Usefulness of catheter pressure measurement using the Navvus RXi system to determine left ventricular outflow tract obstruction and aortic stenosis severity: a case report

BACKGROUND: Left ventricular outflow tract obstruction (LVOTO) sometimes presents with aortic stenosis (AS). Echocardiography is used to assess the diagnosis and severity of LVOTO or AS. However, LVOTO is one of the conditions that makes AS assessment difficult, and catheter pressure measurement is frequently useful in such cases. CASE SUMMARY: An 84-year-old female patient presented with New York Heart Association functional Class III dyspnoea. Transthoracic echocardiography revealed LVOTO caused by upper septal hypertrophy, mitral valve systolic anterior motion with moderate mitral regurgitation, and a highly calcified aortic valve, which suggested the possibility of severe AS. The continuous Doppler echocardiography revealed a late-systolic peaking dagger-shaped profile with a peak jet velocity of 5.6 m/s. Cardiac catheterization was performed to determine the contribution of AS or LVOTO to her symptoms. Catheter pressures were measured at the ascending aorta (using a coronary catheter) and the LV (using the Navvus RXi system). The initial mean pressure gradient between the apex of the LV, just below the aortic valve and aorta, was measured at 65 and 25 mmHg, respectively. The mean pressure gradient between the apex and the aorta decreased from 65 to 40 mmHg after a 50 mg disopyramide administration. Oral medication therapy effectively stabilized her symptom after catheterization. DISCUSSION: To the best of our knowledge, this is the first reported case of assessing the severity of LVOTO and AS using the Navvus RXi system. Catheter pressure measurement using the Navvus RXi system is a useful method of determining the severity of LVOTO and AS.