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Histopathological analysis of surgically resected myocardium in patients with sustained ventricular tachycardia
C Yutani1, M Imakita, H Ishibashi-Ueda
1Division of Pathology, National Cardiovascular Center, Suita, Osaka, Japan.
Insights
Histopathological analysis reveals that abnormal, hydropic cardiac fibers within fibrous and adipose tissue form reentrant pathways. These pathways are crucial in causing ventricular tachycardia (VT) in various heart conditions.
Area of Science:
- Cardiology
- Pathology
- Electrophysiology
Background:
- Surgical resection of endocardial and subendocardial tissue can resolve sustained ventricular tachycardia (VT).
- This intervention is presumed to interrupt reentrant pathways responsible for VT.
- Understanding the histological basis of these pathways is critical for treating VT.
Purpose of the Study:
- To define the morphologic characteristics of histologic components within the reentrant pathway.
- To correlate histological findings with the underlying causes of ventricular tachycardia.
Main Methods:
- Histopathological analysis of surgically resected endocardial and subendocardial specimens from 17 patients.
- Examination of tissue from patients with old myocardial infarct (OMI), arrhythmogenic right ventricular dysplasia (ARVD), and idiopathic VT.
Main Results:
- Bundles of viable, hydropic myocardial fibers were found embedded in dense fibrous and adipose tissue in all OMI, ARVD, and idiopathic VT cases.
- In idiopathic VT cases, resected areas predominantly consisted of ventricular muscle resembling Purkinje fibers.
- Abnormal muscle cells exhibited loss of contractile elements, hydropic cytoplasm, and an elliptical shape.
Conclusions:
- Abnormal cardiac fiber structure and arrangement following injury contribute to transmembrane potential abnormalities.
- These abnormalities facilitate the formation of micro-reentrant circuits, leading to ventricular tachycardia.
- Histopathological identification of these abnormal fibers aids in understanding VT mechanisms.
Abstract:
Surgical resection of the endocardium and subendocardium often abolishes sustained ventricular tachycardia (VT) in patients with old myocarcial infarct (OMI), unknown myocardial disease, and arrhythmogenic right ventricular dysplasia (ARVD), presumably by interrupting the reentrant pathway. In order to define the morphologic characteristics of histologic components in the reentrant pathway, we carried out histopathological analysis of surgically resected specimens from 17 patients who underwent this procedure. Bundles of apparently viable and hydropic myocardial fibers embedded in dense fibrous and adipose tissues were identified throughout the specimens obtained from OMI, ARVD and idiopathic VT cases. In 3 patients with idiopathic VT, most of the resected areas were composed of ventricular muscle, the components of which appeared histologically similar to Purkinje fibres. In all patients, the abnormal muscle cells were characterized by a loss of contractile elements, hydropic cytoplasm and an elliptic shape. Such an abnormal structure and arrangement of surviving cardiac fibers following tissue injury might play an important role in creating abnormalities of transmembrane potential, leading to the micro-reentrant circuits that give rise to ventricular tachycardias.