Biomaterial Database

Effect of stimulation site on ventricular threshold in dogs with heart block. 1975

H C Hughes, and G F Tyers

Ventricular pacing thresholds were measured in barbiturate-anesthetized dogs with complete heart block using an oscilloscope and current probe. All electrode and physiologic variables were carefully controlled in order to compare the effects of stimulus duration and site of ventricular threshold energy requirements. Left ventricular intramyocardial stimulation, at all stimulus durations under 5 msec., required less current and energy, and at all stimulus durations under 2 msec. less voltage, than either right ventricular endocardial or right ventricular intramyocardial stimulation. Chronaxy and polarization losses were lowest and impedance highest with left ventricular intramyocardial stimulation. The two right ventricular sites were almost equivalent electrically. Earlier studies which reported lower thresholds with endocardial stimulation than with intramyocardial stimulation were biased in favor of the endocardial site by lack of control of electrode variables including: material, configuration, cross-sectional area, and epicardial versus intramyocardial location.

UI	MeSH Term	Description	Entries
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D009991	Oscillometry	The measurement of frequency or oscillation changes.	Oscillometries
D010138	Pacemaker, Artificial	A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).	Cardiac Pacemaker, Artificial,Artificial Cardiac Pacemaker,Artificial Cardiac Pacemakers,Artificial Pacemaker,Artificial Pacemakers,Cardiac Pacemakers, Artificial,Pacemaker, Artificial Cardiac,Pacemakers, Artificial,Pacemakers, Artificial Cardiac
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D004567	Electrodes, Implanted	Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.	Implantable Electrodes,Implantable Stimulation Electrodes,Implanted Electrodes,Implanted Stimulation Electrodes,Electrode, Implantable,Electrode, Implantable Stimulation,Electrode, Implanted,Electrode, Implanted Stimulation,Electrodes, Implantable,Electrodes, Implantable Stimulation,Electrodes, Implanted Stimulation,Implantable Electrode,Implantable Stimulation Electrode,Implanted Electrode,Implanted Stimulation Electrode,Stimulation Electrode, Implantable,Stimulation Electrode, Implanted,Stimulation Electrodes, Implantable,Stimulation Electrodes, Implanted
D004699	Endocardium	The innermost layer of the heart, comprised of endothelial cells.	Endocardiums
D005557	Formaldehyde	A highly reactive aldehyde gas formed by oxidation or incomplete combustion of hydrocarbons. In solution, it has a wide range of uses: in the manufacture of resins and textiles, as a disinfectant, and as a laboratory fixative or preservative. Formaldehyde solution (formalin) is considered a hazardous compound, and its vapor toxic. (From Reynolds, Martindale The Extra Pharmacopoeia, 30th ed, p717)	Formalin,Formol,Methanal,Oxomethane
D006327	Heart Block	Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.	Auriculo-Ventricular Dissociation,A-V Dissociation,Atrioventricular Dissociation,A V Dissociation,A-V Dissociations,Atrioventricular Dissociations,Auriculo Ventricular Dissociation,Auriculo-Ventricular Dissociations,Block, Heart,Blocks, Heart,Dissociation, A-V,Dissociation, Atrioventricular,Dissociation, Auriculo-Ventricular,Dissociations, A-V,Dissociations, Atrioventricular,Dissociations, Auriculo-Ventricular,Heart Blocks
D006329	Heart Conduction System	An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.	Conduction System, Heart,Conduction Systems, Heart,Heart Conduction Systems,System, Heart Conduction,Systems, Heart Conduction
D006352	Heart Ventricles	The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.	Cardiac Ventricle,Cardiac Ventricles,Heart Ventricle,Left Ventricle,Right Ventricle,Left Ventricles,Right Ventricles,Ventricle, Cardiac,Ventricle, Heart,Ventricle, Left,Ventricle, Right,Ventricles, Cardiac,Ventricles, Heart,Ventricles, Left,Ventricles, Right