# A Comprehensive Review of Canine and Feline Ventricular Septal Defects—From Pathogenesis to Long-Term Follow-Up

## TL;DR

This paper reviews ventricular septal defects in dogs and cats, covering their causes, diagnosis, and management, and highlights the importance of accurate assessment for treatment decisions.

## Contribution

The paper provides a comprehensive overview of VSDs in companion animals, emphasizing updated diagnostic techniques and management strategies.

## Key findings

- VSDs are common in dogs and cats, with varying clinical outcomes depending on defect size and location.
- Accurate diagnostic measurements like Qp:Qs and VSD:Ao ratios are crucial for determining prognosis and management.
- Emerging technologies like 3D echocardiography improve diagnostic accuracy for VSDs.

## Abstract

Ventricular septal defect (VSD) is a congenital heart disease characterized by an abnormal connection between the left and right ventricles. In dogs, it is the fourth most common congenital heart defect, while in cats it is reported most commonly. Depending on the size of the defect and its hemodynamic significance, it can remain asymptomatic throughout the animal’s life, or lead to significant cardiac remodeling and failure. The key aspect in the management of this type of defect is the constant cardiac monitoring of the patient, pharmacotherapy, and, as a last resort, surgery. Most VSDs are associated with a very good prognosis for the future in both dogs and cats.

Congenital heart defects (CHDs) in dogs and cats represent a definite minority of cardiac patients. One of the most commonly diagnosed is ventricular septal defects (VSDs). These are associated with abnormal ventricular septation during the prenatal period; however, the mutations of the genes responsible for this phenomenon are not fully understood. VSDs pose a significant diagnostic challenge due to the multitude of locations in the ventricular septum where they are likely to occur. Therefore, there are many phenotypes of the defect causing many problems in terms of a common nomenclature. Among the various classifications, the latest terminology issued by The International Society for Nomenclature of Paediatric and Congenital Heart Disease (ISNPCHD) considers both electrical conduction pathways and adjacent structures to standardize nomenclature. Further, defects located at different sites can alter both prognosis and subsequent management for the patient; thus, taking accurate measurements is crucial. Among these, the Qp:Qs and VSD:Ao ratios, the direction of blood flow through the defect, its location, the diameter and maximum flow velocity, and the pressure difference between the RV and LV are indicated. Emerging technologies such as 3D echocardiography and cardiac magnetic resonance may provide additional diagnostic value. Altogether, along with clinical symptoms, we should determine further management, involving the monitoring of the patient, the implementation of pharmacological treatment, or referral for surgical closure of the VSD. This review summarizes current knowledge on VSD, where the pathogenesis of the condition, diagnosis, and management, including conventional and surgical methods as well as long-term follow-up, are described, providing a complete overview of the issue.