Introduction

Chest pain as a symptom can lead to over 400 eventual diagnoses. Up to one third of those patients admitted to an acute medical unit may have chest pain as a component of their presenting complaint. Chest pain is almost ubiquitous in patients admitted to the cardiothoracic intensive care unit (CICU). For example, the preoperative patient with ischaemic heart disease may experience the full range of associated symptoms from central crushing pain with radiation, to the silent myocardial infarction of a long-term diabetic with associated neuropathy. Once these same patients have undergone surgical revascularisation, this ischaemic pain will probably be substituted for the dull, central tenderness of a median sternotomy, or the pleuritic pain of a residual pneumothorax irritated by the intercostal chest drains. The evaluation and subsequent treatment of chest pain on the CICU is vital to enhance the clinical outcome of this patient population.

In this chapter we will endeavour to discuss the rapid yet thorough assessment of chest pain as a symptom, the initial examination and investigation strategy required, and outline the emergent therapeutic options required for each differential diagnosis.

History

As with all clinical encounters the greatest aid to formulation of an accurate differential diagnosis is a thorough clinical history. Several confounding factors exist in the ICU patient that make the history less reliable. The spectrum of confounders ranges from those patients that are sedated and ventilated, through the heavily narcotised and disorientated, to the patient with ‘distraction’ pains who may under-report symptomatic changes. These challenges can result in important delays in the detection of the pathology underlying chest pain.

Given the above issues a focused approach to history taking is required. The mainstays of site, character, radiation, onset, severity, exacerbating factors and timing all still apply although many of these will be very dependent on the preceding interventions and current therapy that the patient is undergoing. The new onset of a complaint of chest pain, therefore, requires a flexible approach to clinical assessment to rule out the most important and potentially life threatening causes in a systematic fashion.

Clinical Examination

The role of clinical examination in the CICU can often be overlooked. With all the intensive monitoring and real time data that are now available, including bedside transthoracic echocardiography and easy access computerised tomography, the stethoscope can become a vestigial appendage. However, this patient population with positive pressure ventilation and invasive procedures is particularly prone to complications such as tension pneumothorax that need to be rapidly assessed, diagnosed and treated to avoid unnecessary morbidity and potential mortality. Indeed, the CICU patient is at particular risk when transferred from the controlled environment of the unit to other departments for investigation, and the role of clinical assessment must not be forgotten.

Differential Diagnosis

The elective patient recovering on the CICU is likely to have been thoroughly investigated prior to admission. Many of the emergent admissions will also have a diagnosis underlying their chest pain by the time they arrive. However, these critically unwell and increasingly aged patients are prone to further, sometimes unrelated, pathologies. Thus a physician must have a widespread understanding of those conditions that most commonly occur in the CICU patient.

It is beyond the scope of this chapter to cover all of the differential diagnoses the CICU staff may encounter in the patient with chest pain. However, we will aim to discuss those that are most common, those that are less common but life threatening, and those that are rare but need highlighting to ensure they are not overlooked.

Myocardial Ischaemia

Most of the patients that arrive on the CICU are likely to have undergone some investigation into their coronary vasculature, be it an invasive coronary angiography or some form of non-invasive functional or anatomical test. In fact, the majority of such patients will be admitted to the CICU to recover from a procedure, performed either percutaneously or surgically, to improve the vascular supply of the myocardial bed. These patients are not, however, immune from further myocardial ischaemia.

Aortic Dissection

Acute aortic dissection is the most common life threatening pathology of the thoracic aorta and carries a mortality of 1% per hour in the early stages. In the simplest Stanford classification, type A aortic dissection involves the ascending aorta, whereas type B dissections are those that do not involve the ascending aorta. This classification is useful, as type A dissections benefit from emergent surgical repair, whereas type B aortic dissections are best managed medically unless they become complicated. Type A aortic dissections are more common in patients in their sixth and seventh decades, whereas type B dissections typically affect the elderly.

Although traditionally thought to be associated with the connective tissue disorders such as Marfan, Loeys–Dietz and Ehlers–Danlos syndromes, more common predisposing factors include hypertension and bicuspid aortic valve anatomy. In the CICU setting, the physician must always be cognisant of the postsurgical patient with sudden onset of intrascapular pain and haemodynamic instability. Any instrumentation of the ascending aorta, be that percutaneously with ostial coronary stent placement, or surgically during aortic cannulation for cardiopulmonary bypass or during aortic valve replacement, may subsequently cause separation of the layers of the aortic wall. Rarely, reports have been published of aortic dissection following cocaine use, during heavy lifting and during systemic inflammatory vasculopathy. Although perhaps the most feared complication of pregnancy, dissection during pregnancy is relatively uncommon.

The typical chest pain associated with aortic dissection is said to be a searing or tearing pain that starts in the chest and rapidly radiates to the intrascapular region. Immediate complications include right coronary artery occlusion and associated inferior ST elevation, cardiac tamponade, acute aortic valve insufficiency and neurological deficit. Atypical presentations include renal failure of uncertain aetiology due to loss of the renal arterial supply, and mesenteric ischaemia manifest by rising serum lactate, abdominal pain and frequently loose stools. The loss of a peripheral pulse was only present in 19% of patients recorded in the International Registry of Acute Aortic Dissection series. In 15% of patients with an acute aortic dissection the chest radiograph will fail to show the classic widened mediastinum, and contrast enhanced computed tomography has become the first line in investigation. In those centres with expertise in transoesophageal echocardiography, this imaging modality has the advantage of being both sensitive and specific, and also relatively rapidly performed.

Once diagnosed, type A aortic dissection is initially treated by stabilisation of the patient using intravenous beta blockade. Thereafter, emergent surgery to obliterate the false lumen and repair the ascending aorta using an interposition graft is required.

Postprocedural management requires tight blood pressure control with beta-blocker therapy providing the pharmacological mainstay. Various authors have reported survival rates of between 50 and 90% 1 year following acute type A aortic dissection.