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The incidence of the redundant cusp syndrome (“floppy valve”) was 5 per cent in 294 routine autopsies carried out at St. George’s Hospital. The incidence increased linearly with age. The characteristic pathological features are expansion and thickening of the valve cusps with lengthening and weakening of the chordae tendineae. Fibrous disintegration begins at the tip of the fibrous core of the valve and spreads toward the annulus and into the chordae tendineae. The natural history of the redundant cusp syndrome is usually benign; however, in approximately 8 per cent of the patients, the valve deteriorates and rapidly progressive mitral regurgitation develops. We reviewed the presenting features and surgical management of 16 patients with this syndrome treated at St. Thomas’ Hospital between 1965 and 1972. The reasons for early deterioration in this series were ruptured chordae, subacute bacterial endocarditis, and associated connective tissue disease. The characteristic clinical features are a mid-systolic click and a late systolic murmur. However, when valve function deteriorates, the patient usually is in atrial fibrillation and has a pansystolic murmur, which makes the syndrome difficult to distinguish from other forms of mitral regurgitation. Fourteen patients in this series had mitral valve replacement with no operative mortality but one late death. None had paravalvular leaks and all are virtually asymptomatic. Two patients were treated by valvoplasty. Both have pansystolic murmurs and dyspnea.

Although echocardiographic analysis reliably diagnoses idiopathic hypertrophic subaortic stenosis by detection of systolic forward anterior mitral valve motion and estimates severity of obstruction by the timed mitral encroachment of the interventricular septum, echographic stenosis may occur without hemodynamic obstruction or pressure gradient across the left ventricular outflow tract. Demonstration and mechanism of this apparent inconsistency are described in three patients with a previously unrecognized state of Idiopathic hypertrophic subaortic stenosis characterized by marked systolic forward movement of the anterior mitral valve without a simultaneous intraventricular pressure gradient, resulting from uneven septal apposition by the anterior leaflet. Echographic obstruction indexes (40, 34 and 31) during cardiac catheterization in the three patients were predictive of respective peak gradients of 37, 25 and 20 mm Hg. The horizontal nonparallel mitralseptal contact consistent with severe systolic forward movement of the anterior mitral valve in the absence of hemodynamic stenosis is believed to be caused by markedly forward displacement of the anterior papillary muscle, so that its chordae tendineae produce greater tension on the posteromedial aspect of the anterior mitral valve. Thereby the posterior portion of the leaflet is pulled forward more than its anterior side, allowing marked systolic forward anterior mitral valve motion without a pressure gradient in idiopathic hypertrophic subaortic stenosis.

Viele Probleme in der medizinischen Forschung und Klinik lassen sich nur mit einer detaillierten Kenntnis des Stoffverhaltens biologischer Gewebe losen. Es ist u. a. die Aufgabe des in der Biomedizinischen Technik tatigen Ingenieurs, dem Mediziner dei seiner Suche nach geeigneten Materialien fur Prothesen und Implantate durch Anwendung moderner Methoden des Materialprufungswesens sowie der Kenntnis der Werkstoffmechanik zu helfen. Diesen Bemuhungen mussen Untersuchungen prinzipieller Art am Gewebe des zu ersetzenden Organ-bzw. Korperteils vorangehen, weil nur dann die wichtigen Forderungen, namlich Kompatibilitat und richtige Funktion in mechanischer und rheologischer Hinsicht, optimal erfullt werden konnen. In einer fruheren Studie haben wir das Festigkeitsverhalten und die rheologischen Eigenschaften der Sehnenfaden (Chordae tendineae) des menschlichen Herzens, die wichtige biomechanische Funktionen ubernehmen, mit einer elektronischen Zugprufmaschine getestet. Die vorliegenden Untersuchungen sollen zeigen, das sich diese biomechanischen Phanomene mit einem nichtlinear viskoelastischen Werkstoffmodell reproduzieren lassen und mit Hilfe eines Analogrechners simuliert werden konnen. Biomechanics and Simulation of the Tensile Behaviour of the Chordae tendineae of the Human Heart: Many problems in the field of medical research and clinical practise can be solved only by a more detailed knowledge of the material properties of biological tissues. Among other things it is the task of the biomedical engineer to support the physician in his research work to develop a material suitable for prothesises and artificial organs by application of the modern methods of the materials testing as well as his knowledge of the materials mechanics. These efforts are preceded by basic investigations of the tissue of that organ or of that part of the body which has to be replaced. For only then the important demands are fulfilled optimally, i. e. compatibility and an accurate function in a mechanical and a rheological sense. In a previous paper we investigated the strength and the rheological properties of the Chordae tendineae of the human heart with an electronic tensile testing machine. The present investigations shall show that these biomechanical phenomena can be reproduced by a nonlinear viscoelastic material model and can be simulated with an analogue computer.

The variety of echographic features associated with the mitral valve prolapse syndrome (MVPS) is not yet completely understood. Therefore, ultrasound recordings were obtained in 33 patients in whom mitral prolapse had been documented by biplane left ventricular cineangiography. Echographic abnormailities of the mitral leaflets during systole were recorded in 26/27 MVPS patients and 6/6 with ruptured chordae tendineae. In MVPS, the midsystolic mitral buckling, emphasized in early echocardiographic studies, was observed in only 12 patients. In our study, the most common aberrancy was abnormal pansystolic mitral motion in 14 patients, which in 12 was similar to the pansystolic bowing observed in all six patients with torn chordae. An additional echographic abnormality in MVPS was localized mitral collapse throughout systole in 10/14 patients with pansystolic prolapse; this finding was the most striking defect noted in five, in two of whom it was the only disturbance. Phonocardiography in MVPS showed typical midsystolic click and/or late systolic murmur in only 15/26 patients of whom ten had midsystolic mitral buckling. A variety of systolic clicks and/or murmurs occurred in the 14 patients with generalized bowing and/or localized collapse throughout systole on echocardiography. Thus, the mitral echographic spectrum of MVPS is comprised of three different abnormal patterns of systolic prolapse: buckling in midsystole, pansystolic bowing, and pansystolic collapse. These echocardiographic disorders commonly occur in the absence of classical auscultatory findings in MVPS and the most frequent abnormality on ultrasound is pansystolic bowing of both mitral leaflets.

Five neonates with congenital tricuspid incompetence due to severe tethering of the tricuspid valve to the right ventricle by abnormal chordal and papillary muscle attachments are described. The abnormality was called tricuspid valvular dysplasia (TVD) if the basal insertion of the valve was normal and the Ebstein malformation if it was displaced into the sinus portion of the ventricle. In the two infants with isolated TVD and severe tricuspid regurgitation the functional obstruction to right ventricular outflow (ORVO) produced by the high perinatal pulmonary vascular resistance (PVR) made the exclusion of pulmonary atresia difficult, despite selective right ventricular angiocardiography. In three infants the tricuspid valvular abnormality was associated with organic ORVO; pulmonary atresia in two and critical pulmonary valve stenosis in one. In the two infants with pulmonary atresia and intact ventricular septum (IVS) the severe tricuspid incompetence produced a clinical, radiological and hemodynamic profile which was clearly different from that usually seen in infants with pulmonary atresia and IVS and a normal right ventricular cavity (type 2 of Greenwold).

Summary The endocardial surfaces were studied by means of the scanning electron microscope. The subendocardial muscle bundles in the heart were separated by deep and spacious grooves. The division of muscle fibres frequently occurs in an X-figure. The central portion of the figure is always elevated, although its length may vary in different fibres. The striae on the muscular fibres have also been described. Functional significance of the above findings was discussed. Zusammenfassung Endokardiale Oberflachen beim Menschen 2: Die Oberflachen der Muskulatur Rasterelektronenmikroskopische Untersuchungen ergaben, das die subendokardialen Muskelbundel durch tiefe und weite Spalten voneinander getrennt sind. Muskelfasern teilen sich haufig x-formig. Die Kreuzungsstelle dieser x-Form ist stets verdickt, wahrend ihre Lange wechselt. Querfurchen der Muskelfasern werden ebenfalls beschrieben. Die funktionelle Bedeutung der Befunde wird diskutiert. Resume Les surfaces endocardiaques chez l' Homme 2: Les surfaces de la musculature Les recherches de microscopie electronique sur coupes ultrafines montrerent que les faisceaux musculaires sous-endocardiques sont separes les uns des autres par des fentes profondes et larges. Les fibres musculaires se bifurquent frequemment en forme d' Le lieu de croisement de ces formes en X est constamment epaissi, alors que sa longueur varie. Les stries transversales des fibres musculaires sont egalement decrites. La signification fonctionnelle de ces faits est discutee. Resumen Superficies endocardiacas en el hombre 2: La superficie de la musculatura Investigaciones con el microscopio electronico demostraron, que las fibras musculares subendocardiales estan separadas por grietas profundas y anchas. Las fibras musculares frecuentemente se dividen en forma de X, con longitud variable y ensanchamiento en la parte donde se entrecruzan. Tambien se describen surcos transversales en las fibras musculares y se discute la importancia funcional de tales hallazgos.

The related atrioventricular valves in 11 instances of polypoid atrial tumors were examined grossly and histologically. Nine of the tumors involved the left atrium and, of these, seven were myxomas. The two right atrial tumors were myxomas. Histologically evident lesions of the mitral valve were present in seven of the nine left atrial tumors. The most common change consisted of fibrous thickening of the endocardium in the angle between the left atrium and posterior mitral leaflet and fibrous thickening of the atrial surfaces of the leaflet. Less common changes were a fibrous thickening of the chordae and of the left ventricular mural endocardium in relation to chordae inserting into the posterior leaflet. The changes described were also evident at gross examination in two of the nine cases with left atrial tumors. In the two cases of right atrial myxoma, both showed fibrous thickening of the atrial surfaces of the tricuspid leaflets; one also exhibited fibrous thickening of the right ventricular endocardium beneath the septal leaflet of the tricuspid valve. The lesions described are considered responses to the effects of friction by the tumor upon the surfaces involved. It is significant that grossly evident lesions may evolve from this rubbing action.

In a patient with a documented nonejection systolic click and late systolic murmur, acute mitral insufficiency developed as a result of spontaneous rupture of mitral chordae tendineae. There was no evidence of previous endocarditis, rheumatic fever or congenital heart disease. The ballooning mitral valve syndrome has previously been considered relatively benign. Chordal rupture has been predicted, and presumptive cases have been alluded to by several investigators. This well documented report of such a complication casts further doubt on the benignity of the syndrome.

Between 1955 and 1972, eight children receiving mediastinal irradiation for intrathoracic malignancy developed constrictive pericarditis. Six of these followed irradiation for Hodgkin's disease and represent 7% of 86 children receiving irradiation for that disease. In patients with Hodgkin's disease, the development of constrictive pericarditis was related to the dose of radiation and the use of orthovoltage technique. Constrictive pericarditis has not yet developed among the 44 children radiated by supravoltage technique. Symptoms of constrictive pericarditis occurred an average of 15 months (4/12 to 3 2/12 years) after irradiation and were preceded in five of the eight patients by acute pericarditis. Prominent clinical findings included dyspnea, Kussmaul sign, pulsus paradoxicus, hepatomegaly, cardiomegaly and electrocardiographic evidence of low QRS voltages with ST-T wave changes. Pericardiectomy was performed in six patients and resulted in immediate but only transient symptomatic relief. There was no operative mortality. Death occurred in six of the eight patients (1 5/12 to 6 6/12 years following irradiation) due to cardiac disease in three, progression of the malignancy in two and infection in one. In addition to constrictive pericarditis, extensive myocardial fibrosis and involvement of the antero-lateral papillary muscle and chordae tendineae of the mitral valve were demonstrated at postmortem examination. These factors may explain the progression of cardiac disease despite an initial symptomatic improvement following pericardiectomy.

A total of 787 cases with various congenital heart anomalies was histopathologically studied for valvular thickening, especially from the view point of response to mechanical stimulation (hemodynaqic changes). Macroscopically, both atrioventricular and semilunar valve leaflets showed difhse and rugous thickening of the body with thickened chordae tendineae or widened noduli Morgagni and/or Arantil and separation of the commissure in cases with increased blood flow or, enlarged volume. They showed localized thickening at the distal ends including the line of closure and prominent noduli in cases with increased pressure. Histological examination revealed that the increased flow made the proximalis thickened, the increased volume made the Abrosa thickened and the increased pressure made the spongiosa hypertrophied. The combined hemodynamic stresses made any of the combination of the 3 types of morphological change. Some of the connective tissue disease such as gargoylism and Marfan syndrome showed the same rule superimposed to their basic disorder. Crasy valvular changes associated with chromosome anomalies such as mongolism, 15 and 18–trisomy were exceptionally out of the rule of hemodynamic changes.

A unique case of traumatic rupture of the chordae tendineae of the tricuspid valve with associated intense cyanosis and successful repair 24 years later has been reported. The clinical findings, hemodynamic and angiographic data, details of the surgical correction, and a year and a half follow-up of the patient have been included.

SUMMARY Insufficiency of the mitral valve was produced surgically in 7 young male beagles. Clinical, radiological, haemodynamic, electrocardiographical and serum biochemical parameters were measured during the pre- and postoperative periods. Following post-mortem examination, lungs were examined histologically. Individual dogs were observed post-operatively for periods ranging from 1 to 20 weeks and on clinical, radiological and haemodynamic assessment could be divided into two groups. Group I showed marked passive pulmonary hypertension and an unusual pattern of exercise intolerance. Group II resembled clinical cases of mild left heart failure with compensation. Each group showed a definite sequence of cardiomegaly. A consistent feature was localized dilatation of the main pulmonary artery. Lung histology revealed mainly vascular congestion, with a relatively high incidence of inflammatory change.

Two unusual abnormalities of the mitral valve and its appendages have been described. The mitral valve “triplication” was an incidental finding at necropsy in a 72-year-old man while the other case, a severe dysplasia of the chordae tendineae, permitted the individual to survice until the age of 26 years. Because of the infrequent occurrence of congenital anomalies of the mitral valve, the clinical and pathological aspects of these two cases have been presented in some detail.

Nineteen dogs which survived occlusion of the left circumflex coronary artery with infarction and scarring of the posterior papillary muscle and adjacent left ventricle were studied by cineangiography 260 to 341 days after occlusion. Development of slight to moderate mitral-valve regurgitation was observed in 4 of the 19. Angiograms showed varying degrees of stiffness and rigidity of the posterior lateral wall of the left ventricle. There was no indication of heart failure. Autopsy studies revealed a dense fibrous scar involving 50 to 100 per cent of the posterior papillary muscle and varying portions of the adjacent left ventricular wall, with no involvement of the mitral-valve leaflets or chordae tendineae. The combination of a papillary muscle and left ventricular wall scar acted together to produce mitral-valve regurgitation in 4 of 19 animals.

Thickening and sclerosis of the chordae tendineae of the mitral valve are seen fairly frequently in hearts that are not ordinarily considered to be rheumatic. In this report a systematic study of these lesions is presented. Factors involved in their pathogenesis and their significance in the development of the chronic rheumatic deformity are discussed.

Four patients who had pure mitral insufficiency due to rheumatic heart disease are reported upon; in these patients, satisfactory surgical repair was accomplished by a simple suture technique. Clefts are often normally present in the posterior mitral leaflet. These clefts are particularly significant in the posterior half of this leaflet where there is a small reserve of tissue. Rheumatic valvulitis causes scarring and contracture of the leaflet tissue and contraction of the chordae tendineae attached to the edges of these clefts, which may cause the clefts to open. It is postulated that these initial areas of regurgitation may increase the left atrial pressure during early systole sufficiently to hinder the normal action of the aortic leaflet of the mitral valve and initiate a vicious cycle, causing significant mitral regurgitation. In the experimental laboratory and in 4 patients with pure mitral regurgitation, these clefts have been sutured together to reconstitute and shorten the arc of the posterior leaflet and thus restore competency of the mitral valve. This surgical approach appears to be applicable to a small but significant number of patients with pure mitral insufficiency.

The echocardiographic findings from six patients with ruptured chordae tendineae from the posterial mitral valve leaflet and three with ruptured chordae from the anterior leaflet are reported; in all cases the diagnosis was later proven by open-heart surgery. The constellation of echocardiographic findings suggesting ruptured chordae tendineae to the posterior leaflet are: (1) The appearance of echoes within the left atrial chamber, representing prolapse of the posterior leaflet and flail chordae tendineae. This finding, although not consistently observed, is the most pathog-nomonic echocardiographic sign. (2) Increased amplitude of systolic excursion of the left atrial wall, in most cases associated with normal or only mildly increased left atrial diameter. (3) Recognition of thin, low-intensity (noncalcified) mitral valve leaflets. (4) The anterior leaflet may also manifest increased amplitude of motion, and may not coapt normally with the posterior leaflet in systole. (5) Increased amplitude of motion of the interventricular septum with an increased estimated stroke volume and normal-to-increased ejection fraction. The findings suggestive of ruptured chordae tendineae to the anterior leaflet are: (1) A markedly increased amplitude of motion of the anterior mitral valve leaflet is evident. This leaflet appears to approach or touch the left ventricular septum in systole and the left atrial wall in diastole. (2) All of the findings of ruptured chordae to the posterior leaflet are also seen here, except for the observation of the posterior leaflet within the left atrial chamber. This constellation of findings has not been seen in normal indiviuals, nor is it present in patients with mitral insufficiency proven to be due to other factors, such as papillary muscle dysfunction or rheumatic heart disease. Hence, this noninvasive technic enables one to diagnose accurately the presence of mitral regurgitation due to ruptured chordae tendineae.

Stenosis of a congenitally bicuspid aortic valve results in a characteristic angiographic appearance: In systole the valve leaflets are domed, and there is a central jet that corresponds to the orifice of the stenotic valve. In diastole the sinuses of Valsalva reflect the morphologic features of the 2 aortic cusps. In contrast, the anatomic derangement of unicommissural aortic stenosis is reflected in an angiogram which can be differentiated from that of bicuspid aortic stenosis. In this case, the stenotic orifice visualized by the jet in systole can be seen in contact with the posterior wall of the aorta; leaflet tissue and valve motion are seen only anteriorly. The diastolic appearance differs from that of the bicuspid valve by the presence of a deep sinus of Valsalva anteriorly and a very shallow posterior sinus, also resulting from the lack of leaflet tissue posteriorly. This differentiation is important since extensive valvulotomy on the unicommissural valve will result in significant aortic regurgitation postoperatively.

In hearts with atrial septal defect of the fossa ovalis type, antemortem catheterization data corresponded to consistent differences in both the distribution and composition of tricuspid and pulmonic valve thickenings. High shunt flows and relatively low right ventricular pressures corresponded to extensive confluent fibrosis of the tricuspid chordae tendineae, leaflets, and annulus fibrosus, probably due to markedly elevated stretching tensions, and to fibroelastosis of the atrialis, probably due to increased flow. High ventricular pressures and relatively small shunts corresponded to characteristic sclerosis about the line of closure related to increased compression of the coapted portions of the leaflets. Pulmonic cusps showed similar distinctive changes attributable to differences in pressure and flow. A striking defcrmity about the posterior commissure of the mitral valve was characteristic of various types of atrial septal defect, providing the valve was generally intact and the shunt was predominantly left to right; the degree of the change increased with age and is probably a consequence of disproportionate enlargement of the septal wall of the left ventricle and modification of atrioventricular flow by the atrial septal defect. There was no evidence that either the right-sided or mitral valve changes were due to previous endocarditis or thrombosis. The findings indicate that the valve changes described represent secondary proliferative and degenerative responses to mechanical stresses resulting from altered flow patterns associated with atrial septal defect.

In 1963 Kay and Egerton 1 and in 1965 Kay, Tsuji, and Redington2 reported on the surgical treatment of mitral insufficiency associated with torn chordae tendineae.

Postoperative cardiovascular studies were carried out in eight patients with ostium primum defect and cleft mitral valve. Apical systolic murmurs were present in all patients, but in seven of them no mitral regurgitation was detected by pulmonary wedge pressure and left ventricular angiography. Surgical repair of the cleft anterior leaflet without resection of subjacent chordae tendineae, as performed in these patients, usually results in a competent mitral valve. Postoperative angiograms showed persistence of the characteristic preoperative deformity of the medial border of the left ventricular outflow tract especially in systole. As illustrated in one of these patients, subaortic obstruction occasionally complicates abnormalities of the atrioventricular valves.

Midsystolic clicks (MSC), or nonejection systolic clicks, were discovered in 15 patients with arteriosclerotic heart disease (ASHD). The diagnosis of ASHD was established by the presence of angina or the history of a documented myocardial infarction (MI) or both. The MSCs were recorded in 13 patients. A late systolic murmur was introduced by the MSC in four patients, and one patient had a soft holosystolic murmur. The mitral origin of the MSCs and murmurs was established by noting their change in timing and intensity following administration of vasoactive drugs. One patient underwent cardiac catheterization, and evidence of an old MI and papillary muscle dysfunction (PMD) was demonstrated. We think that the PMD that occurs secondary to ischemic fibrosis in ASHD permits slack chordae tendineae suddenly to become taut in midsystole and produce a snap. Although the mechanism for the production of chordal snaps has been previously postulated, ASHD has only recently been found responsible for producing these sounds. The diagnosis of ASHD should be considered in patients with MSCs, even though they frequently occur in its absence.

A pathologic study of mitral valvular lesions among 55 infants revealed 29 cases in which the mitral valve was the site of a primary congenital malformation and 26 cases in which the mitral lesion was an acquired infarction of papillary muscles secondary to some other malformation. Among the 29 cases with primary congenital anomalies of the mitral valve, there were 41 lesions represented. Congenital anomalies were identified according to the four components of the valve as follows: leaflets, commissures, chordae tendineae, and papillary muscles. The most common basis for primary congenital mitral valvular disturbance was an abnormality of the papillary muscles. In this group, parachute mitral valve and abnormal position of papillary muscles associated with endocardial fibroelastosis were most common (eight and 10 examples, respectively). Anomalous mitral arcade and obstructing papillary muscles were observed four and three times, respectively. Involvement of leaflets was the second most common type of congenital anomaly, being observed 11 times. In this group, in order of decreasing frequency, were supra-valvular ring (five cases), accessory mitral valvular tissue (three cases), "Ebstein's" malformation of the left atrioventricular valve in corrected transposition (two cases), and cleft mitral valve (one case). Commissural fusion was observed once and, in two cases, involvement of multiple components of the valve was observed. Among the 26 examples of infarction of papillary muscles, exclusive of 10 cases with endocardial fibroelastosis, the fundamental congenital anomalies included aortic stenosis (15 cases), coarctation of the aorta (six cases), and anomalous origin of the left coronary artery from the pulmonary trunk (five cases).

A new physical sign, a systolic thrill over the middle thoracic part of the vertebral column and just to the left of it, is described in patients with mitral valve incompetence secondary to a flail anterior mitral leaflet. This systolic thrill was noted in 7 patients, 6 of whom had ruptured chordae tendineae of the anterior mitral leaflet; the seventh patient had marked elongation of the chordae tendineae to the anterior mitral leaflet which gave rise to a similar pathophysiologic disturbance.

Described in three infants is an anomaly of the mitral valvular mechanism which has the following characteristic: connection of the left ventricular papillary muscles to the anterior mitral leaflet, either directly or through the interposition of unusually short chordae. The condition has been named "anomalous mitral arcade." The anatomic aberration appears to cause incompetence of the mitral valve.

Fifteen cases of severe mitral regurgitation secondary to ruptured chordae tendineae have been reviewed, eight of whom underwent open-heart surgery to correct their lesions. Three patients are living at this time with two being markedly improved. Cardiac catheterization was performed in six prior to surgery. Progressive deterioration within the year following the onset of difficulty or sudden worsening of previous cardiac symptoms characterized the usual clinical course. The apical systolic murmur, always loud, was conspicuously harsh and radiated to the base of the heart, simulating aortic stenosis when the mural cusp was ruptured. Although strongly suggesting the diagnosis, the sudden onset of an apical systolic murmur could be documented in only three instances. The presence of a small left atrium radiographically with tall left atrial "v" waves and marked reflux of contrast material into a paradoxically pulsating left atrium also pointed to the correct diagnosis. Various technics of surgical repair and problems influencing survival of patients in the present series are discussed.

Four patients had evidence that mitral valve prolapse was the etiology of isolated early systolic clicks that were "ejection" in timing, that is, within 80 msec of the first heart sound (S 1 ). Phonocardiography demonstrated movement of the click closer to S 1 (three patients) with no change (three patients) or an increase in click amplitude (one patient) on inspiration. Earlier movement of systolic clicks on inspiration is a known feature of midsystolic clicks related to mitral valve prolapse but not of true aortic ejection sounds. In three patients the early systolic click showed a variable relation to the carotid upstroke, suggesting that the two events were not related. The click of the fourth patient occurred after the carotid upstroke. In one patient the click could be brought out by standing. Apical holosystolic murmurs could be elicited in all patients. Left- and right-heart catheterizations and left ventricular angiograms revealed no evidence of semilunar valve or great vessel root abnormality. Three patients had mitral valve prolapse and mitral regurgitation on left ventriculogram. The cineangiogram on one patient demonstrated maximal prolapse of the mitral valve just before opening of the aortic valve and coincident with the timing of the click. An isolated early systolic click may be due to mitral valve prolapse rather than to the usual ejection phenomena.

A patient with severe mitral regurgitation secondary to ruptured chordae tendineae is described in whom there was a positive pulmonary arterial Kr 85 index and a step-up in oxygen saturation from right ventricle to pulmonary artery, in the absence of an abnormal communication between the systemic and pulmonary circulations. It was demonstrated that left atrial pressure exceeded pulmonary arterial pressure in late systole and early diastole, and the oxygen saturation in the pulmonary arterial bed increased with progressively more distal sampling sites. Following operative correction of the mitral regurgitation, cardiac catheterization showed a marked reduction in the left atrial pressure, and the step-up in oxygen saturation in the pulmonary artery, as well as the positive pulmonary arterial Kr 85 inhalation test, were abolished. It was concluded that the preoperative evidence of left-to-right shunting represented reflux of oxygenated blood into the pulmonary artery resulting from the severe mitral regurgitation.

This report calls attention to the occurrence of acute cardiovascular surgical emergencies involving the mitral valve in Marfan's syndrome by presenting the case history of a 4-year-old girl. This patient with classical features of Marfan's syndrome and known mitral insufficiency, documented by cardiac catheterization and angiocardiography, had an acute episode of profound congestive heart failure which appeared to be secondary to a sudden increase in the volume of mitral regurgitation. At surgical exploration, a flail posterior leaflet of the mitral valve with ruptured chordae tendineae was discovered. The patient died 17 hours after mitral valve prosthetic replacement.

Each atrioventricular valve of the guinea-pig consists of a core of connective tissue and muscle covered by endothelial cells. The muscle forms an annulus at the attached margin of the valve adjacent to the fibrous annulus. Some fibers from the lower part of the muscular annulus turn sharply toward the free margin of the valve and form a complex meshwork. These fibers resemble atrial muscle, but are noteworthy in that each contains myofibrils that are oriented in different directions. Some muscle fibers have features similar to those of conducting fibers, i.e., glycogen rich cytoplasm containing few myofibrils. Unmyelinated nerve fibers are numerous in both the mitral and tricuspid valves, but myelinated fibers were found only in the mitral valve. Typical adrenergic terminals were found adjacent to some cholinergic endings. Mitochondria-filled terminals (sensory?) and a third type of motor terminal were present also. Bundles of collagenous fibers extend from the chordae tendineae into the valve cusps where they fan out into small bundles. The other formed elements of the stroma are microfibrils and a flocculent material. There are a few elastic fibers beneath the endothelium. Interstitial cells, many of which possess solitary flagella are scattered throughout the matrix.

The histories and pathologie observations in seven cases of rupture of the mitral chordae tendineae are reviewed. Patients with bacterial endocarditis were excluded from the series. All showed fibrosis and chronic injury of the mitral valve. In two, the lesions were those of rheumatic heart disease; in the remainder, the changes suggested quiescent rheumatic disease, but were not pathognomonic. The chordae of the two valve cusps were ruptured with equal frequency in this series, and usually more than one was broken. The point of rupture lay close to the papillary muscle. The stumps consisted of hyalinized and partially degenerated connective tissue, with a covering of endothelium. Scarring extended into the subjacent myocardium. The corresponding papillary muscles underwent atrophy if all their chordae were broken, but showed hypertrophy if a number were left attached. It was clear from inspection that rupture of the chordae must have allowed a high degree of mitral regurgitation. All hearts were dilated and hypertrophied, with an average weight of 580 grams. The histories of the patients did not indicate that external violence or vigorous exertion were etiologic factors of primary importance in rupture of the mitral chordae tendineae. The symptoms after rupture of the mitral chordae tendineae are those of congestive heart failure, which may be insidious or abrupt in its onset and progressive or remittent in its course. Months or even years may elapse between rupture and the onset of frank congestive failure. Rupture of the chordae is suggested by the sudden appearance of a loud precordial systolic murmur, maximal at the apex and left sternal border, where it is usually accompanied by a thrill. An apical diastolic murmur may also be present. Auricular fibrillation sometimes occurs. Roentgenograms show cardiac enlargement, and fluoroscopic examination may demonstrate systolic pulsation of the left atrium. The differential diagnosis includes bacterial endocarditis, rupture of a valve cusp, rupture of a papillary muscle, and perforation of an infarcted interventricular septum.

Two patients with mitral insufficiency presumably secondary to rheumatic heart disease are reported in whom loud systolic murmurs and thrills in the aortic area simulated aortic stenosis. Left heart catheterization in both patients disclosed significant mitral insufficiency but no evidence for aortic stenosis or intracardiac shunt such as ventricular septal defect. Phonocardiography demonstrated the holosystolic characteristics of the aortic area murmurs and was indispensable in documenting their mitral origin. A regurgitant jet striking the left atrial wall in close proximity to the aortic valve, previously reported in rupture of the chordae tendineae, appears the probable mechanism of the aortic murmur and thrill.

Summary The causes of mitral insufficiency are primarily considered from an anatomic point of view. Mitral insufficiency may result from anatomic alteration of the papillary muscles, the chordae tendineae, the valve leaflets and/or the commissures. Left ventricular enlargement may contribute to mitral insufficiency by (1) enlargement of the valvular orifice and (2) alteration of the relationships between the valve leaflets, on one hand, and the chordae and papillary muscles, on the other. Left atrial dilatation resulting from one of the foregoing reasons for mitral insufficiency may displace the posterior leaflet and accentuate the degree of mitral insufficiency. Specific problems concerned with persistent common atrioventricular canal are also considered.

A series of forty patients with midsystolic clicks, including twenty-eight patients with late systolic murmurs at the apex, is described. Evidence for the mitral valvular origin of the click and murmur in most cases is presented, in agreement with other studies published in recent years. Left ventricular cineangiograms in four cases showed mitral insufficiency in each instance. The incidence of associated features is emphasized, and it is proposed that these features constitute a distinctive syndrome. These features include a predominant female incidence, low or inverted T waves in leads II, III and aVF, prolonged Q-T interval, prominent U waves, atrial and ventricular extrasystoles, paroxysmal atrial and ventricular arrhythmias with occasional syncope or sudden death, familial occurrence, association with Marfan's syndrome, Turner's syndrome or atrial septal defect, and frequent neuropsychiatric disorders with hyperventilation syndrome. It is proposed that fibrosed or redundant mitral chordae tendineae due to various congenital or acquired causes, together with organic or biochemical dysfunction of the papillary muscles with repolarization delay, may link together the various features of this syndrome. Although generally benign, the prognosis occasionally may be more serious than has been considered previously.

Currently available prostheses used for replacement of the mitral valve feature a rigid ring for fixation to the annulus of the mitral valve. The effect on the hemodynamics of the left heart of fixation of the annulus of the mitral valve bysuturing a ring from a 1M or a 2M Starr-Edwards valve under cardiopulmonary bypass, leaving the valve leaflets and chordae tendineae intact, was studied in 6 dogs. Intracardiac and intravascular pressures, cardiac output, and the size of the left ventricle were measured in these animals and a control group of 5 normal dogs in the “resting state” and during induced changes in peripheral vascular resistance (intra-aortic administration of angiotensin II and acetylcholine). Small diastolic pressure differences were detected between the left atrium and the left ventricle in the dogs operated on during the control resting state. These atrial-to-ventricular pressure gradients were greatly increased with the high flow and tachycardia associated with vasodilatation. This increased resistance to flow across the mitral valve constituted the major hemodynamic difference between the two animal groups under the conditions of the study.