Epidemiology and aetiology

Ischaemic heart disease (IHD) includes all the consequences of narrowing or occlusion of the coronary arteries by atherosclerosis. These include angina, myocardial infarction and heart failure, arrhythmias and mitral valve incompetence. Myocardial infarction is the commonest cause of death in the UK. The risk factors and pathogenesis of atherosclerosis are the same as for peripheral vascular disease, discussed on page 203. The heart is supplied by the right and left coronary arteries. The left coronary artery is the bigger vessel and has a main stem 1 cm in length which divides into the left anterior descending artery and the circumflex artery (Fig. 14.1).

Figure 14.1 Anatomy of the coronary arteries.

Clinical features

The manifestations of coronary artery disease vary depending on which vessels are affected and are summarised in Box 14.1.

Investigation

Coronary angiography is the definitive investigation for patients suspected of having ischaemic heart disease. Non-invasive techniques such as MRA are likely to replace diagnostic coronary angiography in the future.

Treatment

Coronary artery bypass grafting (CABG)

Coronary artery bypass graft is one of the most commonly performed major operations. Most are performed using cardiopulmonary bypass with hypothermia (Fig. 14.2).

Figure 14.2 Cardiopulmonary bypass.

Most operations are carried out through a median sternotomy incision using cardiopulmonary bypass. Mini-thoracotomy and endoscope operations are becoming more widely used. Some procedures are performed on the beating heart without bypass (off-pump surgery). The internal thoracic artery is the first choice conduit, followed by the long saphenous vein or radial artery. First elective operations have a mortality of 0.5–2.5%, rising to as high as 20% for revision or emergency procedures.

The results for angina are excellent, with 85% of patients relieved of symptoms without medication; a further 5% are improved but require anti-anginal drug therapy.

Other procedures that may be carried out at the time of CABG include:

• left ventricular aneurysm excision (mortality 5%)

• mitral valve repair/replacement (mortality 15%)

• ablation of ventricular arrhythmic focus (mortality 30%)

• ventricular septal rupture (mortality 30%).

Complications include:

• death

• stroke (risk raised if carotid arteries stenosed)

• myocardial infarction

• limb ischaemia/compartment syndrome (especially if intra-aortic balloon pump used perioperatively)

• pneumonia

• wound problems from saphenous vein harvest

• intrathoracic bleeding

• graft occlusion with recurrence of angina/infarction

• arrhythmias.

Stenting versus CABG for ischaemic heart disease

Indications for coronary bypass surgery are summarised in Box 14.2.

Box 14.2 Indications for coronary artery bypass surgery

Failure of medical therapy with chronic stable angina

Unstable angina

Left main stem disease

Symptomatic three-vessel disease

Post-infarct angina

Acute myocardial infarction with cardiogenic shock

Failed PTCA

Reoperation for recurrent symptoms

Congenital anomalies, e.g. anomalous origin of any coronary artery

Kawasaki disease

Coronary disease concomitant with other cardiac procedures

Large clinical trials have shown that PTCA and stenting are effective in treating angina, with lower morbidity than surgery. However, the re-intervention rate is higher. CABG achieves better long-term survival, and is more effective in patients with triple vessel disease (Fig. 14.3).

Figure 14.3 An algorithm for the management of patients with suspected coronary artery disease (CAD). This pathway is changing as stent technology improves.

This is a subject of intense international debate.

Infective/subacute infective endocarditis

This is a common condition which mainly affects aortic and mitral valves, and tricuspid in intravenous drug users. There is often an underlying valve abnormality (Table 14.1). The common organisms responsible are indicated in Table 14.2.

Table 14.1 Abnormalities associated with infective endocarditis

Table 14.2 Organisms involved in infective endocarditis

Rheumatic heart disease

Rheumatic fever in childhood may lead to progressive valve damage (mitral or aortic) in later life. This is an autoimmune reaction stimulated by infection by group A haemolytic Streptococcus.

Degenerative

Age-related aortic valve stenosis is the commonest degenerative problem. Marfan’s syndrome and ankylosing spondylitis are both associated with aortic valve incompetence.

Clinical features

Physical signs of valvular disease

General examination reveals many signs of heart disease, especially right heart failure (cyanosis, pitting ankle oedema, liver enlargement). If the JVP is high, it may be necessary to sit the patient up more than the usual 45° (Table 14.3). Thrills, displacement of the apex and sternal lifting may be detected on examination of the precordium. Auscultation should proceed methodically over the aortic, pulmonary, tricuspid and mitral valve areas, listening for the heart sounds and any murmurs.

Table 14.3 Features of physical examination of peripheral circulation in heart disease

Investigations

Treatment

Indications for surgery include:

The operative options and their relative merits are indicated in Table 14.4.

Management

Early disease is managed medically, with cardiac transplantation for severe symptoms and cardiac failure.

Retrieval, tissue typing, transplantation ethics and immune suppression

These topics are all discussed in Chapter 12, pages 196–199.

Indications

Over 3500 heart transplants are performed worldwide each year. The results of heart transplants are now so good that the indications have broadened. Indications include:

Operation

The recipient’s heart is removed, leaving atrial cuffs in situ, to which the donor atria are then sutured. The pulmonary artery and aortic anastomosis are then completed. See Table 14.5 for prognosis.

Table 14.5 Survival for UK cardiac transplant patients

Heart-lung and single lung transplantation

Heart-lung grafting is indicated for severe pulmonary hypertension, end-stage cystic fibrosis and severe congenital cardiac abnormality. Sometimes a ‘domino’ procedure is performed, where a patient with a normal heart but diseased lungs (usually cystic fibrosis) receives a heart-lung graft and donates their heart to a second recipient.

Single lung transplantation is used for young patients with severe emphysema. Results are poor (usually due to chronic lung infection), but improving (Table 14.6).

Table 14.6 Survival after single lung transplantation

Epidemiology, aetiology and pathology

Lung cancer is the commonest cancer in the UK and causes over 20 000 deaths per year. The incidence is rising in females. Risk factors are smoking (especially total number of cigarettes smoked and age on starting smoking) and asbestos exposure. Types of pathology are:

Tumour (local) symptoms are:

Metastatic symptoms include:

Some lung cancers secrete antidiuretic hormone (ADH) causing the syndrome of inappropriate secretion of ADH (SIADH).

General features of cancer are superimposed:

Diagnosis

Investigations aim to establish a tissue diagnosis and assess the stage of the tumour. Biopsy is crucial not only to establish a tissue diagnosis, but to distinguish small cell carcinoma from the other varieties, since behaviour is so different:

Spread is by:

Treatment

Operable tumours may be resected. Metastatic spread may be inhibited by early ligation of the pulmonary vein. More advanced tumours may respond to chemo- or radiotherapy. Palliative therapy is often the most common option for symptom control in advanced cases.

Prognosis

For operable primary lung cancers treated by resection, the 5-year survival is only 45%. The prognosis for squamous cancers is slightly better, early tumours having a 50% 5-year survival, but only 2% of patients with more advanced cancers survive 5 years. Small cell tumours are usually lethal but do initially respond well to chemo.

Bronchiectasis

Bronchiectasis is gross dilatation of the terminal bronchioles caused by chronic infection, sometimes following measles or tuberculosis. Haemoptysis and excessive sputum production are unpleasant. Antibiotics and chest physiotherapy are the mainstays of treatment, but localised highly symptomatic bronchiectasis responds well to surgery.

Tuberculosis

Antibiotics have rendered obsolete many of the operations performed in the past for TB. Remaining indications include:

These interventions for advanced complicated TB carry a high risk of complications.

Aetiology

Traumatic pneumothorax is discussed on page 63. Spontaneous pneumothorax has three main causes:

Pathology

As air enters the pleural cavity the lung collapses. With both spontaneous and traumatic pneumothorax, if air continues to leak out of the lung with each breath, since there is no route for it to escape, the pressure in the pleural cavity increases, causing a tension pneumothorax (see p. 63).

Clinical features

There is pleuritic pain associated with breathlessness. Signs of simple pneumothorax are minimal unless the pneumothorax is large (>25%). They are:

Management

Recurrent pneumothorax may require chemical pleurodesis (instillation of a sclerosant into the pleural cavity to stick visceral and parietal pleura together) or surgical pleurectomy.