There are thousands of divers with mitral valve prolapse who don't even know they have the condition -- and to be fair, most don't really have a problem. Mitral valve prolapse is a fairly common medical problem that is controversial and causes confusion among both physicians and those who suffer from it. Among the most common of heart conditions, mitral valve prolapse (MVP) remains something of a puzzle. Although MVP affects 5% to 7% of the population (7-10 million people), the cause is unknown. MVP occurs more often in women than men, another puzzling aspect of the condition. MVP often occurs in people who have no other heart problems, and the condition may be inherited. Studies have not indicated the MVP increases a person's risk of other heart or blood vessel problems. Many prospective divers are turned away from the sport unnecessarily or made to think they have 'heart disease', when a good explanation and some insight into the condition is all that is needed.

It is puzzling in that there is at the same time less to it and more to it than at first appears. Mitral valve prolapse is named for a heart valve and is usually first diagnosed as a faint heart "click" or murmur, though it isn't a form of "heart disease" in any conventional sense.

Located in the heart between the left atrium (upper chamber) and left ventricle (lower chamber), the mitral valve consists of two flaps or leaflets, which normally open and shut in coordinated fashion to allow blood to flow only in one direction -- from the atrium to the ventricle. The left ventricle is the heart's main pump and propels oxygen-rich blood into the arteries, which carry the blood throughout the body.

In patients with MVP, one or both of the flaps are enlarged, and the leaflets' supporting muscles are too long. Instead of closing evenly, one or both of the flaps collapse or bulge into the atrium, sometimes allowing small amounts of blood to flow backwards into the atrium. The condition produces the distinctive "clicking" sound that can be heard when listening to the heart with a stethoscope.

Related to a baffling array of seemingly unrelated symptoms, from shortness of breath to panic attacks, it is a generally the most benign of the various types of heart murmurs. Thought to be genetic in origin, it occasionally leads to a condition known as mitral regurgitation or insufficiency. This means a large amount of blood is leaking backward through the defective valve instead of continuing in the normal direction. Mitral regurgitation can result in the thickening or enlargement of the heart wall, caused by the extra pumping the heart must do to compensate for the backflow of blood. Mitral regurgitation sometimes causes fatigue or shortness of breath. The condition can usually be treated with medication, but a few people require surgery to repair or replace the defective valve.

Autonomic instability

People with MVP seem to have an underlying instability of the autonomic nervous system and cardiologists are beginning to look at this as a whole spectrum of abnormalities, most harmless, but some troubling. The autonomic nervous system regulates functions of the body over which we have no control, --such as blood pressure, heart rate, sweating, body temperature, gastrointestinal activity, and emptying of the urinary bladder.

People with mitral valve prolapse seem to have an  autonomic response that is much more volatile and unstable, so that normal stresses set off exaggerated responses, causing an excess of  stress hormones called the catecholamines (epinephrine and adrenalin). People with mitral valve prolapse are intermittently and unpredictably flooded with  their own 'catch-cold-amines', leaving them with a 'washed out' feeling.

ER presentation

Emergency room physicians see a great number of people who come in believing that they are having a heart attack, when they are actually experiencing a panic attack. If the sympathetic nervous system of a person with MVP is aroused, they can suddenly feel crushing chest pain, with heartbeat racing and pounding. They may begin to hyperventilate, feel short of breath, and break out into a cold sweat. Certain people with mitral valve prolapse sometimes experience this with no apparent warning or immediate threat. This leads us to think that it is not the valve abnormality that is to blame, but a syndrome that is manifested in other ways than the heart murmur. The murmur is a physical finding that is a marker of the underlying condition. An acute anxiety attack of this nature underwater could be extremely dangerous, if not deadly; patients with this malady should be advised not to dive.

An unstable sympathetic nervous system can arouse a multitude of symptoms and signs that affect widely divergent body systems. Some of these are:

• Migraine headaches (Relative contra-indication to diving)
• Unreality, vertigo (Adverse to diving)
• Difficulty concentrating  (Adverse to diving)
• Insomnia, sleep disturbances
• Hyperventilation; shortness of breath (Adverse to diving)
• Palpitations of the heart; skipped or irregular heart beat
• Panic attacks, with pounding heart beat (Adverse to diving)
• Phantom chest pain with no apparent physiological cause (Confused with decompression sickness)
• Hypersensitive startle reflex
• Cold sweats
• Cold hands and feet
• Numbness or tingling in the fingers or toes (Can be confused with decompression sickness)
• Bowel urgency, diarrhea, constipation (Not very good to have when diving)
• Sensitivity to drugs, including alcohol, caffeine, and medications (caffeine slows catacholamine uptake by the body).

• Hypoglycemia (Adverse to diving--decreased decision-making ability)
• Adrenal instability, with hyperactivity followed by adrenal exhaustion
• Hypothyroidism (Adverse to diving if untreated)
• Chemical sensitivities
• Food reactions
• Fluctuating sex hormones, especially estrogen, PMS and menopause
• Magnesium deficiency

Diagnosis of MVP is by listening to the heart sounds with a stethoscope for the distinctive 'click'; and by confirmation of the diagnosis with echocardiography or sonar. When diagnosed it often leads to apprehension about 'heart disease' and patients are very relieved when the condition is explained to them. The prophylactic use of antibiotics prior to minor surgical procedures is recommended although the morbidity from the ill effects of antibiotics far outweighs the very small incidence of endocarditis in patients with MVP. The use of antibiotics should probably be limited to those with severe regurgitant valve disease and not the common sort of mitral valve prolapse.

Exercise

Exercise should not be a problem--mitral valve prolapse is not  the sort of "heart condition" that should make anyone apprehensive about engaging in diving. In fact, exercise is one of the best therapies available for deconditioning learned sensitivities and relieving neurological symptoms. Studies have shown that people with MVP who engage in regular aerobic exercise report a decline in symptoms of chest pain, fatigue, dizziness and mood swings, and panic attacks.

Before being allowed to dive a patient with MVP should make an attempt to stabilize his/her symptoms with a proper diet. Stimulants, sugar, and artificial flavoring agents like MSG and Nutrasweet should be avoioded. The effects of hypoglycemia that are so dangerous to a diver must be blunted with frequent small meals and internal snacks; complex carbohydrates may be combined with protein to avoid precipitous rises and falls of blood sugar. Adequate hydration with plenty of liquids maintains blood volume to counteract low blood pressure and "wooziness." Moderate salt intake is usually discouraged to stimulate adrenal function.
 

Finally, if the patient with mitral valve prolapse has significant chest pain, palpitation, changes in consciousness, dysrhythmias, or require medication, it is thought that he/she probably should not be allowed to dive.

References:

 Yang S, et al. The effect of panic attack on mitral valve prolapse.
Acta Psychiatr Scand. 1997 Dec; 96(6): 408-411.

 Tse HF, et al.  Relation between mitral regurgitation and platelet activation.
J Am Coll Cardiol. 1997 Dec; 30(7): 1813-1818.

Corrado D, et al.  Sudden death in young people with apparently isolated mitral valve prolapse.
G Ital Cardiol. 1997 Nov; 27(11): 1097-1105.

 Mishiro Y, et al.   Echocardiographic characteristics and causal mechanism of physiologic mitral regurgitation in young normal subjects.
Clin Cardiol. 1997 Oct; 20(10): 850-855.

 Durlach J, et al.  Neurotic, neuromuscular and autonomic nervous form of magnesium imbalance.
Magnes Res. 1997 Jun; 10(2): 169-195. Review. English; French.

 Tamaki K, et al.   [Mitral valve prolapse and autonomic activity in normal women].
Rinsho Byori. 1997 Jun; 45(6): 590-594. Japanese.

 Heidenreich PA, et al.  The clinical impact of echocardiography on antibiotic prophylaxis use in patients with suspected mitral valve prolapse. Am J Med. 1997 Apr; 102(4): 337-343.

 Lichodziejewska B, et al.  Clinical symptoms of mitral valve prolapse are related to hypomagnesemia and attenuated by magnesium supplementation.
Am J Cardiol. 1997 Mar 15; 79(6): 768-772.

 Sagie A, et al.   Echocardiographic assessment of mitral stenosis and its associated valvular lesions in 205 patients and lack of association with mitral valve prolapse.
J Am Soc Echocardiogr. 1997 Mar; 10(2): 141-148.

 Nascimento R, et al.   Is mitral valve prolapse a congenital or acquired disease?
Am J Cardiol. 1997 Jan 15; 79(2): 226-227.