Left ventricular chamber and myocardial systolic function reserve in patients with type 1 diabetes mellitus: insight from traditional and Doppler tissue imaging echocardiography.
OBJECTIVE
We sought to evaluate in patients with type 1 diabetes mellitus (DM1): (1) whether myocardial afterload correlates with left ventricular (LV) circumferential and longitudinal systolic function at rest and during low-dose dobutamine (LDD) infusion, and whether longitudinal and circumferential LV systolic function reserves are correlated; and (2) to explore relations between LV systolic mechanics and LV chamber output reserves.


METHODS
A total of 20 patients with DM1 underwent echocardiography to assess LV systolic function at rest and at peak LDD (7.5 microg/kg/min). At rest, echocardiographic data of patients with DM1 were compared with those from 24 healthy control subjects. LV afterload was estimated by computing circumferential end-systolic stress (ESS). LV chamber systolic function was assessed by computing ejection fraction and ESS/end-systolic volume index; LV circumferential myocardial contractility was explored by computing midwall fractional shortening (MWS) and ESS-corrected MWS. Longitudinal LV systolic function was assessed using color Doppler tissue (DTI) to assess peak systolic velocities and maximal displacement of the lateral and medial mitral annulus in apical 4-chamber view; regional deformation analyses were computed at the midportion of the posterior interventricular septum (peak strain and peak strain rate); strain/ESS was assessed as an alternative indicator of longitudinal myocardial contractility. LV chamber output was assessed by computing stroke index.


RESULTS
DM1 and control groups did not differ in terms of sex distribution, mean age, blood pressure, LV mass index and geometry, and at-rest parameters of LV systolic function (all P > .1), whereas body mass index was higher and systolic lateral mitral annulus velocity was lower in the DM1 than control group (both P < .01). At rest, in both groups, higher ESS correlated with lower ejection fraction and lower MWS; ESS did not show significant correlation with longitudinal systolic function parameters. At peak LDD in DM1, heart rate changed minimally; ESS decreased significantly (P < .01); circumferential and longitudinal LV systolic functions increased significantly but did not show intercorrelation; higher ESS correlated with lower ejection fraction; longitudinal LV systolic function parameters did not show correlation with ESS. In a multivariate analysis, percent increase in stroke index correlated with percent change of MWS (beta = 0.74, P < .01), and to a lesser extent with the percent increase of systolic lateral mitral annulus velocity (beta = 0.47, P = .04), independent to age, sex, percent change of ESS, and heart rate.


CONCLUSIONS
LV longitudinal systolic function (DTI) parameters did not fall into the paradigm of the stress-shortening relationship used to describe LV contractility. However, both LV circumferential contractility and longitudinal systolic function reserves correlated with stroke index reserve during LDD.
Palmieri
Vittorio
V
Department of Clinical and Experimental Medicine, Federico II University School of Medicine, Naples, Italy. vpalmier@med.cornell.edu
Capaldo
Brunella
B
Russo
Cesare
C
Iaccarino
Michele
M
Di Minno
Giovanni
G
Riccardi
Gabriele
G
Celentano
Aldo
A
D000328:Adult; D002302:Cardiac Output; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000000981:diagnostic imaging*; D004280:Dobutamine; D018618:Echocardiography, Doppler, Color / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000150:complications* / Q000000981:diagnostic imaging*
D004280:Dobutamine