SCMR 22nd Annual Scientific Sessions
Description of Clinical Presentation:
Assessment of hemodynamics is essential in the evaluation of hypertrophic obstructive cardiomyopathy (HOCM) (1). We summarized characteristics of hemodynamics in a variety of HOCM subtypes using 4D flow cardiovascular magnetic resonance (CMR).
Diagnostic Techniques and Their Most Important Findings:
Case 1: HOCM with mid ventricular obstruction
A 66-year-old male presented with dyspnea on effort. Echocardiography and CMR revealed diffuse symmetrical left ventricle (LV) hypertrophy (LVH) concomitant with mid ventricular obstruction (Fig. 1A and 1B). On echocardiogram, elevated flow velocity of 5.9 m/s was observed at mid ventricle. Preserved LV ejection fraction (EF) of 75% was observed, whereas reduced end-diastolic volume of 59 ml and increased LV mass of 181 g was demonstrated. 4D flow CMR visualized narrow flow jet from apex to LV outflow tract (LVOT) (Fig. 1C, arrows) with systolic peak velocity as 5.6 m/s. The patient started Cibenzoline 300 mg, followed by decreased peak velocity of 2.2 m/s by echocardiography and improved symptom.
Case 2: HOCM with LV outflow tract (LVOT) obstruction
A 45-year-old male was evaluated for his palpitation and dyspnea. Paroxysmal atrial fibrillation (AF) was detected in his 24 hours monitoring of electrocardiography. Echocardiography revealed LVH and systolic anterior movement of mitral valve resulted in moderate mitral regurgitation (MR) (Fig. 2A, black arrow). Elevated peak velocity of 4.4 m/s at LVOT was observed as well. CMR demonstrated localized LVH in basal septum and patchy LGE in right ventricular insertion point. 4D flow CMR visualized narrow flow jet at LVOT (Fig. 2D, white arrow) and mitral regurgitation in systole (yellow arrow). Surgical septal myectomy or percutaneous transluminal septal myocardial ablation (PTSMA) was proposed.
Case 3: HOCM with LVOT obstruction who underwent PTSMA
A 79-year-old female with HOCM presented with worsening dyspnea. She was initially treated with Cibenzoline 9 years earlier, but gradually worsened to New York Heart Association (NYHA) class III. A pre-procedural echocardiogram revealed an elevated LVOT peak pressure gradient (PG) of 236 mmHg, prompting evaluation for PTSMA. CMR before PTSMA revealed faint LGE scattered in LV (Fig. 3A, white arrow heads). 4D flow CMR exhibited an LVOT obstruction with a narrow flow jet measured at 7.6 m/s at peak systole visualized by streamline image (Fig. 3B, yellow arrow). PTSMA through the 1st septal branch was performed and resulted in significant improvement in LVOT obstruction; peak PG by catheter dropped from 100 to 10 mmHg. Her symptoms improved to NYHA class II. CMR after PTSMA revealed transmural LGE with microvascular obstruction in the basal ventricular septum (Fig. 3C, white arrows). Compared to pre-PTSMA, 4D flow CMR demonstrated wider flow jet in the LVOT with a peak velocity of 2.9 m/s (Fig. 3D, red arrow).
Learning Points from this Case:
Our findings suggest that 4D flow CMR has a potential to visualize the different types of impaired blood flow in patients with a variety of HCM subtypes.