Obesity, heart blood-pumping ability linked in early Cushing’s disease
Study reports changes in blood flow tied to obesity start in early stages
Changes in blood flow linked to obesity start in the early stages of Cushing’s disease, as evidenced by a significant decrease in the blood-pumping ability of the heart, a new study reported.
While obese patients appeared to have normal heart function in standard echocardiographic examinations, a noninvasive method called ICG, short for impedance cardiography, was able to detect early changes in these patients’ heart function, as compared with non-obese patients.
“The results of our study support the usefulness of ICG in diagnosing early heart dysfunction associated with obesity in patients with [Cushing’s disease],” the researchers wrote.
The study, “Obesity-Related Hemodynamic Alterations in Patients with Cushing’s Disease,” was published in the Journal of Clinical Medicine.
Investigating the links between obesity, the heart, and blood flow
Cushing’s disease is one of the most common forms of Cushing’s syndrome, a broader umbrella term that encompasses conditions driven by high levels of the hormone cortisol. It is caused by a tumor in the brain’s pituitary gland.
The disease can cause a wide range of symptoms, including high blood pressure, obesity, impaired regulation of blood sugar, and abnormally high levels of fatty molecules in the blood.
Moreover, greater than normal accumulations of visceral adipose tissue — the fatty tissue that lines internal organs — are a common feature of Cushing’s. Such accumulations increase the risk of cardiovascular diseases, and possibly of disturbances in hemodynamics, or blood flow.
According to the researchers, “more studies are needed to enhance our understanding of the pathophysiology [disease mechanisms] of [Cushing’s disease]-related obesity as a modifiable cardiovascular risk factor.”
Now, a team of researchers in Poland sought to evaluate the relationship between obesity and hemodynamics. To that end, the team conducted a clinical study involving 54 people newly diagnosed with Cushing’s disease.
The participants were admitted to the neurosurgery department of an institute in Warsaw to complete a series of cardiovascular examinations before undergoing pituitary tumor removal surgery — a common procedure in Cushing’s — between 2016 and 2021.
About 40% of the patients were determined to be obese, with a body mass index or BMI equal to or higher than 30 kg/m2. BMI, a ratio of body weight and height, is used as a measure of body fat.
Among the patients, a little more than one-third (37%) had type 2 diabetes, while just less than 10% had prediabetes — higher than normal blood sugar levels, but not high enough for the individual to be considered to have diabetes.
Impairment in heart’s pumping function may be earliest sign of abnormalities
Echocardiography was used to evaluate patients’ heart structure and function, while cardiovascular hemodynamics were assessed using ICG. That method measures several heart-related blood flow parameters, such as the amount of blood pumped by the heart, and blood flow velocity.
Obese patients with Cushing’s disease had significantly larger heart chambers, including the left ventricle, compared with those who had Cushing’s but were not obese. Patients with both conditions also had a higher left ventricular mass index (103.5 vs. 89.7 g/m2); that ratio takes into account the mass of the left ventricle and the body’s surface area.
Despite these structural alterations, there were no differences in the function of the left ventricle. That’s the lower left chamber of the heart that pumps blood through the aorta to be distributed to the entire body.
Regarding hemodynamics, obese patients exhibited significantly lower values in parameters, including velocity and blood flow acceleration, that related to the heart’s pumping function.
Conversely, they had a higher systolic time ratio (0.41% vs. 0.35%). This ratio, which can be used as an indicator of the strength and efficiency of the heart, takes into account the time it takes for a specific heart valve to open and close.
“Asymptomatic impairment of the heart’s pumping function seems to be the earliest clinical sign of cardiovascular hemodynamic abnormalities, which at this stage are still undetectable with standard echocardiography,” the researchers wrote.
The patients’ BMI measures also were found to be significantly correlated with several hemodynamic parameters. These included the velocity index, the cardiac index, or the amount of blood pumped by the heart per minute indexed to the body surface, and the stroke index, which is the amount of blood ejected from the heart per heartbeat indexed to a person’s body surface.
According to researchers, “individual hemodynamic profile assessment with novel noninvasive diagnostic methods encourages further studies on cardiovascular system function in obese individuals with [Cushing’s disease] and on the use of personalized therapies, which aim at preventing adverse cardiovascular events.”
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