| Background and ObjectiveHypertrophic cardiomyopathy(HCM) is an idiopathic or unexplained disease characterized by asymmetry myocardial hypertrophy, the interventricular septum is the most involved site, which can lead to the impairement of the left ventricular filling and the decrease of left ventricular diastolic compliance. HCM is now the most common inherited cardiovascular disease. According to epidemiological data statistics, the incidence of HCM is at least 1 in 500 in the general population, it is also the most common cause of sudden cardiac death(SCD) in young people.In the progression of HCM, the left ventricular systolic function is normal in the majority of patients, but the most common or important pathophysiologic change is diastolic dysfunction of left ventricular which can result in the emergence of symptoms of heart failure and influence the quality of life in these patients. The left ventricular diastolic dysfunction is also the important risk factor leads to many adverse cardiovascular events such as malignant arrhythmia, severe heart failure or sudden death. Therefore, compared with evaluating the left ventricular systolic function, accurately evaluate the diastolic function of HCM may be more important.Undoubtedly, ultrasound is now still the most common method to evaluate the cardiac structure and function, but with the limitation of lower spatial resolution and narrow acoustic window, it is hard to precisely diagnose structure and function of heart in HCM. Recently, as the innovation of magnetic resonance imaging technology and equipment, CMR has played a primary role in the clinical management of patients with cardiovascular disease. With the unique advantages of high spatial and temporal resolution, high reproducibility and without ionizing radiation, CMR is also considered to be the gold standard for the assessment of structure and function of cardiac.In addition, CMR also can easily identify and detect myocardial late gadalinum enhancement(LGE) that is representative of myocardial fibrosis and the apical aneurysms which are associated with poor outcome. So, this study will investigate the clinical value of CMR in HCM, especially in evaluating the left ventricular diastolic function and detecting the myocardial fibrosis and apical aneurysms.Methods1. Twenty six HCM patients(15 males and 11 females, mean age 43.54 years) and twenty eight healthy volunteers(18 males and 10 females, mean age 41.52 years) were enrolled from October 2013 to August 2014 in the first affiliated Hospital of Third Military Medical University. Scan all of the people with Siemens Magnetom Trio A Tim 3.0T MRI to gain the cardiac structure and function data and compare the differences of these CMR data between the two groups.2. To analyze the relativity between left ventricular mass(LVM) and left ventricular peak filling rate(LVPFR), the left atrial diameter which includes left atrial transverse diameter(LATD), left atrial superoinferior diameter(LASID), left atrial anteroposterior diameter(LAAPD) in the HCM group.3. To analyze the feature of myocardial LGE and the incidence of apical aneurysms in HCM, and compare the differences between the two groups.Results1. The mean LVM(190.16±57.38) g, IVS(26.96±5.40) mm, LAAPD(49.05±12.43) mm, LASID(56.13±9.87) mm, LATD(60.12±12.40) mm in HCM group are higher than healthy volunteers group, mean LVPFR(3.29±0.94) EDV/s is lower than healthy volunteers group significantly(all P < 0.05). The other left ventricular parameters include left ventricular ejection fraction(LVEF)(68.66 ± 8.16 vs. 66.14± 6.94) %, left ventricular peak ejection rate(LVPER)(4.23±0.97 vs. 4.39±1.19) EDV/s, stroke volume(SV)(76.10 ± 22.55 vs. 83.72±9.43) ml, cardiac output(CO)(5.18 ± 1.72 vs. 5.85±1.53) L/min, left ventricular end-systolic volume(LVESV)(35.09 ± 13.57 vs. 32.56±14.72) ml, left ventricular end-diastolic volume(LVEDV)(113.08 ± 28.72 vs. 119.14±20.87) ml, left ventricular transverse diameter(LVTD)(40.54±6.84 vs. 43.67±8.39) mm, left ventricular transverse diameter(LVLD)(77.75±18.68 vs. 74.48±16.34) mm and left ventricular end-diastolic anteroposterior diameter(LVEDAPD)(80.37±7.40 vs. 84.17±6.38) mm showed no obvious difference between this two groups(all P>0.05).2. Correlation analysis showed that LVM has obviously inverse correlation with LVPFR(r=-0.509, P<0.05) and positive correlation with LATD(r= 0.466, P<0.05) and LAAPD(r= 0.493, P<0.05), but there was no correlation between LVM and LASID(r= 0.328, P>0.05) in HCM group.3. Myocardial enhancement scan, 20 out of 26 HCM patients had LGE which was very common in IVS, and most of them were patchy or linear enhancement. The ratio of LGE was about 77%.4. The incidence rate of apical aneurysms in HCM patients(6 out of 26 patients) was about 23% which was higher than healthy volunteers group with no one apical aneurysms(P<0.05).Conclusions1. In HCM patients group, most of the patients have normal left ventricular systolic function, but the diastolic function is obviously decreased. CMR plays a crucial role in precisely assessing the diastolic function of left ventricular in HCM patients.2. In HCM patients group, LVM obviously correlate to LVPFR and left atrial diameter, which of them can comprehensively evaluate the left ventricular diastolic function damage.3. CMR has the unique advantages in detecting myocardial fibrosis and apical aneurysms which are very common in HCM. |
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