Long Term Survival Benefits of Different Conduits Used in Coronary Artery Bypass Graft Surgery- A Single Institutional Practice Over 20 Years.

Objective: This study determined hazard factors and long-term survival rate of total arterial coronary artery bypass graft surgery over 20 years in an extensively large, population-based cohort. Methods: A total of 2979 patients who underwent isolated CABG from April 1999 to March 2020 were studied in 4 groups- Group-A (bilateral internal mammary artery ± radial artery), Group-B (single internal mammary artery + radial artery ± saphenous vein), Group-C (single internal mammary artery ± saphenous vein; no radial artery), and Group-D (radial artery ± saphenous vein; no internal mammary artery). The study endpoints analysed the correlation between the number and types of grafts with the survival time following isolated CABG surgery. Results: The total arterial revascularization (Group A) group had an admirable mean long-term survival of ~19 years, compared to 18.6 years (Group B), 15.86 years (Group C), and 10.99 years (Group D). A Kaplan-Meier curve demonstrated confidence interval (CI) for study groups- (95% CI 18.33-19.94), (95% CI 18.14-19.06), (95% CI 15.40-16.32), and (95% CI 9.61-12.38) in Group A, B, C, D respectively. In the Holm-Sidak method analysis, significant associations existed between the number of arterial grafts and the long-term outcome. A statistically significant (P≤0.05) long-term survival advantage for arterial grafting was demonstrated, especially total arterial revascularisation over all other combinations except single internal mammary artery + radial artery grafting. Conclusion: In this series, over 20 years, total arterial CABG use has excellent long-term survival, achieving complete myocardial revascularisation. There is no significant difference between the BIMA group and SIMA with radial artery. However, there is a reduced survival with decreased use of arterial conduits.

Survival and Independent Predictors of Mortality Following Coronary Artery Bypass Graft Surgery in a Single-Unit Practice in the United Kingdom Over 20 Years.

BACKGROUND:  The types of graft conduits and surgical techniques may impact the long-term outcomes of patients after coronary artery bypass graft (CABG) revascularization. This study observed a long-term survival rate following CABG surgery over 20 years in the United Kingdom. METHODS:  A total of 2979 isolated CABG patients were studied from 1999 to 2020, and postoperative data were obtained from the hospital-recorded mortality by the data quality team of the information department. Postdischarge survival was estimated using the Kaplan-Meier method, and statistical significance was obtained with log-rank tests and the Gehan-Breslow test, and the Holm-Sidak method was used for multiple pairwise comparisons. RESULTS:  The study observed male predominance (80%), and the median age was statistically significant (P <0.001) among the groups, 66 years (interquartile range 58-73) and 72 years (interquartile range 66-78) in survivor and non-survivor groups, respectively. In the Holm-Sidak method analysis, the best survival rate (mean 18.7 years) was observed in the total arterial group with significantly decreased survival for the mixed arterial and venous group (mean 16.12 years) and only the vein group (10.44 years). The Cox regression model observed that the New York Heart Association (NYHA) class III-IV (HR 1.57), chest re-exploration (HR 2.14), preoperative dialysis (HR 3.13), and redo surgery (HR 3.04) were potential predictors of the postoperative mortality (P ≤0.05). CONCLUSION:  In our series over 20 years, albeit off-pump and on-pump CABG observed similar survival rates, the total arterial myocardial revascularization population has significantly better long-term survival benefits.

A Chronicle of Hybrid Atrial Fibrillation Ablation Therapy: From Cox Maze to Convergent.

The burden of AF is increasing in prevalence and healthcare resource usage in the UK and worldwide. It can result in impaired quality of life for affected patients, as well as increased risk of stroke, heart failure and mortality. A holistic, integrated approach to AF management is recommended, which may include a focus on reducing risk factors and on medical management with anticoagulation and anti-arrhythmic drugs. There are also various ablation strategies that may be considered when anti-arrhythmic drugs fail to alleviate symptoms and reduce AF burden. These ablation techniques range from standalone percutaneous endocardial catheter ablation to open surgical ablation procedures concomitant with cardiac surgery. More recently, hybrid ablation that combines aspects of both surgical and electrophysiologically targeted ablation has been described. This article reviews the evolution of ablation strategies, beginning with the origin of the Cox maze IV procedure and continuing to the recent hybrid convergent approach, and provides a summary of the associated outcomes.

The Convergent Ablation and AtriClip Exclusion of the Left Atrial Appendage in Long-Standing Persistent Atrial Fibrillation.

We here present a case of a 54-year-old man with longstanding persistent atrial fibrillation refractory to direct current electrical cardioversion who underwent a concurrent convergent ablation and Atriclip exclusion of left atrial appendage. His preoperative echocardiography revealed dilated 5.8 cm left atrium with a normal left ventricular ejection fraction of 50%. Transmural isolation of pulmonary veins was performed through a subxiphoid approach, and 3 left-sided video-assisted thoracoscopic surgery ports were utilised to occlude the base of the left atrium appendage with the Atriclip device. A peri-operative transoesophageal echocardiogram confirmed left atrium appendage base occlusion, and the patient was in sinus rhythm after having a single 200 kJ direct current cardioversion shock. The postoperative period was uneventful, and the patient was discharged with preprocedural anticoagulant after 24 hours of the procedure and advised to come for follow up after 3 months.

Persistent Atrial Fibrillation: The Role of Left Atrial Posterior Wall Isolation and Ablation Strategies.

Atrial fibrillation (AF) is a global disease with rapidly rising incidence and prevalence. It is associated with a higher risk of stroke, dementia, cognitive decline, sudden and cardiovascular death, heart failure and impairment in quality of life. The disease is a major burden on the healthcare system. Paroxysmal AF is typically managed with medications or endocardial catheter ablation to good effect. However, a large proportion of patients with AF have persistent or long-standing persistent AF, which are more complex forms of the condition and thus more difficult to treat. This is in part due to the progressive electro-anatomical changes that occur with AF persistence and the spread of arrhythmogenic triggers and substrates outside of the pulmonary veins. The posterior wall of the left atrium is a common site for these changes and has become a target of ablation strategies to treat these more resistant forms of AF. In this review, we discuss the role of the posterior left atrial wall in persistent and long-standing persistent AF, the limitations of current endocardial-focused treatment strategies, and future perspectives on hybrid epicardial-endocardial approaches to posterior wall isolation or ablation.

Circular mapping catheter entrapment in mitral valve apparatus requiring emergency surgery: a rarely reported complication of pulmonary vein isolation procedure for atrial fibrillation.

Lasso catheter (Biosense Webster) is one of the most commonly employed circular mapping catheters during pulmonary vein isolation (PVI) procedure for atrial fibrillation (AF). Although this catheter has greatly facilitated arrhythmia mapping, it can be associated with serious complications. We report a case of a 59-year-old man who underwent PVI procedure for persistent AF. During the procedure, the Lasso catheter inadvertently slipped into the left ventricular cavity and entangled in the mitral valve apparatus. Various percutaneous manoeuvres to release the catheter were unsuccessful and the patient ultimately required emergency open heart surgery to remove the catheter and repair the valve. To the best of our knowledge, such a case has not previously been reported in the UK necessitating an immediate open heart surgery, avoiding replacement of the valve.

Endothelial function and weight loss in obese humans.

BACKGROUND: Obesity is a major risk factor for the development of endothelial dysfunction. We explored the effect of different degrees of body mass on endothelial function, lipids, systemic inflammation and glucose homeostasis and the effect of surgically-induced weight loss on endothelial function in severely obese humans. METHODS: A cross-sectional study of healthy subjects across a wide range of body fatness was performed to characterize the effect of obesity on flow-mediated dilatation (FMD), systemic inflammation, blood pressure and insulin sensitivity. A longitudinal study was performed to assess the effect of bariatric surgery induced weight loss on these parameters. 73 healthy subjects across a wide range of body mass were recruited; of these, 8 underwent bariatric surgery (median BMI 52.2 kg/m2, interquartile range 50.355.9). Endothelial dependent vasodilatation was measured using the brachial artery vasodilatory response to forearm hyperemia assessed using highresolution ultrasonography. RESULTS: Obese subjects were characterised by a complex collection of abnormalities, with hypertension, impaired glucose homeostasis, systemic inflammation and reduced FMD. BMI < or =25 kg/m2 (median FMD 9.7%, interquartile range 6.8-12.2), BMI >30 kg/m2 (median FMD 6.7% 4.8-7.5), P=0.01 comparing FMD in lean and obese subjects. A mean reduction in weight of 23.4 (4.6) kg produced an improvement in FMD from 5.3% (3.87.0) to 10.2% (7.6-13.3), P=0.01. CONCLUSIONS: Even moderate obesity leads to endothelial dysfunction. In severely obese subjects, FMD is normalized by weight loss. This improvement in FMD is associated with a decline in inflammatory markers, blood pressure and insulin. The improvement in FMD occurred despite patients remaining significantly obese. These results suggest that an integrated approach to improving endothelial function in obese humans may be necessary.

Strain balance of papillary muscles as a prerequisite for successful mitral valve repair in patients with mitral valve prolapse due to fibroelastic deficiency.

AIMS: The aim of this study was to assess the papillary muscle strain as a contributor to recurrent mitral regurgitation (MR) after mitral valve repair for fibroelastic deficiency. METHODS AND RESULTS: Sixty-four patients with isolated posterior mitral valve prolapse and severe MR referred for surgery were prospectively recruited between 2008 and 2012. Two- and three-dimensional echocardiography and speckle tracking were performed in all patients. The longitudinal strain of the anterolateral (AL) and posteromedial (PM) papillary muscles was individually calculated as well as the global longitudinal strain of both papillary muscles was measured before and after mitral repair and normalized to left ventricle end-diastolic volume. Eight patients (12.5%) had at least moderate MR 6 months after mitral repair. The longitudinal strain of the AL (preop -4.94 ± 2.2 vs. postop -3.28 ± 1.3, P < 0.001) and the PM papillary muscles (preop -12.64 ± 5.3 vs. postop -4.12 ± 6.77, P < 0.001) as well as the global strain of both papillary muscles (preop -7.59 ± 3.48 vs. postop -1.07 ± 6, P < 0.001) were all reduced after surgical repair. The longitudinal strain of the PM papillary muscle was the strongest predictor of recurrent MR (when less than or equal to -14.78). The global preoperative papillary muscle strain was also a determinant of recurrent MR when the global strain was greater than -9.05% (area under the curve: 0.895, sensitivity: 100%, and specificity: 76.8%). CONCLUSIONS: Patients with isolated posterior mitral leaflet prolapse are less likely having any residual MR post repair when the global papillary muscle strain of both papillary muscles is close or equal to zero. Strain of the papillary muscles may be an important determinant in predicting residual MR in patients who undergo mitral valve repair.

Relationship between connexin expression and gap-junction resistivity in human atrial myocardium.

BACKGROUND: The relative roles of the gap-junctional proteins connexin40 (Cx40) and connexin43 (Cx43) in determining human atrial myocardial resistivity is unknown. In addressing the hypothesis that changing relative expression of Cx40 and Cx43 underlies an increase in human atrial myocardial resistivity with age, this relationship was investigated by direct ex vivo measurement of gap-junctional resistivity and quantitative connexin immunoblotting and immunohistochemistry. METHODS AND RESULTS: Oil-gap impedance measurements were performed to determine resistivity of the intracellular pathway (Ri), which correlated with total Cx40 quantification by Western blotting (rs=0.64, P<0.01, n=20). Specific gap-junctional resistivity (Rj) correlated not only with Western immunoquantification of Cx40 (rs=0.63, P=0.01, n=20), but also more specifically, with the Cx40 fraction localized to the intercalated disks on immunohistochemical quantification (rs=0.66, P=0.02, n=12). Although Cx43 expression showed no correlation with resistivity values, the proportional expression of the 2 connexins, (Cx40/[Cx40+Cx43]) correlated with Ri and Rj (rs=0.58, P<0.01 for Ri and rs=0.51, P=0.02 for Rj). Advancing age was associated with a rise in Ri (rs=0.77, P<0.0001), Rj (rs=0.65, P<0.001, n=23), Cx40 quantity (rs=0.54, P=0.01, n=20), and Cx40 gap-junction protein per unit area of en face disk (rs=0.61, P=0.02, n=12). CONCLUSIONS: Cx40 is associated with human right atrial gap-junctional resistivity such that increased total, gap-junctional, and proportional Cx40 expression increases gap-junctional resistivity. Accordingly, advancing age is associated with an increase in Cx40 expression and a corresponding increase in gap-junctional resistivity. These findings are the first to demonstrate this relationship and a mechanistic explanation for changing atrial conduction and age-related arrhythmic tendency.

Miniaturized cardiopulmonary bypass: the Hammersmith technique.

BACKGROUND: Conventional Cardiopulmonary Bypass (cCPB) is a trigger of systemic inflammatory reactions, hemodilution, coagulopathy, and organ failure. Miniaturised Cardiopulmonary Bypass (mCPB) has the potential to reduce these deleterious effects. Here, we describe our standardised 'Hammersmith' mCPB technique, used in all types of adult cardiac operations including major aortic surgery. METHODS: The use of mCPB remains limited by the diversity of technologies which range from extremely complex, micro systems to ones very similar to cCPB. Our approach is designed around the principle of balancing the benefits of miniaturisation; reducing foreign surface area while maintaining patient safety. RESULTS: From January 2010 to March 2011, a single surgeon performed 184 consecutive operations (Euro score Logistic 8.4+/-9.9): 61 aortic valve replacements, 78 CABGs, 25 aortic valve replacement and CABG and 17 other procedures (major aortic surgery, re-do operations or double/triple valve replacements).Our clinical experience suggests that: i. Venous drainage is optimally maintained using kinetic energy. ii. Venous collapse pressure depends on the patient's anatomy and cannula size, but most importantly on the negative pressure generated by venous drainage. iii. The patient-prime interaction is optimised with antegrade and retrograde autologous priming, which mixes the blood and prime away from the tissues and results in a reduced oncotic destabilization. iv. mCPB is a safe and reproducible technique CONCLUSION: The Hammersmith mCPB is a "next generation" system which uses standard commercially available components. It aims to maintain safety margin and the benefit of miniaturised system whilst reducing the human factor demands.

Feasibility and safety of minimized cardiopulmonary bypass in major aortic surgery.

OBJECTIVES: Conventional cardiopulmonary bypass causes haemodilution and is a trigger of systemic inflammatory reactions, coagulopathy and organ failure. Miniaturized cardiopulmonary bypass has been proposed as a way to reduce these deleterious effects of conventional cardiopulmonary bypass and to promote a more physiological state. The use of miniaturized cardiopulmonary bypass has been reported in low-risk patients undergoing valve and coronary artery bypass graft (CABG) surgery. However, little is known about its application in major aortic surgery. METHODS: From February 2007 to September 2010, 49 patients underwent major aortic surgery using the Hammersmith miniaturized cardiopulmonary bypass (ECCO, Sorin). Data were extracted from medical records to characterize preoperative comorbidities (EuroSCORE), perioperative complications and the use of blood products. The same data were collected and described for 328 consecutive patients having similar surgery with conventional cardiopulmonary bypass at the Bristol Heart Institute, our twinned centre, during the same period. RESULTS: The miniaturized cardiopulmonary bypass group had a median EuroSCORE of 8 [inter-quartile range (IQR): 5-11], 13% had preoperative renal dysfunction and 20% of operations were classified as emergency or salvage. Thirty-day mortalities were 6.4; and 69, 67 and 74% had ≥ 1 unit of red cells, fresh frozen plasma (FFP) and platelets transfused, respectively. Eight percent of patients experienced a renal complication, and 8% a neurological complication. The conventional cardiopulmonary bypass group was similar, with a EuroSCORE of 8 (IQR: 6-10); 30-day mortalities were 9.4; and 68, 62 and 74% had ≥ 1 unit of red cells, FFP and platelets transfused, respectively. The proportions experiencing renal and neurological complications were 14 and 5%. CONCLUSIONS: Our experience suggests that miniaturized cardiopulmonary bypass is safe and feasible for use in major aortic cardiac surgery. A randomized trial is needed to evaluate miniaturized cardiopulmonary bypass formally.

Reduced nicotinamide adenine dinucleotide phosphate oxidase-derived superoxide and vascular endothelial dysfunction in human heart failure.

OBJECTIVES: We investigated the role of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in endothelial dysfunction in human heart failure. BACKGROUND: Vascular endothelial dysfunction in human heart failure contributes to increased tone, exercise limitation, and dysregulation of venous capacitance and vascular volume. The NADPH oxidases (Nox) are an important source of oxidative stress, but their role in the endothelial dysfunction of human heart failure remains unknown. METHODS: Endothelium-dependent and -independent vasorelaxation were assessed in saphenous vein segments obtained from consecutive patients with heart failure (n = 19) or normal left ventricular function (control; n = 35) undergoing coronary artery bypass graft. Saphenous vein superoxide production was measured by lucigenin-enhanced chemiluminescence and messenger ribonucleic acid expression of relevant transcripts quantified by real-time polymerase chain reaction. RESULTS: Heart failure patients had significantly worse endothelial function than control subjects (15.2 +/- 3% vs. 40.5 +/- 8.4% relative relaxation; p < 0.05), elevated C-reactive protein (CRP) levels (8.6 +/- 2.7 mg/l vs. 2.6 +/- 0.4 mg/l; p < 0.05), over 2-fold higher NADPH-dependent superoxide generation (p < 0.05), and significantly higher expression of the Nox4 isoform and regulatory subunit p67phox. Superoxide levels were positively correlated with New York Heart Association functional class (r = 0.684; p < 0.05) and CRP (r = 0.501; p < 0.005; n = 32). CONCLUSIONS: Venous endothelial dysfunction in human heart failure is associated with increased Nox-derived superoxide generation. Inflammatory mechanisms may be involved in the increased reactive oxygen species generation.

The association between saphenous vein endothelial function, systemic inflammation, and statin therapy in patients undergoing coronary artery bypass surgery.

OBJECTIVES: Endothelial dysfunction and C-reactive protein play a pivotal role in development of atherosclerosis and act as markers for future adverse cardiac events. Statins reduce C-reactive protein levels and improve endothelial function. However, little information is available on endothelial function and its determinants in veins. We investigated the association between saphenous vein endothelial function and C-reactive protein levels in patients treated with statins undergoing coronary artery bypass surgery. METHODS: Seventy-six patients with optimal low-density lipoprotein cholesterol levels (< or =1.6 mmol/L) secondary to regular treatment with a minimum of simvastatin 40 mg were recruited. Each subject underwent detailed characterization according to anthropomorphic data, saphenous vein endothelial function (assessed ex vivo by measuring acetylcholine-induced relaxation of venous rings), and markers of systemic inflammation (C-reactive protein and tumor necrosis factor-alpha). RESULTS: Despite regular treatment with statins, 26% of patients had C-reactive protein levels in the "high-risk" range (>3.0 mg/L). There was a negative linear correlation between acetylcholine-induced venous relaxation and C-reactive protein (r = -.30, P = .02) and waist circumference (r = -0.21, P = .03). In a multivariate regression model, C-reactive protein (P = .02) was the only independent predictor of acetylcholine-induced venous relaxation. In turn, correlates of C-reactive protein were assessed. There was a correlation between C-reactive protein and coronary atherosclerotic burden (r = .46, P < .0001), body mass index (r = .26, P = .03), fasting glucose levels (r = .31, P = .01), and waist circumference (r = .29, P = .01). Using multivariate analysis, coronary atherosclerotic burden (P < .0001) was the only independent predictor of C-reactive protein. CONCLUSIONS: In our cohort of patients with coronary artery disease, C-reactive protein level was the only independent predictor of saphenous vein endothelial function. In turn, its levels were independently influenced by the extent of coronary atherosclerotic burden.

Leptin is an endothelial-independent vasodilator in humans with coronary artery disease: Evidence for tissue specificity of leptin resistance.

AIMS: We sought to define the mechanisms and correlates of leptin's vascular actions in humans with coronary artery disease. METHODS AND RESULTS: In 131 patients (age 65.7+/-0.7 years mean+/-SEM), ex vivo vascular reactivity to leptin (10(-13)-10(-7) M) was assessed in saphenous vein (SV) rings. Leptin led to SV relaxation (maximal relaxation 24.5+/-1.6%). In separate experiments, relaxation to leptin was unaffected by L-NMMA (17.4+/-3.4 vs.17.8+/-3.3%, P = 0.9) or endothelial denudation (17.4+/-4.4 vs. 22.5+/-3.0%, P = 0.4). We explored the possibility that leptin's vascular effects are mediated via smooth muscle hyperpolarization. In the presence of KCl (30 mmol/L) to inhibit hyperpolarization, the vasodilator effect of leptin was completely blocked (0.08+/-4.1%, P < 0.001 vs. control). Similar results were demonstrated in internal mammary artery rings. The only independent correlate of leptin-mediated vasodilatation was plasma TNF-alpha (r = 0.25, P < 0.05). Neither body mass index nor waist circumference correlated with leptin-mediated vasorelaxation. This lack of a correlation with markers of total body fat/fat distribution suggests that leptin resistance may not extend to the vasculature. CONCLUSION: Leptin is a vasoactive peptide in human SV and internal mammary artery. Its action is not nitric oxide or endothelial-dependent. Markers of body fat did not correlate with leptin-mediated vasodilatation, raising the intriguing possibility of selective resistance to leptin's actions.

Incidence of sternal infection in diabetic patients undergoing bilateral internal thoracic artery grafting.

BACKGROUND: Bilateral internal thoracic artery (BITA) bypass grafts have advantages over single internal thoracic artery (SITA) bypass grafts in the medium term, particularly in diabetics. However, the perceived higher sternal complication rates seen in diabetics have led many surgeons to avoid the use of BITA surgery. The aim of our study was to assess the validity of this approach by assessing the incidence of sternal infections over a 10-year period in one institution. METHODS: A retrospective analysis was made of our coronary artery bypass graft (CABG) patients over a 10-year period (7,581 patients). Nine hundred and twenty-two of the patients were diabetics (261 insulin-dependent diabetes mellitus [IDDM]). Of the insulin-dependent diabetics, 166 had SITA, and 95 had BITA grafts. RESULTS: There was no significant difference in this subgroup in terms of gender, preoperative angina, dyspnea class, left ventricular function, and number of distal anastomoses. Comparing the rates of sternal wound complications of SITA and BITA in IDDM are the following: (1) superficial sternal infection, 6.6% in SITA, 1.1% in BITA (p = 0.04); (2) deep sternal infection, 1.2% in SITA, 3.2% in BITA (p = 0.27); (3) sternal dehiscence, 1.2% in SITA, 3.2% in BITA (p = 0.27). CONCLUSIONS: Our data do not support the perception that BITA grafting increases the risk of sternal complications in insulin-dependent diabetic patients.