Electrocardiographic (ECG) interpretation is an essential requirement for higher specialist trainingin emergency medicine[1] and increasingly so in other specialties. [2]The role ofthe ECGin the assessment and management of acutely unwell patients has long since extended beyond the evaluation of chest pain. Electrolyte imbalance is one of many conditions which can produce classical ECG appearances. [3][4]We present a case in which the simultaneous presence of multiple severe electrolyte deficiencies resulted in dramatic ECG changes, namely “camel-hump T waves” [5] and the “Tee-Pee sign”. [6]

Case Report

A 69-year old female presented to our emergency department (ED) with a one-week history of a productive cough and shortness of breath. Her family physician had treated her with antibiotics but nevertheless her symptoms persisted. She was found in a collapsed state by her partner at 08:00am having last seen her at 03:00am when she got up to go to the bathroom. Her past medical history was significant for chronic alcohol abuse and pancolitis, for which, she underwent a total colectomy with fashioning of an end ileostomy, several years earlier. On arrival she was noted to be obtunded (Glasgow coma scale was 13/15). She was confused, opened her eyes to verbal stimuli andshe obeyed commands).Respiratory examination revealed arespiratory rateof48 breaths per minute. She was unable to speak in full sentences and widespread crepitations were noted over both lung fields.

Relevant laboratory investigations, taken shortly after arrival to the ED revealed severe deficiencies of potassium, calcium and magnesium as well as moderate deficiency in phosphate (Table 1). Acid base balance revealed a combined severe respiratory acidosis (PCO₂14.7 KPa) and severe metabolic alkalosis (BE 33.3, HCO3 56) which was almost completely compensated. Correction of electrolyte abnormalities was commenced. Approximately 2 hours and 20 minutes after arrival to the ED she suffered a cardiac arrest. The initial cardiac arrest rhythm was PEA (pulseless electrical activity). The cardiac arrest lasted for 6 minutes (three, two-minute cycles of cardiopulmonary resuscitation) after which return of circulation was achieved. She was intubated and ventilated and admitted to the intensive care unit.

An ECG, performed by paramedics en-route to hospital (Figure 1), revealed a bizarre appearance to the T waves in leads V2 and V3, which have been likened to the appearance of a camel’s hump, hence the name camel-hump T waves (Figures 2& 3). Other findings include pre-existing left bundle branch block, prolonged QTc and U-waves were noted in leads V2-V5. Marked ST segment depression was observed in the inferior and lateral leads (II, III, aVF, V5 and V6).

Discussion

Isolated electrolyte deficiencies can result in classical ECG changes (Table 2). Whendeficiencies in more than one electrolyte ispresent, it is often more difficult to detect the electrolyte abnormalities on ECG alone. [6]Surawicz reported that the QT interval in hypocalcaemia rarely exceeds 140% of the normal. [9] If it does then a second electrolyte abnormality is likely to be present.Johri et al reported a case in which a combination of hyperkalaemia, hypocalcaemia and hypomagnesaemia resulted in pre-cordial QRS complexes with peaked T waves, prominent U waves and prolongation of the descending limb of the T wave. [6] This resulted in the T wave overlapping the U wave and they called it the “Tee-Pee Sign” because the shape of the QRS complexes resembled the shape of native American Indians dwelling. The combination of prolongation of both the ST segment and descending limb of the T-waveresulted in pseudo-prolongation of the QT interval. [6]We identified the same ECG changes in our patient [Figures 1&4] eventhough the electrolyte abnormalitieswere somewhat different. In our patient severe hypokalaemia (1.8 mmol/L) instead of hyperkalaemia was present in addition to severe hypomagnesaemia (0.55 mmol/L), severe hypocalcaemia (1.51 mmol/L), and moderate hypophosphataemia. (0.6 mmol/L) [Table 2].

Christl et al observed the excretion of between 400–1000 ml of isotonic ileostomy fluid resulting in a chronic salt and water depletion. [11] Hypomagnesaemia is the most common electrolyte abnormality in chronic alcohol abuse (29.9%) while hypophosphataemia is the second most common (29.1%). [11]

Camel hump T waves are not specific for electrolyte imbalance. We think that the presence of multiple severe electrolyte abnormalities is the cause for these very dramatic camel hump T waves.The electrolyte imbalances in our patient, were due to a combination of poor intake of electrolytes as seen in chronic alcohol abuse [10], reduction in absorption following total colectomy [11],and loss of isotonic fluid as a result of ileostomy. [11]

Conclusion

Electrolyte imbalanceis common in association with chronic alcohol abuse and in patients with anileostomy. Classical ECG features may be present when single electrolyte imbalance is present facilitating early diagnosis and treatment. The simultaneous presence of multiple electrolyte imbalances can be more difficult to detect. We have identified multiple electrolyte imbalances and have observed dramatic ECG changes of camel-hump T waves and the “Tee-Pee sign”. This combination of electrolyte imbalance has not previously been reported and this is the most dramatic example of camel hump T waves which we have encountered. Further research aimed at early identification of multiple electrolyte deficiencies is required.

Figure 1: ECG performed by paramedics prior to their arrival to hospital–Camel hump T waves are visible in leads V2-V3 (thick arrow) and the “Tee-Pee sign” in leads V4-V5 (thin arrow).

Figure 2: Initial ECG in the emergency department

Figure 3:Camel-hump T waves in lead V3resulting from the fusion of tall T and tall U waves

    A               B   

Figure 4: Lead V4“Tee-Pee sign” resulting from fusion of the T and U waves (Arrow head)

The “Tee-Pee sign”,so called as it resembles the shape of a traditional native American Indian’s home. [6] Initially, in Figure 4, Panel A, the QT interval appears long but once the end of the T wave is identified the QT interval is considerably shorter than first appeared in Panel A. which in fact we can now state was a QU not a QT interval. The start of the U wave is identified as the point where the slope of the T wave deviates away from its normal slope(arrow head).

Figure 5: ECGrecorded 3 hours after correction of both severe hypocalcaemia and severe hypokalaemia (Ca²⁺ =2.14 mmol/L and K⁺ = 3.6 mmol/L)

Table 1: Electrolyte concentrations and acid base result on presentation to hospital. [7] ^†KiloPascals

Table 2: Electrolyte abnormalities and classical ECG features [8][9]

1. The Royal College of Emergency Medicine Curriculum and Assessment Systems for Training in Emergency Medicine August 2015 Curriculum Revised and applicable from August 2016 Approved 23 November 2015
2. The RCGP Curriculum: Professional & Clinical Modules. 2.01–3.21 Curriculum Modules, Version approved 19 January 2016 for implementation from 1 February 2016.
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7. Tables of normal values www.ccpe-cfpc.com/en/pdf_files/drug_lists/normal_values.pdf
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