Hypertrophic cardiomyopathy with latent obstruction: Clinical characteristics and surgical results

BACKGROUND

The role of mitral subvalvular anomalies in the etiology of latent left ventricular outflow tract (LVOT) obstruction has rarely been reported; and the results of surgical treatment for latent LVOT obstruction have been infrequently reported as a separate group by other medical centers other than Mayo clinic.

METHODS

Among 292 eligible patients, 45 with resting gradients <30 mmHg had provoked obstruction. Their clinical characteristics and surgical results were compared with those of 247 patients with resting LVOT obstruction. The patients were followed up for a median of 13 months.

RESULTS

Comparatively, patients with latent obstruction were younger (51.6±12.1 years vs. 57.2±11.6 years, p=0.003) and had higher prevalence of mitral subvalvular abnormalities (73.3% vs. 16.2%, p<0.001) and basal variant of hypertrophic cardiomyopathy (84.5% vs. 62.0%, p=0.014), less marked septal thickness (16.9±2.8 mm vs. 18.6±3.8 mm, p=0.005), lower resting gradients (22.2±5.7 mmHg vs. 93.0±25.7 mmHg, p < 0.001), and lower mitral regurgitation severity (median, 2.0 vs. 3.0, p<0.001). After surgery, no surgical death occurred in patients with latent LVOT obstruction. Only one (2.2%) patient from the latent group developed complete atrioventricular block. No follow-up death or reoperation was recorded with a significant improvement in New York Heart Association functional status in either group. The provoked LVOT gradients of patients with latent obstruction decreased sharply from the preoperative value (11.8±3.7 mmHg vs. 89.8±16.4 mmHg, p < 0.001), with no occurrence of residual obstruction.

CONCLUSIONS

Symptomatic patients with latent LVOT obstruction may have a higher prevalence of mitral subvalvular abnormalities and have less marked septal hypertrophy; and concomitant mitral management during myectomy for the treatment of this patient group achieved excellent results.

Agitated Saline Contrast Echocardiography in the Identification of Intra- and Extracardiac Shunts: Connecting the Dots

Agitated saline contrast studies are an essential component of contemporary echocardiography. Agitated saline contrast plays a critical role in the elucidation of intracardiac versus intrapulmonary shunting and can have major therapeutic implications, particularly in light of the evolution of percutaneous treatment options for atrial septal defects or a patent foramen ovale. Despite their perceived simplicity, however, there are numerous pitfalls of these investigations that can occur during their performance and interpretation. As such, the authors review the "bubble study" in identifying intracardiac and extracardiac shunts, including the history of its development, the physics and physiology of contrast enhancement, how to optimally perform and interpret an agitated saline contrast study, and its safety in unique populations.