Fouad , Kumar , Gabriel , Tarun , and Christopher: Posture related symptoms in left ventricular outflow tract obstruction.

A 70 year old man presented with breathlessness on minimal exertion. He was previously diagnosed with asymmetric hypertrophic cardiomyopathy, small airway disease, dyslipidemia, hypertension and paroxysmal atrial fibrillation. BMI was >25 and he used to consume alcohol generously.

Clinical examination showed him in sinus rhythm with blood pressure of 120/80 mmHg. Heart sounds were normal and chest examination was clear. The patient was on Atenolol 50 mg, Digoxin 125 mcg, Ramipril 10 mg, Simvastatin 40 and Tamsulosin 400 mcg once a day.

A transthoracic echocardiogram showed hypertrophied interventricular septum, in particular mid to basal (22 mm) segments but with no cavity obliteration. The left ventricular (LV) cavity size was normal, left atrium enlarged with a diameter of 5.5 cm and there was trivial mitral and aortic regurgitation. Lung function test showed FEV1 2.76, FVC 3.74 and a ratio off 72.8.

A CT coronary angiogram showed extensive calcification at all right and left coronary branches with a total Agatston score of 1600. Cardiac MRI confirmed small LV volumes with preserved ejection fraction, asymmetrical septal hypertrophy (24 mm), chordal SAM, mid-wall inducible perfusion defects and prominent focal patches of fibrosis at mid-wall.

A conventional coronary angiogram showed 80% mid-LAD lesion and two circumflex lesions of 50% and 20% narrowing but myocardial scintigraphy showed normal perfusion.

A stress echocardiogram showed restrictive LV physiology, and outflow tract (OT) gradient of 20mmHg, at rest. With increase in heart rate from 67 to 140 bpm with dobutamine, BP dropped from 132/77 to 86/57 mmHg, and the patient developed severe LVOT obstruction with peak gradient of 145mmHg, moderate mitral regurgitation, atrial fibrillation with BBB. Interestingly, despite peak stress HR of 165, significant LVOT obstruction and drop of systolic blood pressure the patient did not experience breathlessness or other symptoms on supine position.

Discussion: LV outflow tract obstruction with exertion is a well known cause of drop of systolic blood pressure breathlessness and potentially syncope in the elderly. Our patient developed clear evidence of LVOT obstruction and a drop in BP, in addition to arrhythmia with conduction disturbances on supine position with no symptoms, suggesting the important role of posture in acute pathophysiological disturbances. These changes in cardiac function are likely to contribute to his breathlessness when vertical, due to the additional effect of gravity, compromising venous return and stroke volume, worse LVOT and hence symptoms. Such pathophysiology also explains the traditional use of Valsalva manoeuvre in patients with HCM to diagnose LVOT obstruction non-invasively. Ideally, most patients with such condition respond to heart rate control medications and if not alcohol septal reduction or even surgical myectomy in severe conditions.

Figure:

Parasternal long axis view (left) and apical 4 chamber view (right) showing septal hypertrophy and SAM

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Copyright (c) 2015 Fouad Hasson, Kumar Ganesan, Gabriel Fernandes, Tarun Mittal, Christopher Travill

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