Heart, Lung and Circulation
Image| Volume 27, ISSUE 6, e78-e81, June 2018

Brokenbrough-Braunwald-Morrow Sign

Published:February 16, 2017DOI:
      A 35-year-old woman with known familial hypertrophic obstructive cardiomyopathy (HOCM) with severe, symptomatic resting and exertional left ventricular outflow tract (LVOT) gradient underwent assessment prior to elective myectomy. Hypertrophic obstructive cardiomyopathy was diagnosed aged 17 with primary prevention implantable cardioverter defibrillator (ICD) implanted 3 years earlier for syncope. Other relevant history included triple-negative breast carcinoma with surgery and adjuvant chemo-radiotherapy in remission and a treated left-arm, provoked deep venous thrombosis. Clinically, she had deteriorated with worsening exertional dyspnoea and pre-syncope and was unable to tolerate beta blocker therapy. Examination revealed a loud systolic murmur extenuated by the Valsalva manoeuvre. Electrocardiogram (ECG) showed non-pathological Q waves and diffuse T-wave inversion (Panel A ). Asymmetrical hypertrophy measuring 2.0 cm at the septum with systolic anterior motion (SAM) of the anterior mitral valve leaflet with obstruction in the LVOT was seen on 2D transthoracic echocardiogram (Panel B ) and M-mode (Panel C ). A resting peak gradient of 87 mmHg with mild mitral regurgitation (MR) increased with exercise to a peak gradient of 228 mmHg with worsening MR severity (Panel D ). Left ventricular (LV) apex, LVOT and aortic pressure tracings were recorded prior to surgery and demonstrated a peak-to-peak gradient from the LV apex to LVOT to be 85 mmHg (pre-angiography) and 79 mmHg (post angiography) (Panel E ) with LV obliteration during systole (Panel F ). Frequent ventricular ectopy during the procedure highlighted the Brokenbrough-Braunwald-Morrow sign: the paradoxical decrease in pulse pressure due to post-extrasystole potentiation whereby, according to the Frank-Starling curve, increased diastolic filling increases the LVOT obstruction by worsening the anterior mitral valve leaflet SAM. The patient went on to have an uncomplicated radical myectomy with abolition of SAM and residual LVOT gradient of 4 mmHg.
      Panel A
      Panel AECG showing sinus rhythm rate of 70 beats per minute, inferior Q waves and diffuse T-wave inversion.
      Panel B
      Panel B2D echocardiography (using parasternal long axis view) showing septal asymmetrical hypertrophy (measuring 2.0 cm) and LVOT obstruction resulting from SAM mitral valve.
      Panel C
      Panel CM-mode echocardiography (using parasternal long axis view) with intermittent SAM of the anterior mitral valve leaflet (arrows).
      Panel D
      Panel DContinuous-wave Doppler (using apical 5-chamber view) during exercise echocardiography. Image on the left demonstrates a resting peak gradient of 87 mmHg compared with peak gradient during exercise (image on right) of 228 mmHg.
      Panel E
      Panel EPressure tracings recording LV apex (solid arrows) and LVOT/aorta (hollow arrows) using a 6F Langston pigtail catheter. The eighth beat is a ventricular premature complex (asterisk) followed by a compensatory pause with increased diastolic filling, increased contraction and rise in LV pressure associated with paradoxical reduction in aortic pressure due to increase LVOT obstruction (Brokenbrough-Braunwald-Marrow Sign).
      Panel F
      Panel FLeft ventriculography (in RAO projection) in diastole (image on left) and systole (image on right) demonstrating LV cavity obliteration. ICD leads are also seen.
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