Jumat, 21 Januari 2011



From Wikipedia, the free encyclopedia
Jump to: navigation, search
Classification and external resources
ICD-10 D56.
ICD-9 282.4
MedlinePlus 000587
eMedicine ped/2229 radio/686
MeSH D013789
Thalassemia (also spelled thalassaemia) is an inherited autosomal recessive blood disease. In thalassemia the genetic defect, which could be either mutation or deletion, results in reduced rate of synthesis or no synthesis of one of the globin chains that make up hemoglobin. This can cause the formation of abnormal hemoglobin molecules, thus causing anemia, the characteristic presenting symptom of the thalassemias.
Thalassemia is a quantitative problem of too few globins synthesized, whereas sickle-cell anemia (a hemoglobinopathy) is a qualitative problem of synthesis of an incorrectly functioning globin. Thalassemias usually result in underproduction of normal globin proteins, often through mutations in regulatory genes. Hemoglobinopathies imply structural abnormalities in the globin proteins themselves.[1] The two conditions may overlap, however, since some conditions which cause abnormalities in globin proteins (hemoglobinopathy) also affect their production (thalassemia). Thus, some thalassemias are hemoglobinopathies, but most are not. Either or both of these conditions may cause anemia.
The two major forms of the disease, alpha- and beta- (see below), are prevalent in discrete geographical clusters around the world - probably associated with malarial endemicity in ancient times. Alpha is prevalent in peoples of Western African descent, and is nowadays found in populations living in Africa and in the Americas. Beta is particularly prevalent among Mediterranean peoples, and this geographical association was responsible for its naming: Thalassa (θάλασσα) is Greek for the sea, Haema (αἷμα) is Greek for blood. In Europe, the highest concentrations of the disease are found in Greece, coastal regions in Turkey, in particular, Aegean Region such as Izmir, Balikesir, Aydin, Mugla and Mediterranean Region such as Antalya, Adana, Mersin, in parts of Italy, in particular, Southern Italy and the lower Po valley. The major Mediterranean islands (except the Balearics) such as Sicily, Sardinia, Malta, Corsica, Cyprus and Crete are heavily affected in particular. Other Mediterranean people, as well as those in the vicinity of the Mediterranean, also have high rates of thalassemia, including people from the West Asia and North Africa. Far from the Mediterranean, South Asians are also affected, with the world's highest concentration of carriers (16% of the population) being in the Maldives.
The thalassemia trait may confer a degree of protection against malaria, which is or was prevalent in the regions where the trait is common, thus conferring a selective survival advantage on carriers, and perpetuating the mutation. In that respect the various thalassemias resemble another genetic disorder affecting hemoglobin, sickle-cell disease.[2]



[edit] Pathophysiology

Normal hemoglobin is composed of two chains each of α and β globin. Thalassemia patients produce a deficiency of either α or β globin, unlike sickle-cell disease which produces a specific mutant form of β globin.
The thalassemias are classified according to which chain of the hemoglobin molecule is affected. In α thalassemias, production of the α globin chain is affected, while in β thalassemia production of the β globin chain is affected.
β globin chains are encoded by a single gene on chromosome 11; α globin chains are encoded by two closely linked genes on chromosome 16. Thus in a normal person with two copies of each chromosome, there are two loci encoding the β chain, and four loci encoding the α chain. Deletion of one of the α loci has a high prevalence in people of African or Asian descent, making them more likely to develop α thalassemias. β thalassemias are common in Africans, but also in Greeks and Italians.

[edit] Alpha (α) thalassemias

The α thalassemias involve the genes HBA1[3] and HBA2,[4] inherited in a Mendelian recessive fashion. There are two gene loci and so four alleles. It is also connected to the deletion of the 16p chromosome. α thalassemias result in decreased alpha-globin production, therefore fewer alpha-globin chains are produced, resulting in an excess of β chains in adults and excess γ chains in newborns. The excess β chains form unstable tetramers (called Hemoglobin H or HbH of 4 beta chains) which have abnormal oxygen dissociation curves.

[edit] Beta (β) thalassemias

Beta thalassemias are due to mutations in the HBB gene on chromosome 11 ,[5] also inherited in an autosomal-recessive fashion. The severity of the disease depends on the nature of the mutation. Mutations are characterized as (βo or β thalassemia major) if they prevent any formation of β chains (which is the most severe form of β thalassemia); they are characterized as (β+ or β thalassemia intermedia) if they allow some β chain formation to occur. In either case there is a relative excess of α chains, but these do not form tetramers: rather, they bind to the red blood cell membranes, producing membrane damage, and at high concentrations they form toxic aggregates.

[edit] Delta (δ) thalassemia

As well as alpha and beta chains being present in hemoglobin about 3% of adult hemoglobin is made of alpha and delta chains. Just as with beta thalassemia, mutations can occur which affect the ability of this gene to produce delta chains.

[edit] In combination with other hemoglobinopathies

Thalassemia can co-exist with other hemoglobinopathies. The most common of these are:
  • hemoglobin E/thalassemia: common in Cambodia, Thailand, and parts of India; clinically similar to β thalassemia major or thalassemia intermedia.
  • hemoglobin S/thalassemia, common in African and Mediterranean populations; clinically similar to sickle cell anemia, with the additional feature of splenomegaly
  • hemoglobin C/thalassemia: common in Mediterranean and African populations, hemoglobin C/βo thalassemia causes a moderately severe hemolytic anemia with splenomegaly; hemoglobin C/β+ thalassemia produces a milder disease.

[edit] Cause

Thalassemia has an autosomal recessive pattern of inheritance
α and β thalassemia are often inherited in an autosomal recessive fashion although this is not always the case. Cases of dominantly inherited α and β thalassemias have been reported, the first of which was in an Irish family who had a two deletions of 4 and 11 bp in exon 3 interrupted by an insertion of 5 bp in the β-globin gene. For the autosomal recessive forms of the disease both parents must be carriers in order for a child to be affected. If both parents carry a hemoglobinopathy trait, there is a 25% chance with each pregnancy for an affected child. Genetic counseling and genetic testing is recommended for families that carry a thalassemia trait.
There are an estimated 60-80 million people in the world who carry the beta thalassemia trait alone.[citation needed] This is a very rough estimate and the actual number of thalassemia major patients is unknown due to the prevalence of thalassemia in less developed countries.[citation needed] Countries such as India and Pakistan are seeing a large increase of thalassemia patients due to lack of genetic counseling and screening.[citation needed] There is growing concern that thalassemia may become a very serious problem in the next 50 years, one that will burden the world's blood bank supplies and the health system in general.[citation needed] There are an estimated 1,000 people living with thalassemia major in the United States and an unknown number of carriers.[citation needed] Because of the prevalence of the disease in countries with little knowledge of thalassemia, access to proper treatment and diagnosis can be difficult.[citation needed]

[edit] Treatment

Patients with thalassemia minor usually do not require any specific treatment.[citation needed] Treatment for patients with thalassemia major includes chronic blood transfusion therapy, iron chelation, splenectomy, and allogeneic hematopoietic transplantation.[citation needed]

[edit] Medication

Medical therapy for beta thalassemia primarily involves iron chelation. Deferoxamine is the intravenously or subcutaneously administered chelation agent currently approved for use in the United States. Deferasirox (Exjade) is an oral iron chelation drug also approved in the US in 2005. Deferoprone is an oral iron chelator that has been approved in Europe since 1999 and many other countries. It is available under compassionate use guidelines in the United States.
The antioxidant indicaxanthin, found in beets, in a spectrophotometric study showed that indicaxanthin can reduce perferryl-Hb generated in solution from met-Hb and hydrogen peroxide, more effectively than either Trolox or Vitamin C. Collectively, results demonstrate that indicaxanthin can be incorporated into the redox machinery of β-thalassemic RBC and defend the cell from oxidation, possibly interfering with perferryl-Hb, a reactive intermediate in the hydroperoxide-dependent Hb degradation.[6]

[edit] Carrier detection

  • A screening policy exists in Cyprus to reduce the incidence of thalassemia, which since the program's implementation in the 1970s (which also includes pre-natal screening and abortion) has reduced the number of children born with the hereditary blood disease from 1 out of every 158 births to almost zero.[7]
  • In Iran as a premarital screening, the man's red cell indices are checked first, if he has microcytosis (mean cell hemoglobin < 27 pg or mean red cell volume < 80 fl), the woman is tested. When both are microcytic their hemoglobin A2 concentrations are measured. If both have a concentration above 3.5% (diagnostic of thalassemia trait) they are referred to the local designated health post for genetic counseling.[8]
In 2008, in Spain, a baby was selectively implanted in order to be a cure for his brother's thalassemia. The child was born from an embryo screened to be free of the disease before implantation with In vitro fertilization. The baby's supply of immunocompatible cord blood was saved for transplantation to his sister. The transplantation was considered successful.[9] In 2009, a group of doctors and specialists in Chennai and Coimbatore registered the successful treatment of thalassemia in a child using a sibling's umbilical cord blood.[10]

[edit] Epidemiology

Generally, thalassemias are prevalent in populations that evolved in humid climates where malaria was endemic. It affects all races, as thalassemias protected these people from malaria due to the blood cells' easy degradation.
Thalassemias are particularly associated with people of Mediterranean origin, Arabs, and Asians.[11] The Maldives has the highest incidence of Thalassemia in the world with a carrier rate of 18% of the population. The estimated prevalence is 16% in people from Cyprus, 1%[12] in Thailand, and 3-8% in populations from Bangladesh, China, India, Malaysia and Pakistan. There are also prevalences in descendants of people from Latin America and Mediterranean countries (e.g. Greece, Italy, Portugal, Spain, and others). A very low prevalence has been reported from people in Northern Europe (0.1%) and Africa (0.9%), with those in North Africa having the highest prevalence. It is also particularly common in populations of indigenous ethnic minorities of Upper Egypt such as the Beja, Hadendoa, Sa'idi and also peoples of the Nile Delta, Red Sea Hill Region and especially amongst the Siwans.

[edit] Benefits

Epidemiological evidence from Kenya suggests another reason: protection against severe anemia may be the advantage.[13]
People diagnosed with heterozygous (carrier) β thalassemia have some protection against coronary heart disease.[14]

[edit] References

  1. ^ Hemoglobinopathies and Thalassemias
  2. ^ Weatherall David J, "Chapter 47. The Thalassemias: Disorders of Globin Synthesis" (Chapter). Lichtman MA, Kipps TJ, Seligsohn U, Kaushansky K, Prchal, JT: Williams Hematology, 8e: http://www.accessmedicine.com/content.aspx?aID=6123722.
  3. ^ Online 'Mendelian Inheritance in Man' (OMIM) 141800
  4. ^ Online 'Mendelian Inheritance in Man' (OMIM) 141850
  5. ^ Online 'Mendelian Inheritance in Man' (OMIM) 141900
  6. ^ Tesoriere L, Allegra M, Butera D, Gentile C, Livrea MA (July 2006). "Cytoprotective effects of the antioxidant phytochemical indicaxanthin in beta-thalassemia red blood cells". Free Radical Research 40 (7): 753–61. doi:10.1080/10715760600554228. PMID 16984002. 
  7. ^ Leung TN, Lau TK, Chung TKh (April 2005). "Thalassaemia screening in pregnancy". Current Opinion in Obstetrics & Gynecology 17 (2): 129–34. doi:10.1097/01.gco.0000162180.22984.a3. PMID 15758603. 
  8. ^ Samavat A, Modell B (November 2004). "Iranian national thalassaemia screening programme". BMJ (Clinical Research Ed.) 329 (7475): 1134–7. doi:10.1136/bmj.329.7475.1134. PMID 15539666. 
  9. ^ Spanish Baby Engineered To Cure Brother
  10. ^ His sister's keeper: Brother's blood is boon of life, Times of India, 17 September 2009
  11. ^ E. Goljan, Pathology, 2nd ed. Mosby Elsevier, Rapid Review Series.
  12. ^ http://www.dmsc.moph.go.th/webrOOt/ri/Npublic/p04.htm
  13. ^ Wambua S, Mwangi TW, Kortok M, et al. (May 2006). "The effect of alpha+-thalassaemia on the incidence of malaria and other diseases in children living on the coast of Kenya". PLoS Medicine 3 (5): e158. doi:10.1371/journal.pmed.0030158. PMID 16605300. 
  14. ^ Tassiopoulos S, Deftereos S, Konstantopoulos K, et al. (2005). "Does heterozygous beta-thalassemia confer a protection against coronary artery disease?". Annals of the New York Academy of Sciences 1054: 467–70. doi:10.1196/annals.1345.068. PMID 16339699. 



14 Desember 2007

Belajar EKG

Belajar EKG gratis sepuasnya? Mau? Boleh mampir kesini.

Memahami EKG dapat kita mulai dengan mempelajari gambaran EKG normal. Kita lihat gambar dibawah.
Gambar I : EKG Normal

Keterangan :
- Garis putus-putus hijau adalah garis isoelektrik.
- Garis putus-putus merah adalah interval PR, durasi normal adalah < 5 kotak kecil (kk) atau < 0,2 detik.
- Garis putus-putus biru adalah kompleks QRS, durasi normal adalah < 3 kk atau < 0,12 detik.
- Garis putus-putus hitam adalah Interval RR.
- Garis Kuning adalah segmen ST.
Gelombang P adalah defleksi positif pertama, gambarnya menyerupai bukit-cembung keatas. Gelembang Q adalah defleksi negatif pertama sebelum gelombang R, bentuknya kerucut menghadap kebawah, tetapi kadang-kadang gelombang ini hampir tidak kelihatan. Gelombang S adalah defleksi negatif pertama setelah gelombang R. Gelombang R sendiri membentuk kerucut yang selalu menghadap keatas, kecuali di lead aVR atau pemasangan elektroda ekstremitasnya terbalik. dan Gelombang T berbentuk seperti bukit letaknya setelah kompleks QRS

Gambar 2 (Lead II)

Beri nama masing-masing gelombang pada gambar 2 seperti contoh !
Hitung durasi interval PR dan kompleks QRS!
Hitung interval RR!
Hitung frekwensi nadi dari gambar diatas dengan cara :
1500 : Interval RR

Gangguan perfusi pada jantung disebabkan adanya penempitan atau sumbatan arteri koroner. Kondisi ini mengakibatkan otot jantung mengalami iskemi, injury bahkan kematian otot jantung. Pada sadapan EKG ditunjukan dengan perubahan segmen ST, gelombang T yang terbalik, dan gelombang Q Patologi. Gelombang T terbalik yang dikenal dengan T Inversi menunjukan kondisi otot jantung yang kekurangan oksigen atau iskemi, Q Patologi menunjukkan kematian otot jantung (old infark) sedangkan ST depresi dan ST elevasi menunjukan otot jantung sedang mengalami injuri menuju kematian (Infark akut). Pada pembahasan berikutnya kita akan melakukan latihan mengenal gangguan perfusi.

1. Mengenal gangguan perfusi.
Gambar 3 (Perubahan segmen ST)

a. ST elevasi (segmen ST berada diatas garis isoelektrik) artinya otot jantung sedang mengalami infark yang akut(baca:serangan jantung), dapat dilihat di lead II, III dan AVF pada gambar 3.
b. ST depresi (segmen ST dibawah garis isoelektrik) artinya sama dengan ST elevasi hanya kedalaman infarknya yang berbeda. Pada ST elevasi otot yang infark meliputi otot jantung dalam sampai yang terluar (disebut Transmural) sedangkan pada ST Depresi otot yang kena infark "hanya" meliputi otot jantung bagian dalam (subendocardial). ST depresi dapat dilihat di lead I dan aVL.

2. Menentukan lokasi yang terkena gangguan.
Gambar 4 (Lokasi Kelainan)

Keterangan :
Lead-lead yang berada diblok biru muda memproyeksikan kondisi jantung area Depan (Anterior) yakni Lead V1 sd V4, Lead yang berada diblok warna merah muda memproyeksikan kondisi jantung area kiri (Lateral) yakni Lead I, V5 dan V6, dan lead yang berada diblok warna kuning memproyeksikan kondisi jantung area bawah (inferior) yakni II, III dan aVF. Sedangkan lead aVR jarang dihiraukan.
Contoh : Bila kita melihat gambaran ST Elevasi di lead I, aVL, V5, dan V6 artinya terdapat "Infark Akut" di otot jantung sebelah kiri (Baca: Infark Akut Lateral kiri)

Kita lihat kembali Gambar 3.
Disana terdapat ST Elevasi di lead II, III dan aVF, maknanya kondisi jantung sebelah bawah sedang mengalami "injuri" disebut Infark Akut Inferior.
ST depresi di lead I dan aVL artinya terdapat kematian akut otot jantung subendocardial yang lokasinya berada di sebelah bawah jantung, disebut Non ST Elevasi Miocardial Infarction (Non STEMI)inferior.

Segini aja dulu belajar EKGnya, kalo masih binun, boleh kok posting pertanyaannya kesini. Mudah-mudahan bisa dijawab, terima kasih.

belajar EKG

        Kebanyakan para perawat kita ahli dalam pemasangan EKG, tapi sebagian  besar dari mereka tidak tahu apa itu EKG, cara membaca dan bahkan lokasi pemasangan yang benar. Berikut sedikit tutorial yang dapat saya berikan.
        Saya sajikan dalam bahasa sederhana, sehingga mudah dipahami, untuk mempelajari lebih mendalam silahkan baca buku dan jangan malas untuk membaca.

        Modul lengkap EKG dalam English ada di terakhir halaman, silahkan di Download (Gratis).
1.       Pendahuluan 
Elektrokardiografi adalah ilmu yang mempelajari aktifitas listrik jantung. Sedangkan Elektrokardiogram (EKG) adalah suatu grafik yang menggambarkan rekaman listrik jantung. Kegiatan listrik jantung dalam tubuh dapat dicatat dan direkam melalui elektroda-elektroda yang dipasang pada permukaan tubuh.
Prinsip utama belajar EKG adalah mengetahui anatomi fisiologi jantung, dan persyarafan jantung sehingga pada saat belajar EKG sudah dapat membayangkan keadaan jantung. 

2.    Anatomi Fisiologi Jantung
       Jantung terdiri dari 4 bagian yaitu atrium (dextra & sinistra) & ventrikel (dextra & sinistra). Jantung mempunyai aktifitas listrik meliputi: Sino Atrio Nodus, Atrio Ventrikuler Nodus, Berkas His dan Serabut Purkinje, inilah point penting dalam pembacaan EKG.
        Lihat gambar dibawah bagaimana aktifitas listrik jantung bekerja:
   Gambar 1     normal
4.     EKG Normal
        Bagaimana sih gambaran EKG normal ?
       Pada dasarnya EKG terdiri dari banyak gelombang, yang tiap gelombang mewakilkan satu denyut jantung (satu kali aktifitas listrik jantung).
        Lihat gambar satu gelombang EKG:
Gambar 2        608px-sinusrhythmlabels_svg
        Dalam satu gelombang EKG terdiri ada yang disebut titik (lihat gambar), interval dan segmen. Titik terdiri dari titik P, Q, R, S, T dan U (kadang sebagian referensi tidak menampilkan titik U) sedangkan Interval terdiri dari PR interval, QRS interval dan QT interval dan Segmen terdiri dari PR segmen, dan ST segmen.              
        Penjelasan gambar :
        -  Titik P mempunyai arti bahwa terjadinya denyutan/kontraksi pada atrium jantung      (dextra & sinistra)
        -  Titik Q, R dan S mempunyai arti bahwa terjadinya denyutan/kontraksi (listrik)      pada ventrikel jantung     (dextra & sinistra)
         –  Sedangkan titik T berarti relaksasi pada ventikel jantung.

         Mungkin terlihat mudah belajar EKG dengan satu gelombang, coba lihat gambar di bawah:

Gambar 3 EKG 12 sadapan normal

       Gambar 3 adalah gambar EKG sebenarnya, melihat sepintas mungkin ga kebayang bisa membacanya.
        Kok ada tulisan I, II, aVR dan lain-lain ?
        I, II, aVR dan lain-lain disebut dengan sadapan atau lead. Aktifitas listrik jantung hanya dapat direkam dari luar jantung (yaitu tubuh), ga mungkin langsung di tempelin ke jantung toh ? makanya perlu lokasi-lokasi tertentu untuk penyadapan tersebut.
       Pada prinsipnya ada 3 jenis sadapan yaitu Prekordial (dada), Bipolar (Kaki dan Tangan 2 elektroda)  dan Unipolar (Kaki dan Tangan 3 elektroda).

5.       Sandapan (lokasi penempatan) EKG
Untuk memperoleh rekaman EKG dipasang elektroda-elektroda di kulit pada tempat-tempat tertentu. Lokasi penempatan elektroda sangat penting diperhatikan, karena penempatan yang salah akan menghasilkan pencatatan yang berbeda.

Gambar  4 Pemasangan Lead EKG

Terdapat 3 jenis sandapan (lead) pada EKG, yaitu :

a.     Sadapan Prekordial
         Merupakan sadapan V1, V2, V3, V4, V5, dan V6 yang ditempatkan secara   langsung di dada.       
         -  Sadapan V1 ditempatkan di ruang intercostal IV di kanan sternum.
                 -  Sadapan V2 ditempatkan di ruang intercostal IV di kiri sternum.
                 -  Sadapan V3 ditempatkan di antara sadapan V2 dan V4.
                 -  Sadapan V4 ditempatkan di ruang intercostal V di linea (sekalipun detak                     apeks berpindah).
                 -  Sadapan V5 ditempatkan secara mendatar dengan V4 di linea axillaris                      anterior.
                 -  Sadapan V6 ditempatkan secara mendatar dengan V4 dan V5 di linea                      midaxillaris.

b.       Sandapan Bipolar,
 Merekam perbedaan potensial dari 2 elektroda, yang ditandai dengan angka romawi I, II dan III
 a)  Sandapan I     :  merekam beda potensial antara tangan kanan (RA)                             yang  bermuatan negatif (-) tangan kiri bermuatan positif                             (+).
 b)    Sandapan II   :  merekam beda potensial antara tangan kanan (-) dengan                            kaki   kiri (LF) yang bermuatan (+)
 c)    Sandapan III  : merekam beda potensial antara tangan kiri (LA)                           yang  bermuatan (-) dan kaki kiri (+). 
b.       Sandapan Unipolar
a)       Sandapan Unipolar Ekstremitas
·         aVR      :   merekam potensial listrik pada tangan kanan (RA) yang                   bermuatan (+),  dan  elektroda (-)  gabungan  tangan kiri                   dan kaki kiri membentuk elektroda indifiren.
·         aVL     :    merekam potensial listrik pada tangan kiri (LA) yang                  bermuatan (+), dan  muatan (-) gabungan  tangan kanan                  dan kaki kiri membentuk elektroda  indifiren.
·         aVF      :  merekam potensial listrik pada kaki kiri (LF) yang                  bermuatan (+) dan elektroda (-) dari gabungan                  tangan kanan dan kaki kiri membentuk elektroda indifiren.  

 Klik disini untuk download

Be the first to like this post.


  1. Good Information.
  2. Semangat!perdalem lg ilmunya..jadilah perawat yg bukan hanya bs merawat..tp jg mengobati..
    • Bukan mengobati, itu haknya dokter. Tapi mempunyai ilmu tersendiri sehingga diakui di dunia Intelektual.