Anti-Anginal Efficacy of Zibotentan in the Coronary Slow-Flow Phenomenon

BACKGROUND

Patients with coronary microvascular disorders often experience recurrent angina for which there are limited evidence-based therapies. These patients have been found to exhibit increased plasma levels of endothelin; thus, selective endothelin-A (Et-A) receptor blockers such as zibotentan may be an effective anti-anginal therapy in these patients. The study evaluated the impact of a 10 mg daily dose of zibotentan on spontaneous angina episodes in patients with the coronary slow-flow phenomenon who had refractory angina (i.e., experiencing angina at least three times/week despite current anti-anginal therapy).

METHODS

Using a randomized, double-blind, placebo-controlled, crossover trial design with 4-week treatment periods, 18 patients (63.2 ± 9.9 years, 33% females) were recruited. The primary endpoint was angina frequency as measured by an angina diary, with secondary endpoints including nitrate consumption, angina duration/severity and the Seattle Angina Questionnaire (SAQ) domains.

RESULTS

During the 4 weeks of therapy, angina frequency significantly improved with zibotentan therapy (placebo 41.4 (58.5) vs. zibotentan 29.2 (31.6), p < 0.05), and sublingual nitrate consumption significantly reduced (placebo 11.8 (15.2) vs. zibotentan 8.8 (12.9), p < 0.05.

CONCLUSIONS

Zibotentan improved the frequency of spontaneous angina episodes and reduced sublingual nitrate consumption in patients unresponsive to standard anti-anginal therapy.

Angina and Non-Obstructive Coronary Artery (ANOCA) Patients with Coronary Vasomotor Disorders

Angina and Non-Obstructive Coronary Artery (ANOCA) patients often lack a clear explanation for their symptoms, and are frequently discharged with the label of "unspecified chest pain", despite the availability of functional coronary angiography (provocative spasm and microvascular function testing) to identify potential underlying coronary vasomotor disorders. This study compared the outcomes of ANOCA patients with a coronary vasomotor disorder diagnosis post elective coronary angiography to patients discharged with unspecified chest pain. Using the CADOSA (Coronary Angiogram Database of South Australia) registry, consecutive symptomatic patients (n = 7555) from 2012 to 2018 underwent elective angiography; 30% had ANOCA (stenosis <50%). Of this cohort, 9% had documented coronary vasomotor disorders diagnosed, and 91% had unspecified chest pain. Patients with coronary vasomotor disorders were younger and had a similar female prevalence compared with those with unspecified chest pain. New prescriptions of calcium channel blockers and long-acting nitrates were more common for the coronary vasomotor cohort at discharge. In the 3 years following angiography, both groups had similar all-cause mortality rates. However, those with coronary vasomotor disorders had higher rates of emergency department visits for chest pain (39% vs. 15%, p < 0.001) and readmissions for chest pain (30% vs. 10%, p < 0.001) compared with those with unspecified chest pain. This real-world study emphasizes the importance of identifying high-risk ANOCA patients for personalized management to effectively address their symptoms.

Do Chest Pain Characteristics in Patients with Acute Myocardial Infarction Differ between Those with and without Obstructive Coronary Artery Disease?

The universal definition of acute myocardial infarction (MI) requires both evidence of myocardial injury and myocardial ischaemia. In MINOCA (MI with non-obstructive coronary arteries), patients must fulfil this MI criteria, but is their chest pain similar to those who have MI with obstructive CAD (MICAD)? This study compares prospectively collected chest pain features between patients with MINOCA and MICAD. Utilising the Coronary Angiogram Database of South Australia (CADOSA), consecutive MI patients were categorized as MINOCA or MICAD based on angiographic findings. Chest pain data were collected via direct patient interviews by trained staff members. Of 6811 consecutive patients fulfilling a clinical MI diagnosis, 411 (6.0%) were MINOCA, and 5948 MICAD. The MINOCA patients were younger, more often female and had less cardiovascular risk factors than those with MICAD. There were no significant differences in chest pain characteristics between the MINOCA and MICAD cohorts in relation to pain location, quality, associated symptoms, or duration. In conclusion, MINOCA patients have chest pain characteristics that are indistinguishable from MICAD patients, suggesting that their pain is ischaemic in nature. Thus, in the presence of positive myocardial injury markers, ischaemic chest pain fulfils the universal criteria for MI, despite the absence of obstructive coronary artery disease.

Survival in Patients With Suspected Myocardial Infarction With Nonobstructive Coronary Arteries: A Comprehensive Systematic Review and Meta-Analysis From the MINOCA Global Collaboration

BACKGROUND

Suspected myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) occurs in ≈5% to 10% of patients with MI referred for coronary angiography. The prognosis of these patients may differ to those with MI and obstructive coronary artery disease (MI-CAD) and those without a MI (patients without known history of MI [No-MI]). The primary objective of this study is to evaluate the 12-month all-cause mortality of patients with MINOCA.

METHODS

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the terms "MI," "nonobstructive," "angiography," and "prognosis" were searched in PubMed and Embase databases from inception to December 2018, including original, English language MINOCA studies with >100 consecutive patients. Publications with a heterogeneous cohort, unreported coronary stenosis, or exclusively focusing on MINOCA-mimicking conditions, were excluded. Unpublished data were obtained from the MINOCA Global Collaboration. Data were pooled and analyzed using Paule-Mandel, Hartung, Knapp, Sidik & Jonkman, or restricted maximum-likelihood random-effects meta-analysis methodology. Heterogeneity was assessed using Cochran's Q and I² statistics. The primary outcome was 12-month all-cause mortality in patients with MINOCA, with secondary comparisons to MI-CAD and No-MI.

RESULTS

The 23 eligible studies yielded 55 369 suspected MINOCA, 485 382 MI-CAD, and 33 074 No-MI. Pooled meta-analysis of 14 MINOCA studies accounting for 30 733 patients revealed an unadjusted 12-month all-cause mortality rate of 3.4% (95% CI, 2.6%-4.2%) and reinfarction (n=27 605; 10 studies) in 2.6% (95% CI, 1.7%-3.5%). MINOCA had a lower 12-month all-cause mortality than those with MI-CAD (3.3% [95% CI, 2.5%-4.1%] versus 5.6% [95% CI, 4.1%-7.0%]; odds ratio, 0.60 [95% CI, 0.52-0.70], P<0.001). In contrast, there was a statistically nonsignificant trend towards increased 12-month all-cause mortality in patients with MINOCA (2.6% [95% CI, 0%-5.9%]) compared with No-MI (0.7% [95% CI, 0.1%-1.3%]; odds ratio, 3.71 [95% CI, 0.58-23.61], P=0.09).

CONCLUSIONS

In the largest contemporary MINOCA meta-analysis to date, patients with suspected MINOCA had a favorable prognosis compared with MI-CAD, but statistically nonsignificant trend toward worse outcomes compared to those with No-MI. Registration: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42020145356.

Randomized Evaluation of Beta Blocker and ACE-Inhibitor/Angiotensin Receptor Blocker Treatment for Post Infarct Angina in Patients With Myocardial Infarction With Non-obstructive Coronary Arteries: A MINOCA-BAT Sub Study Rationale and Design

Introduction: Myocardial infarction with non-obstructive coronary arteries (MINOCA) occurs in ~10% of all patients with acute myocardial infarction (AMI), with an over-representation amongst women. Remarkably, it is estimated that as many as 1 in 4 patients with MINOCA experience ongoing angina at 12 months despite having no flow-restricting stenoses in their epicardial arteries. This manuscript presents the rationale behind Randomized Evaluation of Beta Blocker and Angiotensin-converting enzyme inhibitors/Angiotensin Receptor Blocker Treatment (ACEI/ARB) for Post Infarct Angina in MINOCA patients-The MINOCA BAT post infarct angina sub study. Methods: This trial is a registry-based, randomized, parallel, open-label, multicenter trial with 2 × 2 factorial design. The primary aim is to determine whether oral beta blockade compared with no oral beta blockade, and ACEI/ARB compared with no ACEI/ARB, reduce post infarct angina in patients discharged after MINOCA without clinical signs of heart failure and with left ventricular ejection fraction ≥40%. A total of 664 patients will be randomized into four groups; (i) ACEI/ARB with beta blocker, (ii) beta blocker only, (iii) ACEI/ARB only, or (iv) neither ACEI/ARB nor beta blocker and followed for 12 months. Results: The trial is currently recruiting in Australia and Sweden. Fifty six patients have been recruited thus far. Both sexes were equally distributed (52% women and 48% men) and the mean age was 56.3 ± 9.9 years. Conclusions: It remains unclear whether conventional secondary preventive therapies are beneficial to MINOCA patients in regard to post infarct angina. Existing registry-based literature suggest cardioprotective agents are less likely to be used in MINOCA patients. Thus, results from this trial will provide insights for future treatment strategies and guidelines specific to MINOCA patients.

Abstract 374: Trans-radial Access Angiography Learning Curve

Introduction: Radial artery access has been adopted widely around the world as standard best practice for coronary angiography with or without percutaneous coronary intervention. Radial artery access offers benefits in regard to reduced major bleeding, reduced hospital stay, fewer vascular complications, similar procedural times, patient preference and a mortality benefit in acute coronary syndrome/STEMI management. Despite transradial access being best practice, there has been a slow uptake of this technique amongst some cardiologists/interventionalists, particularly in the USA. This may partially be attributed to uncertainties regarding the learning curve and concerns regarding delaying treatment in STEMI if radial access fails.

Methods: Using the data from the Coronary Angiography Database Of South Australia registry (CADOSA), we sought to determine the radial access failure rates for acute cases during transition from routine femoral access to routine radial access from 2012 to 2016, a period when the greatest transition in practice occurred. Data regarding initial vascular access, success or failure, and subsequent vascular access was prospectively recorded for all cases. Operators with at least a 70% rate of initial radial access were deemed to be established radial operators and acted as controls for operators transitioning from femoral access (at least 70% of cases) to radial access during the study period. Cases were further classified as elective, urgent (eg inpatient ACS) or emergency (eg STEMI).

Results: There were 23 operators with sufficient volumes, responsible for 20,073 cath lab visits during the 5 year period studied. The overall radial access rate increased from 57% in 2012 to 78% in 2016. For operators transitioning from a default femoral access (76% of case) to a default radial access (75% of cases), the radial access failure rate for urgent and emergency cases was 3.7%, compared to 3.5% for experienced radial operators over the same period.

Conclusion: Despite strong evidence of benefit for radial access angiography and intervention, compared to femoral access, some operators remain reluctant to transition. Utilising the CADOSA database, we observed a safe transition from femoral to radial access without an increased risk of access site failure for acute cases. Transition from femoral to radial access can be made safely by a range of clinicians managing acute cases.

Validation of contemporary electrocardiographic indices of area at risk and infarct size in acute ST elevation myocardial infarction (STEMI)

BACKGROUND

Electrocardiographic (ECG) methods to assess area at risk (AAR) and infarct size (IS) in patients with ST-elevation myocardial infarction (STEMI) have been previously established but not validated against contemporary benchmark Cardiac Magnetic Resonance (CMR) measures. We compared ECG-determined and CMR-determined measures for (a) AAR, (b) IS, and (c) myocardial salvage.

METHODS

Sixty patients with ECG evidence of STEMI and CMR imaging performed within 13 days were included. The ECG-determined (a) AAR scores (Aldrich and Wilkins), (b) IS (Selvester score), and (c) myocardial salvage (i.e. [AAR-IS] / AAR × 100%), were compared with CMR-determined measures.

RESULTS

Compared with CMR-determined AAR, both the Wilkins & Aldrich scores underestimated AAR, although the Wilkins (r = 0.72, p < 0.001) showed a better correlation than the Aldrich (r = 0.54, p < 0.001). Bland-Altman analysis revealed a bias of 2.6% (95% limits of agreement: 18.5%, -13.3%) for the Wilkins and 5.9% (95% limits of agreement: 25.6%, -13.8%) for the Aldrich. Estimation of IS was similar between the Selvester score and CMR, with good correlation (r = 0.77, p < 0.001) and agreement (fixed bias 0.4%, 95% limits of agreement 20.8%, -15.5%). However, ECG-determined myocardial salvage significantly underestimated CMR-determined myocardial salvage, with an inverse correlation (r = -0.33, p = 0.01).

CONCLUSIONS

The Wilkins score is superior to Aldrich score as an ECG-AAR index, Selvester score is a reasonable ECG estimate of infarct size, though ECG derived myocardial salvage does not have enough accuracy to be used in the clinical setting; it may be an inexpensive surrogate for myocardial salvage in large research studies. Further validation and prognostic studies are required.

Risk of Thrombosis in Patients Presenting with Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA)

Patients presenting with myocardial infarction (MI) in the absence of obstructive coronary artery disease (CAD) is termed MI with nonobstructive coronary arteries (MINOCA). The underlying pathophysiology of MINOCA is multifactorial and in situ formation and subsequent spontaneous lysis of a coronary thrombus is often hypothesized as one of the mechanisms. The objective of this study is to determine whether MINOCA patients had a greater prothrombotic tendency in comparison to MI patients with obstructive CAD (MICAD). Prospectively, blood samples of 25 consecutive MINOCA patients (58 (interquartile range [IQR]: 48, 75) years, 48% women) and 25 age-/gender-matched MICAD patients (58 (IQR: 50, 66) years, 48% women) were obtained at 1 month after the initial presentation and overall thrombin generation potential and congenital/acquired thrombophilia states were assessed. As regard to results, overall thrombin generation parameters were similar ( p  > 0.05) between the MINOCA and MICAD groups, highlighting similar endogenous thrombin potential (1,590 nM/min; IQR: 1,380, 2,000 vs. 1,750 nM/min; IQR: 1,500, 2,040, respectively). There were no significant differences between MINOCA and MICAD, respectively, in respect to the numbers of patients with congenital thrombophilia states including factor V Leiden (0 vs. 4%) and prothrombin gene mutation (8 vs. 4%), decreased antithrombin (8 vs. 0%), protein C (0 vs. 0%), and protein S (4 vs. 0%). None of the patients demonstrated presence of lupus anticoagulant and anticardiolipin antibodies. Although MINOCA patients revealed thrombotic characteristics that are similar to those with MICAD, the results from this study are inconclusive and a larger study with healthy control subjects is required to assess the risk of thrombosis in MINOCA.

Early Use of N-acetylcysteine With Nitrate Therapy in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction Reduces Myocardial Infarct Size (the NACIAM Trial [N-acetylcysteine in Acute Myocardial Infarction])

BACKGROUND

Contemporary ST-segment-elevation myocardial infarction management involves primary percutaneous coronary intervention, with ongoing studies focusing on infarct size reduction using ancillary therapies. N-acetylcysteine (NAC) is an antioxidant with reactive oxygen species scavenging properties that also potentiates the effects of nitroglycerin and thus represents a potentially beneficial ancillary therapy in primary percutaneous coronary intervention. The NACIAM trial (N-acetylcysteine in Acute Myocardial Infarction) examined the effects of NAC on infarct size in patients with ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention.

METHODS

This randomized, double-blind, placebo-controlled, multicenter study evaluated the effects of intravenous high-dose NAC (29 g over 2 days) with background low-dose nitroglycerin (7.2 mg over 2 days) on early cardiac magnetic resonance imaging-assessed infarct size. Secondary end points included cardiac magnetic resonance-determined myocardial salvage and creatine kinase kinetics.

RESULTS

Of 112 randomized patients with ST-segment-elevation myocardial infarction, 75 (37 in NAC group, 38 in placebo group) underwent early cardiac magnetic resonance imaging. Median duration of ischemia pretreatment was 2.4 hours. With background nitroglycerin infusion administered to all patients, those randomized to NAC exhibited an absolute 5.5% reduction in cardiac magnetic resonance-assessed infarct size relative to placebo (median, 11.0%; [interquartile range 4.1, 16.3] versus 16.5%; [interquartile range 10.7, 24.2]; P=0.02). Myocardial salvage was approximately doubled in the NAC group (60%; interquartile range, 37-79) compared with placebo (27%; interquartile range, 14-42; P<0.01) and median creatine kinase areas under the curve were 22 000 and 38 000 IU·h in the NAC and placebo groups, respectively (P=0.08).

CONCLUSIONS

High-dose intravenous NAC administered with low-dose intravenous nitroglycerin is associated with reduced infarct size in patients with ST-segment-elevation myocardial infarction undergoing percutaneous coronary intervention. A larger study is required to assess the impact of this therapy on clinical cardiac outcomes.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry. URL: http://www.anzctr.org.au/. Unique identifier: 12610000280000.

Abstract 129: Chest Pain Characteristics of Myocardial Infarction With Non-Obstructive Coronary Arteries (MINOCA) in Comparison to Myocardial Infarction With Coronary Artery Disease (MI-CAD)

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is being increasingly recognized with the frequent use of angiography following Acute Myocardial Infarction (AMI); yet there is little evaluation of these patients in the literature. The current study is a prospective, contemporary analysis of clinical features and chest pain characteristics between patients with MINOCA and Myocardial Infarction with coronary artery disease (MI-CAD).

Methods: All consecutive patients undergoing coronary angiography for AMI (as per the Third Universal AMI Definition) in South Australian public hospitals from January 2012 - December 2013 were included. Data was captured by Coronary Angiogram Database of South Australia (CADOSA), a comprehensive registry compatible with the NCDR ® CathPCI ® Registry. The AMI patients were classified as MI-CAD or MINOCA on the basis of the presence or absence of a significant stenosis (≥50%) on angiography.

Results: From 3,431 angiography procedures undertaken for AMI, 359 (11%) were classified as MINOCA. MINOCA patients were younger (59 ± 15 vs. 64 ± 13, p <0.01) and more likely to be female (60% vs. 26%, p<0.01), with age adjusted analysis revealing less cardiovascular risk factors in MINOCA compared to MICAD: current smoker (21% vs. 35%, p< 0.01), hypertension (56% vs. 65%, p<0.01), dyslipidaemia (46% vs. 61%, p<0.01), and diabetes (20% vs. 32%, p<0.01). Analysis of presenting chest pain characteristics showed no significant differences between MICAD and MINOCA for the presence of retrosternal pain (81% vs. 82%, p>0.05,) or shoulder pain (27% vs. 26%, p>0.05) respectively, however MINOCA patients were less likely to experience arm pain (33% vs. 40%, p<0.01). In regards to precipitating factors, emotional stress was more common (14% vs. 5%, p<0.001) and exertion related chest pain was less common (27% vs. 40%, p<0.001) in MINOCA patients. Quality of pain for MINOCA and MICAD was similar with the most frequent descriptors being burning (11% vs. 9%, p>0.05), sharp 21% vs. 23%, p>0.05) and tightness (41% vs. 44%, p>0.05). In addition, there were no significant differences observed between groups in relieving factors and duration of chest pain

Conclusions: In contemporary cardiology practice, MINOCA presentation is more common than previously appreciated, with younger women frequently implicated. Delineating a MINOCA patient from MICAD on the basis of chest pain characteristics is not feasible.

Abstract 273: Myocardial Infarction with Non Obstructive Coronary Artery Disease: Prevalence, Clinical Features and Outcomes

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is an enigma that is being increasingly recognized with the frequent use of angiography following Acute Myocardial Infarction (AMI). The current study is a prospective, contemporary analysis of MINOCA vs. Myocardial Infarction with obstructive coronary artery disease (MI-CAD) in regards to prevalence, clinical features, and in-hospital outcomes.

Methods: All consecutive patients undergoing coronary angiography for AMI (as per the Third Universal AMI Definition) in South Australian public hospitals from January 2012 - December 2013 were included. Data was captured by Coronary Angiogram Database of South Australia (CADOSA), a comprehensive registry compatible with the NCDR® CathPCI® Registry. The AMI patients were classified as MI-CAD or MINOCA on the basis of the presence or absence of a significant stenosis (≥50%) on angiography.

Results: From 4,189 angiography procedures undertaken for AMI, 468 (11%) were classified as MINOCA. Patients with MINOCA were younger (59±15 vs. 64±13 years, p <0.01) and more likely to be female (53% vs. 26%, p <0.01), compared to those with MI-CAD. Age-adjusted analysis comparing patients with MINOCA to MI-CAD revealed differences in: (1) cardiovascular risk factors including hypertension (52% vs. 66%, p<0.01), diabetes (19% vs. 32%, p<0.01), dyslipidemia (46% vs. 62%, p<0.01), and current smoker status (27% vs. 37% p<0.01); (2) AMI type and size with fewer ST elevation myocardial infarcts (27% vs. 41%, p<0.01) and lower peak troponin values (180 ng/L, IQR 353 vs. 264 ng/L, IQR 680, p<0.01) amongst MINOCA patients. Furthermore, the GRACE Score for acute coronary syndrome risk stratification was lower for the MINOCA patients compared to MICAD (150±34 versus 160±35, p <0.01). Despite fewer cardiovascular risk factors, the absence of obstructive coronary artery disease, smaller infarcts, and a lower GRACE score, the in-hospital mortality was similar for MINOCA and MI-CAD patients (2.2% vs. 3.0%, p=0.22). Moreover, MINOCA patients were less likely to receive secondary prevention therapies at discharge including antiplatelet therapy (60% vs. 92%, p<0.01) beta-blockers (41% vs. 65%, p<0.01), statin (55% vs. 88%, p<0.01), ACE-inhibitor/angiotensin receptor blocker (59% versus 81%, p<0.01), or referral to cardiac rehabilitation (15% versus 52%, p<0.01).

Conclusions: In contemporary cardiology practice, MINOCA may be more frequent than previously appreciated and has a guarded prognosis despite its apparent lower risk profile. Improving the use of secondary prevention therapies in these patients may improve their prognosis.

Systematic review of patients presenting with suspected myocardial infarction and nonobstructive coronary arteries

BACKGROUND

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a puzzling clinical entity with no previous evaluation of the literature. This systematic review aims to (1) quantify the prevalence, risk factors, and 12-month prognosis in patients with MINOCA, and (2) evaluate potential pathophysiological mechanisms underlying this disorder.

METHODS AND RESULTS

Quantitative assessment of 28 publications using a meta-analytic approach evaluated the prevalence, clinical features, and prognosis of MINOCA. The prevalence of MINOCA was 6% [95% confidence interval, 5%-7%] with a median patient age of 55 years (95% confidence interval, 51-59 years) and 40% women. However, in comparison with those with myocardial infarction associated with obstructive coronary artery disease, the patients with MINOCA were more likely to be younger and female but less likely to have hyperlipidemia, although other cardiovascular risk factors were similar. All-cause mortality at 12 months was lower in MINOCA (4.7%; 95% confidence interval, 2.6%-6.9%) compared with myocardial infarction associated with obstructive coronary artery disease (6.7%, 95% confidence interval, 4.3%-9.0%). Qualitative assessment of 46 publications evaluating the underlying pathophysiology responsible for MINOCA revealed the presence of a typical myocardial infarct on cardiac magnetic resonance imaging in only 24% of patients, with myocarditis occurring in 33% and no significant abnormality in 26%. Coronary artery spasm was inducible in 27% of MINOCA patients, and thrombophilia disorders were detected in 14%.

CONCLUSIONS

MINOCA should be considered as a working diagnosis with multiple potential causes that require evaluation so that directed therapies may improve its guarded prognosis.

Myocardial Infarction With Non-obstructive Coronary Arteries - Diagnosis and Management

MI with non-obstructive coronary arteries (MINOCA) is an enigma that is being increasingly recognised with the frequent use of angiography following acute MI. To diagnose this condition, it is important to determine the multiple potential underlying mechanisms that may be responsible, many of which require different treatments. This review evaluates the contemporary diagnosis and management of MINOCA.

Metabolic-Bariatric Surgery: An Emerging Specialty

After the end of the second world war, the world saw a significant period of growth and prosperity unlike any previously. By the 1950s, morbid obesity was proving to be a clinical problem in many developed societies in Europe and North America. Diet, lifestyle and medication alone did not appear to be effective in controlling morbid obesity, and surgical interventions were developed. Surgical therapies to combat the epidemic of obesity evolved from intestinal bypasses (which had the potential for serious fluid, electrolyte and nutritional disturbances) to eventually settle on manipulations that involve restrictive procedures of the stomach with or without bypass of the duodenum and jejunum. This branch of surgery was referred to as “bariatric” (from the Greek “baros” for weight), but recent awareness that concomitant obesity-related metabolic diseases can also be effectively treated by these procedures has given rise to the new specialty of metabolic-bariatric surgery (MBS). This review looks at current MBS procedures and their impact on gastro-intestinal physiology to achieve both weight loss and metabolic control.

Endovascular exclusion of aberrant splenic artery aneurysm with covered stent

The splenic artery arising from the superior mesenteric artery is an uncommon anatomical variant. This aberrant origin may rarely be associated with an aneurysm. Previous cases have been managed with surgery and combined surgical/endovascular or endovascular techniques, with the latter involving occlusion of the aneurysm with coils. We report a case of aberrant splenic artery aneurysm that was excluded with a balloon-mounted covered stent, and discuss the technical issues encountered in using this approach. A follow-up computed tomography performed six months after the covered stent placement showed persistent exclusion with marked shrinkage of the aneurysm sac.

Laparoscopic sleeve gastrectomy: a novel procedure for weight loss

INTRODUCTION

Morbid obesity is associated with increased morbidity and mortality. Bariatric surgery offers morbidly obese individuals substantial and sustainable weight loss and reduction in obesity-related comorbidities. Laparoscopic sleeve gastrectomy (LSG) is a new restrictive procedure in bariatric surgery. We aimed to evaluate our experience with LSG with regard to its safety and feasibility and early weight loss.

METHODS

The surgical outcome, complications and early clinical results of all patients who underwent LSG at Singapore General Hospital were studied.

RESULTS

30 patients underwent LSG between December 2008 and October 2010. The mean preoperative weight of the patients was 113.4 (range 91.0-170.0) kg, while the mean body mass index (BMI) was 42.6 (range 33.0-60.0) kg/m². Diabetes mellitus was present in 39 percent of the patients, hypertension in 43 percent, hyperlipidaemia in 35 percent, obstructive sleep apnoea in 30 percent and osteoarthritis in 22 percent. The majority of patients had two or more obesity-related comorbidities (52 percent). Mean operative time was 142 (range 80-220) minutes and median duration of postoperative stay was three days. At two weeks, one, three and six months post operation, the mean BMI was 38.6 kg/m², 37.8 kg/m², 34.5 kg/m² and 30.8 kg/m², the mean percentage of excess weight loss was 17.7 percent, 23.3 percent, 40.9 percent and 56.7 percent, and absolute weight loss was 8.00 kg, 11.52 kg, 18.77 kg and 26.85 kg, respectively.

CONCLUSION

LSG is a promising procedure for surgical treatment of obesity, with good early weight loss and low morbidity.

Self-expanding nitinol stents in recanalisation of long-length superficial femoral artery occlusions in patients with critical limb ischaemia

INTRODUCTION

This study aims to evaluate our experience with self-expanding nitinol stent- enabled recanalisation of long-length occlusions (30 cm or more) of the superficial femoral artery (SFA).

METHODS

573 patients underwent 842 lower limb interventions from August 2006 to December 2008. A retrospective review of patients undergoing recanalisation of long-length SFA occlusions with self-expanding nitinol stents and an evaluation of their patency and impact on limb salvage, were done.

RESULTS

22 patients (mean age 62.5 years, male: female ratio 11:11) underwent 22 long-length SFA stenting procedures. The spectrum of critical limb ischaemia included rest pain (five), ulcer (six) and gangrene (11). Length of occlusions varied from 30 cm to 45 cm (average length 36.4 cm). Five patients had stents placed through the ipsilateral popliteal artery approach, and the rest had stents placed through the femoral artery approach. All patients were followed up over an average duration of 12 months. One patient died due to associated medical conditions during this period. Six out of 21 (28.6 percent) of the stents thrombosed completely on one year follow-up. Of these, two patients underwent amputation, one patient had a bypass, and the stent in two patients were recanalised with balloon angioplasty. All remaining patent stents showed varying degrees of stenoses at one year. The overall limb salvage rate at one year following stent placement was 81 percent.

CONCLUSION

Our experience showed the beneficial result of long-length SFA stent placement with good limb salvage outcome. Repeat interventions may be required to maintain the patency of stents in these patients.

Effects of warm-up on exercise capacity, platelet activation and platelet-leucocyte aggregation in patients with claudication

BACKGROUND

The effects of exercise and warm-up were investigated in patients with claudication.

METHODS

This case-control crossover study involved two treadmill exercise tests, one preceded by a warm-up. Exercise continued until maximal leg pain (patients with claudication) or exhaustion (controls). Blood was taken before, and 5 and 60 min after exercise for flow cytometric analysis of platelet activation and platelet-leucocyte aggregation.

RESULTS

Both cohorts (eight patients with claudication of median age 63 years and eight healthy controls of median age 63.5 years) demonstrated improvement in exercise capacity after warm-up (13.1 per cent, P = 0.012 and 15.6 per cent, P = 0.008 respectively). Platelet activation increased after exercise in patients with claudication (fibrinogen binding: 1.11 per cent before exercise versus 2.63 per cent after exercise, P = 0.008; P-selectin: 0.68 versus 1.11 per cent, P = 0.028). Neither agonist stimulation nor warm-up altered this trend. Platelet-leucocyte (PLA) and platelet-neutrophil (PNA) aggregation were similarly increased immediately after exercise in patients with claudication (PLA: 7.6 versus 13.0 per cent, P = 0.004; PNA: 6.8 versus 10.2 per cent, P = 0.012). These remained high 60 min after exercise only in patients with claudication, but recovered to baseline levels when preceded by warm-up. Warm-up significantly desensitized PNA after stimulation with 10 micromol/l adenosine 5'-diphosphate at all time points.

CONCLUSION

Warm-up increased the exercise capacity of patients with claudication. Exercise induced a thromboinflammatory response, with PLA and PNA persistently increased after 60 min in patients with claudication, an effect diminished after warm-up.

Ischaemic Preconditioning Protects Against Ischaemia/Reperfusion Injury: Emerging Concepts

INTRODUCTION

Ischaemic preconditioning (IP) has emerged as a powerful method of ameliorating ischaemia/reperfusion (I/R) injury to the myocardium. This review investigates whether this phenomenon is universally applicable in modulating I/R injury to other tissues.

METHODS

A Medline search was conducted to identify both animal and human studies that described IP-induced protection from I/R injury in a variety of non-cardiac organ systems. Particular emphasis was placed on elucidation of underlying physiological concepts.

RESULTS AND CONCLUSIONS

IP utilises endogenous mechanisms in skeletal muscle, liver, lung, kidney, intestine and brain in animal models to convey varying degrees of protection from I/R injury. To date there are few human studies, but recent reports suggest that human liver, lung and skeletal muscle acquire similar protection after IP. Specifically, preconditioned tissues exhibit reduced energy requirements, altered energy metabolism, better electrolyte homeostasis and genetic re-organisation, giving rise to the concept of 'ischaemia tolerance'. IP also induces 'reperfusion tolerance' with less reactive oxygen species and activated neutrophils released, reduced apoptosis and better microcirculatory perfusion compared to non-preconditioned tissue. Systemic I/R injury is also diminished by preconditioning. IP is ubiquitous but more research is required to fully translate these findings to the clinical arena.

Systemic administration of naked DNA with targeting specificity to mammalian kidneys

A major challenge for gene therapy is to be able to deliver efficiently the gene of interest to specific cell types. Here we describe a safe and simple effective naked DNA gene delivery method, via inferior vena cava (IVC) injection, to the recipient's kidneys. It was further demonstrated that gene expression was concentrated in the proximal tubular epithelial cells of the cortico-medullary region of the kidney. Confocal microscopy analyses demonstrated the presence of the exogenous DNA in the renal cell membrane 10 min postgene delivery. However, it was only by 30 min that the presence of the exogenous DNA could be detected in the cell cytoplasm and in the nuclei of the renal cells. Stable expression of the beta-galactosidase gene could be detected for up to 35 days and no toxicity or any adverse pathological effect associated with the delivery method could be observed. Importantly, this IVC gene delivery method could promote the targeting of genes to carcinoma established in the kidney of SCID mice. These results provide the first evidence to support that stable gene expression could be achieved in the renal cells of kidney and the established carcinoma in the kidneys following in vivo gene delivery with naked DNA and could therefore provide the potential to design protocols for the gene therapy of the kidney diseases.

Acute embolic occlusion of the superior mesenteric artery: a case report and discussion of management

INTRODUCTION

We present a case of acute embolus to the superior mesenteric artery (SMA).

CLINICAL PICTURE

A 70-year-old gentleman with atrial fibrillation complained of colicky abdominal pain with clinical signs of tenderness and mild guarding.

TREATMENT AND OUTCOME

Laparotomy revealed extensive bowel ischaemia but no overt infarction. The SMA was occluded by an embolus at the root of the mesentery and balloon catheter embolectomy was carried out at once. Bowel resection was deferred in order to allow clear demarcation of gangrene to avoid sacrificing unnecessary length. At second look laparotomy, 1.2 m of bowel from mid-jejunum to mid-ileum was resected, salvaging about 1 m of previously dusky small and large bowel.

CONCLUSION

This case illustrates the importance of accurate history taking, the role of early intervention and the usefulness of a second look laparotomy in cases of mesenteric ischaemia to minimise the extent of bowel resection.

A comparison between open versus laparoscopic assisted colonic pouches for rectal cancer

The aim of this prospective study was to compare the surgical outcomes in patients undergoing laparoscopic assisted vs. open ultralow anterior resection (ULAR) with the creation of a colonic pouch-anal anastomosis. Patients undergoing ULAR with creation of a colonic pouch and who either had conventional open (CO) or laparoscopic assisted (LA) surgery in colorectal cancer were studied and compared. There were 33 patients, 22 in CO group and 11 in LA group. The groups were comparable for age, sex, tumour and anastomotic heights from anal verge, stage of disease, length of specimen removed and duration of surgery. Incisions were significantly shorter in the LA group (median, 9 cm vs. 16 cm, p = 0.01). Less parenteral analgesia was required in the LA group (2 days vs. 3 days, p = 0.05), but there were no significant differences in the time to passage of flatus, commencement of oral fluids or solid foods and length of hospital stay. There was no difference in morbidity or mortality. With regards to patients with Dukes A to C disease only, at a median of 12 months of follow-up, there was no patient with local or port site recurrence in the LA group. In the CO group, there was one local recurrence and two with distal metastases. In conclusion, laparoscopic assisted ULAR with colonic J pouch anal anastomosis is feasible, easy to perform and safe. It s advantages include significantly shorter incision and lower analgesic requirements postoperatively. Return of bowel function and length of hospital stay, however, are comparable to those of conventional open surgery.

Optimal structure for automatic processing of DNA sequences

The faithful recovery of the base sequence in automatic DeoxyriboNucleic Acid (DNA) sequencing fundamentally depends on the underlying statistics of the DNA electrophoresis time series. Current DNA sequencing algorithms are heuristic in nature and modest in their use of statistical information. In this paper, a formal statistical model of the DNA time series is presented and then used to construct the optimal maximum-likelihood (ML) processor. The DNA-ML algorithm that is derived in this paper features Kalman prediction of peak locations, peak parameter estimation, whitened waveform comparison and multiple hypothesis processing using the M-algorithm. Properties of the algorithm are examined using both simulated and real data. Model parameters of critical importance and their impact on different types of error mechanisms, such as insertions and deletions, are pointed out. The statistical model of the DNA time-series and the structure of the DNA-ML algorithm provides a basis for future investigation and refinement of DNA sequencing techniques.

Models of local behavior of DNA electrophoresis peak parameters

Many base calling algorithms implicitly or explicitly rely on predictions of local sequence parameters such as amplitude, peak time and peak width. For example, an algorithm may search for the next peak about a predicted peak time formed by adding the mean peak separation to the last position measurement. In this paper, covariance models are presented which characterize the dependence of peak parameters on those of other peaks. Based on experimental measurements, the model features an exponential decay in peak time jitter covariance with respect to base separation. Both peak amplitude and peak width are modelled as being uncorrelated with those of adjacent bases. In the model, linear expressions are given to describe the growth in peak time jitter and peak width as a function of base position while other parameters, such as amplitude variance, are modeled by constants. Together, these results form a simple model which may be used in the derivation of new sequencing algorithms or in simulations for the testing of such algorithms. We suggest that the correlation of the peak times is related to the Kuhn length of the single-stranded DNA fragments.

Predictive head movement tracking using a Kalman filter

The use of head movements in control applications leaves the hands free for other tasks and utilizes the mobility of the head to acquire and track targets over a wide field of view. We present the results of applying a Kalman filter to generate prediction estimates for tracking head positions. A simple kinematics approach based on the assumption of a piecewise constant acceleration process is suggested and is shown to track head positions with an rms error under 2 degrees for head movements with accelerations smaller than 3000 degrees /s. To account for the wide range of head dynamic characteristics, an adaptive approach with input estimation is developed. The performance of the Kalman filter is compared to that based on a simple polynomial predictor.