CLINICAL INVESTIGATION Paradoxical and pseudoparadoxical interventricular septal motion in patients with right ventricular volume overload

Cross-sectional echocardiographic measurements of normalized septal curvature (NSC), systolic anterior motion of the center of the left ventricular cavity (CAM), and the M mode ratio of left ventricular posterior wall epicardial motion (PEM) to posterior wall thickening (PWT) were made in eight normal subjects, 16 patients with right ventricular volume overload (RVVO) and five with pressure overload (RVPO). Paradoxical M mode septal motion was confined to early systole in six patients with RVVO (group I) and was sustained in 10 (group II). Similar end-diastolic septal flattening was observed in RVVO group I (NSC 0.50 + 0.16 [SDI) and group 11 (0.49 + 0.23) when compared with the normal group (0. 83 + 0.07, both p < .005). NSC increased in both RVVO groups during the first one-third of systole (p < .002) to values not significantly different from normal, but did not change significantly thereafter. CAM in RVVO group 11 (5.4 ± 2.2 mm) exceeded CAM in both the normal group (1.8 + 1.9 mm, p < .001) and group 1 (2.1 ± 1.4 mm, p < .005). Similarly, the PEM/PWT ratios in group LI (mean 2.94; range 2.13 to 8.0) exceeded those in both the normal group (mean 1.59; range 1.11 to 2.13, p < .01) and group I (mean 1.32; range 1.10 to 1.67, p < .01). In the RVPO group, CAM was insignificant, the PEM/PWT ratios were lower than normal (p < .01), and marked enddiastolic septal flattening was incompletely corrected during early systole, after which the septum was flattened further until end-systole (p < .005). Midsystolic septal flattening was also observed in those with RVVO in whom the right ventricular/left ventricular peak systolic pressure ratio exceeded 0.4. Thus, true septal paradox in patients with RVVO is an early systolic event. The apparent persistence of septal paradox beyond early systole is an artifact due to anterior left ventricular translation. These findings help explain the preservation of left ventricular systolic function in RVVO despite apparently sustained septal paradox, support the role of the transseptal pressure gradient in determining septal curvature, and indicate that regional wall motion analysis from a fixed reference point in patients with RVVO is inappropriate. Circulation 74, No. 2, 230-238, 1986. PARADOXICAL systolic motion of the interventricular septum is a characteristic feature of right ventricular volume overload (RVVO). 1-3 Reasoning that truly paradoxical septal motion could not occur in the absence of an abnormal systolic increase in septal curvature, Weyman et al.4 qualitatively demonstrated diastolic flattening of the septum toward the left ventricle in patients with RVVO and showed that septal curvaFrom the Cardiovascular Unit, St. Vincent's Hospital, and the University of New South Wales, Sydney, Australia. Address for correspondence: Dr. Michael Feneley. Box 3818, Duke University Medical Center, Durham, NC 27710. Received March 8, 1985; revision accepted April 17, 1986. Dr. Feneley was the recipient of a Postgraduate Medical Research Scholarship from the National Health and Medical Research Council of Australia while this work was being conducted. 230 ture returned toward normal (i.e., rightward) during systole. These observations were consistent with the demonstration by Pearlman et al.5 that the systolic motion of the septum was determined by its position at end-diastole. Furthermore, the septal curvature changes observed by Weyman et al.4 were maximal at the base of the heart and decreased toward the apex, a finding consistent with the observation by Hagan et al.6 of downward displacement of the normal "hinge point" between anterior aortic wall motion and posterior contraction of the septum in patients with RVVO. Weyman et al.4 concluded that the systolic correction of diastolic septal flattening constituted the major mechanism of paradoxical septal motion in patients with RVVO. CIRCULATION by gest on Jne 4, 2017 http://ciajournals.org/ D ow nladed from PATHOPHYSIOLOGY AND NATURAL HISTORY-VENTRICULAR INTERACTION Although quite variable patterns of septal motion may be observed in those with RVVO, the predominant previously described abnormalities have been observed to persist throughout the greater part of systole. 7If persistently abnormal systolic septal motion could result from diastolic septal flattening,4 then abnormal left ventricular systolic function might be expected in most patients with RVVO. Although left ventricular systolic function may appear to be depressed by RVVO when it is related to the left ventricular end-diastolic pressure as the index of preload,f this predominantly reflects the reduced left ventricular compliance associated with leftward diastolic septal shifting.9' 10 Left ventricular systolic function is found to be well preserved when it is related to left ventricular end-diastolic volume as the index of left ventricular preload, consistent with the "reversed Bernheim effect" originally postulated by Dexter'" to explain left ventricular dysfunction in some patients with atrial