Clinical Research
LV Function in Pulmonary Hypertension
Abnormal Left Ventricular Diastolic Filling in Chronic Thromboembolic Pulmonary Hypertension: True Diastolic Dysfunction or Left Ventricular Underfilling?

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Objectives

The purpose of this study was to investigate the cause of abnormal left ventricular (LV) Doppler diastolic filling characteristics in chronic thromboembolic pulmonary hypertension (CTEPH).

Background

In CTEPH, LV diastolic function often appears abnormal. It is unclear whether this “impaired relaxation” (E<A) filling pattern is caused by septal hypertrophy, right ventricular (RV) enlargement and LV chamber distortion, or low LV preload and underfilling.

Methods

We studied 61 patients with an E<A transmitral pattern and CTEPH who underwent pulmonary thromboendarterectomy (PTE). We compared the results of pre- and postoperative transthoracic echocardiography and right heart catheterization measurements.

Results

After PTE, mitral E velocity increased (from 54 ± 16 cm/s to 81 ± 20 cm/s, p < 0.001), whereas A velocity decreased (77 ± 22 cm/s to 71 ± 20 cm/s, p < 0.001). E/A ratio normalized (0.72 ± 0.16 cm/s to 1.22 ± 0.40 cm/s, p < 0.001). Pulmonary venous systolic and diastolic velocities both increased (57 ± 13 cm/s to 68 ± 16 cm/s and 39 ± 15 cm/s to 70 ± 21 cm/s, respectively, p < 0.001 for both). Diastolic velocity of the septal mitral annulus (Em) did not change after PTE (8.0 ± 3.1 cm/s to 8.1 ± 2.0 cm/s, p = ns), whereas the velocity of the lateral mitral annulus increased (9.3 ± 3.2 cm/s to 11.8 ± 3.1 cm/s, p < 0.001). Mean pulmonary capillary wedge pressure increased from 9.3 ± 3.2 mm Hg to 10.6 ± 3.8 mm Hg (p = 0.035). Despite these marked changes in LV inflow, M-mode measurements of LV septal and posterior wall thickness were normal before PTE and did not change after surgery (septal: 10 ± 2 mm vs. 10 ± 1 mm; posterior: 10 ± 2 mm vs. 10 ± 1 mm; p = NS for both comparisons).

Conclusions

The results of this study strongly suggest that the impaired relaxation pattern observed in patients with CTEPH is not solely the result of geometric effects of RV enlargement and LV chamber distortion but is caused in large part by low LV preload and relative underfilling.

Abbreviations and Acronyms

CTEPH
chronic thromboembolic pulmonary hypertension
D
diastolic component of pulmonary venous flow velocity
Em
early diastolic mitral annular velocity
LV
left ventricle/ventricular
PAH
pulmonary arterial hypertension
PAP
pulmonary artery pressure
PCWP
pulmonary capillary wedge pressure
PTE
pulmonary thromboendarterectomy
RV
right ventricle/ventricular
S
systolic component of pulmonary venous flow velocity

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Itzhak Kronzon, MD, FACC, FACP, acted as the Guest Editor for this article.