Atypical Pattern of Electrical Alternans in a Patient With Severe Bronchial Asthma Exacerbation.

SESSION TITLE: Cardiovascular Global Case ReportsSESSION TYPE: Global Case ReportPRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PMINTRODUCTION: Electrical alternans is an electrocardiographic phenomenon consisting of alternating QRS amplitude or axis in any or all leads. The most readily recognized and understood form of electrical alternans is QRS alternans associated with pericardial effusion. Here we present a case of atypical pattern of electrical alternans in a patient with severe bronchial asthma exacerbation and this is to our knowledge represents a second case of this unusual electrocardiographic sign after a previous case reported by Dr. Apte in 1992 in a young male with similar medical conditions [1].

CASE PRESENTATION: 29 year-old man with bronchial asthma, well-controlled, presented for worsening dyspnea of 2 days duration. On examination, patient was hemodynamically stable; however he was in severe respiratory distress with oxygen saturation of 86% on room air, respiratory rate of 44 breath/min, and heart rate of 88 beat/min. Bilateral high pitched expiratory wheezes, with decreased bilateral breath sounds and prolonged expiratory phase were noted. His arterial blood gases showed acute severe respiratory acidosis with pH level of 7.24, PaCO2 of 55 mmHg, PaO2 of 96 mmHg and bicarbonate level of 23 mmol. Chest x-ray showed hyper-inflated lungs with air trapping. Electrocardiogram, revealed a sinus rhythm, heart rate of 88 bpm, with normal axis, but the QRS axis revealed an alternating pattern of gradual increment and decrement in the amplitude of QRS waves every two to three heart beats. Trans-thoracic echocardiography did not reveal any evidence of cardiac or pericardial pathology. Patient was treated with bronchodilators and corticosteroids. He improved markedly with normalization of this abnormal pattern on his EKG 3 hours later.

DISCUSSION: Typical causes of electrical alternans are usually intrinsic to the heart itself. Common causes include either pericardial effusion or conduction abnormalities within the myocytes themselves. When the former is the cause, mainly due to wobbling of the heart in the pericardial sac filled of fluid, such electrocardiographic finding is referred to as "Electrical Alternans" [2]. In our case we noticed gradual change in the QRS amplitude with no axis change and no beat to beat alternation. This pattern does not fit into the typical electrical alternans well described in pericardial effusion due to periodic swimming of the heart into the pericardial sac or due to conduction abnormality seen in pseudo-electrical alternans [3]. In our patient's situation the heart rate was 88 beats /min, however the respiratory rate was 44 breaths /min, relatively similar to the previously described case report by Dr Apte et al in 1992 where the patient's heart rate was double his respiratory rate. The mechanism(s) for this finding may be complex. However, we postulate that it is multifactorial and due to: air trapping, rapid respiratory rate and excessive chest movements during bronchial asthma exacerbation. Varying degrees of air trapping results in fluctuation in transthoracic impedance that would in turn result in variable QRS amplitude. In addition, changes in the three dimensional intra-thoracic heart orientation and position with respect to the ECG electrodes during inspiration and expiration may also affect QRS amplitude. We speculate that this electrical waving probably reflects severe asthma exacerbation with significant air trapping; however we recommend further studies to understand the real pathophysiologic cause of this change.CONCLUSIONS: Severe asthma exacerbation can be an additional cause of electrical change with atypical pattern of alternans. It possibly acquires a severity index in such patients that may warrant prompt and aggressive management. Reference #1: Apte NM. An unusual cause of electrical alternans. Chest 1992; 102:983-984.Reference #2: Kapoor J. A swimming heart. N Engl J Med 2009; 361:18.Reference #3: Klein H. Procainamide-induced left anterior hemiblock of the 2:1 type (pseudoelectrical alternans). Chest 1978; 74:230-3.

DISCLOSURE: The following authors have nothing to disclose: Mouhamad Nasser, Jad Degheili, Mohamed Kanj, Nadim KanjNo Product/Research Disclosure Information.