ECMO can either provide total cardiopulmonary support (veno-arterial or VA-ECMO) or pulmonary support (veno-venous or VV-ECMO). The technique effectively enables the use of CPB in an ICU setting. In adult practice, ECMO was initially reserved for patients with severe respiratory failure secondary to ARDS. ECMO in adults fell out of favour, largely because of poor outcomes. In paediatric practice, where outcomes are generally better, ECMO has remained in routine use for over three decades. Recent H1N1 (‘swine flu’) epidemics have led to a re-examination of the role of ECMO in adults with respiratory failure and a re-emergence of VV-ECMO.

Pulmonary vascular surgery comprises emergency procedures such as pulmonary embolectomy and post-traumatic repair, and elective procedures such as palliation of PHT, pulmonary thromboendarterectomy (PTE), tumour resection and the Ross procedure. The focus of this chapter will be PHT and the management of patients undergoing PTE.

Historically, the cardiac catheterization laboratory has been used for blood sampling, contrast-enhanced imaging and intravascular pressure measurement to provide diagnostic and prognostic information and to guide surgical intervention. In recent years, technological advancements have made less invasive therapies feasible and driven tremendous growth in percutaneous procedures. While this now encompasses a wide range of cardiovascular interventions, this chapter will focus on percutaneous therapies for structural heart disease, where the anaesthetist is most likely to be involved.

Despite the widespread availability of investigational tests and imaging techniques for the diagnosis and management of cardiac disease, eliciting a comprehensive history and performing a systematic physical examination remain essential clinical skills.

Since its introduction into clinical practice in the early 1950s, the indications for CPB have broadened, from operations on or within the heart, to include non-cardiac thoracic, abdominal and neurological procedures. The indications for CPB for non-cardiac surgery are shown in Box 28.1.

Ventricular dysfunction is associated with increased cardiovascular morbidity and mortality after both cardiac and non-cardiac surgery. Traditionally, invasive pressure monitoring has been used to make inferences regarding ventricular function. However, the relationship between pressure and organ perfusion may be affected by many variables in the dynamic intraoperative environment. TOE has the advantage of real-time visualization of ventricular filling, contractility and ischaemia. As such, TOE is now considered to be the ‘gold standard’ intraoperative monitor of ventricular function.

Cardiac surgery has made extraordinary progress in the last few decades. This is largely the result of dedicated effort and almost perfect teamwork among cardiac surgeons and the allied specialty groups (anaesthesists are obviously part of it). The creativity, imagination and skills that have given rise to numerous technical innovations and surgical procedures have brought to reality the surgical treatment of the majority of the congenital malformations and the acquired lesions of the heart. The basic principles of patient selection and surgical technique in current adult cardiac surgical practice are outlined below.

Congenital heart disease (CHD) occurs in approximately 8:1,000 live births and may be associated with recognizable syndromes or chromosomal abnormalities in 25% of cases. Abnormalities are often complex, affecting structure and function. Surgery may be corrective or palliative and can be staged. Over half of these operations occur in the first year of life. The timing of surgery is dictated by the severity of the lesion, the need to avoid the development of pulmonary vascular disease or the complications of cyanotic heart disease.

Failure of tissue oxygenation represents an emergency during CPB. The principal causes are gaseous embolism, inadequate oxygenation and inadequate CPB flow.

In animals that maintain body temperature within a tight range (homeotherms), thermoregulation represents the balance between heat production (thermogenesis) and heat loss. Thermogenesis occurs as a result of metabolic activity, particularly in skeletal muscle, the kidneys, the brain, the liver and (in infants) adipose tissue. Body heat is lost by conduction, convection, radiation and evaporation (Table 24.1). Cold-induced hypothalamic stimulation activates autonomic, extra-pyramidal, endocrine and behavioural mechanisms to maintain the core temperature.

Despite more than six decades of clinical experience and considerable research, the characteristics of ‘optimal’ CPB remain imprecisely defined. This chapter discusses the main areas of controversy (Box 26.1).

Cardiac surgery is a major insult to homeostasis. Attempts have been made to reduce the inflammatory response to cardiac surgery by limiting the stimulus. The two biggest stimuli to this inflammation are thought to be surgical tissue destruction and the interaction with the extracorporeal circuit. Therefore, techniques have been developed to reduce these stimuli – either by minimizing them (minimally invasive surgery) or eliminating them completely (off-pump surgery).

Cardiac disease has been the leading cause of overall maternal mortality in the UK since the 2002–2004 triennium. The maternal death rate from cardiac disease has increased from 1.65 per 100,000 maternities in the 1997–1999 triennium to 2.34 per 100,000 maternities in the 2013–2015 triennium. This is thought to be due to increasing maternal age, increasing levels of obesity and better recognition of cardiac pathology at autopsy.

The AV is composed of three semilunar cusps left (posterior), right (anterior) and non-coronary cusp, which are related to the three sinuses of Valsalva. The main functions of the AV are to permit unimpeded LV systolic ejection and to prevent regurgitation of the LV stroke volume during diastole. The normal adult AV orifice area is 2-4 cm2.

Failure to wean a patient from CPB at the first attempt after routine cardiac surgery is a relatively uncommon occurrence. Following prolonged, complex or emergency surgery, however, failure to wean is relatively common. In the majority of cases, weaning difficulty can be attributed to myocardial ischaemia secondary to a prolonged AXC time, inadequate myocardial protection, frank MI or coronary embolism. Less common causes include extremes of prosthetic valve malfunction, anastomotic strictures, extremes of vascular resistance and cardiac compression from retained surgical swabs.

When the rapid detection of haemodynamic change is imperative, the ‘gold standard’ is direct arterial pressure monitoring. Other indications for invasive arterial pressure monitoring include severe underlying cardiovascular disease, the inability to obtain indirect measurements and the need for frequent blood sampling. While the radial artery is the most frequently used site, other commonly used arterial cannulation sites include the femoral, brachial, axillary and dorsalis pedis arteries. Complications of arterial cannulation include haemorrhage, thrombosis, vasospasm, distal ischaemia, dissection, infection, unintentional arterial drug administration, pseudoaneurysm and arteriovenous fistula formation.