Page 50 - Medicine and Surgery

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46 Chapter 2: Cardiovascular system

Aetiology ECG shows left ventricular strain or hypertrophy re-
Congenital bicuspid aortic valves can initially open lated to the degree of stenosis.

with little obstruction. There is however turbulent Echocardiography is diagnostic, often showing cusp
flow across these valves, which become thickened and thickening and calcification. Doppler studies quantify
calcified. Severe stenosis may develop over a period of the degree of stenosis and can measure left ventricular
20–30 years. function.
Congenital aortic valve narrowing leads to presenta- Cardiac catheterisation can demonstrate the pressure

tion in infancy or childhood. difference between the left ventricle and aorta, and
Rheumaticfeverresultsinprogressivecuspadherence, is required to examine the coronary arteries prior to

thickening and calcification. It is often associated with surgery.
aortic incompetence and mitral valve disease.
Sclerotic aortic stenosis is due to degenerative changes

Management
in the cusps seen in the elderly. It may lead to thicken- Treatment includes management of angina and car-
ing and calcification of the aortic valve, which is often
diac failure. Vasodilators such as nitrates must be
mild and asymptomatic.
avoided in severe aortic stenosis as they can cause syn-
cope due to a fall in systolic blood pressure. ACE in-
Pathophysiology
hibitors are also relatively contraindicated. β-blockers
The outflow of the left ventricle is obstructed causing
are often the drug of choice.
the pressure within the left ventricle to rise. This pres- Severe stenosis (pressure gradient over 60 mmHg) or
sure overload results in left ventricular hypertrophy and
symptomatic stenosis are indications for surgery (see
arelative ischaemia of the myocardium with associ-
page 30). Operative mortality is approximately 2%,
ated angina. As the stenosis becomes more severe, re-
but this is increased if coronary artery bypass is also
duced coronary artery perfusion exacerbates myocardial required. Balloon valvuloplasty may be used in pa-
ischaemia even if the coronary arteries are normal. Im-
tients unfit for surgery or to improve cardiac function
paired left ventricular emptying is most apparent dur-
prior to surgery.
ing times of increased cardiac demand such as exercise.
Ischaemia and hypertrophy of the left ventricle may lead
Prognosis
to arrhythmias and left ventricular failure.
When symptomatic, death occurs within a few years
without surgical intervention.
Clinical features
Patients are asymptomatic until there is severe steno-
sis when they present with exercise-induced syncope, Pulmonary stenosis
angina or dyspnoea. Sudden cardiac death may also oc-
cur. Late symptoms include orthopnoea and paroxysmal Definition
Narrowing of the pulmonary valve, resulting in pressure
nocturnal dyspnoea.
overload of the right ventricle.
On examination the pulse is low volume and slow ris-
ing (see page 27). On palpation there may be an aortic
systolic thrill felt in the right second intercostal space. Aetiology
The apex is slow and thrusting in nature but not dis- This is almost invariably a congenital lesion either as an
placed. On auscultation there may be a systolic ejection isolated lesion or as part of the tetralogy of Fallot. Rarely
click, followed by a mid-systolic ejection murmur heard itmaybeanacquiredlesionsecondarytorheumaticfever
best in the right second intercostal space and radiating or the carcinoid syndrome.
to carotids. The murmur is best heard with the patient
leaning forward with breath held in expiration. Pathophysiology
The obstruction to right ventricular emptying results
Investigations in right ventricular hypertrophy and hence decreased
Chest X-ray may show a post-stenotic dilation of the ventricular compliance, which leads to right atrial

ascending aorta and left ventricular hypertrophy. hypertrophy. If severe, the condition leads to right