A 48 year old woman is brought in by ambulance with

  • SOB
  • Palpitations
  • 1 week of fever, cough, diarrhea and anorexia

On examination

  • HR 200/min, irregularly irregular
  • BP 109/70
  • RR 40/min
  • saturations 94% on room air
  • temperature 37.5

This is her ECG

What is your differential diagnosis?

Differential diagnosis includes

  • sepsis
  • pneumonia
  • myocarditis
  • heart failure
  • thyrotoxicosis

 

A septic screen is performed along with biochemistry, FBC and ABG

  • UEC : normal
  • LFT : Total bilirubin 14.8 mmol/l Unconjugated bilirubin 615 umol/l ALP 160 g/l, GGT 35U/l, ALT 84U/l, AST 74U/l
  • WCC 10.9   Hb 84
  • ABG on 35% oxygen : pH 7.4 PO2 96 mmHg PCO2 35 mmHg HCO2 5.3mmol/l lactate 5.8

What other blood tests would you like to add?

  • TFT
  • troponin

 

How would you manage this patient?

  •  iv fluids
  • oxygen
  • broad spectrum antibiotcs: 2g  ceftriaxone
  • magnesium 20mmols for AF
  • assess cadiac function

 

A POCUS ECHO was performed to assess her cardiac function.

 

 

How would you describe her RV and LV function?  Does this change your views regarding treatment of her AF . In order to help you with this, compare the following ECHO from a 20 year old who is tachycardic (HR 130 -150) from an overdose.

It is difficult to assess LV function in patients who are tachycardic or in AF,  but have a look at the parasternal long axis view of our patient and especially at the anterior mitral valve leaflet. It is not getting near the interventricular septum. Look at the radial contraction but also the longitudinal contraction of the left ventricle in the 4 chamber view. Look at the relative size of the RV compared to the LV. It should be 2/3 of the size of the RV.

Our patient has  poor biventricular function with an estimated EF of around 30- 40% . There is also biventricular dilatation.

Compare our patient with the normal ECHO of the 20 year old tachycardic patient. Compare the squeeze of the left ventricle, the way the anterior mitral valve leaflet slaps onto the interventricular septum in the parasternal long axis view,  the way the 4 chamber view shows the medial annulus of the  mitral valve  literally bouncing up towards the apex in systole (longitudinal contraction) and the better radial contraction in the 4chamber view.

In view of her cardiac function B blockers were not given in the Emergency Department.

She was given a loading dose of Digoxin 500 mcg and responded well over the next 2 hours. Her HR improved to hover around 100/min.

 

Her added blood tests return

  • troponin 8
  • TSH  undetectable

What are some of the precipitants of thyroid storm? What are the complications of elevated levels of thyroid hormones?

Precipitants of thyroid storms in patients with hyperthyroidsim  include

  • infection (most common)
  • surgery
  • trauma
  • discontinuation of antithyroid drugs
  • amiodarone

Elevated levels of circulating thyroid hormones can increase metabolic demand, leading to adverse effects on multiple organ systems – cardiovascular/gastrointestinal/renal/haematological

The cardiac complications  include

  • cardiomyopathy
  • myocardial infarction
  • ventricular arrhythmias
  • coronary vasospasm.

 

How would you treat AF/tachycardia in a patient with a thyroid storm?

  • The classic medication in a thyroid crisis to control HR has been propranolol.
  • The reason for this is that propranolol is a non-selective, beta-1 and beta-2-blocker that can treat the symptomatic tachycardia and may also treat some of the reduced systemic vascular resistance which occurs in this clinical scenario. It may also inhibit the peripheral conversion of T4 to the more biologically active hormone, T3.
  • Despite the above theoretical advantages of propranolol in thyrotoxic crisis the Endocrinologists Medical Guidelines for the Evaluation and Treatment of Hyperthyroidism and Hypothyroidism do not specifically recommend one beta-blocker over another when discussing the use of beta blockers in this situation and it is probably wise to use a shorter acting and easily titrated B blocker such as esmolol in this scenario.

Esmolol dose in thyroid storm:

Optional bolus: 500 mcg/kg IV
Infusion: 50–200 mcg/kg/min IV

  • In patients who have contraindications to B blockers (e.g., asthma or reactive airway disease), the use of diltiazem can be considered as an alternative.
  • If patients have concurrent low-output heart failure during thyrotoxicosis, all negative inotropic medications such a B blockers  should be  avoided completely.

 

What is the treatment of patients presenting with thyroid storm in the Emergency department?

The mortality rate for thyroid storm varies between 10 -30%

Treatment includes

  • Supportive IV fluids, electrolytes replacement, oxygen
  • POCUS before Beta-blocker: Propranolol,  Esmolol – It is easily titratable
  • Anti-thyroid: Propylthiouracil. lugol iodine, potassium iodide, hydrocortisone. These can block synthesis (PTU)  block release (Iodine) or block conversion of T4 to T3 (PTU/steroids). Steroids also covers  adrenal insufficiency.
  • Second line: Lithium, colestipol, cholestyramine (blocks reabsorption of thyroid hormone in digestive tract) dialysis, plasmapheresis, or thyroid surgery
  • ECMO in cardiovascular collapse

Long-acting beta blockers such as propranolol have been found to have  causal association with circulatory collapse and cardiac arrest in thyroid storm patients.

Most  patients will not survive a  beta blocker-triggered cardiac arrest despite all resuscitation and supportive measures including ECMO.

 

Unfortunately this lady was given a B blocker in intensive care after consultation with the cardiologists  which precipitated  a cardiac arrest. She was put on  VA ECMO but did not survive.

Teaching points

  1. Think about thyrotoxicosis as a cause of AF with RVR in all patients. Always add TFT. A thyroid storm can mimic sepsis.
  2. Never give a B blocker in a patient with AF who presents to the ED without first checking their cardiac function irrespective of the suspected cause of the AF.