Patients
In this study, 14 patients (9 male,
5 female,
mean age 69±7.3years) with severe aortic stenosis and RV ejection fraction (EF) <49% submitted to AVR (11 patients SAVR,
1 patient SAVR + CABG,
2 patients TAVI) were included.
Risk factors,
patient characteristics and comorbidity are summarized in Table 1 .
SAVR - Surgical Aortic Valve Replacement
TAVI - Transcatheter Aortic Valve Implantation
CABG - Coronary Artery Bypass Grafting
Patient preparation
Before the exam all patients fulfilled a safety questionnaire to check for any contraindication for MRI and gave written informed consent to participate.
24 hours prior to the exam the patients couldn't smoke,
drink tea,
coffee or caffeine drinks; should remove any nicotine patches and stop medication (beta blockers,
calcium blockers and nitrates).
Image acquisition
All patients underwent an CMR exam before (baseline) and 6 months after AVR.
Images were acquired in a 1.5 T scanner (Siemens Symphony,
Erlangen,
Germany) equipped with Quantum gradients: Max amplitude = 20mT/m; Slew rate = 125 T/m/s and Rise time = 240 μs.
A phased array - 6 channel body coil and a CP spine array were used in the study.
The CMR protocol include multi-planar,
multi-slice ECG triggered DB SS-FSE (DB HASTE),
first pass stress perfusion and rest perfusion imaging (SR Turbo GRE - TurboFLASH),
cine ECG gated multi-phase balanced Steady State Free Precession b-SSFP (TrueFISP),
and late gadolinium enhancement (2D-segmented IR GRE),
according to the timeline presented in Fig. 1 .
During adenosine perfusion and before acquiring first pass stress perfusion it’s important to check Blood Pressure (BP) and monitor ECG to see if there is hemodynamic response.
Adenosine dose is 140 μg/kg/min (consider 170 or 210 μg/kg/min,
if hemodynamic response is inadequate).
A bolus of 0.1 mmol/kg of Gadobutrol (Gadovist,
Bayer,
Germany) is injected at a 4ml/s rate using a power injector during first pass stress perfusion,
and another bolus for rest perfusion.
Image analysis
We evaluated CMR images performed prior to (baseline) and 6 months after AVR using commercially available Circle Cardiovascular Imaging 42 software (CVI-42).
Global RV function is achieved by drawing RV extension from long axis 4ch cine at end-diastolic and end-systolic phase (see Fig. 2 ).
End-diastolic (RVEDV) and end-systolic (RVESV) endocardium contours are drawn from the short axis cine images (see Fig. 3 ).
After that,
the software provides RV ejection fraction (RVEF),
RV Cardiac Output (RVCO) and RV Stroke volumes (RVSV).
Statistical analysis
Statistical analysis was conducted using SPSS.
Variation of the RV mass and ventricular volumes were obtained through the difference between baseline and 6 months after AVR.
Normality tests (Shapiro-Wilk) were conducted and paired samples T Test was used with CI = 95%.