Conduction system abnormalities in symptomatic mitral valve prolapse: an electrophysiologic analysis of 60 patients

An autopsy case of sudden unexpected death with Barlow's disease

A 45-year-old man was clinically diagnosed with mitral valve regurgitation 2 years before death. The autopsy showed left ventricular hypertrophy and mitral valve prolapse of the bileaflet with billowing valve and excessively thickened leaflet, the findings of which were consistent with Barlow's disease. Microscopically, destruction of the three-layer structure of the mitral valve and advanced interstitial fibrosis of the left ventricular wall were evident. Additionally, a marked but limited reduction in conduction fibers was found in the branching point of the left and right branches, as seen in cases of idiopathic complete atrioventricular block. Genetic investigation using whole-exome sequencing showed some genetic variants with uncertain significance. In patients with Barlow's disease, a marked reduction of conduction fibers might be a subtype of sudden cardiac death. The overlap of some arrhythmogenic substrate in the heart may increase the risk of sudden cardiac death with asymptomatic Barlow's disease.

Characteristics and outcomes of ventricular tachycardia and premature ventricular contractions ablation in patients with prior mitral valve surgery

BACKGROUND

Data regarding ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation following mitral valve surgery (MVS) is limited. Catheter ablation (CA) can be challenging given perivalvular substrate in the setting of mitral annuloplasty or prosthetic valves.

OBJECTIVE

To investigate the characteristics, safety, and outcomes of radiofrequency CA in patients with prior MVS and ventricular arrhythmias (VA).

METHODS

We identified consecutive patients with prior MVS who underwent CA for VT or PVC between January 2013 and December 2018. We investigated the mechanism of arrhythmia, ablation approach, peri-operative complications, and outcomes.

RESULTS

In our cohort, 31 patients (77% men, mean age 62.3 ± 10.8 years, left ventricular ejection fraction 39.2 ± 13.9%) with prior MVS underwent CA (16 VT; 15 PVC). Access to the left ventricle was via transseptal approach in 17 patients, and a retrograde aortic approach was used in 13 patients. A combined transseptal and retrograde aortic approach was used in one patient, and a percutaneous epicardial approach was combined with trans-septal approach in one patient. Heterogenous scar regions were present in 94% of VT patients and scar-related reentry was the dominant mechanism of VT. Forty-seven percent of PVC patients had abnormal substrate at the site targeted for ablation. Clinical VA substrates involved the peri-mitral area in six patients with VT and five patients with PVC ablation. No procedure-related complications were reported. The overall recurrence-free rate at 1-year was 72.2%; 67% in the VT group and 78% in the PVC group. No arrhythmia-related death was documented on long-term follow-up.

CONCLUSION

CA of VAs can be performed safely and effectively in patients with MVS.

Ventricular tachycardia in valvular heart disease: facilitation of sustained bundle-branch reentry by valve surgery

BACKGROUND

The clinical characteristics of sustained monomorphic ventricular tachycardia (SMVT), when it develops after valve surgery, have not been described.

METHODS AND RESULTS

Between 1985 and 1996, 31 patients (30 men and 1 woman) who had undergone valve surgery were found to have inducible SMVT. Nine patients (29%) had sustained VT due to bundle-branch reentry (BBR) (group 1). Four of these patients had normal left ventricular function, and VT with a right bundle-branch morphology was inducible in 4 patients. Group 2 included 20 patients with inducible myocardial (ie, non-BBR) VT. Coronary artery disease was present in 15 group 2 patients (75%) due to atherosclerotic (n=12) and nonatherosclerotic (n=3) causes. Two patients had both inducible sustained BBR and myocardial VT (group 3). Sustained BBR VT occurred significantly earlier after valve surgery (median, 10 days) than the onset of postoperative myocardial VT (median, 72 months; P<.005).

CONCLUSIONS

Myocardial VT was the most common type of inducible SMVT in patients with valvular heart disease. The majority of these patients had underlying coronary artery disease and significant left ventricular dysfunction. However, in almost one third of the patients, sustained BBR VT was the only type of inducible SMVT. This type of VT was facilitated by the valve procedure occurring within 4 weeks after surgery in most patients. In these patients, left ventricular function was relatively well preserved, and the right bundle-branch block type of BBR was frequently induced. Because a curative therapy can be offered to these patients (ie, bundle-branch ablation), BBR should be seriously considered as the mechanism of VT in patients with valvular heart disease, particularly if the arrhythmia occurs soon after valve surgery.

Significance of QT dispersion on ventricular arrhythmias in mitral valve prolapse

The present study was designed to detect the arrhythmogenic effect of mitral valve prolapse, and the relationship between QT, QT dispersion and ventricular arrhythmias in subjects with mitral valve prolapse. Sixty-four mitral valve prolapse subjects (24 men and 40 women, mean age 27 +/- 6), and 80 healthy control subjects (32 men and 48 women, mean age 28 +/- 7) were studied. The frequency of ventricular arrhythmias by means of 24-h ambulatory electrocardiographic (ECG) monitoring was investigated. Grade > or = 3 ventricular arrhythmias according to modified Lown and Wolf classification were accepted as complex arrhythmias. The QT intervals were measured from the beginning of depolarization of the QRS complex to the end of the T wave. Using the Bazett formula, QT interval was corrected (QTc) for heart rate. QT dispersion was calculated as the difference between the maximum and minimum QT intervals on any of 12 leads. Premature ventricular complexes seemed to develop in 56 of 64 (87.5%) subjects with mitral valve prolapse. Thirty-eight of the mitral valve prolapse subjects had complex premature ventricular complexes during 24-h ECG and the prevalence of premature ventricular complexes was found to be higher than the control subjects (P < 0.001). We found QT and QTc intervals of 388 +/- 27 and 406 +/- 33 ms in mitral valve prolapse subjects, these values in control subjects were 382 +/- 18 and 402 +/- 11 ms respectively (P > 0.05). QT dispersion and QTc dispersion intervals were 71 +/- 17 and 78 +/- 19 ms in mitral valve prolapse subjects and these values were 43 +/- 16 and 52 +/- 22 ms in control subjects, respectively (P < 0.001). No correlation was found between complex premature ventricular complexes and QT, but there was a correlation between complex premature ventricular complexes and QT dispersion in the mitral valve prolapse subjects. It was concluded that QT dispersion might be a useful marker of cardiovascular morbidity and mortality due to complex ventricular arrhythmias.

Atrial septal aneurysm and cardiac arrhythmias

Atrial septal aneurysm has been associated with thromboembolic events, interatrial shunting, mitral valve prolapse, and systolic click. An association between atrial septal aneurysm and cardiac arrhythmias has been also described. Twenty patients with atrial septal aneurysm and 19 control subjects performed 24-h Holter monitoring. Frequent (> 10/h) atrial premature beats were observed in seven patients vs. none of the controls (P = 0.008). The mean number of episodes of supraventricular tachycardia and the prevalence of ventricular tachycardia were also higher in the atrial septal aneurysm group (P = 0.044 and P = 0.046, respectively). Left atrial enlargement, mitral valve prolapse and left ventricular hypertrophy were more frequent than in the normal subjects. In conclusion, atrial and ventricular 'complex' arrhythmias occurred more frequently in patients with atrial septal aneurysm than in normal subjects. Further studies in patients with atrial septal aneurysm without other associated echocardiographic abnormalities need to be done to ascertain a potential arrhythmogenicity of this condition.

Ventricular arrhythmia factors in mitral valve prolapse

To assess the prevalence of ventricular arrhythmias and late potentials (LPs) in mitral valve prolapse (MVP) and to identify clinical, ECG, and echocardiographic markers of spontaneous ventricular arrhythmias, we studied 58 consecutive patients (mean age 46.6 +/- 17.8 years; 29 males, 29 females) with MVP diagnosed by echocardiography. Patients underwent ambulatory ECG recording (n = 58), exercise stress test (n = 56), signal-averaged ECG (n = 58), and programmed ventricular stimulation (n = 52). Ten patients (17.2%) had spontaneous nonsustained ventricular tachycardia (NSVT), 26 patients (44.8%) had premature ventricular contractions (PVCs), Lown grade > or = 3 during 24-hour ECG, and 19 had Lown grade > or = 3 PVCs during exercise stress test; 13 patients had LPs (22.4%). We provoked sustained VT in one case and NSVT in ten cases. Patients with complex ventricular arrhythmias during 24-hour ECG and exercise stress test were older and more often had mitral regurgitation. There was a statistical correlation between the presence of LPs and spontaneous VT (46.1% vs 8.9%; P < 0.005) and induced ventricular arrhythmias (50% vs 12.8%; P < 0.005). No correlation was found between spontaneous ventricular arrhythmias and thickness or posterior displacement of the mitral valve. In conclusion, complex ventricular arrhythmia (especially VT) and LPs are frequent in MVP. Patient age and mitral regurgitation seem to be determinant factors of complex ventricular arrhythmias in MVP. On signal-averaged ECG, absence of LPs seems to be a good additional marker to identify MVP patients without spontaneous VT. On the other hand, programmed ventricular stimulation does not appear valuable in determining a MVP subgroup with a high risk of ventricular arrhythmias.

Autonomic control of cardiovascular function: clinical evaluation in health and disease

The high- and low-pressure baroreceptor reflexes are integral to the control of blood pressure by the autonomic nervous system. Tests of the integrity of these baroreflexes make it possible to identify the site of autonomic dysfunction in patients with orthostatic hypotension. Clinical characteristics and typical results of autonomic testing in patients with autonomic failure, with carotid sinus hypersensitivity, and with hyperadrenergic autonomic dysfunction are described in this review.

The Marfan syndrome: cardiovascular physical findings and diagnostic correlates

Correlations among cardiac symptoms and auscultatory and phonoechocardiographic findings in Marfan syndrome have not been completely defined. A total of 24 patients with Marfan syndrome (16 men and 8 women; mean age 28.2 +/- 8.6 years) were studied. Mitral valve prolapse was noted in 22, of whom 19 had either nonejection systolic click or mitral regurgitation murmur. Mitral regurgitation was noted in 12 patients by Doppler imaging. Aortic root dilatation was noted in 20 patients and aortic regurgitation in six, five of whom had aortic regurgitation murmur (5 of 20 patients had undergone surgery). Proximal aortic dissection was noted in two. Dyspnea (n = 12) was associated with progressive mitral or aortic regurgitation in four, but in the others dyspnea could not be explained by valvular or ventricular abnormalities. Chest pain was related to pneumothorax in five and aortic dissection in two but was not associated with either in 15 patients. Palpitations (n = 12) and lightheadedness (n = 6) were not associated with specific arrhythmias. In conclusion, mitral valve prolapse and aortic root dilatation were the most common cardiovascular abnormalities in Marfan syndrome. Mitral valve prolapse was frequently associated with typical auscultatory findings and symptoms including dyspnea, chest pain, palpitations, and lightheadedness, whereas aortic root dilatation could be clinically silent unless complicated by aortic regurgitation or aortic dissection.

Myxoid heart disease: an assessment of extravalvular cardiac pathology in severe mitral valve prolapse

Because of the microscopic features of the affected leaflets in mitral valve prolapse (MVP), myxoid degeneration of the valve is a common pathologic designation applied to this condition. We undertook this study as a means of gaining an insight into the occurrence and prevalence of extravalvular cardiac alterations in hearts with severe MVP. Tissues of 24 hearts with severe myxomatous transformation of the mitral valve as the sole cardiac abnormality were examined. Eighteen of the 24 subjects with severe MVP died suddenly. Only two of these had pathologic evidence of severe mitral insufficiency. Twenty-four normal hearts served as controls. The two groups of hearts came from victims of homicide, suicide, accident, or natural death. Sections of the mitral valve, working myocardium, conduction system, and cardiac nerves and ganglia were studied by routine and special connective tissue and proteoglycan stains. Similar to the findings in severely affected mitral valves, prominent deposits of proteoglycans in neural and conduction tissue readily distinguished hearts with myxomatous valve changes from the control hearts. We conclude that the commonly recognized local derangement of valvular tissue in MVP is but one specific reflection of a more general myxomatous alteration in cardiac connective tissue.

The spectrum of mitral regurgitation in idiopathic mitral valve prolapse: a color Doppler study

To characterize the spectrum of mitral regurgitation in mitral valve prolapse, one hundred patients were studied by color Doppler flow mapping. The findings were correlated with the clinical presentation and with the possible complications. Mitral regurgitation was absent in 46 patients, mild in 26 patients, moderate in 18 patients and severe in 10 patients. The jet orientation was central in 15 patients, antero-medial in 13 patients and postero-lateral in 26 patients. The regurgitation was early systolic in 7 patients, late systolic in 20 patients and holosystolic in 27 patients. A good agreement was observed between the color flow patterns and the presence, timing and radiation of a murmur. Systolic clicks were not predictors of the presence or the severity of regurgitation. The grade of mitral regurgitation was positively correlated with, age, left heart enlargement and valvular redundancy. No sex difference was observed. The prevalence of serious arrhythmias or cerebral ischemic events was not significantly increased when a regurgitation was present.

Mitral valve prolapse: cardiac arrest with long-term survival

Cardiac arrest has been reported in patients with mitral valve prolapse; however, clinical characteristics and survival information are limited since most of the cases reported include autopsy data. Nine patients (2 male, 7 female) with mitral valve prolapse were identified who had cardiac arrest; ventricular fibrillation was documented in 8 patients; resuscitation was unsuccessful in 2. Eight had a history of palpitations (months to 15 years duration) and ventricular arrhythmias, 3 had a history (5-15 years) of recurrent syncope, and 1 was totally asymptomatic. Cardiac catheterization-angiographic studies in 8 patients demonstrated normal coronary artery anatomy and mitral valve prolapse. All 9 patients had auscultatory and echocardiographic evidence of mitral valve prolapse. Seven survivors (6 still alive) were followed from 3 to 14 years after cardiac arrest. A subset of patients with mitral valve prolapse and cardiac arrest is described in whom past medical history is compatible with cardiac arrhythmias or syncope, and whose long-term prognosis appears better than patients with other causes of cardiac arrest.

Esophageal dysfunction and chest pain in patients with mitral valve prolapse: a prospective study utilizing provocative testing during esophageal manometry

PURPOSE

The cause of chest discomfort in patients with mitral valve prolapse (MVP) remains unknown. Our aim was to determine prospectively the incidence of esophageal disorders and abnormal responses to edrophonium chloride and esophageal acid infusions in patients with MVP and troublesome non-ischemic chest pain.

PATIENTS AND METHODS

After coronary artery disease was excluded, 20 patients with MVP and chest pain underwent esophageal manometry and provocative testing with edrophonium chloride and acid infusion. Seven patients with MVP but without chest pain served as control subjects; they also underwent esophageal manometry with provocative testing.

RESULTS

Esophageal manometry revealed esophageal disorders in 16 patients: diffuse esophageal spasm in 14 patients, nutcracker esophagus in one, and hypotensive lower esophageal sphincter in one. Esophageal motility was normal in four patients. Injection of edrophonium and acid infusion tests evoked typical chest discomfort in three of 18 and five of 19 patients, respectively. In six of seven control subjects with MVP but with no chest discomfort, esophageal motility was normal and provocative testing did not produce chest discomfort (p less than 0.05 versus results in patients).

CONCLUSION

Esophageal disorders were common and may account for chest discomfort in certain patients with MVP and persistent chest pain syndromes.

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.