Understanding vasovagal syncope: a role for sex and gender

Prevalence and factors associated with vasovagal reaction among whole blood donors in hospital Universiti Sains Malaysia

Adverse donor reactions (ADR) are common to occur during the blood donation process. The most common is vasovagal reactions (VVR) and it cause negative impact in the donor return rate. The aim of this study is to determine the prevalence of VVR among blood donors and to study its associated factors, at Hospital University Sains Malaysia (USM). This retrospective case-control study was conducted from June 2018, until June 2021. Data was extracted from the blood bank database system and from donor adverse reaction form. Donors who developed adverse donor reactions were chosen and without VVR were chosen at random as controls. A total of 159 donors, out of 35 134 donors were reported to have VVR which resulted in an overall prevalence of 0.45 %. Dizziness or mild VVR were the most frequently observed adverse reactions, accounting for approximately 87/159 (54.7 %) of all adverse reactions. Multiple logistic regression (MLR) analysis showed VVR were significantly associated with age, female gender, first-time donor, and 450 ml volume of blood collected. The prevalence of vasovagal reactions among blood donors in this study was low which was similar to a few previous studies. Although it was low, still it is very important to reduce risks to a minimum so that the donor return rate could be maintained. The information regarding its associated factors can be used to identify high-risk donors to prevent the incidence in the future.

Posture-Related Differences in Cardiovascular Function Between Young Men and Women: Study of Noninvasive Hemodynamics in Rural Malawi

Background

Cardiovascular risk is higher in men than in women, but little information exists about sex‐related differences in cardiovascular function from low‐income countries. We compared hemodynamics between sexes in rural Malawi in a cohort followed up since their birth.

Methods and Results

Supine, seated, and standing hemodynamics were recorded from 251 women and 168 men (mean age, 21 years; body mass index, 21 kg/m²) using oscillometric brachial waveform analyses (Mobil‐O‐Graph). The results were adjusted for estimated glomerular filtration rate, and plasma potassium, lipids, and glucose. Men had higher brachial and aortic systolic blood pressure and stroke index regardless of posture (P<0.001), and higher upright but similar supine diastolic blood pressure than women. Regardless of posture, heart rate was lower in men (P<0.001), whereas cardiac index did not differ between sexes. Women presented with lower supine and standing systemic vascular resistance index (P<0.001), whereas supine‐to‐standing increase in vascular resistance (P=0.012) and decrease in cardiac index (P=0.010) were higher in women. Supine left cardiac work index was similar in both sexes, whereas standing and seated left cardiac work index was higher in men than in women (P<0.001).

Conclusions

In young Malawian adults, men had higher systolic blood pressure, systemic vascular resistance, and upright cardiac workload, whereas women presented with higher posture‐related changes in systemic vascular resistance and cardiac output. These findings show systematic sex‐related differences in cardiovascular function in a cohort from a low‐income country with high exposure to prenatal and postnatal malnutrition and infectious diseases.