# Severe Sinus Dysfunction in the Context of Chronic Lithium Intoxication and Poorly Controlled Hypothyroidism

## TL;DR

A patient with severe heart rhythm issues due to lithium poisoning and untreated hypothyroidism made a full recovery after intensive care and kidney treatment.

## Contribution

This case highlights a rare but severe cardiac manifestation of chronic lithium intoxication and poorly controlled hypothyroidism.

## Key findings

- The patient exhibited extreme sinus bradycardia and sinus pauses without ischemic changes.
- Elevated lithium and TSH levels were found alongside acute kidney injury.
- Supportive care and renal replacement therapy led to full recovery without long-term cardiac devices.

## Abstract

Cardiotoxicity associated with lithium is not a common event; however, it is potentially life-threatening, manifesting electrocardiographically with sinoatrial blocks, high-degree atrioventricular blocks, QT prolongation, and ventricular tachyarrhythmias. This case report presents a patient with severe sinus dysfunction in a clinically severe presentation secondary to cardiogenic shock. The patient sought medical attention for a one-week history of non-anginal chest pain, dizziness without syncope, generalized weakness, and somnolence progressing to bedridden status in the days preceding hospital admission. Laboratory findings revealed elevated blood levels of lithium and thyroid-stimulating hormone (TSH), along with concomitant Acute Kidney Injury Network (AKIN) II acute kidney injury. Subsequently, the patient was admitted to the intensive care unit, where persistent extreme sinus bradycardia of 30 bpm (beats per minute) with sinus pauses without ischemic changes was observed. The patient received supportive treatment, including renal replacement therapy, resulting in complete recovery of hemodynamic status without the need for long-term cardiac conduction devices.