses were performed for postoperative invasive and non-invasive ventilation, superficial wound infections, length of hospital stay, in-hospital mortality and long-term survival. RESULTS: Overall mortality was 1.9% for all cases (n = 917). The median follow-up was 6.8 years. Univariate analysis demonstrated that RDW has a significant effect on hospital length of stay (P < 0.001), in-hospital mortality rates (P < 0.001), postoperative invasive and non-invasive ventilation (P < 0.001), superficial wound infections (P = 0.06) and long-term survival (P < 0.0001). Multivariate analysis revealed that RDW is a significant factor determining postoperative invasive and non-invasive ventilation, superficial wound infections, length of hospital stay, in-hospital mortality and long-term survival. Confounding factor analysis revealed that in the absence of anaemia, RDW was still a significant factor in the above analysis. CONCLUSIONS: RDW is a significant factor after risk adjustment, determining in-hospital morbidity, mortality and long-term survival in patients post-potentially curative resections for non-small-cell lung cancer. Further work is needed to elucidate the exact mechanism of RDW impact on in-hospital morbidity, mortality and long-term survival. We speculate that subtle bone marrow dysfunction may be an issue.

Is single-unit blood transfusion bad post-coronary artery bypass surgery?

OBJECTIVES: Publications in the surgical literature are very consistent in their conclusions that blood is dangerous with regard to in-hospital mortality, morbidity and long-term survival. Blood is frequently used as a volume expander while simultaneously increasing the haematocrit. We investigated the effects of a single-unit blood transfusion on long-term survival post-cardiac surgery in isolated coronary artery bypass grafting patients. METHODS: A prospective single-institution cardiac surgery database was analysed involving 4615 patients. Univariate, multivariate stepwise Cox regression analysis and propensity matching were performed to identify whether a single-unit blood transfusion was detrimental to long-term survival. RESULTS: Univariate analysis revealed that blood was significantly associated with a reduced long-term survival even with a single-unit transfused, P = 0.0001. Cox multivariate regression analysis identified age, ejection fraction, preoperative dialysis, logistic EuroSCORE, postoperative CKMB, blood transfusion, urgent operative status and atrial fibrillation as significant factors determining long-term survival. When the Cox regression was repeated with patients who received no blood or only one unit of blood, transfusion was not a risk factor for long-term survival. An interaction analysis revealed that blood transfusion was significantly interacting with preoperative haemoglobin levels, P = 0.02. Propensity analysis demonstrated that a single-unit transfusion is not associated with a detrimental long-term survival, P = 0.3. CONCLUSIONS: Cox regression and propensity matching both indicate that a single-unit transfusion is not a significant cause of reduced long-term survival. Preoperative anaemia is a significant confounding factor. Despite demonstrating the negligible risks of a single-unit blood transfusion, we are not advocating liberal transfusion and would recommend changing from a double-unit to a single-unit transfusion policy. We speculate that blood is not bad, but that the underlying reason that it is given might be.

Female sex and long-term survival post curative resection for non-small-cell lung cancer.

OBJECTIVES: To determine whether patient sex has a significant effect on long-term outcomes post curative resection of non-small-cell lung cancer. METHODS: We retrospectively analysed a prospectively validated thoracic surgery database (n = 4212), from a single institution, from September 2001 to October 2012. Univariate, Cox multivariate and propensity analysis was performed. Long-term follow-up was carried out via the National Strategic Tracing Service that operates in the United Kingdom. RESULTS: One hundred per cent follow-up was achieved. Overall institutional in-hospital mortality was 2.0% for all thoracic resections. Median survival was 2.78 years (range 0-13 years). Two thousand two hundred and thirty-three males and 1979 females were included. Kaplan-Meier survival of all the patients demonstrated superior survival of females for all stages, P = 0.0003, and stage I, P = 0.0006. Female sex conferred no survival advantage in stage II, P = 0.7, and IIIa, P = 0.1. Sub-analysis by histological type demonstrated that females had superior survival with adenocarcinoma compared with males, P < 0.001, but no sex difference existed with squamous carcinomas, P = 0.2. Cox analyses demonstrated that female sex was an advantageous prognostic factor for the entire study group [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.69-0.96] and Stage I only (HR 0.70, 95% CI 0.57-0.63). Sex was of no significance in Stage II and IIIa disease with regard to survival. Sub-analysis demonstrated that female sex was not a significant factor determining survival in patients with squamous carcinoma; however, it was significantly associated with increased survival in patients with adenocarcinoma (HR 0.63, 95% CI 0.51-0.78). A 1:1 propensity analysis confirmed the above findings. CONCLUSION: Propensity matching and Cox multivariate regression analysis confirmed the univariate finding that female sex is only associated with improved survival in patients with Stage I adenocarcinoma. Patient sex does not affect survival of patients with squamous carcinoma.

The concept of aortic replacement based on computational fluid dynamic analysis: patient-directed aortic replacement.

OBJECTIVES: Aortic replacement is based on the aortic diameter in the absence of dissection or connective tissue diseases. Frequently, a number of different aortic-to-prosthetic anastomotic positions are possible depending on patient factors and surgeon preferences. High stress on residual aortic tissue may result in aneurysm formation or aneurysmal dilatation. Utilizing a computational fluid dynamic evaluation, we aimed to define possible optimal operative interventions with regard to the extent of aortic replacement. METHODS: For proof of principle, a computational fluid dynamic (CFD) analysis, using Fluent 6.2 (Ansys UK Ltd, Sheffield, UK), was performed on a simplified ascending arch and descending aortic geometry. Wall shear stress in three dimensions was assessed for the standard operations: ascending aortic replacement, arch replacement and proximal descending aortic replacement. RESULTS: Hermiarch replacement is superior to isolated ascending aortic replacement with regard to residual stress analysis on tissues (up to a 10-fold reduction). Aortic arch replacement with island implantation of the supra-aortic vessels may potentially result in high stress on the residual aorta (10-fold increase). Aortic arch replacement with individual supra-aortic vessel implantation may result in areas of high stress (10-fold increase) on native vessels if an inadequate length of supra-aortic tissue is not resected, regardless of it being aneurysmal. CONCLUSIONS: Computational fluid dynamic evaluation, which will have to be patient-specific, 3D anatomical and physiological, potentially has enormous implications for operative strategy in aortic replacement surgery. CFD analysis may direct the replacement of normal-diameter aortas in the future.

Red cell distribution width and coronary artery bypass surgery.

OBJECTIVES: The red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with coronary artery disease with or without heart failure. We sought to investigate the role of RDW in patients undergoing isolated coronary artery bypass graft surgery (CABG). METHODS: Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Univariate and multivariate analysis was performed for in hospital mortality, long-term survival, length of hospital stay, length of intensive care unit stay and creatinine kinase muscle-brain (CKMB) release. RESULTS: Overall mortality was 2.1% for all cases, N = 8615. Median follow up was 5.8 years. Univariate analysis demonstrated that the RDW has a significant effect on CKMB release, P = 0.001, in-hospital mortality, P < 0.0001, and long-term survival, P < 0.0001, but no significant effect on the ITU length of stay, P = 0.9, or hospital length of stay, P = 0.2. Multivariate analysis revealed that the RDW was a significant factor determining in-hospital mortality and long-term survival, but had no significant effect on CKMB release, ITU or hospital length of stay. Confounding factor analysis revealed that in the absence of anaemia, the RDW was still a significant factor determining in-hospital mortality and long-term survival. CONCLUSIONS: The RDW is a significant factor determining in-hospital mortality and long-term survival in patients undergoing isolated CABG. The mechanism of association requires further study.

Wedge resection verses lobectomy for stage 1 non-small-cell lung cancer.

BACKGROUND: Lobectomy remains the gold standard with regard to potentially curative resection of non-small-cell lung carcinoma. We aimed to investigate whether there is a survival difference in stage 1 non-small-cell lung cancer patients who undergo lobectomy compared to a wedge resection. METHODS: We retrospectively analyzed a prospective database of 1283 patients who had potentially curative resection for stage 1 non-small-cell lung cancer. Only patients with adenocarcinoma, squamous or adenosquamous carcinoma were included. We benchmarked our 5-year survival against the 6th International Association for the Study of Lung Cancer results. Three techniques were used to assess the effect of a lobectomy compared to a wedge resection with regard to long-term survival: Cox multivariate regression analysis, neuronal network analysis, and propensity matching. RESULTS: Benchmarking failed to reveal any significant difference compared to the 6th International Association for the Study of Lung Cancer results. Crude analysis demonstrated superiority of lobectomy compared to wedge resection, p = 0.02. Cox regression analysis confirmed that age, body mass index, female sex, being a current smoker, tumor diameter, and preoperative forced expiratory volume in 1 s were all significant factors determining long-term survival. Wedge resection was not a significant factor. Neuronal network analysis concurred with the Cox regression analysis. Propensity matching with 1:1 matching demonstrated that wedge resections was not inferior to a lobectomy, p = 0.10. CONCLUSIONS: Cox regression analysis, neuronal network analysis, and propensity matching in stage 1 non-small-cell lung cancer demonstrate no difference in long-term survival after wedge resection compared to lobectomy.

Patient directed perfusion pressure on bypass, an analogy from electrical engineering--a new concept.

Organ ischemia, particularly mesenteric and renal, can occur despite a seemingly adequate perfusion flow and pressure during a period of cardiopulmonary bypass. The blood pressure to run bypass at remains a contentious issue. We present the concept that perfusion pressure during cardiopulmonary bypass should be patient specific, depending on an individual's resting pre-procedural blood pressure. Four simulated arterial traces with variable morphology, but identical systolic and diastolic blood pressures, were analyzed to calculate the medical mean, arithmetic mean, and root mean square of the blood pressure tracing. Using the standard medical formula for calculation of mean blood pressure, you can potentially underestimate perfusion pressure by 12 mmHg in a normotensive subject. The root mean square pressure calculates the equivalent non pulsatile pressure that will deliver the same hydraulic power to the circulation as its pulsatile equivalent. Patient specific perfusion pressures, calculated via root mean square may potentially help reduce the incidence of organ ischemia during cardiopulmonary bypass. Clinical trials are needed to confirm or refute this concept.

Preoperative hyponatremia and cardiopulmonary bypass: yet another factor for cerebral dysfunction?

Hyponatremia is common in patients prior to cardiopulmonary bypass (CPB), usually secondary to diuretic therapy. Rapid correction of chronic hyponatremia, which potentially occurs on commencing CPB, may in susceptible patients result in central pontine myelomatosis. There are three parts to this study. Part 1: Patients (n = 170) undergoing CPB with preoperative hyponatremia were analyzed by degree of hyponatremia, additive EuroSCORE, length of stay - intensive care and total hospital, and mortality. Part 2: Sodium concentrations of different prime constituents used clinically were collated from the literature. Part 3: Mathematical modeling of the effects of patient size, sex, preoperative hemoglobin, prime solution, and prime volume with regard to the effect on serum sodium during cardiopulmonary bypass was analyzed, assuming a preoperative serum sodium of 125 mmol/L. Part 1: Patients with preoperative hyponatremia, even after matching by additive EuroSCORE, have longer length of stay - intensive care and total hospital, but not significantly different mortality rates. Part 2: Sodium concentrations of different primes used clinically varied from 0 mmol/L to 160 mmol/L. Part 3: Mathematical modeling revealed that patient size, sex, preoperative hemoglobin, prime solution, and prime volume all can exert a significant effect on serum sodium on initiation of cardiopulmonary bypass. Further work is needed to evaluate the roles of sudden changes in serum sodium, with regard to a rapid correction of chronic hyponatremia, or the rapid creation of acute hyponatremia, and cerebral outcomes in patients undergoing CPB.

Mathematical modelling to identify patients who should not undergo left ventricle remodelling surgery.

A mathematical model was developed to predict the cardiac output post left ventricle volume reduction surgery (LVVRS) to establish who should not undergo surgery. Two scenarios were evaluated: dilated cardiomyopathy (DCM), and left ventricular wall aneurysm (LVA). In DCM, a left ventricular diastolic volume (LVDV) of 380 ml, ejection fraction (EF) of 15%, and a heart rate of 80, produces a cardiac output of 4.5 l/min. After LVVRS for DCM to reduce the LV volume to 315 ml, the EF is unchanged, but the cardiac output drops by 0.7 l/min. In LV aneurysms, a LVDV of 380 ml, EF of 15%, and a heart rate of 80, produces a cardiac output of 4.5 l/min. After LVVRS for LVA reducing the LV volume to 320 ml, the EF increases to 56%, and the predicted cardiac output doubles. LVVRS is potentially very hazardous in the setting of DCM, confirmed by the international registry report and the Surgical Treatment for Ischemic Heart Failure Trial. However, in the setting of LVA, the surgery can result in marked improvement in cardiac output. The effect on postoperative cardiac output, due to the extent of LV resection can potentially be modelled for preoperatively.