Mechanics of the Single Left Ventricle

Abstract

Background-Left ventricular (LV) effects on right ventricular (RV) function are well known. Less is understood about the effect of the RV on systemic LV mechanics. To determine this interaction, we compared systemic LVs with and without an RV mechanically coupled to them. Methods and Results-MR myocardial tagging was used to examine 18 subjects with systemic LVs: 10 with functional single LVs (SLV) and 8 normal subjects (NL). Tracking the systolic motion of the intersecting stripes were used to determine regional twist and radial motion. Finite strain analysis was applied to derive principal strains at the atrioventricular valve (AVV) and apical short-axis levels and in 4 anatomic wall regions. Similar E 1 (circumferential shortening) strain and heterogeneity of strain were noted between SLV and NL except in the septal wall. At the septal wall, NL displayed greater absolute strain (AVVϭϪ0.16Ϯ0.02, apexϭϪ0.17Ϯ0.02) and less heterogeneity of strain than SLV (AVVϭϪ0.12Ϯ0.02, apexϭϪ0.13Ϯ0.02). Similar E 2 (wall thickening) strain and heterogeneity of strain were also noted between SLV and NL except again at the septal wall. At the septal wall, SLV displayed greater absolute E 2 strain (AVVϭ0.17Ϯ0.08, apexϭ0.19Ϯ0.09) and less heterogeneity of strain than NL (AVVϭ0.07Ϯ0.07, apexϭ0.05Ϯ0.05). SLV twisted significantly less counterclockwise than NL in 6 of 8 wall regions and actually twisted clockwise at the AVV lateral wall. Although there was no significant difference between groups in radial wall motion, the septal and inferior walls of SLV demonstrated significantly less radial motion compared with other SLV walls. Conclusions-A major influence of the RV on systemic LV strain and radial motion occurs in the septal wall, whereas absence of the RV causes marked differences in LV twist. These findings may yield clues to the long-term functioning of the SLV and be useful in determining strategies for RV augmentation of LV function. (Circulation. 1998;98:330-338.)

ACC/AHA 2008 Guidelines for the Management of Adults With Congenital Heart Disease

“…[202][203][204] MRI studies of systemic right ventricles and single ventricles may show abnormalities of myocardial twist, torsion, radial motion, shortening, and strain relations. 205,206 The frequent presence of abnormal ventricular anatomy warrants the addition of a Doppler echocardiography-derived index of myocardial performance index (or Tei index) or measurement of blood levels of brain natriuretic peptide (BNP). [192][193][194]207,208 BNP production is affected by ventricular wall stress (eg, pressure overload such as AS, in which BNP appears to be influenced by both systolic and diastolic load).…”

Model-based cardiac diagnosis of pulmonary embolism

“…Ventricular interaction is an important dynamic [22,23] and is included in the model. The septum volume is described by a time-varying P-V relationship defined [7,19,14]:…”

Comparison of Pressure–Volume Loop and Echocardiographic Measures of Diastolic Function in Patients With a Single-Ventricle Physiology

“…Septal TDI measures did not correlate well with invasive measures. This is likely secondary to the variable effects the hypoplastic ventricle has on the myocardial mechanics of the septal wall [21]. …”