Clinical manifestation and images of a patient having cardiovascular involvement in myxoedema coma

Abstract

Myxoedema coma is an endocrine emergency characterised by diminished sensorium associated with features of severe hypothyroidism. The disease carries a high mortality of 30%–60 %. The cardiac manifestation of the disease consists of bradycardia, hypotension, pericardial effusion and certain echocardiographic changes such as heart block and features of hypothermia. Here, we report a case of myxoedema coma with characteristic cardiac manifestations. These manifestations revert promptly on starting treatment, and achieving a eumetabolic status as was demonstrated in this patient.

Introduction

Myxoedema coma or myxoedema crisis is a rare life-threatening emergency which presents as physiological decompensation in severe underlying hypothyroidism.¹ The disease often presents with multisystem involvement. Awareness and early diagnosis make florid cardiac manifestation a rarity. We present images of an elderly individual presenting with myxoedema coma and, among other systemic involvements, florid cardiac manifestations.

Case report

A 58-year-old male patient presented to the emergency department with insidious onset progressive worsening of sensorium of 3–4 days duration in the month of December. Initially, the individual could carry out the activities of daily living but progressively went through lethargy, stupor and, finally, to a comatose state over 3–4 days. On physical examination, he had a heart rate of 34/min, a blood pressure of 98/64 mm Hg, a respiratory rate of 12/min and core body temperature of 24 °C. There was no pulsus paradoxus. He had oedema of the face (Fig. 1) and non-pitting oedema of both legs (Fig. 2). Jugular venous pressure (JVP) could not be visualised as the neck was thick. The skin was coarse, and the hair was thin and brittle (Fig. 1). He did not have any goitre. His heart sounds were muffled and distant. He was comatose with a Glasgow Coma Scale (GCS) of E1M1V1, and deep tendon jerks were diminished. Other systemic examination was unremarkable. Investigations revealed a normocytic normochromic anaemia with Hb of 8.8 gm/dl. Arterial blood gas analysis showed a compensated respiratory acidosis consistent with hypoventilation. The biochemical evaluation revealed a thyrotropin level of >85 mIU per litre (normal range, 0.4–4.2), a total thyroxine level of 1.2 ug/dl (normal range, 4.5 to 11.2 ug/dl) and a serum sodium level of 130 mmol per litre (normal range, 135 to 145). His anti-thyroid peroxidase (TPO) antibodies were 432 IU/ml (Normal < 40 IU/ml). A chest radiograph revealed cardiomegaly with 'moneybag' appearance of the cardiac silhouette (Fig. 3). An electrocardiogram (ECG) revealed a complete heart block and Osborn wave (Fig. 4). Transthoracic 2D-echocardiography revealed a massive pericardial effusion with collapse of the right ventricle. Left ventricle contractility was diminished. A magnetic resonance imaging brain was within normal limits (WNL). There was no leucocytosis. Procalcitonin was WNL.

Fig. 1.

Facial and periorbital oedema. Also noted are thin and brittle hair (photograph taken after resolution of myxoedema coma).

Fig. 2.

Bilateral non-pitting pedal oedema.

Fig. 3.

Chest radiograph anteroposterior supine view showing cardiomegaly with ‘moneybag’ or ‘waterbottle’ appearance of the cardiac silhouette.

Fig. 4.

ECG of the patient. Complete heart block with a pulse of 36/min and ‘Osborn’ wave (marked with black arrows).

With this constellation of signs and symptoms, a diagnosis of myxoedema coma was established. There were no identifiable precipitating events. Immediate pericardiocentesis was performed, and 650 ml of pinkish pericardial fluid was drained. After this, his blood pressure and cardiac contractility improved. He was given a loading dose of 400 ug of l-thyroxine through a nasogastric tube followed by 150 ug once daily. Anticipating adrenal insufficiency, hydrocortisone was started 100 ug intravenous (IV) every 8 hours. This was gradually tapered off and stopped after 2 weeks. Gradual rewarming with blankets and bed warmers were initiated. IV fluids (normal saline) and other supportive measures were given. Over the next several days, his vital signs and mental status returned to normal. A repeat ECG at day 3 of admission showed a normal sinus rhythm with a pulse rate of 74/min. There was no reaccumulation of the pericardial fluid. Repeat thyroid stimulating hormone (TSH) at the end of 6 weeks was 5.2 uIU/ml.

Discussion

Myxoedema coma is an endocrine emergency. The disease contains a high mortality ranging from 30% to 50%.^{2, 3} The predictors of mortality are older age, cardiac complication, reduced consciousness, persistence of hypothermia, need for mechanical ventilation and sepsis.^{2, 3} The diagnosis should be considered in all patients presenting with depressed mental and a hypometabolic state associated with hypothermia and bradycardia. Evaluation usually reveals overt features of severe hypothyroidism. Cardiovascular manifestations are due to severe hypothyroidism in these groups of patients. They include bradycardia, decreased myocardial contractility, low cardiac output and sometimes hypotension.⁴ Pericardial effusion may be present. Owing to lower tissue demand for oxygenation and decreased cardiac output, frank congestive cardiac failure is rare in the absence of underlying cardiac disease. ECG may reveal bradycardia and low voltages. Features of hypothermia may be present and may include prolonged PR interval, prolonged QRS complex, prolonged QTc and an extra deflection at the end of QRS complex called the Osborn wave.^{5, 6}All the cardiac abnormalities are reversed on optimal treatment.⁷Initiating treatment with l-Thyroxine may precipitate myocardial infarction or atrial fibrillation, and these possibilities should be kept in mind.

Investigations in myxoedema coma will reveal a high thyrotropin level and low T3 and T4 levels which is consistent with primary hypothyroidism in most cases. However, central hypothyroidism is also known to be present in these group of patients.⁸ Other prominent features may be anaemia, hyponatremia and mild renal dysfunction. Occasionally, a precipitating or coexisting illness may exist and may have to be managed simultaneously. The treatment consists of rapid replacement of thyroid hormone. The optimal dose of thyroid hormone is debatable. Both high dose (>500 ugm/day of l-Thyroxine) and low doses (<100ug/day) of l-thyroxine seem less effective than intermediate doses.⁹ There is no difference in the outcome in oral vs intravenous route of thyroid hormone administration.² Pituitary adrenocorticotrophic hormone (ACTH) is blunted in severe hypothyroidism, and l-thyroxine replacement causes an accelerated metabolism of cortisol. There is also a concern of central hypothyroidism and associated corticotropin deficiency.¹⁰ It is, therefore, recommended to administer hydrocortisone in stress doses and later taper off when cortisol insufficiency has been ruled out. Supportive measures include passive rewarming, IV fluids and respiratory support. Antibiotics should be considered until infections have been conclusively ruled out.

Conflicts of interest

The authors have none to declare.