Bradycardia with mitral valve prolapse: a potential mechanism of sudden death

Fibromuscular dysplasia of small coronary arteries and fibrosis in the basilar ventricular septum in mitral valve prolapse

The mechanism of sudden cardiac death in patients with mitral valve prolapse is poorly understood. Twenty-four hearts from patients with mitral valve prolapse who suddenly died (mean age 34 +/- 8 years) and 16 trauma control hearts (mean age 30 +/- 7 years) were histologically studied. Dysplasia of the atrioventricular nodal artery was present in 18 of 24 hearts with mitral valve prolapse and four of 16 controls hearts (p = 0.003). The degree of luminal narrowing, as morphometrically measured, was significantly greater in hearts with mitral valve prolapse (p = 0.003). The degree of fibrosis in the base of the ventricular septum, as calculated by computerized morphometry, was greater in hearts with mitral valve prolapse (p = 0.0002) and independent of age, sex, and heart weight (p = 0.005). We conclude that arterial dysplasia in mitral valve prolapse may contribute to sudden cardiac death mediated by ventricular fibrosis.

Mitral valve prolapse

Mitral valve prolapse is a common mitral valve disorder manifested clinically as a midsystolic click and/or a late systolic murmur (the click-murmur syndrome) and pathologically as billowing or prolapsing mitral leaflets (the floppy valve syndrome). Not only is it one of the two most common congenital heart diseases and the most common valve disorder diagnosed in the United States, but it is also prevalent throughout the world. Mitral valve prolapse may be associated with a variety of other conditions or diseases. Diagnosis of mitral valve prolapse should be made on clinical grounds and, if necessary, supported by echocardiography. The majority of patients with mitral valve prolapse suffer no serious sequelae. However, major complications such as disabling angina-like chest pains, progressive mitral regurgitation, infective endocarditis, thromboembolism, serious arrhythmias, and sudden death may occur. Unless these serious complications occur, most of the patients with mitral valve prolapse need no treatment other than reassurance, including those with atypical chest pain or palpitation unconfirmed by objective data. Therapy with a beta-blocker for disabling chest pain and/or arrhythmias and antiplatelet therapy for cerebral embolic events may be indicated. In occasional patients with significant mitral regurgitation surgery may be necessary.

The QT and QS2 intervals in patients with mitral leaflet prolapse

The QT interval was plotted against the R-R interval in 92 patients with mitral prolapse and 92 age- and sex-matched control subjects. Ten patients (11%) lay above the upper 95% confidence limit for the control group, and analysis of variance confirmed a small group effect (p less than 0.05). Despite this, the mean QT intervals in the two groups differed by only 7 msec and a t test showed no significant difference between the groups. The prevalence of QT prolongation was exaggerated by Bazett's rate correction formula (62%) or historical control groups published by Simonson (58%) or Ashman (70%). Simultaneous QT and QS2 intervals were measured in 67 patients with mitral prolapse. Inversion of the normal QT:QS2 relationship occurred in nine patients (13%) and was more common in the presence of severe mitral regurgitation. It was not associated with an increased prevalence of absolute QT prolongation and was therefore thought to be caused by relative shortening of the QS2 interval. In conclusion, the prevalence of QT prolongation in mitral prolapse is low (11%). The QT:QS2 ratio is unlikely to be a reliable indicator of QT prolongation in these patients.

Mitral valve prolapse: a cardiomyopathic state?

Patients with diseases of the myocardium, structural abnormalities of the heart, and valvular disease may have mitral valve prolapse demonstrated as a consequence of these disease entities. However, there appears to be a primary disease of the mitral leaflets in which left ventricular cineangiography has demonstrated abnormal contraction patterns of the left ventricle in some patients. The cause of these abnormal contraction patterns is controversial, but most of the evidence points to these abnormalities being a consequence of the abnormal leaflet tissue motion during systole creating abnormal stress on the papillary muscles and supporting left ventricle wall. Biopsy evidence of myocardial changes and abnormal cardiac metabolic studies in some patients have suggested that myocardial function may not be entirely normal in every patient with mitral valve prolapse. However, there is not sufficient evidence currently to ascribe these histologic, metabolic and angiographic changes to a primary cardiomyopathic condition.

Arrhythmias in patients with mitral valve prolapse. Types, evaluation, and therapy

A wide spectrum of cardiac rhythm and conduction disorders occur in patients with all types of valvular heart disease. However, certain types of valvular disease have a special predilection for arrhythmias, including atrial and ventricular tachyarrhythmias as well as bradyarrhythmias, inherent to the etiology of the condition itself. Most notable in this regard is mitral valve prolapse, in which cardiac dysrhythmia is now recognized as the complication of highest frequency. The principal purpose of this article is the delineation of the characteristics and management of rhythm disorders in the mitral valve prolapse syndrome.

Anaesthetic considerations in patients with mitral valve prolapse

Mitral valve prolapse (MVP), reported as occurring in up to 17% of healthy individuals, is considered to be the commonest cardiac valvular abnormality. Although the anaesthetic course may be uneventful, complications may arise for the first time in the peri-operative period and include life threatening dysrhythmias, mitral regurgitation and infective endocarditis. Anaesthetic management of three of the seven patients with MVP treated at our institution over a 12-month period is discussed and the literature reviewed.

Increased plasma catecholamine levels in patients with symptomatic mitral valve prolapse

Total plasma catecholamine levels, plasma norepinephrine levels, heart rate, and systolic and diastolic pressures were measured in 15 symptomatic patients with mitral valve prolapse and in 19 normal subjects in supine baseline conditions and in a standing position. In the 15 symptomatic patients, total plasma catecholamine levels and plasma norepinephrine levels were significantly elevated in both positions, and heart rate was lower than in normal subjects in the supine position but returned to normal in the upright position. Thus, symptomatic patients with mitral valve prolapse demonstrate increased resting sympathetic tone. In addition, the associated supine bradycardia suggested that increased vagal tone might also be present at rest. These observations support the hypothesis of a dual autonomic dysfunction in these patients and could account for some of the clinical manifestations of the mitral valve prolapse syndrome.

Sensitivity and specificity of M mode echocardiographic signs of mitral valve prolapse

To assess the sensitivity and specificity of previously described M mode echocardiographic signs of mitral valve prolapse, 100 subjects with a mobile mid systolic click and 100 matched normal control subjects were prospectively studied. Late systolic posterior motion and holosystolic hammocking of the mitral leaflets were common, highly specific signs of mitral valve prolapse. When these signs were combined as a single criterion, sensitivity was 85 percent and specificity was 99 percent. Other signs, including systolic echoes in the mid left atrium, systolic anterior motion, early diastolic anterior motion of the posterior mitral leaflet and shaggy or heavy cascading linear diastolic echoes posterior to the mitral valve, were highly specific but uncommon. They occurred only in combination with late systolic posterior motion or holosystolic hammocking. The remaining signs tested did not differentiate subjects with mitral valve prolapse from normal persons.

Pathological view of sudden cardiac death

The common cause of sudden cardiac death is ischaemic heart disease. Such patients may have an occlusive recent thrombosis in a major coronary artery but the largest group has no recent occlusion. Comparison of such patients without occlusion with non-cardiac death control hearts suggests that an area of stenosis of 85 per cent is the best discriminating level. Most subjects who die of ischaemic heart disease suddenly have this degree of stenosis in two or three major arteries. Non-ischaemic sudden cardiac death occurs in hypertrophic obstructive cardiomyopathy and in severe left ventricular hypertrophy particularly from aortic valve stenosis. When the heart is macroscopically normal, review of previous electrocardiograms is the most helpful guide and may disclose conditions such as a long QT interval or pre-excitation. When no such data are available examination of the conduction system histologically may be helpful but is often non-specific. Use of the term "cardiomyopathy" by pathologists to cover all non-ischaemic sudden cardiac death is clinically misleading.

Primary myxomatous degeneration of cardiac valves. Clinical, pathological, haemodynamic, and echocardiographic profile

Four hundred and ninety-nine surgically excised valves were examined for pathological evidence of myxomatous degeneration. Thirty-six valves (7%) had myxomatous degeneration as a major pathological finding. Fourteen valves (3%) had significant myxomatous degeneration of the pars fibrosa, a finding which we define as "primary myxomatous degeneration". Echocardiographic findings and catheterisation results were correlated with the clinical course, surgical results, and follow-up in these 14 patients. Echocardiograms in 10 of the 11 patients who had them (91%) showed abnormalities suggesting the presence of primary myxomatous degeneration. Echocardiography was more helpful than angiography in diagnosis. The histological pattern of primary mitral myxomatous degeneration appears to be identical to that seen in patients with mitral valve prolapse and five of six patients with mitral lesions had echocardiographic evidence of prolapse. None of the patients with primary myxomatous degeneration of the aortic valve had syphilis of Marfan's syndrome. While the aetiology of primary myxomatous degeneration of cardiac valves is not known, a link to a more generalised disorder is suggested.

Site of origin of ventricular premature beats in patients with mitral valve prolapse

This study examines the site of origin and possible etiology of ventricular premature beats (VPB) in patients with mitral valve prolapse. Ten patients with mitral valve prolapse documented by echocardiogram from the study group. All patients had prolapse of the posterioir leaflet and three additionally had anterior prolapse. There were eight females and two males, with a mean age of 29.1 +/- 11.1 years. All patients were having unifocal VPBs at rest. A vectorcardiogram (VCG) was taken of the VPB by a technique which allowed all VCG loops to be written from the same beat. The VCG analysis indicated that the VPB forces were directed anteriorly, inferiorly, and to the left in six patients. In two patients the VPB was directed posteriorly, inferiorly, and to the left, consistent with right ventricular origin. One of these patients had episodes of ventricular tachycardia. One was anterior, superior, and to the left, and one was markedly anterior, superior, and to the right. In all patients the initial portion of the QRS was inscribed slowly. The three patients with additional anterior prolapse did not show a common difference from those with isolated posterior prolapse. It is concluded that: (1) The majority of these VPBs originate from the posteriorbasal portion of the left ventricle. (2) They originate in the myocardium and not in the Purkinje tissue. (3) There is no relationship between the location of prolapse and the VPB morphology.

AV node dysfunction in the mitral valve prolapse syndrome

The mitral valve prolapse syndrome is associated with a variety of atrial and ventricular arrhythmias. A portion of these patients manifest bradyarrhythmias, which in turn, may be the cause of lightheadedness and syncope. Thie study details the clinical and electrophysiologic characteristics of seven patients with symptomatic mitral valve prolapse and AV node dysfunction. The electrophysiology study demonstrated either a prolonged AH interval or abnormal response to atrial pacing in six of seven patients. A significant proportion of these patients had abnormalities of sinus node function and distal His-Purkinje conduction in addition to AV node dysfunction. AV node dysfunction in symptomatic patients with mitral valve prolapse may be secondary to autonomic dysfunction of diffuse conduction system disease.

Wenckebach second-degree A-V block in top-ranking athletes: an old problem revisited

The occurrence of Wenckebach second-degree (Mobitz I) A-V block in apparently normal persons still provides a puzzle for the cardiologist, as the benign nature of this event has been recently questioned. This problem becomes more intriguing when Wenckebach A-V block is encountered in asymptomatic top-ranking athletes, because of medico-legal implications. We report 10 cases of highly-trained athletes, including three with mitral valve prolapse (MVP) features, with a spontaneous or induced Wenckebach second-degree A-V block. Previous ECGs of six subjects, dating from a maximum of 6 years to a minimum of 18 months, were available. Deterioration of A-V conduction has never been documented and all six cases have remained asymptomatic for the whole follow-up period. Athletes have been submitted to a protocol study consisting of ECG recording at rest, during, and after vagal and sympathetic reflex maneuvers, drug administration (isoproterenol and atropine), submaximal and maximal exercise. Nine subjects have been considered to have "normal" responses of the A-V node to provocative tests, since conduction disturbances were improved or normalized by reflex sympathetic stimulations and were completely normalized by autonomic drug administration and exercise. One athlete showed "abnormal" responses to tests. In order to give a conclusive prognostic and medico-legal assessment, we advised him to submit to an invasive electrophysiological investigation. Wenckebach second-degree A-V block in athletes may be a more common finding than so far described, especially when a systematic search is made. In our opinion, this event can still be considered a vagally-induced benign feature of athlete's heart, provided that an immediate improvement of A-V conduction is obtained in response to reflex sympathetic maneuvers, and that a complete normalization after sympathomimetic and vagolytic drug administration and physical exercise is observed. The clinical histories of our athletes and the observed complete disappearance of conduction disturbances after detraining, strongly support this opinion. Wenckebach second-degree A-V block in asymptomatic athletes with MVP features probably does not affect the prognosis if similar favorable responses to the aforesaid tests are observed.

Sudden death in young females with floppy mitral valve syndrome

Three cases of sudden death in young females with clinical and pathological features of the floppy mitral valve syndrome are presented. Two patients had a history of syncopal attacks and were found to have intermittent cardiac arrhythmias, in addition to auscultatory findings consistent with mitral valve prolapse. The third patient had complained of attacks of giddiness associated with tachycardia. Sudden, unexpected death in all three cases resulted in coronial autopsies being performed. The clinical and autopsy findings are presented and discussed.

Ventricular fibrillation in a patient with unsuspected mitral valve prolapse and a prolonged Q-T interval

Mitral valve prolapse is a common cardiac abnormality associated with arrhythmias and sudden death. In most instances it can be diagnosed on the basis of physical findings. Those patients who are symptomatic or who display electrocardiographic abnormalities appear to be most susceptible to arrhythmias and, therefore, may be at increased risk for anaesthesia. Because the syndrome is relatively common and may present a very innocent clinical picture, anaesthetists should be aware of this condition and the problems it may present. A case of mitral valve prolapse syndrome associated with ventricular fibrillation on induction of anaesthesia is reported. The symptoms and pathophysiology of the disorder are reviewed and the potential problems and the anaesthetic management are discussed.

Dysautonomia in mitral valve prolapse

Many of the clinical features of patients with mitral valve prolapse can logically be attributed to abnormal autonomic neural function. Accordingly, we have studied heart rate and blood pressure response to a standardized Valsalva maneuver and postural test in 44 untreated patients with demonstrated mitral valve prolapse. Fifteen healthy subjects of similar age served as controls. The directional changes of blood pressure and heart rate were similar in control subjects and patients in both tests, but patients differed from control subjects by their widely oscillating heart rate during the upright posture, and their exaggerated and prolonged bradycardia during the recovery phase of the Valsalva maneuver and following their return to recumbency in the postural test. This bradycardia persisted for 30 to 90 seconds after blood pressure returned to control values. Patients also showed a greater respiratory variation of R-R interval, which became especially marked during the adjustment to changes of posture. We postulate an abnormal central modulation of baroreflexes as the best explanation for the dysautonomic responses of symptomatic patients with prolapsed mitral valves.

Sudden unexpected cardiac death--a practical approach to the forensic problem

Sudden cardiac death can usually be resolved by the pathologist into ischaemic heart disease, non-vascular cardiac disease such as aortic stenosis or hypertrophic obstructive cardiomyopathy and infrequently a morphologically normal heart on naked eye examination. When ischaemic heart disease is present one third of cases have a recent occlusive coronary artery thrombosis. Two thirds of patients have coronary stenosis only; the minimum degree of disease reasonably associated with sudden death is one area of 85% stenosis. The majority of patients, however, have multiple areas of stenosis. The predominant causes of non-ischaemic sudden death are severe LV hypertrophy, hypertrophic obstructive cardiomyopathy and the prolapsing mitral valve syndrome. Where the heart and coronary arteries are morphologically normal, review of any previous ECG's, a family history and histological examination of the myocardium and conduction system may reveal a cause or at least allow a reasonable assumption of cardiac arrhythmia to be made. Sudden unexpected death where the circumstances strongly suggest a cardiac cause may pose problems for the pathologist. Ischaemic heart disease (coronary atherosclerosis) is undoubtedly the most frequent cause but even when this is so the detailed pathology is controversial. It is when coronary artery disease is conspicuously absent, often in young individuals previously in good health, that a problem exists. Sudden death in infancy (cot death) is a different entity with its own problems and is not here discussed further.

Multiple floppy valves: an echocardiographic syndrome

Echocardiograms of 400 patients with mitral valve prolapse examined at the Peter Bent Brigham Hospital between 1974 and 1977 were reviewed. Eleven patients (3 per cent) were found to have prolapse (10 patients) or large excursion of the tricuspid valve (one patient) and large excursion of the aotric valve (four patients) or dilatation of the aotric root (seven patients) in addition to mitral valve prolapse. Two of these 11 patients underwent mitral valve replacement, and myxomatous degeneration of the valves was noted on pathologic examination. Almost half of the patients with multiple floppy valves (five of 11) had symptoms of congestive heart failure. In contrast to reported series of isolated mitral valve prolapse, in which female preponderance has been documented, 10 of the 11 patients were male. The syndrome of multiple floppy valves may represent either a unique entity or a more advanced form of the same process which underlies mitral valve prolapse.

Incidence of mitral valve prolapse in subjects with thoracic skeletal abnormalities--a prospective study

The incidence of mitral valve prolapse (MVP) in 80 patients with various thoracic skeletal abnormalities (TSA) was examined prospectively using compete history and physical examination, chest x-rays, electrocardiography, phonocardiography, and echocardiography. There were 76 males and four females, ranging in age from 18 to 80 years. Thirty-four patients had narrow anteroposterior diameter of the chest (asthenic habitus) (Group 1), 13 had straight back (Group 2), and 33 had pectus excavatum (Group 3). Twenty-five of the 80 patients (31 per cent) had evidence of MVP, 22 by echocardiographic criteria and three by phonocardiographic criteria. The incidence of MVP in this predominantly male population was substantially higher than that reported in the general adult population. Thoracic skeletal abnormality is an important nonauscultatory feature of mitral valve prolapse syndrome. The association between TSA and MVP may be a manifestation of a single connective tissue defect during embryonic development of the bony thoracic cage and the atrioventricular valves. All patients with TSA, even when asymptomatic, should be screened for MVP by noninvasive investigations. The recognition of MVP in patients with TSA may be of potential value in prevention of life-threatening endocarditis and cardiac arrhythmia.

Mitral Valve Prolapse in a Professional Basketball Player

The sequence of events in this case suggests that mitral valve prolapse may be an underlying cause of 'athlete's heart syndrome,' especially when it's accompanied by symptomatic arrhythmias.