Page 330 - fbkCardioDiabetes_2017

306 Diabetic Cardiomyopathy :
Mechanisms, Diagnosis and Treatment

tion of the left ventricle is dependent on the integri- and posterior wall of the left ventricle and estimates
ty of longitudinal subendocardial myocardial fibres, the percentage CVI(cyclic variation index). Subjects
whereas radial (short-axis) contraction depends on with high LV masses and concentric hypertrophy
integrity of the circumferential fibres. The former is demonstrate an increased CVI.This has not yet been
more susceptible to ischaemia and fibrosis which applied to diabetic patients.
may result in a relative increase in short-axis velocity
compared with a decrease in long-axis function due Intravenous contrast echocardiography
to compensatory ventricular remodelling. Thus, in 53 During the last decade, the use of contrast echocar-
patients with diabetes but no LV hypertrophy,normal diography has gained considerable interest because
ejection fraction and no ischaemia on dobutamine it provides a non-invasive means of assessing integ-
echocardiography, radial contractility was increased rity of the coronary microcirculation and myocardial
and appeared to compensate for reduced longitudi- perfusion as well as improving assessment of LV
nal contractility. In a recent study of 35 patients with function. Contrast agents are used to enhance vi-
Type II diabetes, the presence of regional systolic sualization of the blood–endocardial interface to as-
abnormalities in patients with an apparently normal sess myocardial perfusion. Furthermore, the proper
ejection fraction questions the concept of isolated delineation of the endocardial border observed after
diastolic dysfunction. 21
contrast administration increases the clarity of the
TDI does not differentiate between active contrac- images and improves the results provided by the al-
tion and passive movement of a myocardial seg- gorithms orientated to the assessment of ventricular
ment. Thus rotation and translation movements of motion. 23
the whole heart,as well as active contraction of seg- Direct assessment of myocardial blood flow and flow
ments adjacent to the analysed segment,may affect reserve is possible, as microbubble contrast agents
the determined velocity.Strain and strain rate echo- remain entirely within the intravascular space andt
cardiography is a technique for assessing myocardial heirpresence in any myocardial segment denotes the
systolic and diastolic function. This modality has im- status of microvascular perfusion within that region.
proved the quantitative assessment of regional wall Inastudy by Senior and Swinburn, the sensitivity and
motion and the accuracy and reproducibility of test negative predictive value of dobutamine echocardi-
readings. Myocardial strain and strain rate can detect ography for the prediction of recovery of dysyner-
inducible ischaemia and at earlier stages than visual gistic segments improved significantly from 59% to
estimation of wall motion or wall thickening param- 79% and 88% to 95% when contrast opacification
eters. Changes in systolic strain rate and strain have was observed in the dobutamine non-response seg-
the potential to discriminate between different myo- ments. Thus contrast LV opacification studies allow
cardial viability states. Measurement of the diastolic more accurate measurements of LV size and mass,
rate of deformation can differentiate physiological and myocardial contrast echocardiography provides
from pathological hypertrophy and restrictive from an alternative non-invasive assessment of CAD.
constrictive cardiomyopathy. Strain rate assessment Echocardiography relies on resonance of microbub-
has also been implemented in 3D (three-dimensional) ble contrast agents when excited by diagnostic ul-
echocardiography with promising results.
trasound frequencies, thus producing an increased
ultrasound backscatter from the blood.
Doppler acoustics
Fibrosis alters the acoustic properties of the heart 3D Echocardiography
in animals and humans, and the magnitude of cyclic Conventional 2D echocardiography only provides
variation of myocardial ultrasound integrated back- partial information about cardiac function. Although
scatter and its phase delay with respect to the onset multiple studies have validated the superiority of 3D
of the cardiac cycle can be quanti∼ed via de∼ning over 2Dechocardiography to assess LV function, 3D
alteration in Doppler acoustics.In 54 diabetic patients methods have not been embraced in clinical prac-
with normal ventricular systolic function, the cyclic tice because of the cumbersome methodology used
variation of backscatter in the septum and posterior until recently for data acquisition and analysis. In
wall of the left ventricle was signi∼cantly reduced and contrast with 2D echocardiography, 3D echocardi-
was related to the presence of neuropathy, retinopa- ography does not rely on geometric assumptions
thy and nephropathy. This technique has evolved in to calculate LV volumes. This constitutes a real ad-
22
the form of video-densitometry which uses Doppler vantage in ventricles with odd shapes, wall motion
echocardiography to digitize images of the septum abnormalities and in patients with cardiomyopathy.

GCDC 2017