Thursday 16 September 2010

MRCP revision battle 13.1: Brugada Syndrome

I'm afraid I'm too tired to even attempt an insightful intro today so lets just go straight to listing the battles:

MRCP revision battle 13.1: Brugada Syndrome
MRCP revision battle 13.2: SVC obstruction
MRCP revision battle 13.3: Causes long PR
MRCP revision battle 13.4: Cauda equina syndrome
MRCP revision battle 13.5: Surviving Sepsis

MRCP revision battle 13.1: Brugada Syndrome

Brugada Syndrome is an autosomal dominant condition that causes abnormal sodium channel proteins, leading to a risk of VF/VT and sudden death.

It is commonest in Asians.

20-40% of cases are associated with a SCN5A mutation.

ECG shows partial/complete RBBB with ST elevation in V1 to V2.  The classical ECG is type 1 below, with the other 2 possible variations.

 Treatment is ICD.

Next up - SVC obstruction...

MRCP revision battle 13.2: SVC obstruction

SVC obstruction can be frightening for the doctor as well as the patient - the first lady I saw with it came in with a lovely slim face and as time went on it became more and more puffy and she became increasingly dyspnoeic.  Once seen it will never be forgotten; I can post this photo:
                                                                     Herbert L. Fred, MD and Hendrik A. van Dijk, Wiki Commons

which demonstrates the type of difference I saw in my patient (normal on right, SVC on left).  My patient however was female and smiled more!

Anyway, lets refocus on points to learn for the MRCP exam:

Features of SVC obstruction:
  • dyspnoea
  • orthopnoea
  • headache 
  • cyanosis
  • cough
  • swollen face/arm
  • engorged veins

There is a rather nice test called Pemberton's Test which involves asking the patient to lift their arms above their head for >1 min and watch for increasing plethora/cyanosis, raised JVP and listen for stridor (that sound every doctor wants to induce in their patient...)  If these things occur it is a positive Pembertons test and suggestive of SVC obstruction.

Causes of SVC obstruction include:
  • lung cancer
  • lymphoma
  • thymus malignancy
  • thrombus around central line

Treatment is surgical, with dexamethasone whilst awaiting this.

Lets return to the small-squared world of the ECG to consider causes of a long PR...

MRCP revision battle 13.3: Long PR interval

The PR interval represents the time taken for the electrical impulse to travel from the sino-atrial node and through the atrioventricular node to the ventricles.

Normal range is 0.12 to 0.2 milliseconds (= 3 to 5 small squares)

A long PR = first degree heart block.

Causes of a long PR ( can be remembered as DRIP SAL, easier to remember if you have a drippy friend called Sally):
  • Drugs (beta blockers, calcium channel blockers, digoxin)
  • Rheumatic fever
  • IHD (anterior MIs in particular can prolong the PR interval)
  • Potassium - either high or low levels
  • Sarcoidosis
  • Aortic root pathology
  • Lyme disease

So that was short and sweet.  Onto another brief battle that should be familiar, cauda equina syndrome...

MRCP revision battle 13.4: Cauda Equina Syndrome

Cauda equina syndrome refers to a set of features caused by compression of the cauda equina.

The cauda equina begins in most people at around L1/L2.

Features of cauda equina syndrome include:
  • low back pain
  • sciatica
  • urinary incontinence/retention
  • faecal incontinence/retention
  • variable motor/sensory loss
  • classically saddle/perianal paraesthesia

Causes of cauda equina are logical when you think about it, you just need to consider what could be there to press on it:
  • commonest = large central disc herniation at L4/L5 or L5/S1
  • tumours
  • trauma
  • epidural abscess (consider this one in MRCP questions that mention a 'post op patient')
  • post op haematoma (another reason to look out for that 'post-op patient')
  • IVC thrombus
  • ankylosing spondylitis
  • sarcoidosis

Treatment is urgent surgery.

So to the final (and juiciest) battle of the day, surviving sepsis...

MRCP revision battle 13.5: Surviving sepsis

There has been a concerted push in recent years to improve the prognosis of patients presenting with sepsis, led by the international 'Surviving Sepsis' campaign.  But what are the key points to pick up for MRCP?

Firstly, a few definitions.

SIRS = systemic inflammatory response = 2 or more of:
  • temperature >38 or <36
  • WCC >12 or <4
  • RR>20 or pCO2 <4.3
  • pulse >90 (note this is lower than you'd probably have expected)

Sepsis is then defined as SIRS plus infection.

Severe sepsis is then defined as sepsis with evidence of organ dysfunction (hypoxia, anuria, raised lactate... so many possible options for the evidenve)

And then septic shock is defined as severe sepsis plus hypotension.

Now we know what sepsis is, what are the key messages from the surviving sepsis campaign?

  1. resuscitate
  • if hypotensive or lactate >4 give fluids
  • aim 
    • CVP 8-12mmHg
    • MAP>65
    • urine output >0.5mls/kg/hr
    • central venous O2 >70% or mixed venous >65%
  • if fluid alone not achieving goals, consider:
    • packed RBC to haematocrit >30% or
    • dobutamine infusion
  1.  =
  2. give antibiotics
  3. keep MAP >65mmHg
    1. norepinephrine 
    2. dopamine
  4. consider hydrocortisone if fluids and vasopressors aren't working
  5. consider recombinant human activated protein c 
    • if apache >25 or multiple organ failure
  6. remember DVT prophylaxis
  7. consider peptic ulceration prophylaxis

As Bugs Bunny would say, thaatts all folks... unless you fancy participating in today's war to check your recall of yesterday's topics...

MRCP questions: War 12

As with previous 'wars' after 'battles' these are just a few quick questions to see if your brain cells have retained the information provided in battles 11.1 to 11.4.

Grab a piece of paper, jot down your answers then compare them to my answers here

Question 1:
Which atria are atrial myxomas found in 75% of the time?

Question 2:
What murmur is associated with aortic dissection?

Question 3:
What % of patients with aortic dissection will have a pulse deficit?

Question 4:
What is the commonest form of aortic dissection?

Question 5:
How are type A dissections managed?

Question 6:
What is the classic cell associated with CLL on blood film?

Question 7:
List 5 features that suggest a poorer prognosis in CLL

Question 8:
What condition does tartrate resistant acid phosphatase positive suggest?

Question 9:
What is Richters syndrome?

Question 10:
How often is the mediastinum wide on a CXR if the patient has aortic dissection?

The answers are here

MRCP revision battle 13


MRCP revision battle 13