Diverse geometric changes related to dynamic left ventricular outflow tract obstruction without overt hypertrophic cardiomyopathy

Abstract

BackgroundDynamic left ventricular (LV) outflow tract (LVOT) obstruction (DLVOTO) is not infrequently observed in older individuals without overt hypertrophic cardiomyopathy (HCM). We sought to investigate associated geometric changes and then evaluate their clinical characteristics.MethodsA total of 168 patients with DLVOTO, which was defined as a trans-LVOT peak pressure gradient (PG) higher than 30 mmHg at rest or provoked by Valsalva maneuver (latent LVOTO) without fixed stenosis, were studied. Patients with classical HCM, acute myocardial infarction, stress induced cardiomyopathy or unstable hemodynamics which potentially induce transient-DLVOTO were excluded.ResultsTheir mean age was 71 ± 11 years and 98 (58%) patients were women. Patients were classified as pure sigmoid septum (n = 14) if they have basal septal bulging but diastolic thickness less than 15 mm, sigmoid septum with basal septal hypertrophy for a thickness ≥15 mm (n = 85), prominent papillary muscle (PM) (n = 20) defined by visually large PMs which occluded the LV cavity during systole or 1/2 LVESD, or as having a small LV cavity with concentric remodelling or hypertrophy (n = 49). The prominent PM group was younger, had a higher S’ and lower E/e’ than other groups. In all groups, a higher peak trans-LVOT PG was related (p < 0.10) to higher E/e’, systolic blood pressure, relative wall thickness, and pulmonary arterial systolic pressure. In multivariate analysis, resting trans-LVOT PG correlated to pulmonary arterial pressure (ß = 0.226, p = 0.019) after adjustment for systolic blood pressure, relative wall thickness, and E/e’.ConclusionsDLVOTO develops from various reasons, and patients with prominent PMs have distinct characteristics. We suggest to use DLVOTO-relieving medication might reduce pulmonary pressure in this group of patients.

Editorial: Left ventricular outflow tract obstruction is seen in various clinical settings of diverse patients

“…Mechanisms of LVOT obstruction are diverse among patients. As also described in the Discussion section of this case report, not only LV size, LV systolic function, and basal septal bulge due to true septal hypertrophy or sigmoid septum but also papillary muscle displacement, increased mitral leaflet area, and both Venturi and drag forces were considered as contributing factors of SAM, the following LVOT obstruction, and MR [2] , [3] , [4] , [11] , [12] , [14] , [15] . Preload reduction, afterload reduction, and the hyperadrenergic state due to exercise, inotropic agents, or worsening heart failure can modify the LV size and contractility.…”

“…However, LVOT obstruction is observed also in hypertensive patients with the diffuse type of LVH [9] , [10] . In addition, LVOT obstruction is observed also in patients even without overt LVH [11] , [12] . LVOT obstruction seen in patients without LVH is generally latent, and is observed by provocation with exercise, inotropic agents, vasodilators, or Valsalva maneuver.…”

“…Preload reduction, afterload reduction, and the hyperadrenergic state due to exercise, inotropic agents, or worsening heart failure can modify the LV size and contractility. It leads to dynamic deterioration of preexisting LVOT obstruction or unmasking of latent LVOT obstruction [1] , [3] , [10] , [11] , [12] , [13] , [15] .…”

Commentary: Now you see me, now you don't—the peek-and-boo left ventricular outflow obstruction gradient

“…5 Rarely, dynamic LVOT obstruction may be present without overt diagnosis of HCM due to a sigmoid septum, prominent papillary muscles, or concentric LV hypertrophy. 6 Lack of a baseline gradient in symptomatic patients, however, should not dull the diagnostic senses, as emphasized by the current authors. The dynamic nature of LVOT obstruction in patients with HCM may not infrequently lead to intraoperative consternation when transesophageal echocardiographic assessment under general anesthesia does not reveal significant outflow obstruction, systolic anterior motion (SAM), or mitral regurgitation that were all visualized on preoperative transthoracic echocardiography.…”

Echocardiography in shock management

“…Dynamic LVOT obstruction can be present in the aged ambulatory population in the absence of wall hypertrophy [ 51 ]. Factors that make the critically ill population more susceptible, apart from age, include tachycardia, hypovolemia, and inotropes [ 52 , 53 ].…”