RESUMO
Systolic anterior motion (SAM) of the mitral valve or chordate is one characteristic seen in hypertrophic cardiomyopathy (HCM) either in obstructive or non-obstructive phenotypes. More often than not, the obstruction is caused by valvular rather than chordal SAM. We describe the role of echocardiography in identifying the actual anatomical location of the mitral valve apparatus involved in SAM and in assessing consequent left ventricular outflow tract (LVOT) obstruction in an otherwise asymptomatic patient. We report a case of a 29-year-old male admitted for an elective non-cardiac surgery, presenting with a cardiac murmur and left axis deviation with biventricular hypertrophy on electrocardiogram. On 2D transthoracic echocardiography (TTE), an asymmetrically hypertrophied left ventricle with systolic motion of anterior mitral valve was incidentally seen. Continuous wave Doppler assessment across the LVOT showed some gradient of obstruction (peak gradient: 9 mm Hg). Transesophageal echocardiography (TEE) demonstrated a redundant anterior mitral valve with the subchordal apparatus mainly causing SAM and confirmed the gradient obtained on TTE, with a mild degree, yet non-significant, degree of LVOT obstruction (mean gradient: 10 mm Hg) documented. Because of this finding, patient was cleared for surgery. Management was deemed conservative with emphasis on close surveillance for signs and symptoms attributable to development of significant LVOT obstruction in patients with HCM. To our knowledge, this is the first reported case in our country of an echocardiographic pattern of systolic anterior motion primarily of the subchordal mitral valve apparatus causing some, though non-significant, degree of LVOT obstruction in HCM. Echocardiographic features such as asymmetric left ventricular hypertrophy and presence of some LVOT obstruction caused primarily by subchordal apparatus could impact management in asymptomatic patients.
RESUMO
INTRODUCTION: Ventricular tachycardias (VT) are commonly associated with structural heart disease. However, 10% of VTs have no identifiable cause. Right ventricular outflow tract ventricular tachycardia (RVOT VT), a small subgroup of idiopathic VTs localized in the right ventricular outflow tract is highly sensitive to adenosine (ADO). Only 11% of RVOT VT is ADO-insensitive, posing a diagnostic challenge. We present a peculiar case of an ADO-insensitive RVOT-VT storm and the challenges of recognizing and managing it in a resource-limited setting. CASE SUMMARY: A 15-year-old female, asthmatic, complained of palpitations, lightheadedness, chest pain and dyspnea a few hours prior to admission. She had a similar episode a month ago, which necessitated ER admission, electrical cardioversion and amiodarone. On admission, she was tachycardic but normotensive. She had diffuse wheezes. Cardiac exam was normal. ECG revealed a wide complex tachycardia (WCT). Work-up revealed a normal chest x-ray, thyroid function tests and electrolytes. Echocardiogram showed a structurally normal heart. She was managed as a case of viral myocarditis and SVT with aberrancy. Vagal maneuvers and adenosine was given which slowed down the tachycardia. She was then started on IV anti-arrhythmics however, sustained symptomatic VT recurred on the same day. ECG analysis showed a WCT, LBBB, AV dissociation with positive QRS complexes in inferior leads suggestive of VT originating from the RVOT. RVOT VT storm was considered and adenosine (maximum dose) was given. The patient did not revert to sinus, hence, ADO-insensitive RVOT VT was considered. Cardioversion terminated the VT storm. On electrophysiology study, the VT was induced/ localized at the RVOT via 3D mapping. Ablation of the RVOT focus was performed, immediately terminating the VT. Post ablation, the patient was asymptomatic and was discharged improved with excellent prognosis. DISCUSSION: This case report highlights two things. The ECG remains a reliable tool in recognizing and localizing VTs clinically. Secondly, it highlights the importance of prompt recognition of ADO-insensitive RVOT VT because its management and prognosis is very different from the common causes of VT.
