A case of DiGeorge Syndrome presenting in SVT.
Case
A previously healthy and fully immunized eight-year-old female presented to a Children’s Emergency Department with palpitations after minor chest trauma. While playing at home she was hit in the chest by her cousin, and subsequently felt a sensation of her heart racing. She additionally endorsed shortness of breath.
Upon arrival, the patient was placed on a monitor and her initial set of vitals were as follows: Heart rate of 224, respiratory rate of 20, blood pressure of 96/71, temperature of 36.4C, and SpO2 of 100% on room air.
On physical examination, the patient appeared in moderate distress, was anxious and tearful. Cardiopulmonary exam was remarkable for tachycardia, normal S1/S2, normal perfusion, brisk cap refill and lungs were clear to auscultation bilaterally. Patient had normal mentation and was acting age appropriate.
The 12 lead ECG obtained was consistent with supraventricular tachycardia or SVT. Given the patient was hemodynamically stable, vagal maneuvers were attempted. We had our patient blow into a straw, and bear down to mimic a bowel movement; both to help increase intrathoracic pressure and stimulate the vagus nerve.
After those failed, we attempted our version of ice water immersion therapy by applying an ice pack to our patient’s face. Ultimately the patient required pharmacological cardioversion. She received adenosine 0.1mg/kg, which had no effect, after which the dose was doubled to adenosine 0.2mg/kg. The second round of adenosine converted the patient to normal sinus rhythm.
As the labs were resulted, complete blood count (CBC) with differential was within normal limits, troponin was slightly elevated at 0.053, complete metabolic panel (CMP) was remarkable for hypocalcemia with a total calcium level of 6.8.
Hyperphosphatemia was noted with a phosphorus level of 9.3, and significant hypomagnesemia with a magnesium level of 1.87. Ionized calcium was later discovered to be 0.83mg/dl or mmol/L.
Given these lab findings there was concern for hypoparathyroidism and thus a parathyroid hormone (PTH) level was later added on and discovered to be low at 4.80. Patient was given calcium gluconate 2gm IV and her magnesium was corrected. In light of the recent cardioversion and new onset hypoparathyroidism she was admitted. Cardiology and Endocrinology were both consulted.
Case Resolution
During her hospitalization, the patient was evaluated by cardiology, endocrinology and the genetics teams. The underlying cause of her hypocalcemia and hypoparathyroidism was found to be DiGeorge’s syndrome.
Family later provided collateral history that at birth, the patient did require cardiac surgery at an outside facility for a congenital defect. The remainder of the hospital course was uneventful and the patient was ultimately discharged home with calcium and vitamin D supplements.
Discussion
DiGeorge syndrome is a condition characterized by partial deletion of chromosome 22. This deletion occurs on the long or Q arm of the chromosome in region one and band one, hence this is known as 22q11. DiGeorge syndrome leads to failure and underdevelopment of the pharyngeal pouches during embryogenesis. These pharyngeal pouches give rise to the face, heart, thymus and parathyroid glands; which are hence affected in this syndrome.
Many children present with all or some features of classic symptoms known as CATCH-22, which are as follows: cardiac anomalies, abnormal facies, thymic hypoplasia thus immunodeficiency, cleft palate and hypocalcemia secondary to hypoparathyroidism. Fluorescent In-Situ Hybridization or FISH is used to confirm diagnosis.
Of significance for us in the Emergency Department was the hypocalcemia causing an arrhythmia. There have been a few case reports that have discussed the effect of hypocalcemia precipitating supraventricular tachycardia secondary to vitamin D deficiency as it affects calcium absorption.
Hypocalcemia can also prolong QT, which was not seen in this case, and cause ventricular arrhythmias such as Torsades. Maintaining optimal calcium levels are integral to protecting the cardiac membrane and decreasing susceptibility to depolarization and arrhythmias. The hyperphosphatemia noted above, was consistent with the hypocalcemia given that in normal physiology calcium and phosphate levels are inversely related.
One other point worth mentioning is that low levels of magnesium, which our patient had, leads to increased intracellular concentrations of calcium that inhibits the release of PTH and further causes hypocalcemia and arrhythmias. Thus maintaining electrolyte homeostasis is important.
Take Home Points
- Look for the underlying etiology of cardiac arrhythmias (electrolyte abnormalities, vs. trauma, vs. idiopathic)
- In pediatric patients with hypocalcemia, keep a broad differential and consider ordering a PTH level to evaluate for hypoparathyroidism
- Electrolyte abnormalities are often implicated in cardiac arrhythmias
References:
- Cecchi E;Grossi F;Rossi M;Giglioli C;De Feo ML; “Severe Hypocalcemia and Life-Threatening Ventricular Arrhythmias: Case Report and Proposal of a Diagnostic and Therapeutic Algorithm.” Clinical Cases in Mineral and Bone Metabolism : the Official Journal of the Italian Society of Osteoporosis, Mineral Metabolism, and Skeletal Diseases, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/26811710/.
- John D. Johnson, MD. “Hypocalcemia and Cardiac Arrhythmias.” American Journal of Diseases of Children, JAMA Network, 1 Mar. 1968, jamanetwork.com/journals/jamapediatrics/article-abstract/502582.
- UpToDate, www.uptodate.com/contents/digeorge-22q11-2-deletion-syndrome-clinical-features-and-diagnosis.
