Scholars@Duke
Madison Stockton Spach

Madison Stockton Spach

James B. Duke Distinguished Professor Emeritus of Medicine
Pediatrics, Cardiology
cspach@duke.edu
Box 3475 Med Ctr, Durham, NC 27710
108 Research Park Bldg. 4, Durham, NC 27710

Overview

The aims of the research are to: 1) establish an experimental basis for cardiac propagation at a cellular level; 2) develop a quantitative representation (model) of microscopic multidimensional propagation based on natural differences in cell geometry and the distribution of the cellular connections; and, 3) explore the sensitivity of the major determinants of conduction (e.g., sodium current, maximum dV/dt) and macroscopic conduction events to variations in cellular geometry and the topology of the side-to-side connections between cells. The most common cause of tachyarrhythmias in patients is some form of reentry. Our results indicate that changes in the distribution of the gap junctions, previously considered of minor importance, create new microscopic structural mechanisms that cause reentry. Consequently, the research is designed to
study the interrelationships between cell-to-cell current flow, ionic current flow through cell membranes, the extracellular potential field, and propagation phenomena. Experimentally, transmembrane potentials and extracellular potentials are measured with high temporal and spatial resolution at a microscopic level. The effects of normal and altered initial conditions of the ion
channel currents are being evaluated, and multidimensional cellular models of propagation are being developed. Such models are essential since they provide the linear passive properties at a cellular level that are necessary to link the ion channel currents to the macroscopic propagation events. The major focus is on exploring the sensitivity of macroscopic propagation events to changes in cell geometry and the loss of side-to-side electrical connections between fibers that
occur during development and aging.

Current Appointments & Affiliations

James B. Duke Distinguished Professor Emeritus of Medicine · 1996 - Present Pediatrics, Cardiology, Pediatrics
Professor Emeritus of Pediatrics · 1996 - Present Pediatrics, Cardiology, Pediatrics

Recent Publications

Mechanism of origin of conduction disturbances in aging human atrial bundles: experimental and model study.

Journal Article Heart Rhythm · February 2007 BACKGROUND: Aging is associated with a significant increase in atrial tachyarrhythmias, especially atrial fibrillation. A macroscopic repolarization gradient created artificially by a stimulus at one site before a premature stimulus from a second site is w ... Full text Link to item Cite

Cell size and communication: role in structural and electrical development and remodeling of the heart.

Journal Article Heart Rhythm · October 2004 With the advent of new information about alterations of cardiac gap junctions in disease conditions associated with arrhythmias, there have been major advances in the genetic and metabolic manipulation of gap junctions. In contrast, in naturally occurring ... Full text Link to item Cite

Changes in anisotropic conduction caused by remodeling cell size and the cellular distribution of gap junctions and Na(+) channels.

Journal Article J Electrocardiol · 2001 Because gene therapy presents a new frontier in the treatment of arrhythmias, it has become important to know how manipulation of the cellular distribution of proteins changes electrical events within individual cells, and whether these cellular changes af ... Full text Link to item Cite
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Recent Grants

Microscopic Discontinuities as a Basis for Arrhythmias

ResearchPrincipal Investigator · Awarded by National Institutes of Health · 2000 - 2006

Microscopic Discontinuities As A Basis For Arrhythmias

ResearchPrincipal Investigator · Awarded by National Institutes of Health · 1993 - 2000

Training of Cardiovascular Biomedical Engineers

Inst. Training Prgm or CMECo-Principal Investigator · Awarded by National Institutes of Health · 1991 - 1996

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Education, Training & Certifications

Duke University · 1954 M.D.