Bab 3: Anomali Struktural Jantung

“Divers who suffer decompression sickness have a patent foramen ovale (PFO) prevalence twice that of the population in general.”

Having healthy heart valves is essential if your heart is to properly pump and circulate blood throughout your body. Some people are born with structural anomalies in their heart valves or in the walls. Many such disorders are diagnosed early in life and corrected, restoring the affected individuals’ exercise capacity and enabling them to dive safely. However, some inborn structural disorders, like a condition known as patent foramen ovale, may not become obvious until after an affected individual has taken up diving — and may result in an increased risk of certain diving injuries. In addition, some people are impacted later in life by acquired valvular damage that may affect their fitness to dive.

Dalam bab ini, Anda akan belajar tentang:

Gambaran Umum Gangguan Katup (Valvular Disorder)

Illustration of the valves of the heart showing blood flow

Jantung memiliki empat katup utama yang memfasilitasi aktivitas pemompaan jantung:

  • Katup trikuspid, antara atrium kanan dan ventrikel kanan.
  • Katup pulmonal, antara ventrikel kanan dan arteri pulmonalis.
  • Katup mitral, antara atrium kiri dan ventrikel kiri.
  • Katup aorta, antara ventrikel kiri dan aorta.

Each valve consists of a set of flaps (also called “leaflets” or “cusps”) that open and close to enable blood to flow in the correct direction. The function of the valves may be compromised by either congenital or acquired abnormalities. Damage to the valves can occur due to infection, rheumatic fever or aging. For example, the opening in a valve may narrow (a condition known as “stenosis”), meaning the heart has to work harder to get blood through the opening; this generates higher pressure within the heart and eventually causes the cardiac muscle to overdevelop. Another common valvular problem is incomplete closure, which allows the blood to flow backward through the valve (a condition known as “regurgitation”); this overloads the heart with blood, eventually resulting in enlargement (or “dilatation”) of the heart’s cavities.

The two most common valvular disorders in older adults are aortic stenosis and mitral regurgitation. The symptoms of valvular disorders vary depending on which valve is affected as well as on the type and severity of the change. Mild changes may cause no symptoms; a heart murmur — detected when the heart is examined with a stethoscope — is often the first sign of valve damage. In aortic stenosis, however, exertion can cause chest pain (known as “angina”) or a feeling of tightness in the chest, shortness of breath, fainting or heart palpitations. Sudden death in otherwise healthy athletes is sometimes caused by aortic stenosis. Regurgitation can also cause detectable symptoms, such as shortness of breath or wheezing when lying down; these complaints may be intensified by exercise, increased resistance to breathing and immersion.

Perawatan untuk gangguan katup umumnya melibatkan pembedahan. Katup yang rusak dapat diperbaiki atau diganti dengan katup prostetik.

Mencegah kerusakan katup, tentu saja, merupakan pendekatan terbaik. Pemeriksaan fisik rutin dapat mengungkap bukti penyakit katup awal. Dalam kasus seperti itu, pengawasan medis rutin yang ketat disarankan untuk mengidentifikasi, dan semoga memperlambat, perkembangan kerusakan.

Efek pada Menyelam

Significant valvular anomalies may preclude diving until they can be corrected. Even after corrective surgery, there must be an assessment of such factors as exercise capacity, the presence of any residual regurgitation and the need for anticoagulation. Such an assessment should include a detailed examination of the heart and of the individual’s ability to exercise at a level consistent with diving, without evidence of ischemia, wheezing, cardiac dysfunction or a problem known as “right-to-left shunting.”

Prolaps Katup Mitral

Mitral valve prolapse (MVP) may also be referred to as “click-murmur syndrome” or “floppy-valve syndrome.” It is a common condition, especially in women. The problem arises as a result of excess tissue and loose connective tissue in the heart’s mitral valve, so that part of the valve protrudes down into the left ventricle during each contraction of the heart.

An individual with MVP may have absolutely no symptoms or may exhibit symptoms ranging from occasional palpitations or an unusual feeling in the chest when the heart beats, to chest pain or a myocardial infarction (or heart attack). MVP is also associated with a slightly increased risk of small strokes (known as “transient ischemic attacks”) or a transient loss of consciousness.

Beta blockers — drugs commonly used to treat high blood pressure — are occasionally prescribed for mitral valve prolapse. They often cause a drop in maximum exercise capacity and may also affect the airways. These side effects normally pose no problem for the average diver, but they may be significant in emergency situations.

Illustration of mitral valve prolapse vs normal and regurgitation state

Efek pada Menyelam

Seringkali, MVP tidak menghasilkan perubahan aliran darah yang akan mencegah seseorang menyelam dengan aman. Seorang penyelam dengan MVP yang tidak memiliki gejala (yaitu, tidak ada nyeri dada, perubahan kesadaran, palpitasi atau detak jantung yang tidak normal) dan yang tidak meminum obat untuk masalah tersebut dapat berpartisipasi dengan aman dalam menyelam. Tetapi siapa pun dengan MVP yang menunjukkan irama jantung abnormal, yang dapat menyebabkan palpitasi, tidak boleh menyelam kecuali palpitasi dapat dikontrol dengan obat antiaritmia dosis rendah.

Patent Foramen Ovale

Patent foramen ovale (PFO) is a fairly common, congenital, generally benign hole between the heart’s left and right atria (see illustration).

While a fetus is developing in utero, the wall separating the left and right atria of the heart develops from the septum primum, which grows up, and septum secundum, which grows down. The septa overlap, creating a sort of trap door (known as the “foramen ovale”), which allows oxygenated blood from the mother’s placenta that has entered the fetus’ right atrium to pass through to its left atrium. At birth, the baby’s lungs expand, and the resulting pressure in the left atrium closes the foramen ovale. Typically, shortly after birth, this former opening fuses shut — but in about 27 percent of babies, it fails to fuse completely and results in a PFO.

A PFO often causes no symptoms, and most people who have one are never aware of the fact. PFO is diagnosed by injecting a small amount of air into a vein and observing its passage through the heart using echocardiography. There are two methods of echocardiography. Transthoracic echocardiography (TTE) is easy and noninvasive — it involves simply placing an ultrasound probe on the outer wall of chest — but it detects a PFO in only 10 percent to 18 percent of the population — about half of those who probably have one. Transesophageal echocardiography (TEE) — which involves local anesthesia and intravenous sedation, so the probe can be passed into the esophagus — detects a PFO in 18 percent to 33 percent of the population. However, even though TEE is more sensitive than TTE, there are still many false-negative results with both techniques; a properly conducted TTE may in fact be more reliable than a TEE.

Salah satu perawatan paling umum untuk PFO adalah prosedur yang disebut penutupan transkateter; ini melibatkan pemasangan kateter melalui selangkangan dan naik ke vena femoralis ke dalam jantung, di mana alat yang disebut occluder ditanamkan di seluruh PFO. Occluder datang dalam berbagai bentuk dan bentuk, tetapi sebagian besar bertindak seperti payung ganda yang terbuka di setiap sisi dinding atrium dan menutup lubang. Seiring waktu, jaringan tumbuh di atas ocluder dan menutupi permukaannya sepenuhnya. Implantasi dilakukan dengan anestesi lokal dan sedasi intravena, dan pasien tetap sadar. Dibutuhkan kurang dari satu jam dan dapat dilakukan dengan rawat jalan atau menginap satu malam. Kebanyakan pasien dapat kembali ke aktivitas normal mereka dalam dua hari, tetapi mereka harus minum obat antikoagulan dan/atau antiplatelet selama tiga sampai enam bulan. Pembatasan pasca operasi lainnya termasuk tidak ada perawatan gigi elektif (seperti pembersihan) selama tiga bulan, tidak ada olahraga kontak selama tiga bulan dan tidak ada angkat berat selama satu minggu. Seorang penyelam yang menjalani penutupan transkateter PFO harus tidak melakukan penyelaman selama tiga sampai enam bulan.

Tidak ada data yang tersedia tentang hasil penutupan PFO pada penyelam. Tetapi hasil berikut dicatat pada pasien yang menjalani penutupan PFO untuk pencegahan stroke (namun, perhatikan bahwa pasien ini memiliki kondisi medis yang mendasari yang dapat berkontribusi pada risiko hasil buruk yang lebih besar dari rata-rata):

  • Keberhasilan: Penutupan saluran lengkap dicapai pada 95 persen kasus dan penutupan tidak lengkap pada 4 hingga 5 persen kasus; tidak ada perbaikan yang ditunjukkan hanya pada 1 persen kasus.
  • Komplikasi: Kematian keseluruhan kurang dari 1/10 dari 1 persen (0,093 persen). Kebutuhan untuk operasi tindak lanjut karena kejadian buruk yang terkait dengan perangkat kurang dari 1 persen (0,83 persen).
  • Komplikasi serius: Angka kejadian kematian, stroke, infeksi, perdarahan atau cedera pembuluh darah sebesar 0,2 persen; pergerakan atau pelepasan alat, 0,25 persen; pembentukan bekuan pada perangkat, 0,3 persen; komplikasi utama pada periode perioperatif, 1,2 persen; dan komplikasi jangka menengah ringan, 2,4 persen.

Efek pada Menyelam

Penyelam yang menderita penyakit dekompresi (DCS) memiliki prevalensi PFO dua kali lipat dari populasi pada umumnya. Dan pada penyelam yang menunjukkan gejala DCS neurologis, prevalensi PFO empat kali lebih besar. Risiko DCS tampaknya meningkat dengan ukuran PFO. Berdasarkan fakta-fakta ini, diasumsikan bahwa penyelam dengan PFO memiliki risiko DCS yang lebih besar daripada mereka yang tidak memiliki PFO; namun, satu-satunya studi prospektif yang dirancang untuk secara langsung mengukur risiko relatif DCS pada penyelam dengan PFO masih berlangsung.

Berikutnya Chapter 4 – Ischemic Heart Disease >

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