Journal of the Practice of Cardiovascular Sciences

QUIZ TIME
Year
: 2021  |  Volume : 7  |  Issue : 3  |  Page : 239--240

A “Cutie” - Diagnosis using cute heuristics


HS Kiran 
 Department of Internal Medicine, JSS Medical College and Hospital, JSSAHER, Mysore, Karnataka, India

Correspondence Address:
H S Kiran
Department of Internal Medicine, JSS Medical College and Hospital, JSSAHER, Mysore, Karnataka
India




How to cite this article:
Kiran H S. A “Cutie” - Diagnosis using cute heuristics.J Pract Cardiovasc Sci 2021;7:239-240


How to cite this URL:
Kiran H S. A “Cutie” - Diagnosis using cute heuristics. J Pract Cardiovasc Sci [serial online] 2021 [cited 2022 May 24 ];7:239-240
Available from: https://www.j-pcs.org/text.asp?2021/7/3/239/332492


Full Text



An interesting case is presented here with electrocardiography (ECG) to illustrate the clinical reasoning involved in the diagnosis. Two concepts of diagnostic reasoning are described.

 Case Illustration



Two months posttotal thyroidectomy (for thyroid carcinoma), a 70-year-old patient presented with stridor requiring emergency tracheostomy and seizures. She was on thyroxine supplementation only. An ECG was taken in emergency medicine department [Figure 1].{Figure 1}

 What is the Diagnosis?



Before arriving at a diagnosis, let us visit two vital concepts in clinical diagnostic reasoning:

Heuristics: Cognitive shortcuts or rules of thumb are referred to as heuristics.[1] These are a type of intuitive mental processes that are utilized by physicians to solve complex problems which are encountered in day-to-day clinical practiceOccam's razor: It is simplicity heuristic. “The simplest solution is usually the correct one,” says the Law of Parsimony. In medical parlance, it is often translated into the law of diagnostic parsimony, i.e. to try to come up with a “unifying” diagnosis that can explain all the patient's problems (i.e. to invoke Occam's razor).

ECG clinches the diagnosis [Figure 1] – Q-T prolongation – as per a rule of thumbHeuristic/cognitive shortcut/rule of thumb involved, “If the patient is not markedly tachycardic, the QT interval should not be more than half of the R–R interval.”[2] In this case, heart rate is within normal limits and QT is >½, the RR interval and hence definitely prolonged.

(In this case, against the backdrop of her history and presentation, QT prolongation is most probably due to hypocalcemia)

Most probable diagnosis in this case based on Occam's razor: Hypocalcemia due to iatrogenic hypoparathyroidism (2 months posttotal thyroidectomy), leading to stridor (laryngospasm) and seizures.

It was corroborated by the following:

Q–T interval in this case = 0.48 s; R–R interval = 0.72 s. QTc: Q–T/√R–R = 0.57 s (normal QTc range: 0.39 ± 0.04 s)Serum (SE) calcium in this case: 6.0 mg/dL (normal range: 8.5–10.5 mg/dL). In the absence of ionized calcium measurement, the SE calcium should be interpreted with knowledge of the SE albumin; corrected [Ca2+] = [Ca2+] + {0.8× (4.0− [albumin])} or the rule of thumb is to add 0.8 to SE calcium for every 1 g/dL decrease in SE albumin.SE albumin in this case: 3.9 g/dL (which was within normal limits, and hence, SE calcium could be interpreted as it is in this case). Thyroid profile, urea, creatinine, sodium, potassium, magnesium, phosphorus, and RBS were within normal limits. PTH was very low.

Hypocalcemia was treated successfully as per protocol, and she was discharged with thyroxine and calcium supplementation.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Mark D, Wong J. Harrison's Principles of Internal Medicine. 20th ed. USA: McGraw Hill; 2019. p. 14.
2Garcia TB, Garcia TB. Introduction to 12-lead ECG: The Art of Interpretation. Burlington, MA: Jones and Bartlett Learning; 2015.