Hypocalcaemia, long QT interval and atrial arrhythmias: BMJ
This case introduces the concept of ‘atrial torsades de pointes’ as well as providing a reminder of the late complications of thyroid surgery.

A 34-year-old woman presented with a 5 day history of palpitations associated with dyspnoea. She reported palpitations occurring up to 20 times a day, with episodes lasting between 5–30 min. There had been no syncopal episodes or collapse. Caffeine use was minimal and no other stimulants were being taken.

There was no history of alcohol excess. No regular medication was taken. She had undergone partial thyroidectomy in the Philippines, aged 11 years, for a multinodular goitre. On examination, a thyroidectomy scar was noted and pronounced dystrophy of the nails was present (fig 1). Carpopedal spasm could be induced using a sphygmomanometer, and Chovstek’s sign was present. The resting pulse was 98 beats/min and blood pressure was 129/81 mm Hg.

An electrocardiogram (ECG) (fig 2) while in sinus rhythm demonstrated a corrected QT interval (QTc) of 503 ms (normal range (NR) for women <450 ms). An outpatient 24 h Holter monitor was reported as showing frequent runs of uncontrolled atrial flutter, with rates up to 202 beats/min. The patient was symptomatic, with dyspnoea and palpitations, during these episodes.

Subsequent ECGs and telemetry as an inpatient revealed uncontrolled atrial fibrillation (AF) or atrial tachyarrhythmia (fig 3). Several electrophysiology specialists reviewed the data and felt AF was the predominant arrhythmia present, but other atrial arrhythmias could not be excluded.

No persistent organised atrial activity was noted to suggest ongoing atrial flutter. Some short bursts of apparently organised atrial activity were occasionally seen, but it rapidly degenerated into an irregularly irregular rhythm suggestive of AF. An echocardiogram revealed a left ventricular end diastolic dimension of 54 mm (NR 39–53 mm for women). The left ventricle appeared mildly hypokinetic for a young woman.

Endocrine assessment showed a parathyroid hormone (PTH) value of 1.40 pmol/l (NR 1.6–9.3), free thyroxine (T4) of 10.80 mmol/l (NR 7.5–21.1), and thyroid stimulating hormone (TSH) of 2.81 mmol/l (NR 0.34–5.6).

A diagnosis of surgical hypoparathyroidism was made. The patient was reviewed by the endocrinology service and given intravenous calcium replacement (calcium gluconate 10 mg) at intervals and intravenous magnesium supplementation.

Oral calcium replacement and 1-α-calcidol were subsequently started. Long acting cardioselective β-blockers were used to help control the atrial arrhythmia and aspirin instigated for stroke prophylaxis.

The QTc was monitored following oral calcium replacement therapy. Once the calcium concentration was restored to the normal range, atrial arrhythmias resolved and only sinus rhythm was recorded on Holter monitoring.

Learning points
• Hypocalcaemia is a cause of QTc prolongation and this predisposes to ventricular arrhythmias.

• Atrial arrhythmias have an increased incidence in those with congenital long QTc syndrome. While a genetic basis may be involved, acquired causes of QTc prolongation may similarly predispose to atrial arrhythmias.

• Hypocalcaemia due to hypoparathyroidism is a known late complication of thyroid surgery. In our case, it presented 23 years after initial surgery.

Read more here: http://casereports.bmj.com/content/2010/bcr.08.2009.2216.long
V●●●●●●●●h J●a and 13 others like this2 shares
Like
Comment
Share
V●●●●●●●h K●●●●●●●●●n
V●●●●●●●h K●●●●●●●●●n General Medicine
Great one!
Aug 10, 2018Like1
Dr. A●●●●h j●●●●v
Dr. A●●●●h j●●●●v General Medicine
Nice 1!?
Aug 14, 2018Like1
Dr. M●●●r P●●●l
Dr. M●●●r P●●●l General Medicine
Why does nail dystrophy occur??
Aug 14, 2018Like