You are attending a rapid response call (RRC) for a 60-year-old male who is hypotensive following coronary angiography and angioplasty.

a)    What is your differential diagnosis for the hypotension?    (20% marks)

b)    List the findings from the history, examination and investigations that would help determine the cause of the hypotension.    (30% marks)

c)    Outline your management priorities.    (50% marks)
 

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College answer

Diagnoses

Pericardial collection with tamponade

Stent occlusion

Coronary dissection or rupture

Evolving MI

Anaphylaxis

Effects of sedation and respiratory depression

Blood loss from cannulation site or retroperitoneal haematoma (femoral access)

Pulmonary oedema

Arrhythmias including heart block

History

-known allergies

-indication for procedure

-procedure performed, anatomical site of access, ease of procedure, coronary anatomy and disease, stents deployed

-medications given (anticoagulants, antiplatelets, vasodilators, inotropes or vasoconstrictors, sedatives, hypnotics etc)

-current symptoms (chest or abdo pain, SOB, dizziness etc)

Examination

-signs of cardiogenic shock (cold, clammy, diaphoretic, altering mentation, pulmonary oedema etc)

-signs of tamponade (soft HS / Elevated JVP and distended neck veins / pulsus paradoxus)

-Assess access sites especially groin and look for signs of local or retroperitoneal bleeding

-signs of anaphylaxis e.g. wheeze, flushing etc.

Blood pressure, heart rate and rhythm, respiratory rate, signs of respiratory distress, heart sounds

Investigations

ECG and echo mandatory

-ECG: new or ongoing ST elevation may indicate thrombus, stent occlusion or coronary dissection. Inferior MI may lead to 2/3rd degree heart block, and ongoing ischaemia may result in ventricular arrhythmias.

-Echocardiography looking or pericardial effusion/tamponade, which may be the result of coronary artery perforation, or cardiac perforation. Also looking for regional wall motion abnormalities or new VSD, cardiac function etc.

-Bloods including blood gas and troponin; drop in Hb, elevated lactate, significant hypoventilation etc Chest x-ray if signs of respiratory distress

Management priorities

Should focus on stabilisation of ABC and correction of reversible causes.

Haemorrhage should be excluded as quickly as possible, as should a contrast or other drug reaction. Judicious fluid challenge and use of inotropic agents/vasopressors to achieve a safe blood pressure. The need for urgent return to the Cath Lab or proceeding to the operating theatre should be decided on as soon as possible. In the absence of local haemorrhage or another clear precipitant, and after the deployment of stents, return to the Cath Lab is almost mandated to exclude stent occlusion/dissection

The need for intubation should be very carefully assessed, as the procedure carries

significant risk in the setting of severe hypovolemia or cardiac tamponade. Oxygen should be given, and judicious use of CPAP may help with pulmonary oedema although this may worsen RV dysfunction/tamponade physiology etc

Temporary pacing (transvenous or percutaneous) as indicated. Anti-arrhythmics such as amiodarone should be given as required.

Examiners Comments:

Often unstructured general resuscitation answers without reference to the specific clinical scenario. The crucial possibilities of reinfarction and cardiac tamponade were missed by many candidates as were the potential need for specific therapies. Unfortunately, some candidates spent a lot of time writing on very general aspects.

Discussion

Though the college list pulmonary oedema in their list of differentials, it is unclear how this is supposed to produce hypotension. Rather, it is an expected epiphenomenon seen in association with cardiogenic shock.

The list of differentials can be divided into categories:

  • Complications of the anaesthetic
    • Anaphylaxis (eg. to the contrast)
    • Cardiodepressant effect of general anaesthetics
    • Local anaesthetic toxicity
  • Complications of the procedure
    • Cardiac tamponade
    • Coronary artery dissection or perforation
    • Aortic injury
    • Stent thrombosis
    • Retroperitoneal haematoma
    • Intestinal ischaemia due to cholesterol emboli
  • Complications of the underlying disease
    • Cardiogenic shock due to ischaemia
    • Brady or tachyarrhythmia
  • Unrelated catastrophic event
    • Pulmonary embolism
    • Sepsis

"List the findings from the history, examination and investigations that would help determine the cause of the hypotension" they asked. This is a potentially massive time-wasting exercise for 30% of the marks. Because minimal history is given (60 years old, male, post angio), the possible answer may be quite broad. The college examiners have done quite a good job of listing the most informative examination findings in this model answer. In short, the following broad categories of question need to be asked to help determine the cause of the hypotension":

Presenting history

  • R​​​​​eason for angiography
  • Anaesthetic and procedure history (eg. which drugs did they give?)
  • Pre-procedure course (i.e. were they already in shock?)

Past history

  • Allergies
  • Medications (eg. anticoagulated?)

Examination findings and symptoms

  • Features of anaphylaxis (urticarial rash, wheeze, etc)
  • Features of cardiogenic shock (chest pain, cool extremities, shortness of breath, creps in the chest, etc)
  • Features of cardiac tamponade (pulsus paradoxus, raised JVP, etc)
  • Features of aortic dissection (back pain, differential limb pulses, abdominal pain)
  • Features of retroperitoneal haematoma (abdominal pain, distension, obvious haematoma)

Investigations:

  • ECG (STEMI, arrhythmias)
  • TTE 
  • CXR (tamponade)
  • ABG (haemoglobin, lactate)
  • Coags

Management priorities, one would have to say, depend entirely on what one finds during the process of investigating the cause of the hypotension. One would have rather different priorities in dealing with cardiac tamponade as compared to anaphylaxis. Because of this, it would have been difficult for the trainees to offer anything but "unstructured general resuscitation answers".  Moreover, though the college complained about generic responses lacking in elements specific tot he scenario, they also recommended the trainees to focus on "stabilisation of ABC and correction of reversible causes", which is as generic as it gets. With these conflicting directives, the following answer attempts to walk a fine line between specifics and generalities.

A - Assess the need for immediate airway control (eg. in context of contrast anaphylaxis)

B - Establish adequate oxygenation 

C - Correct hypotension:

   - Confirm that vascular access is secure

   - Administer short-acting vasopressor, eg. metaraminol

   - Assess the need for fluid resuscitation (eg. is the patient already in pulmonary oedema?)

   - Assess the need for immediate return to the cath lab or operating theatre (ECG looking for MI)

D - Address the patients' pain and distress

E - Correct any urgently lifethreatening electrolyte derangements (eg. give magnesium if the patient is having polymorphic VT)

H - Assess the need for blood products and coordinate urgent surgical referral if a retroperitoneal haematoma is discovered

References

References

Tavakol, Morteza, Salman Ashraf, and Sorin J. Brener. "Risks and complications of coronary angiography: a comprehensive review." Global journal of health science 4.1 (2012): 65.