Choose how you want to revise

Select Questions

Revise with my preferences. Choose your difficulty or recap questions you've found hard.

Mock tests

Test myself against recent exam themes and ones curated by BMJ’s editorial team of doctors.

Group Learning

Play under a username and join friends or others for 10 questions. Move up of the daily leaderboard.

On the go

Download the app for offline access. Make revision easily fit into your schedule.

Select the best subscription for your exam date

Join 200,000+ OnExamination users who have successfully become medical professionals

Revise with quality questions and detailed explanations

Demo Question


A 55-year-old man is admitted to the Cardiac Intensive Care Unit from theatre following cardiac bypass surgery.

He has a history of diabetes and hypertension. An intra-aortic balloon pump is inserted for low cardiac output towards the end of surgery. His drains seem not to be draining much after 6 hours postoperatively. His blood pressure is low and urine output has tailed off.

Which of the following best describes the complications and management of this patient?

  Enlarged cardiac shadow on the chest X ray is highly sensitive and specific in diagnosing a cardiac tamponade

   Diastolic collapse of the right ventricle on a transoesophageal echo is a pathognomonic feature of tamponade

  Low urine output is a very sensitive measure of cardiac output in the postoperative period

  The intra-aortic balloon pump improves myocardial blood flow and oxygen delivery during systole

  The presence of drains and lack of drainage precludes the cardiac tamponade

Key Learning Point


Characteristic echocardiographic features of a pericardial tamponade include abnormal septal movement with right atrial and ventricular diastolic collapse. 



Cardiac tamponade is the acute or chronic cardiac compression caused by the accumulation of pericardial fluid resulting in haemodynamic compromise. The classic Becks triad of raised JVP, hypotension and quiet heart sounds.

The principal haemodynamic disturbance is a reduction in atrial filling with a fall in atrial diastolic volume. Trans-oesophageal echocardiography is the most reliable, non-invasive and convenient way of diagnosing the presence of an effusion, with or without thrombus and its haemodynamic effects. Characteristic features include abnormal septal movement with right atrial and ventricular diastolic collapse.

The chest X ray is not particularly sensitive, nor specific as it may be normal. Features suggestive of pericardial fluid include an enlarged globular cardiac shadow with a normal pulmonary vascular pattern.

Inflation of an intra-aortic balloon pump during diastole increases the pressure difference between aorta and left ventricle (diastolic pressure time index or DPTI). The haemodynamic consequence of this is an increase in coronary blood flow and, therefore, myocardial oxygen supply.

The urine output may fall as a result of a reduction of cardiac output and renal plasma flow. However, a fall in urine output may result from any changes in any of the Starling's forces acting across the glomerulus or nephrotoxic agents.

The presence of pericardial drains and lack of drainage does not rule out a pericardial effusion and cardiac tamponade.


Smart features to maximise your revision efforts

Daily questions

Keep on track. Set a time that suits you, we will send you a personalised revision question every day.

Revision plans

Turn weaknesses into strengths. Focus on the specialities that will give you the biggest learnings.

Feedback & peer comparison

Indicates how likely you are to pass. Detailed performance graphs show how you’re currently performing and benchmark you against your peers.

Save time and focus on the most important questions

High Impact Questions

Maximise your revision time. High Impact Questions instantly delivers you the most important questions, ranked by our clinical tutors and your peers.