TAVI and its role in treatment of aortic stenosis

submitted by Dr Gokulnath Rajendran & Dr Stephen T Webb both at Papworth Hospital NHS Foundation

Aortic stenosis (AS) is the most common type of valvular heart disease in developed countries. It is a progressive disease and the incidence of
severe stenosis increases with age, ~2% at 65 years and 4% at 85 years[1]. Patients may be asymptomatic or present with syncope, angina or exertional breathlessness. Surgical replacement of aortic valve is the standard treatment to improve quality of life in symptomatic severe AS. However patients who are considered too high risk for surgery could benefit from minimally invasive transcatheter aortic valve implantation (TAVI).

TAVI was first performed in 2002. Since then, technology has evolved rapidly and in the last decade, more than 50,000 procedures have been performed worldwide2. The procedure involves balloon valvuloplasty of the stenosed valve followed by deployment of a bioprosthetic valve by transfemoral or transapical route.
In UK, TAVI is currently performed in cardiac catheterisation suites with operating theatre facilities (‘hybrid’ catheter rooms) in specialist cardiothoracic centres by interventional cardiologists. Patients undergo comprehensive investigations including echocardiography, coronary angiography and computed tomographic (CT) angiography. Multi-disciplinary assessment of the patient is essential prior to the procedure.

Although TAVI can be performed under local anaesthesia, the majority of patients receive general anaesthesia. General anaesthesia provides
the patient immobility and facilitates the use of transoesophageal echocardiography. Anaesthetic management can be potentially challenging as these patients often have multiple comorbidities. The procedure involves rapid ventricular transvenous pacing to temporarily reduce cardiac motion. Pacing wires are inserted in case of bradyarrhythmias. Vasopressors are usually administered to treat intraoperative hypotension and maintain coronary perfusion pressure.

As the procedure may lead to potentially catastrophic haemodynamic instability, a cardiopulmonary bypass circuit and clinical perfusion team are kept on stand-by in the hybrid catheter room. Intraaortic balloon counterpulsation may be necessary to support patients with very poor ventricular function.

Complications of TAVI include delirium, seizure, stroke or TIA, myocardial infarction, cardiac arrhythmia, access site arterial injury and cardiac tamponade. Moderate to severe para-valvular regurgitation may occur after TAVI3.

Two-year survival rate is similar following TAVI compared to surgical procedure3 and is superior compared to medical treatment4. The UK National Institute for Health & Clinical Excellence (NICE) concluded that evidence for the efficacy of TAVI is sufficient to recommend the procedure for those unsuitable for surgery, but that there is0 insufficient evidence to support it for those considered suitable for surgery. Technological refinements could result in expansion of this less-invasive procedure to a broader spectrum of patients in the future.

1 Carabello BA, Paulus WJ. Aortic stenosis. Lancet 2009;373:956-66.
2 Vahanian A. Transcatheter aortic valve implantation: our vision of the future. Arch
Cardiovasc Dis. 2012 Mar;105(3):181-6.

The changing world of vascular surgery

Blog Post by Mr Vish Bhattacharya MB BS, FRCS (Glas & Edin), FRCS (Gen Surg) Consultant General and Vascular Surgeon, Queen Elizabeth Hospital, Gateshead, UK.

Vascular surgery has changed dramatically over the last 10 years. The major emphasis has been on prevention of vascular disease and on minimally invasive surgery. There has been much better awareness among the general body of doctors especially GPs about arterial disease and their management. Early detection of peripheral arterial disease and its management is gaining increased importance in order to reduce the number of amputations.

Venous disease management has also changed and less invasive forms of treatment for example foam sclerotherapy, radiofrequency ablation and laser treatment of veins have emerged.

The future of heart and lung transplantation

Blog Post by Clive Lewis, Andrew Klein, Nick Lees and Stephen Webb, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, CB23 3RE

The field of transplantation has spawned more new specialties and Nobel prize winners than any other in medicine. Christiaan Barnard’s performed the first heart transplant in 1969 in Cape Town, South Africa. The first lung transplant was performed even earlier, in 1963, by Hardy and colleagues at the University of Mississippi in the USA, although two decades passed before this procedure become a viable option for end stage lung disease. Heart transplant is now the treatment of choice for selected patients with advanced heart failure, with over 85,000 procedures having been performed worldwide during the last 40 years. On average, more than 5000 heart transplants are undertaken every year, in more than 225 centres.

Two important challenges transplantation are the increasing numbers of referrals, and the falling number of suitable donor organs available. This has lead to a major imbalance between supply and demand.

Non-invasive ventilation for acute cardiogenic pulmonary oedema

Blog Post by Mr Tim Case MPhil MA (Cantab) Medical Student, Hughes Hall, University of Cambridge, Cambridge, CB1 2EW, UK, and Dr Stephen T Webb MB BCh BAO FRCA EDIC, Consultant in Anaesthesia & Intensive Care Medicine, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, CB23 3RE, UK

Acute cardiogenic pulmonary oedema (ACPO) is a life-threatening consequence of acute heart failure that affects more than 17000 patients in the UK per year[i].  As the left ventricle fails, increased hydrostatic pressure causes fluid to leave the pulmonary capillaries and fill the alveoli.  Clinical features of ACPO include dyspnoea, tachypnoea, wheeze, pulmonary crepitations and hypoxaemia. 

The Ongoing Challenges with the Peri-operative Care of the Morbidly Obese Patient

Blog Post by Jay B. Brodsky, MD and Harry J.M. Lemmens, MD, PhD, and Stanford University School of Medicine, Stanford, CA, 94305

We are all aware that the world is experiencing an obesity epidemic. Given the great numbers of morbidly obese patients currently undergoing surgery and the predicted increases in those numbers for the future, every health care professional must be familiar with the unique management concerns of these potentially complex patients.          

The morbidly obese patient can be especially challenging for their anesthesiologist and surgeon.  There are physiologic changes to almost every organ system, numerous associated medical co-morbidities, altered uptake and distribution of anesthetic agents and other drugs, potentially difficult airways, as well as technical difficulties related to the large size of these patients.

Post-thoracotomy regional analgesia

Blog Post by Dr Darcy M Pearson FRCA, Specialty Trainee in Anaesthesia & Intensive Care, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK and Dr Stephen T Webb MB BCh BAO FRCA EDIC, Consultant in Anaesthesia & Intensive Care Medicine, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK

Inadequate postoperative pain relief after thoracotomy increases the risk of respiratory complications and chronic post-surgical pain. A number of regional analgesic techniques may be used for post-thoracotomy analgesia including intercostal,intrapleural, extrapleural, paravertebral, intrathecal and epidural analgesia. Extrapleural and paravertebral techniques may be performed by percutaneously or under direct vision and may involve single injections or continuous infusions.

“So you want to become a COLORECTAL consultant surgeon” Career Pathways 5

Blog Post by Mr Nigel Hall, Colorectal Consultant Surgeon

·         What does the speciality offer?                 

Coloproctology encompasses a wide variety of  conditions (benign and malignant, acute and chronic, functional and organic, sporadic and hereditary, trivial and life threatening), in both sexes and all age groups, treatable through a range of techniques – open surgery, laparoscopic, transanal and endoscopic.  Our patients require holistic care and challenge us to improve their lives.  It is a stimulating and rewarding environment, and friendly too with a lot of multidisciplinary and team working. There is plenty of scope for research, teaching and training.  Coloproctology is the backbone of general surgery – and a major specialty in every hospital – you need look no further for a great job!

“So you want to become a vascular consultant surgeon?” Career Pathways 4

Blog Post by Mr. Kevin Varty, Vascular Consultant Surgeon 

·         What does speciality offer?  

Rewarding surgery. Interesting patients who are both a surgical and medical challenge.  New technology, stents to treat aneurysms, combined endovascular and open surgical skills.

Anesthesia awareness

Blog Post by George Mashour, University of Michigan School of Medicine

“Anesthesia awareness” refers to consciousness and explicit memory of surgical events.  This complication is thought to occur in approximately 1-2 cases/1000 and can range from a transient auditory perception to the experience of being fully awake, in pain, and chemically paralyzed. Risk factors for this event traditionally include certain cardiac procedures, emergency cases with blood loss, emergency cesarean section, difficult airway management, and cases with total intravenous anesthetic.  Many of these cases (cardiac, trauma, cesarean section) represent situations in which giving adequate anesthesia could be potentially life-threatening.  Other causes include resistance to anesthetics, machine or equipment malfunction, and human error.  The experience of anesthesia awareness can be psychologically devastating.  In a new study by Dr. Kate Leslie and colleagues (Anesthesia & Analgesia, March issue), 5 of 7 awareness patients identified in a larger study met criteria for post-traumatic stress disorder.  The role of brain monitoring for the prevention of awareness is still unclear; several large studies are ongoing to determine the value of one such monitor.  Part of the difficulty of detecting awareness in the surgical setting relates to our limited understanding of the neural correlates of consciousness.  As we develop more sophisticated knowledge of the mechanisms of both consciousness and anesthesia, improved monitoring capabilities may become available.  In the meantime, recognizing high risk cases and vigilance on the part of the anesthesia provider is the first line of defense.    

Now published in the US, and available from the UK and Europe in March 2010, Consciousness, Awareness, and Anesthesia, edited by George Mashour, is a fascinating insight into both the scientific problem of consciousness and the clinical problem of awareness during general anesthesia.

“So you want to become a cardiothoracic consultant surgeon” Career Pathways 3

Blog Post by Mr Large, Cardiothoracic Consultant Surgeon

·         What does your speciality offer?             

Cardio-thoracic surgery offers an exceptional combination of medicine, physiology and delicate technical skills. It is one of the few surgical specialities which is truly reconstructive rather than ablative. It offers patients substantial improvements in quality of life and prognosis. It is probably one of the most evidence-based practices in medicine. CT surgery is a small surgical speciality with some 250 consultant in about 35 centres. It’s very well organised and it is closely monitored. Cardio-thoracic disease is changing with heart failure is on the rise along with patient age. With age comes atrial fibrillation and degenerative valve disorders.