Named the condition under which heart medications become dangerous

Scientists reveal dangerous connection between sodium levels and heart medications

American researchers from Virginia have discovered a critically important relationship between blood sodium levels and the action of medications for heart rhythm control. A new study published in the authoritative journal Heart Rhythm has shown why even a slight decrease in sodium can pose a serious threat to patients taking medications such as flecainide.

During experiments on guinea pig hearts, which are physiologically similar to human hearts, scientists found that when taking sodium channel blockers, the heart muscle becomes particularly sensitive to low sodium concentrations. Such a situation can arise in various conditions: from vomiting and diarrhea to taking diuretics, and is also often observed in hospitalized and elderly patients.

"Doctors have long known that sodium channel blockers slow conductivity, and low sodium is a risk. But now we've shown why their combination is particularly dangerous," explained the study's lead author Steven Poelzing from the Fralin Institute at Virginia Tech.

The study revealed the mechanism of the problem: when sodium channels are partially blocked, the heart tries to conduct electrical signals through alternative pathways. One such mechanism is the interaction between cells through narrow intercellular spaces. Another is the outflow of potassium ions, responsible for restoring electrical potential. However, when sodium levels decrease, both of these bypass routes work less effectively, leading to a delay in the passage of electrical signals through the heart.

An important discovery was that affecting these bypass pathways can reduce the heart's sensitivity to low sodium levels, which opens prospects for developing new treatment methods.

Although the study results do not mean that all patients taking antiarrhythmic drugs need to urgently check their sodium levels, doctors should pay special attention to electrolyte balance when prescribing such medications, especially in patients from risk groups.

"Sometimes a simple test and a conversation with a doctor can prevent a serious problem," Poelzing emphasized.