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Case 7: Tachycardia with a Twist. Hassan E, Nazari P. 7:10-5-26
An 18-year-old male presented with progressive dyspnoea over one month, which acutely worsened on the day of admission. He reported associated chest, back and abdominal pain, and had experienced two episodes of collapse within 24 hours.
He had previously undergone CT pulmonary angiography three weeks earlier for suspected pulmonary embolism, which was normal. He had no past medical history and denied drug use, fever or infective symptoms.
On examination, he was tachycardic (heart rate 167 bpm), with blood pressure 107/70 mmHg, respiratory rate 26 breaths per minute and oxygen saturation 96% on room air.
An ECG demonstrated a regular narrow-complex tachycardia. A Supraventricular tachycardia (SVT) was initially suspected and the patient was treated with Adenosine (6 mg, 12 mg and 18 mg), which did not result in a sustained resolution of the arrhythmia and revealed the underlying rhythm was Atrial flutter. Discussed with cardiologist who advised DC synchronised cardioversion and local admission. At this point a bedside focused ECHO was carried out.
PLAX.mp4SUBXYPHOID.MOVThe first image is a Parasternal Long Axis (PLAX) view. The second image is a Subxyphoid view. Both confirm the presence of a large pericardial effusion measuring a maximal depth of 5.5cm and reduced contractility of the ventricles. Given the risk of developing cardiac tamponade and critical haemodynamic instability, the patient was urgently transferred to a tertiary cardiac centre for definitive management, including pericardiocentesis.
This case demonstrates how tachyarrhythmias may represent a secondary physiological response rather than a primary diagnosis. In this patient, atrial flutter likely occurred in the context of haemodynamic compromise due to progressive pericardial fluid accumulation. Failure of adenosine to terminate the arrhythmia prompted reconsideration of the diagnosis. Importantly, clinical features including progressive dyspnoea, syncope and chest pain were suggestive of an underlying structural pathology.
Bedside echocardiography proved critical, rapidly identifying a large effusion and prompting escalation of care. In patients with tamponade physiology, interventions such as sedation or electrical cardioversion may precipitate cardiovascular collapse due to preload dependence. This case highlights the importance of maintaining diagnostic flexibility and using point-of-care ultrasound in the evaluation of undifferentiated tachycardia.
Learning Points:
This case demonstrates how tachyarrhythmia may represent a secondary physiological response rather than a primary diagnosis. In this patient, atrial flutter likely occurred in the context of haemodynamic compromise due to progressive pericardial fluid accumulation.
Failure of adenosine to terminate the arrhythmia prompted reconsideration of the diagnosis. Importantly, clinical features including progressive dyspnoea, syncope and chest pain were suggestive of underlying structural pathology.
Bedside echocardiography proved critical, rapidly identifying a large effusion and prompting escalation of care. In patients with tamponade physiology, interventions such as sedation or electrical cardioversion may precipitate cardiovascular collapse due to preload dependence.
This case highlights the importance of maintaining diagnostic flexibility and using point-of-care ultrasound in the evaluation of undifferentiated tachycardia.
Trainee Lead Editor: Dr Amy Knowles, ST5
Checked: Dr Ahmed Abdul-Ghani, Lead Project Consultant
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