11.6.8 Barlow's disease

As mentioned above, Barlow's disease is quite a broad spectrum, ranging from a benign, female-predominant syndrome characterised by vague cardiac symptoms to severe structural mitral valve disease with severe dysfunction [3]. In the West, Barlow's disease is very common, affecting 1.7-2.4% of the adult population [4]. However, it is associated with significant MI in only 10-15% of cases. It is most common in men and usually develops after the age of 50, leading to surgical repair in only 5% of patients [1,8]. Its incidence is higher in certain conditions such as Marfan's syndrome, von Willebrand's disease, pectus excavatum or ASD ostium secundum [2].

Barlow's disease can cause arterial embolism due to fibrin deposition or paroxysmal arrhythmias: AF, SSEVT, ventricular or supraventricular tachyarrhythmia, AV block. The rate of sudden death is 1% per year [3,9]. The incidence of endocarditis is increased only if there are severe anatomical lesions of the valve, but not if the leaflets are simply ballooned or displaced in the LA. Prophylactic antibiotic therapy is only indicated in cases of severe tissue damage [6,7].

Manifestations of the syndrome are protean: fatigue, dyspnoea, anxiety, pseudoangina and palpitations. When failure occurs, symptoms of MI dominate the clinical picture. On auscultation, accentuated by manoeuvres to reduce preload, there is a mesosystolic click at the apex and a discrete telesystolic murmur. The click is caused by the sudden tension on the chords as the prolapse tilts into the LA [2]. The ECG is not specific.

Barlow's prolapse is a type II mitral insufficiency (see Figure 26.13 on page 156). The more the telesystolic volume (Vts) of the ventricle is reduced, the more the coaptation point in the atrium recedes as the course of the chords is lengthened (see Figure 11.70). Unlike other types of MI, prolapse regurgitation worsens as preload decreases and contractility increases. The effect of afterload is ambivalent: beneficial in that it increases telesystolic ventricular volume, but harmful if it is high enough to increase regurgitation. Classically, Barlow auscultation increases when the patient inhales amyl nitrite and rises abruptly (decreased Vts). However, it should be remembered that prolapse at the stage of chord rupture causes massive MI. In this case, the type II mechanism is overwhelmed by the large size of the regurgitant orifice. The MI then becomes directly dependent on an increase in systolic pressure [5].

Treatment of Barlow's syndrome consists mainly of β-blockers for arrhythmias and aspirin (75-250 mg/d) for transient neurological symptoms. Anticoagulation is recommended in the event of stroke or atrial thrombus, or if atrial fibrillation develops [2].

 Principles of anaesthesia

The following recommendations apply only to patients with Barlow's disease with mild or moderate MI undergoing non-cardiac surgery. To counteract regurgitation in simple Barlow's disease, the ventricle must be kept relatively dilated. This is achieved by targeting the following points.

• Preload: this must be high to maintain increased telesystolic and end-diastolic volumes: generous perfusions, CVP > 10 mmHg, PCWP > 12 mmHg.
• Afterload: must be maintained at normal levels, using vasoconstrictors if necessary.
• Contractility: must be reduced; deep anaesthesia is used, possibly with a β-blockers (esmolol); ongoing β-blocker treatment is not interrupted.
• Rate: a slower rhythm favours filling and dilates the ventricle; with equal contractility, the telesystolic volume is greater.

In both cardiac and non-cardiac surgery, TEE is the only effective intraoperative means of assessing blood volume adequacy, ventricular function and the evolution of regurgitation in patients with Barlow's disease. Pharmacological treatment (β-blockers, aspirin) is maintained perioperatively.

 Anaesthesia technique

• Induction can be achieved with propofol, midazolam or thiopental.
  • Midazolam reduces sympathetic tone; it is adequate but lasts long;
  • Propofol reduces preload, which needs to be compensated by infusions;
  • Thiopental is only indicated if ventricular function is normal (EF ≥ 0.6);
  • Etomidate is only recommended if ventricular function is severely impaired.
• For maintenance of anaesthesia, sevoflurane or propofol are well suited; halothane was the ideal agent because it acts as a β-blocker, but it has been withdrawn from clinical use in most countries.
• Maintain systemic arterial resistance (SAR) with a vasoconstrictor, avoid arterial hypotension (do not use isoflurane).
• Maintain circulating volume (perfusions) and avoid any drop in preload (avoid hypovolemia).
• Inhibit contractility (esmolol).

References

1. AVIERINOS JF, INAMO J, GRIGIONI F, et al. Sex differences in morphology and outcomes of mitral valve prolapse. Ann Intern Med 2008; 149:787-95
2. BONOW RO, CARABELLO B, CHATTERJEE K, et al. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease. J Am Coll Cardiol 2008; 52:e1-e142
3. BOUDOULAS H, KOLIBASH, AJ, BAKER P, et al. Mitral valve prolapse and the mitral valve prolapse syndrome: A diagnostic classification and pathogenesis of symptoms. Am Heart J 1989; 118:796-803
4. FREED  LA, LEVY D, LEVINE RA, et al. Prevalence and clinical outcome of mitral valve prolapse. N Engl J Med 1999; 341:1-7.
5. LANCELLOTTI P, FATTOUCH K, LA CANNA G. Therapeutic decision-making for patients with fluctuating mitral regurgitation. Nat Rev Cardiol 2015; 12:212-9
6. NISHIMURA RA, CARABELLO BA, FAXON DP, et al. 2008 focused update incorporated into the ACC/AHA 2006 Guidelines for the management of patients with valvular disease. J Am Coll Cardiol 2008; 52:e1-e42
7. NISHIMURA RA, OTTO CM, BONOW RO, et al. 2014 AHA/ACC Guideline for the management of patients with valvular          heart disease. Circulation 2014; 129:e521-e643
8. WILCKEN DEL, HICKEY AJ, Lifetime risk for patients with mitral valve prolapse of developing severe valve regurgitation requiring surgery. Circulation 1988; 78:10-8
9. ZUPPIROLI A, RINALDI M, KRAMER-FOX R, et al. Natural history of mitral valve prolapse. Am J Cardiol 1995; 75:1028-32.