Echocardiography
All patients underwent a screening echocardiographic examination within
6-72 h of CICU admission. Relevant data were collected from the clinical
echocardiographic exam reports. Echocardiography was performed by
Philips IE-33 equipped with S5-1 transducers (Philips Healthcare,
Andover, MA, USA), and GE Vivid 7 model equipped with M4S
transducer.
RV qualitative size and function assessment were based on multiple views
of the right ventricle (short-axis parasternal at basal, mid, and apical
levels; lower parasternal RV inflow view; apical four-chamber view and,
if possible, RV long-axis view; and subcostal short-axis and
four-chamber views). Using these multiple views, an integrative
qualitative grading was
formulated by the physician responsible for the echocardiographic study.
From four-chamber views encompassing the entire right ventricle,
end-systolic and end-diastolic RV areas and the tricuspid annulus were
measured. Apart from qualitative grading, RV function was evaluated by
tricuspid annular plane systolic excursion (TAPSE) 12.
TR severity was determined using an integrative, semiquantitative
approach as recommended by the American Society of Echocardiography13.
Regarding the gravity of tricuspid regurgitation, we first assessed the
severity of valve regurgitation by evaluating specific signs that would
point to either less than mild or severe regurgitation, including color
jet area (thin small central vs large >50% jet area), vena
contracta (VC) width (<0.2 cm or ≥7 mm), density of continuous
Doppler jet (faint or dense and triangular), hepatic vein flow pattern
(systolic dominant vs systolic reversal), trans tricuspid inflow pattern
(A-wave dominant or high-velocity E-wave dominant), annular diameter
(normal vs dilated annulus with lack of valve coaptation), and RV and
right atrial (RA) size (normal vs dilated). If all of the signs and
indices were concordant, we defined TR as less than mild or severe. If
the signs or values of the qualitative or semiquantitative parameters
were in the intermediate range between mild and severe, we defined TR as
at least moderate to severe if the majority (five or more) of the signs
and indices were concordant with severe TR13.
In patients with measurable tricuspid regurgitation jet on Doppler
echocardiography peak systolic pulmonary artery pressure (SPAP) was
estimated using the modified Bernoulli formula (4 × TRV2max) + RAP,
where TRVmax is the peak systolic tricuspid regurgitation velocity at
end expiration, and RAP is the right atrial pressure. Left ventricular
(LV) diameters and interventricular septal and posterior wall width were
measured from the parasternal short axis by means of a 2-dimensional (2D
or a 2D-guided M-mode echocardiogram of the LV at the papillary muscle
level using the parasternal short-axis view14. LV
ejection fraction was calculated by the Biplane method of disks
(modified Simpson’s rule). Early trans mitral flow velocity (E) was
measured in the apical 4-chamber view to provide an estimate of LV
diastolic function 15. Early diastolic mitral annular
velocity (e′) was measured using spectral tissue Doppler imaging in both
septal and lateral positions. The ratio of peak E to peak e′ was
calculated (E/e′ ratio) from the average of at least 3 cardiac cycles.
In patients with atrial fibrillation we have used the average measured
from 5-7 cardiac cycles. Left atrial volume was calculated using the
biplane area length method at end systole 16. Cardiac
output was calculated as the product of aortic stroke volume and heart
rate as demonstrated on pulse wave Doppler. Valvular regurgitation was
qualitatively assessed using color Doppler according to the guidelines
of the American Society of Echocardiography (normal/trivial = 1, mild =
2, moderate = 3,severe = 4) 17. Diastolic function was
assessed by integrating measurements of the mitral inflow, left atrial
volume, and Doppler tissue imaging of the mitral annulus using the
average annulus velocity, and classified into four categories: normal
diastolic function = 0, impaired relaxation = 1, pseudo-normal = 2 and
restrictive pattern = 3, based on recent guidelines15. Right atrial (RA) pressure was estimated by the
inferior vena cava diameter as well as its response to inspiration as
previously described 18. Briefly, expiratory and
inspiratory inferior vena cava (IVC) diameters and percent collapse were
measured in subcostal views within 2 cm of the right atrium. IVC
diameter <2.1 cm that collapsed >50% with a
sniff suggested a normal RA pressure (assigned as 5 mmHg), whereas an
IVC diameter >2.1 cm that collapsed <50% with a
sniff suggested a high RA pressure (15 mmHg). In patients with IVC
diameter <2.1 cm and no collapse (<20%) with a
sniff, RA pressure was upgraded to 20 mmHg. In indeterminate cases in
which the IVC diameter and collapse did not fit this paradigm, secondary
indices of elevated RA pressure were integrated. If uncertainty
remained, RA pressure was left as intermediate value of 10 mmHg.