Page 68 - Medicine and Surgery

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64 Chapter 2: Cardiovascular system

pleural effusions and Kerley B lines. In acute pul- can aggravate myocardial ischaemia and cause further
monary oedema there may be ‘bat wing’ or ground reductionincardiac output.
glass pulmonary shadowing.
Blood gases: There is an initial fall in arterial pO 2 and Clinical features

pCO 2 due to hyperventilation. As the patient tires or The patient has cool peripheries with a rapid low vol-
in severe cases the pCO 2 rises. ume pulse. There is tachypnoea, oligo/anuria and ex-
Other investigations include ECG and an echocardio- treme distress. There may be associated symptoms of

gram to look for the underlying cause. left ventricular failure, including pulmonary oedema.

Management Investigations
The patient is placed in the sitting position and should ECG to look for evidence of myocardial infarction or

be given high flow oxygen. Careful fluid balance is any cardiac arrhythmias.
essential and may include urinary catheterisation. Chest X-ray to look for evidence of cardiomegaly and
Additional ventilatory support may be required in- cardiac failure (see page 62).

cluding continuous positive airway pressure. Echocardiogramshouldideallybeperformedurgently
Intravenous diuretic gives immediate venodilatation to identify any correctable valve lesions and assess car-

and later increased renal fluid excretion. diac structure and function.
Intravenous diamorphine (with an antiemetic) re-

duces distress, venodilates and relieves dyspnoea.
Management
Intravenous glyceryl trinitrate is used to venodilate

Patients require intensive care, high flow oxygen and
and thus reduce the cardiac preload.
careful fluid management.
Aminophylline infusion can be considered if there is

Cardiac inotropes are usually necessary to maintain
bronchoconstriction. It also increases vasodilatation
systemic blood pressure. Increasing skin temperature
and increases cardiac contractility.
and oxygen saturation are a guide to improvement.
If patient is hypertensive hydralazine or diazoxide (ar-

Any cardiac arrhythmia should be corrected and
terial dilators) can be used to reduce cardiac afterload
angioplasty considered in patients with cardiogenic
and hence increase stroke volume.
shock in the setting of acute myocardial infarction.
Any underlying problem such as arrhythmia should

Intra-aortic balloon pumping may be instituted but it
be corrected.
does not improve mortality unless there is an under-
lying correctable cause.
Cardiogenic shock Surgical intervention may be life saving in cases of
mitralvalveincompetence,acquiredventricularseptal
Definition
defect or critical coronary artery disease.
Severe circulatory failure resulting from a low cardiac
output usually characterised by severe hypotension.
Prognosis
Mortality of 80%.
Aetiology
This is an extreme type of acute cardiac failure the most
common cause of which is myocardial infarction. Other Chronic cor pulmonale
causes include acute severe valve incompetence, or ven-
Definition
tricular septal defect post-MI.
Right-sidedheartfailureresultingfromchroniclungdis-
ease.
Pathophysiology
Cardiogenic shock is severe heart failure despite an ad-
equate or elevated central venous pressure, distinguish- Incidence
ing it from hypovolaemic or septic shock. Hypotension Commonest cause of pulmonary hypertensive heart dis-
may result in a reduction in coronary blood flow, which ease.