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A reassessment of mitral valve anatomy and its significance in prolapsed posterior leaflet
ABSTRACTS
fiable right ventricular myocardium in II, and morphologically dysplastic right ventSricular myocardium in three. Uhl’s disease (marked deficiency or absence of right. ventricular free wall myocardium) involved t#he posteroinferior wall of t,he “atrialized right vent)ricle” in 4 cases and the entire free wall in one. The septal and posterior tricuspid valve leaflets were partly absent in 4 cases, totally absent in one. A new entity of Ebstein’s anomaly with membranous tricuspid atresia was found in 2 cases. This malformation has a distinctive angiocardiographic appearance : a blind pouch
formed by the “atrialized right ventricle.” The first. case of Ebstein’s anomaly with complete &transposition of the great art,eries was documented, and correct,ed Z-transposition was present) in t#wo. Other significant associated anomalies included ventricular sept.al defect (5), pulmonary atresia (2), pulmonary valvular st,enosis (2), and aortic atresia (1). The intimat’e relation between the development of t,he tricuspid valve and right ventricle appears to be the embryologic basis of the observed spectrum of anatomic findings linking Ebstein’s, Uhl’s and absent tricuspid leaflets.
The Reversal of Heart Failure During Chronic Left Ventricular Bypass C. GRANT LAFARGE, MD/l-. Waltham, Massachusetts
C. ROBINSON
and WILLIAM
During chronic left ventricu1a.r bypass (76 to 120 days), 89 calves have been studied physiologically. One purpose was to determine the qualitative and quantitative function of t.he implanted 60 ml or 100 ml stroke volume pumps in a normal, resting state and during experimentally induced left ventricular failure. The left ventricular-aortic assist device is interposed between t,he left ventricular apex and descending thoracic aorta, and pumps, continuously, up to 8 liters/min, by synchronous counterpulsation or asynchronously. Blood flows and pressures were studied by catheterization, with implanted electromagnetic flow probes and catheter tip transducers, respectively. Left ventricular systolic and diast,olic volumes, stroke volume, ejection fraction, left ventricular mass, maximal rate of change of pressure and velocity of contractile element shortening (V,.,) were also assessed by biplane angiographic measurement and sub-
F. BERNHARD
sequent computer calculation. Reversible ventricular failure was induced experimentally by two methods of impinging on coronary blood supply: infusion of CO, and periarterial ba,lloon cuff occlusion. Data from these studies confirmed that, in a control state or in ventricular failure, the left ventricular assist device, by pumping up to 8 liters/min, could: (1) maintain a normal awake cardiac output, and tissue perfusion; (2) could reduce both abnormally increased left ventricular end-diastolic pressures and systolic pressure t’o zero mm Hg and volumes to normal levels; and, (3) could improve &roke volume, ejection fraction and V,.,. This improvement in ventricular function and clinical state implies that chronic irreversible left ventricular failure, w&h low cardiac output, could be reversed and a normal cardiac output maintained by longterm left ventricular-aortic bypass pumping.
A Reassessmentof Mitral Valve Anatomy and Its Significance in Prolapsed Posterior Leaflet JAMES H. LAM, BSc/NARASIMHAN RANGANATHAN, MB E. DOUGLAS WIGLE, MD, FRCP(C) and MALCOLM D. SILVER, MB, PhD Toronto, Canada
Mitral valves from 50 normal adult hea.rts were studied. Commissures, identified by “commissural” chordae and the tips of papillary muscles, separate the valvular tissue into anterior and posterior leaflets. The posterior leaflet is further divided into scallops by clefts in its tissue. “Cleft” chordae provide a guide to these interscallop clefts. Partitioned this way, the posterior leaflet was triscalloped in 46 hearts. A large middle scallop with two small but equal sized scallops on either side was present in 42 hearts. The anterior leaflet can be divided into a “rough zone,” defined by t,he leaflet free margin and the line of closure, and
112
a “clear zone” t,hat lies between the line of closure and the valve annulus. The posterior leaflet has three zones. Its “rough zone” is comparable to t’hat on the anterior leaflet but the clear zone is separated from the annulus by a basal zone 2 mm wide. Division of the mitral valve into two cusps includes, in the posterior leaflet, struct,ures formerly regarded as accessory leaflets. Prolapse of the posterior leaflet may affect one or more scallops. Affected scallops can be identified in left ventricular cineangiograms. Ability to identify prolapse of an individual scallop will further delineate and classify the clinical spect,rum of this obscure condition.
The American Journal of CARDIOLOQY
fiable right ventricular myocardium in II, and morphologically dysplastic right ventSricular myocardium in three. Uhl’s disease (marked deficiency or absence of right. ventricular free wall myocardium) involved t#he posteroinferior wall of t,he “atrialized right vent)ricle” in 4 cases and the entire free wall in one. The septal and posterior tricuspid valve leaflets were partly absent in 4 cases, totally absent in one. A new entity of Ebstein’s anomaly with membranous tricuspid atresia was found in 2 cases. This malformation has a distinctive angiocardiographic appearance : a blind pouch
formed by the “atrialized right ventricle.” The first. case of Ebstein’s anomaly with complete &transposition of the great art,eries was documented, and correct,ed Z-transposition was present) in t#wo. Other significant associated anomalies included ventricular sept.al defect (5), pulmonary atresia (2), pulmonary valvular st,enosis (2), and aortic atresia (1). The intimat’e relation between the development of t,he tricuspid valve and right ventricle appears to be the embryologic basis of the observed spectrum of anatomic findings linking Ebstein’s, Uhl’s and absent tricuspid leaflets.
The Reversal of Heart Failure During Chronic Left Ventricular Bypass C. GRANT LAFARGE, MD/l-. Waltham, Massachusetts
C. ROBINSON
and WILLIAM
During chronic left ventricu1a.r bypass (76 to 120 days), 89 calves have been studied physiologically. One purpose was to determine the qualitative and quantitative function of t.he implanted 60 ml or 100 ml stroke volume pumps in a normal, resting state and during experimentally induced left ventricular failure. The left ventricular-aortic assist device is interposed between t,he left ventricular apex and descending thoracic aorta, and pumps, continuously, up to 8 liters/min, by synchronous counterpulsation or asynchronously. Blood flows and pressures were studied by catheterization, with implanted electromagnetic flow probes and catheter tip transducers, respectively. Left ventricular systolic and diast,olic volumes, stroke volume, ejection fraction, left ventricular mass, maximal rate of change of pressure and velocity of contractile element shortening (V,.,) were also assessed by biplane angiographic measurement and sub-
F. BERNHARD
sequent computer calculation. Reversible ventricular failure was induced experimentally by two methods of impinging on coronary blood supply: infusion of CO, and periarterial ba,lloon cuff occlusion. Data from these studies confirmed that, in a control state or in ventricular failure, the left ventricular assist device, by pumping up to 8 liters/min, could: (1) maintain a normal awake cardiac output, and tissue perfusion; (2) could reduce both abnormally increased left ventricular end-diastolic pressures and systolic pressure t’o zero mm Hg and volumes to normal levels; and, (3) could improve &roke volume, ejection fraction and V,.,. This improvement in ventricular function and clinical state implies that chronic irreversible left ventricular failure, w&h low cardiac output, could be reversed and a normal cardiac output maintained by longterm left ventricular-aortic bypass pumping.
A Reassessmentof Mitral Valve Anatomy and Its Significance in Prolapsed Posterior Leaflet JAMES H. LAM, BSc/NARASIMHAN RANGANATHAN, MB E. DOUGLAS WIGLE, MD, FRCP(C) and MALCOLM D. SILVER, MB, PhD Toronto, Canada
Mitral valves from 50 normal adult hea.rts were studied. Commissures, identified by “commissural” chordae and the tips of papillary muscles, separate the valvular tissue into anterior and posterior leaflets. The posterior leaflet is further divided into scallops by clefts in its tissue. “Cleft” chordae provide a guide to these interscallop clefts. Partitioned this way, the posterior leaflet was triscalloped in 46 hearts. A large middle scallop with two small but equal sized scallops on either side was present in 42 hearts. The anterior leaflet can be divided into a “rough zone,” defined by t,he leaflet free margin and the line of closure, and
112
a “clear zone” t,hat lies between the line of closure and the valve annulus. The posterior leaflet has three zones. Its “rough zone” is comparable to t’hat on the anterior leaflet but the clear zone is separated from the annulus by a basal zone 2 mm wide. Division of the mitral valve into two cusps includes, in the posterior leaflet, struct,ures formerly regarded as accessory leaflets. Prolapse of the posterior leaflet may affect one or more scallops. Affected scallops can be identified in left ventricular cineangiograms. Ability to identify prolapse of an individual scallop will further delineate and classify the clinical spect,rum of this obscure condition.
The American Journal of CARDIOLOQY