Evaluating the effects of insulin resistance and hypertension in obese children on cardiac functions using echocardiography

Abstract

Objective: The purpose of this research was aimed to evaluate the cardiac functions of obese children by echocardiography and in addition to find out the affects of insulin resistance and/or hypertension on cardiac functions. 

Material and Method: The Obese group included 52 children in this study (32 boys and 20 girls) with ages ranged between 4-19 years old (mean 11.6±3.7 years) and BMI ≥ 95 percentiles. Children with appropriate for age (4-19 years, mean 11.0±4.1 years), sex (25 boys and 19 girls), and with normal BMI were selected as control group. Serum fasting glucose, thyroid functions, lipid profile, insulin and cortisole levels were measured in the obese group. The patients were also divided into 4 subgroups according to existing of hypertension and/or insulin resistance, and they were also compared between each other. Echocardiographic measurements of both groups were made by using M-mode, 2-D and PW Doppler techniques and MPI values of the left and the right ventricles were calculated. The student’s t test was used to compare the main groups, and analysis of variance (One Way ANNOVA) was used to compare the obese subgroups between each other and with the controls. Post hoc testing was also applied by using the Sidak multiple comparisons test. Probability values of p <0.05 in all tests were considered significant.

Results: The mean BMI value of obese children was 29.37±5.08 kg/m2 whereas mean BMI of controls was 26.66±7.84 kg/m2 (p<0.05). The mean SBP (115.9±13.2 mmHg) and also the mean DBP (70.6±10.1 mmHg) values of the obese group were significantly higher from the control group values (respectively 110.8±8.8 and 65.7±7.8 mmHg). LVDd, IVSd, LVM, LVM/height^2.7, SV, IVRT, EF and FS values of the obese group were significantly higher than the values of control group. It was revealed that these parameters were higher in the subgroup with IR alone and the subgroup with HT&IR, when compared to the control group. There was no significant difference between the values of E, A, and E/A of the control and the obese groups On the other hand, both IVRT and MPI values of right and left ventricle were significantly higher in children with obesity than controls. No differences of MPI values of the left ventricle were noted between obese subgroups. Finally, it was found out that the significant difference between obese and control groups for the MPI values of right ventricle was originated from obese subgroups with IR alone and with HT&IR.

Conclusion: HT and/or IR accompanying to obesity could worsen the present cardiac dysfunction. We suggest that the measurement of MPI and IVRT values in children with obesity, as it used in many other diseases, can reveal the cardiac dysfunction at the early stages, and should be considered as a useful and valuable parameters.

Keywords

• Child, Echocardiography; Hypertension; Insulin resistance; Myocardial Performance Index; Obesity

Obez Çocuklardaki Hipertansiyon ve İnsülin Direncinin Kardiyak İşlev Bozukluğuna Etkisinin Ekokardiyografi İle Değerlendirilmesi

Öz

Amaç: Bu çalışmada obez çocukların kardiyak işlevlerinin ekokardiyografi ile değerlendirilmesi, ayrıca bulunan sonuçlara insülin direnci ve hipertansiyonun ne şekilde etki ettiğinin araştırılması amaçlanmıştır.

Gereç ve Yöntem: Yaşları 4–19 arasında değişen (ortalama 11,6±3,70 yıl) ve VKİ 95 persantil ve üzerindeki 52 çocuk (Erkek:32, Kız:20) çalışmaya dahil edildi. VKİ normal sınırlarda olan, yaş (4-19, ortalama 11,0±4,1 yıl) ve cinsiyeti (Erkek:25, Kız:19) uyumlu 44 sağlıklı çocuk kontrol grubunu oluşturdu. Obezlerde açlık kan şekeri, tiroit hormonları, lipit profili, insülin ve kortizol düzeyleri ölçüldü. Obez hastalar ayrıca hipertansiyon ve/veya insülin direnci olup olmamasına göre 4 alt gruba da ayrılarak kıyaslandı. Hasta ve kontrol grubunun hem sağ hem de sol ventrikülün M mod, iki boyutlu ve Doppler ekokardiyografi ölçümleri yapıldı. Sağ ve sol ventrikülün MPİ değerleri hesaplandı. Grupların karşılaştırılmasında bağımsız örneklem t-testi, Tek Yönlü Varyans Analizi Testi (One-Way ANOVA) kullanıldı, Post Hoc testinde Sidak yöntemi kullanıldı, p<0.05 anlamlı olarak kabul edildi.

Bulgular: Obez çocukların VKİ ortalaması 29,37±5,08 kg/m2 kontrol grubunun VKİ ortalaması ise 26,66±7,84 kg/m2 bulundu (p<0.05). Obez çocukların hem SKB ortalaması (115,9±13,2 mmHg) hem de DKB ortalaması (70,6±10,1 mmHg) kontrol grubunun ortalamalarından (sırasıyla 110,8±8,8 ve 65,7±7,8 mmHg) anlamlı olarak yüksek idi. Obez grubun SVDSÇ, IVSd, SVK, SVK/boy^2.7, SV, IVGZ, EF ve KF değerleri kontrol grubunkinden anlamlı olarak yüksek bulundu. Kontrol grubu ile alt gruplar kıyaslandığında bu istatistiksel farklılığın tek başına İR ve hem İR hem de HT’nun birlikte olduğu obez alt gruplarda daha belirgin olduğu saptandı. Kontrol grubuyla obez çocuk grubunun hem sağ ventrikül ve hem de sol ventrikülün erken ve geç dolum hızları, E/A oranları arasında istatiksel anlamlı farklılık saptanmadı. Buna karşın hem sol ventrikülün hem de sağ ventrikülün İVGZ ve MPİ değerleri obezlerde kontrole göre anlamlı olarak artmıştı. Sol ventrikülün MPİ değeri obez alt grupları arasında farklılık göstermez iken, sağ ventrikül MPİ değerinin kontrollere göre asıl anlamlı farklılığının ise tek başına İR olan ve hem İR hem de HT olan iki obez alt gruptan kaynaklandığını saptadık.

Sonuç: Obezite ile İR ve/veya HT birlikteliği kardiyak işlev bozukluğunu belirginleştirebilir. MPİ ve İVGZ değerlerinin, diğer birçok hastalıklarda olduğu gibi obezitede de ve henüz hastalığın asemptomatik evresinde kalp işlev bozukluğunu göstermede kullanışlı ve değerli parametreler olduğu kanısındayız.

Anahtar Kelimeler

• Çocuk; Ekokardiyografi; Hipertansiyon; İnsülin Direnci; Miyokardiyal Performans İndeksi; Obezite

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