Myocardial Contrast Echocardiography in Septic Patients
Myocardial Contrast Echocardiography in Septic Patients
Myocardial microcirculatory alterations may be involved in the pathogenesis of acute cardiac
 dysfunction or septic cardiomyopathy in septic patients. The investigators study the cardiac
 function (systolic and diastolic) with two-dimensional echocardiography (TTE), and the
 myocardial microcirculation with contrast echocardiography (MCE) and sulphur hexafluoride
 microbubbles Sonovue injection in ICU septic patients.
Using the IE33 device (Philips Medical Systems, the Netherlands), two-dimensional and
 myocardial contrast echocardiography (TTE and MCE) are performed following the
 recommendations of the American Heart Association and the European Society of Cardiology
 (2006), and the European Association of Cardiovascular Imaging (2017). TTE and MCE are
 performed at the same time in the first 24 hours after ICU admission, at 48-72 hours, at 5-10
 days after withdrawal of vasopressors and inotropes.

 First, TTE evaluates from the apical and parasternal views:

 -  The Wall motion score index (WMSI) of 16 myocardial segments of the left ventricle (LV).

 -  The diastolic function using pulsed-wave doppler and pulsed tissue doppler at the mitral
 valve.

 -  Quantify valvular insufficiency

 -  Estimation of cardiac output (L/ minute).

 -  Evaluation of the right ventricle (RV) dimension and its the longitudinal contractility
 by the Tricuspid annular plane systolic excursion (TAPSE) with pulsed tissue doppler.

 -  Left atrial volume (ml).

 -  Systolic pulmonary pressure and pulmonary resistance with both continuous and
 pulsed-wave doppler at the tricuspid valve and the pulmonary outflow tract,
 respectively.

 Second, MCE is performed if:

 -  Systolic blood pressure < 200 mmHg or > 90 mmHg,

 -  Heart rate < 130 or > 50 beats/minute

 -  Peripheral pulse oxygen saturation > 90%

 -  Arterial oxygen partial pressure (PaO2) ≥ 70 mmHg

 -  Arterial pH ≥ 7.25.

 Administration of contrast agent Sonovue requires an infusion pump (Vueject, Bracco, Milan,
 Italy), which provides constant agitation to maintain the homogeneity distribution of
 Sonovue. Injection of Sonovue allows an enhancement of LV endocardial border and regional
 function to evaluate:

 -  LV end-diastolic and end-systolic volumes (ml) and ejection fraction (%) using the
 Simpson method.

 -  The WMSI of the left ventricle (LV) after Sonovue injection.

 After optimization of transthoracic cardiac views, the mechanical index will settle between
 0.1-0.2 and keeps unchanged during the procedure. Sonovue vial of 5 ml will dilute in in 10
 ml saline solution and administrate at 0.7-1.5 ml/min. Using acquire flash-replenishment
 sequences during15 cardiac cycles of the apical 4-2-3 chamber views with the flash delivered
 after the second cardiac cycle. This technique destroys the microbubbles presents in the
 myocardium and allows replenishment with new microbubbles concentrations.

 The volume of blood within the entire coronary circulation at rest in diastole is
 predominantly resided within the capillaries. The myocardial signal intensity emanating from
 the contrast agent reflects the concentration of microbubbles within the myocardium. It takes
 5 seconds for complete replenishment of the myocardium. Any decrease in myocardial blood flow
 prolongs replenishment time in proportion to its reduction.

 Immediately after microbubble infusion is started, all real-time MCE procedures are recorded
 for one minute and stored as DICOM (Digital Image Communications in Medicine) images. Offline
 analysis uses a specific quantification software named QLAB10 (Philips Medical Systems, the
 Netherlands) to convert myocardial perfusion images into time-intensity curves (TIC)
 corresponding to different regions of interest (ROI) of the 16 myocardial segments.

 Four variables are analyzed from these TIC curves to evaluate qualitatively the myocardial
 microcirculation:

 -  peak intensity (PI) in decibel (dB).

 -  time to peak intensity in seconds (TTP).

 -  mean transit time in seconds (MTT).

 -  Area under the curve in dB/seconds (AUC).

 The cardiac biomarkers including High sensivity cardiac troponin I for myocardial injury and
 N-terminal pro-brain natriuretic peptide (NT-proBNP) for heart failure are measured once
 daily in routine clinical practice.
Inclusion Criteria:

 -  Sepsis: a life-threatening organ dysfunction (defined as an acute change in total
 Sequential Organ Failure Assessment (SOFA) score > 2 points consequent to infection)
 caused by a dysregulated host response to infection.

 -  Sepsis shock : a subset of sepsis with persisting hypotension requiring vasopressors
 to maintain the mean arterial pressure > 65 mmHg and having a serum lactate level > 2
 mmol/L after fluid resuscitation.

 Exclusion Criteria:

 -  Non-survivors in the first 24 hours from sepsis

 -  Sepsis post-acute cardiac arrest

 -  Pregnancy

 -  Younger than 18 years old

 -  Acute Respiratory Distress Syndrome (ARDS) with the ratio of arterial oxygen partial
 pressure (mmHg) to fractional inspired oxygen (PaO2/ FiO2) < 200)

 -  Advanced malignancy

 -  Untreated and unstable acute coronary syndrome

 -  History of myocardial infarction with severe left ventricular dysfunction. (Ejection
 fraction < 20 %).

 -  Inoperable valvular and coronary disease

 -  Significant right-left cardiac shunt

 -  Untreated congenital heart disease

 -  Severe systolic pulmonary hypertension > 80 mmHg

 -  Insufficient echogenicity

 -  Prior anaphylaxis reaction to the Sonovue microbubbles