Hypertrophic cardiomyopathy

From Wikipedia, the free encyclopedia

Jump to: navigation, search
Hypertrophic cardiomyopathy
Classification and external resources
ICD-10 I42.1-I42.2
ICD-9 425.4
OMIM 192600
DiseasesDB 6373
MedlinePlus 000192
eMedicine med/290  ped/1102 radio/129
MeSH D002312

Hypertrophic cardiomyopathy, HCM or HOCM, is a disease of the myocardium (the muscle of the heart) in which a portion of the myocardium is hypertrophied (thickened) without any obvious cause.[1][2][3][4][5][6] It is perhaps most famous as a leading cause of sudden cardiac death in young athletes [7] The occurrence of hypertrophic cardiomyopathy is a significant cause of sudden unexpected cardiac death in any age group and as a cause of disabling cardiac symptoms.

A cardiomyopathy is a primary disease that affects the muscle of the heart. With hypertrophic cardiomyopathy (HCM), the sarcomeres (contractile elements) in the heart replicate causing heart muscle cells to increase in size and so the heart muscle to thicken. In addition, the normal alignment of muscle cells is disrupted, a phenomenon known as myocardial disarray. HCM also causes disruptions of the electrical functions of the heart. HCM is most commonly due to a mutation in one of 9 sarcomeric genes that results in a mutated protein in the sarcomere, the primary component of the myocyte (the muscle cell of the heart).

While most literature so far focuses on European, American, and Japanese populations, HCM appears in all racial groups. The incidence of HCM is about 0.2% to 0.5% of the general population.

Contents

[edit] Obstructive and non-obstructive

Depending on whether the distortion of normal heart anatomy causes an obstruction of the outflow of blood from the left ventricle of the heart, HCM can be defined as obstructive or non-obstructive.

  • The obstructive variant of HCM, Hypertrophic obstructive cardiomyopathy (HOCM) has also historically been known as idiopathic hypertrophic subaortic stenosis (IHSS) and asymmetric septal hypertrophy (ASH).
  • Another, non-obstructive variant of HCM is apical hypertrophic cardiomyopathy[8], first described in individuals of Japanese descent).

[edit] Genetics

Hypertrophic cardiomyopathy is inherited as an autosomal dominant trait and is attributed to mutations in one of a number of genes that encode for one of the sarcomere proteins including:

Gene Locus Type
MYH7 14q12 CMH1
TNNT2 1q32 CMH2
TPM1 15q22.1 CMH3 (115196)
MYBPC3 11p11.2 CMH4 (115197)
 ?  ? CMH5
PRKAG2 7q36 CMH6 (600858)
TNNI3 19q13.4 CMH7
MYL3 3p CMH8 (608751)
TTN 2q24.3 CMH9
MYL2 12q23-q24 CMH10
ACTC1 15q14 CMH11 (612098)
CSRP3 11p15.1 CMH12 (612124)

About 50-60% of patients with a high index of clinical suspicion for HCM will have a mutation identified in at least 1 of 9 sarcomeric genes. Approximately 45% of these mutations occur in the β myosin heavy chain gene on chromosome 14 q11.2-3, while approximately 35% involve the cardiac myosin binding protein C gene. Since HCM is typically an autosomal dominant trait, children of an HCM have 50% chance of inheriting the disease-causing mutation. Whenever a mutation is identified through genetic testing, family-specific genetic testing can be used to identify relatives at-risk for the disease (HCM Genetic Testing Overview). In individuals without a family history of HCM, the most common cause of the disease is a de novo mutation of the gene that produces the β-myosin heavy chain.

An insertion/deletion polymorphism in the gene encoding for angiotensin converting enzyme (ACE) alters the clinical phenotype of the disease. The D/D (deletion/deletion) genotype of ACE is associated with more marked hypertrophy of the left ventricle and may be associated with higher risk of adverse outcomes [9] [10].

[edit] Anatomic characteristics

Individuals with HCM have some degree of left ventricular hypertrophy. Usually this is an asymmetric hypertrophy, involving the inter-ventricular septum, and is known as asymmetric septal hypertrophy (ASH). This is in contrast to the concentric hypertrophy seen in aortic stenosis or hypertension. About two-thirds of individuals with HCM have asymmetric septal hypertrophy.

About 25% of individuals with HCM demonstrate an obstruction to the outflow of blood from the left ventricle during rest. In other individuals obstruction only occurs under certain conditions. This is known as dynamic outflow obstruction, because the degree of obstruction is variable and is dependent on the amount of blood in the ventricle immediately before ventricle systole (contraction).

[edit] Dynamic outflow obstruction
Systolic anterior motion of the mitral valve
Hypertrophic Cardiomyopathy - Echocardiogram - Sam.ogg
Echocardiogram demonstrating systolic anterior motion of the anterior leaflet of the mitral valve
Problems listening to this file? See media help.

Dynamic outflow obstruction (when present in HCM) is usually due to systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. Systolic anterior motion of the mitral valve (SAM) was initially thought to be due to the septal subaortic bulge, narrowing the outflow tract, causing high velocity flow and a Venturi effect—a local underpressure in the outflow tract. Low pressure was thought to suck the mitral valve anteriorly into the septum. But SAM onset is observed to be a low velocity phenomenon: SAM begins at velocities no different from those measured in normals [11] [12]. Hence, the magnitude and importance of Venturi forces in the outflow tract are much less than previously thought, and Venturi forces cannot be the main force that initiates SAM.

Recent echocardiographic evidence indicates that drag, the pushing force of flow is the dominant hydrodynamic force on the mitral leaflets [11] [12] [13] [14] [15] [16]. In obstructive HCM the mitral leaflets are often large [17] and are anteriorly positioned in the LV cavity [11] [18] due to anteriorly positioned papillary muscles[11] that at surgery are often "agglutinated" onto the LV anterior wall by abnormal attachments [15] [16].

The mid-septal bulge aggravates the malposition of the valve and redirects outflow so that it comes from a lateral and posterior direction[13]. The abnormally directed outflow may be visualized behind and lateral to the enlarged mitral valve, where it catches it, and pushes it into the septum [11] [12] [13] [14]. There is a crucial overlap between the inflow and outflow portions of the left ventricle [19]. As SAM progresses in early systole the angle between outflow and the protruding mitral leaflet increases. A greater surface area of the leaflets is now exposed to drag which amplifies the force on the leaflets – drag increases with increasing angle relative to flow[13]. An analogy is an open door in a drafty corridor: the door starts by moving slowly and then accelerates as it presents a greater surface area to the wind and finally it slams shut. The necessary conditions that predispose to SAM are: anterior position of the mitral valve in the LV, altered LV geometry that allows flow to strike the mitral valve from behind, and chordal slack [11] [12] [13] [14]. SAM may considered anteriorly directed mitral prolapse [12] [13] [14]. In both conditions the mitral valve is enlarged and is displaced in systole by the pushing force of flow resulting in mitral regurgitation.

Because the mitral valve leaflet doesn't get pulled into the LVOT until after the aortic valve opens, the initial upstroke of the arterial pulse will be normal. When the mitral valve leaflet gets pushed into the LVOT, the arterial pulse will momentarily collapse and be followed by a second rise, as the left ventricular pressure overcomes the increased obstruction that SAM of the mitral valve causes. This can be seen on the physical examination as a double tap upon palpation of the apical impulse and as a double pulsation upon palpation of the carotid pulse, known as pulsus bisferiens.

[edit] Associated symptoms

The clinical course of HCM is variable. Many patients are asymptomatic or mildly symptomatic. The symptoms of HCM include dyspnea (shortness of breath), chest pain (sometimes known as angina), uncomfortable awareness of the heart beat (palpitations), lightheadedness, fatigue, fainting (called syncope) and sudden cardiac death. Dyspnea is largely due to increased stiffness of the left ventricle, which impairs filling of the ventricles and leads to elevated pressure in the left ventricle and left atrium. Symptoms are not closely related to the presence or severity of an outflow tract gradient.[20] Often, symptoms mimic those of congestive heart failure (esp. activity intolerance & dyspnea), but it must be noted that treatment is very different. To treat with diuretics (a mainstay of CHF treatment) will exacerbate symptoms in hypertrophic cardiomyopathy by decreasing ventricular volume and increasing outflow resistance.

Risk factors for sudden death in individuals with HCM include a young age at first diagnosis (age < 30 years), an episode of aborted sudden death, a family history of HCM with sudden death of relatives, specific mutations in the genes encoding for troponin T and myosin, sustained supraventricular or ventricular tachycardia, ventricular septal wall thickness over 3cm, hypotensive response to exercise, recurrent syncope (especially in children), and bradyarrhythmias (slow rhythms of the heart).[21]

[edit] Physical examination

Differentiating hypertrophic cardiomyopathy and valvular aortic stenosis
  Aortic stenosis Hypertrophic cardiomyopathy
Echocardiography
Aortic valve calcification Common No
Dilated ascending aorta Common Rare
Ventricular hypertrophy Concentric LVH Asymmetric, often involving the septum
Physical examination
Murmur of AI Common No
Pulse pressure after PVC Increased Decreased
Valsalva maneuver Decreased intensity of murmur Increased intensity of murmur
Carotid pulsation Normal or tardus et parvus Brisk, jerky, or bisferiens pulse (a collapse of the pulse followed by a secondary rise)

The physical findings of HCM are associated with the dynamic outflow obstruction that is often present with this disease.

Upon auscultation, the cardiac murmur will sound similar to the murmur of aortic stenosis. However, a murmur due to HCM will increase in intensity with any maneuver that decreases the volume of blood in the left ventricle (such as standing or the strain phase of a Valsalva maneuver).

If dynamic outflow obstruction exists, physical examination findings that can be elicited include the pulsus bisferiens and the double apical impulse with each ventricular contraction. These findings, when present, can help differentiate HCM from aortic stenosis. In addition, if the individual has premature ventricular contractions (PVCs), the change in the carotid pulse intensity in the beat after the PVC can help differentiate HCM from aortic stenosis. In individuals with HCM, the pulse pressure will decrease in the beat after the PVC, while in aortic stenosis, the pulse pressure will increase.

[edit] Diagnostic testing

A diagnosis of hypertrophic cardiomyopathy is based upon a number of features of the disease process. While there is use of echocardiography, cardiac catheterization, or cardiac MRI in the diagnosis of the disease, other important factors include ECG and genetic test findings and if there is any family history of HCM or unexplained sudden death in otherwise healthy individuals.

[edit] Cardiac catheterization

Pressure tracings demonstrating the Brockenbrough–Braunwald–Morrow sign
AO = Descending aorta; LV = Left ventricle; ECG = Electrocardiogram.
After the third QRS complex, the ventricle has more time to fill. Since there is more time to fill, the left ventricle will have more volume at the end of diastole (increased preload). Due to the Frank–Starling law of the heart, the contraction of the left ventricle (and pressure generated by the left ventricle) will be greater on the subsequent beat (beat #4 in this picture). Because of the dynamic nature of the outflow obstruction in HCM, the obstruction increases more than the left ventricular pressure increase. This causes a fall in the aortic pressure as the left ventricular pressure rises (seen as the yellow shaded area in the picture).

Upon cardiac catheterization, catheters can be placed in the left ventricle and the ascending aorta, to measure the pressure difference between these structures. In normal individuals, during ventricular systole, the pressure in the ascending aorta and the left ventricle will equalize, and the aortic valve is open. In individuals with aortic stenosis or with HCM with an outflow tract gradient, there will be a pressure gradient (difference) between the left ventricle and the aorta, with the left ventricular pressure higher than the aortic pressure. This gradient represents the degree of obstruction that has to be overcome in order to eject blood from the left ventricle.

The Brockenbrough–Braunwald–Morrow sign is observed in individuals with HCM with outflow tract gradient. This sign can be used to differentiate HCM from aortic stenosis. In individuals with aortic stenosis, after a premature ventricular contraction (PVC), the following ventricular contraction will be more forceful, and the pressure generated in the left ventricle will be higher. Because of the fixed obstruction that the stenotic aortic valve represents, the post-PVC ascending aortic pressure will increase as well. In individuals with HCM, however, the degree of obstruction will increase more than the force of contraction will increase in the post-PVC beat. The result of this is that the left ventricular pressure increases and the ascending aortic pressure decreases, with an increase in the LVOT gradient.

While the Brockenbrough–Braunwald–Morrow sign is most dramatically demonstrated using simultaneous intra-cardiac and intra-aortic catheters, it can be seen on routine physical examination as a decrease in the pulse pressure in the post-PVC beat in individuals with HCM.

[edit] Treatment

In all patients with hypertrophic cardiomyopathy risk stratification is essential to attempt to ascertain which patients are at risk for sudden cardiac death.[2][5] In those patients deemed to be at high risk the benefits and infrequent complications of defibrillator therapy are discussed; devices have been implanted in as many as 15% of patients at HCM centers. Treatment of symptoms of obstructive HCM is directed towards decreasing the left ventricular outflow tract gradient and symptoms of dyspnea, chest pain and syncope. Medical therapy is successful in the majority of patients. The first medication that is routinely used is a beta-blocker (metoprolol, atenolol, bisoprolol, propranolol).[2] If symptoms and gradient persist, disopyramide may be added to the beta-blocker.[22] Alternately a calcium channel blocker such as verapamil may be substituted for a beta blocker. It should be stressed that most patients' symptoms may be managed medically without needing to resort to inteventions such as surgical septal myectomy, alcohol septal ablation or pacing. Severe symptoms in non-obstructive HCM may actually be more difficult to treat because there is no obvious target (obstruction) to treat. Medical therapy with verapamil and beta-blockade may improve symptoms. Diuretics should be avoided, as they reduce the intravascular volume of blood, decreasing the amount of blood available to distend the left ventricular outflow tract, leading to an increase in the obstruction to the outflow of blood in the left ventricle.[23]

[edit] Surgical myectomy

Surgical septal myectomy is an open heart operation done to relieve symptoms in patients who remain severely symptomatic despite medical therapy.[2][3][5][6][22][24] It has been performed successfully for more than 25 years. Surgical septal myectomy uniformly decreases left ventricular outflow tract obstruction and improves symptoms, and in experienced centers has a surgical mortality of 1%. It involves a median sternotomy (general anesthesia, opening the chest, and cardiopulmonary bypass) and removing a portion of the interventricular septum.[2] Surgical myectomy resection focused just on the subaortic septum, to increase the size of the outflow tract to reduce Venturi forces may be inadequate to abolish systolic anterior motion (SAM) of the anterior leaflet of the mitral valve. With this limited sort of resection the residual mid-septal bulge still redirects flow posteriorly: SAM persists because flow still gets behind the mitral valve. It is only when the deeper portion of the septal bulge is resected that flow is redirected anteriorly away from the mitral valve, abolishing SAM.[3][25] With this in mind, a modification of the Morrow myectomy termed extended myectomy, mobilization and partial excision of the papillary muscles has become the excision of choice.[3][15][16][26] In selected patients with particularly large redundant mitral valves, anterior leaflet plication may be added to complete separation of the mitral valve and outflow.[26][27]

[edit] Alcohol septal ablation

Alcohol septal ablation, introduced by Ulrich Sigwart in 1994, is a percutaneous technique that involves injection of alcohol into one or more septal branches of the left anterior descending artery. This is a technique with results similar to the surgical septal myectomy procedure but is less invasive, since it does not involve general anaesthesia and opening of the chest wall and pericardium (which are done in a septal myomectomy). In a select population with symptoms secondary to a high outflow tract gradient, alcohol septal ablation can reduce the symptoms of HCM. In addition, older individuals and those with other medical problems, for whom surgical myectomy would pose increased procedural risk, would likely benefit from the lesser invasive septal ablation procedure.[2][5][28]

When performed properly, an alcohol septal ablation induces a controlled heart attack, in which the portion of the interventricular septum that involves the left ventricular outflow tract is infarcted and will contract into a scar. Which patients are best served by surgical myectomy, alcohol septal ablation, or medical therapy is an important topic and one which is intensely debated in medical scientific circles.[29]

[edit] Ventricular pacing

The use of a pacemaker has been advocated in a subset of individuals, in order to cause asynchronous contraction of the left ventricle. Since the pacemaker activates the interventricular septum before the left ventricular free wall, the gradient across the left ventricular outflow tract may decrease. This form of treatment has been shown to provide less relief of symptoms and less of a reduction in the left ventricular outflow tract gradient when compared to surgical myectomy.[30]

[edit] Cardiac transplantation

In cases that are refractory to all other forms of treatment, cardiac transplantation is an option.

[edit] Related disorders

Feline hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats; the disease process and genetics are believed to be similar to the disease in humans.[31] In Maine Coon and American Shorthair cat breeds, HCM has been confirmed as an autosomal dominant inherited trait.[32] The first genetic mutation (in cardiac myosin binding protein C) responsible for feline hypertrophic cardiomyopathy was discovered in 2005 in Maine Coon cats.[33] A test for this mutation is available.[34] About one third of Maine Coon cats tested for the mutation have been shown to be either heterozygous or homozygous for the mutation, although many of these cats have no clinical signs of the disease. Some Maine Coon cats with clinical evidence of hypertrophic cardiomyopathy test negative for this mutation, strongly suggesting that a second mutation exists in the breed. The cardiac myosin binding protein C mutation identified in Maine Coon cats has not been found in any other breed of cat with HCM but more recently another myosin binding protein C mutation has been identified in Ragdoll cats with HCM.[35]

While there is no cure for HCM, early detection and regular echocardiograms are key to trying to ward off life-threatening problems. Early signs may include a murmur or even heart failure. Unfortunately, death may occur without any other signs present, making the disease a difficult and often deadly one. While medication is commonly given to cats with HCM that have no clinical signs, no medication has been shown to be helpful at this stage and it has been shown that an ACE inhibitor is not beneficial until heart failure is present (at which time a diuretic is most beneficial). Diltiazem generally produces no demonstrable benefit. Atenolol is commonly administered when systolic anterior motion of the mitral valve is present.

Thromboembolic disease (TED) is relatively common sequel to Feline HCM. The aetiology remains a little uncertain, but it is thought that ischaemic damage to the hypertrophied left ventricular myocardium facilitates thrombus formation and subsequent embolism. Classically the embolus lodges at the iliac bifurcation of the aorta, occluding either one or both of the common iliac arteries. Clinically this presents as a cat with complete loss of function in one or both hindlimbs. The hindlimbs are cold, and the cat is in considerable pain. This pain derives from the exaggerated inflammatory response to the embolus at the point of impact, and the inflammatory mediators released generally have a vasoconstrictor effect further exacerbating the problem. Emboli may, rarely, lodge in other locations, typically the renal or ovarian/testicular arteries as they exit the abdominal aorta.

Treatment of TED is viable - typically very low doses of aspirin may be prescribed (it should be noted however that aspirin is extremely toxic to cats and should under no circumstances be given to them for pain relief under other circumstances, and should in any case only be prescribed and administered by a veterinary surgeon). Tissue Plasminogen Activators (e.g. Streptokinase) have been used successfully, but their cost is usually prohibitively high in veterinary medicine. Despite the relative efficacy of treatment, the prognosis for cats with TED is poor as they are likely to have significant HCM already, and a recurrent bout of TED is very likely. For this reason euthanasia is often considered in TED cats.

[edit] HCM in popular culture

[edit] Notable people

Miklós "Miki" Fehér a Hungarian football player died during a match with his team SL Benfica against Vitória Guimarães, on January 25, 2004. Marc-Vivien Foé is believed to have died due to hypertrophic cardiomyopathy.

Other noted athletes believed or suspected to have died from HCM include NFL players Thomas Herrion, Mitch Frerotte, Damien Nash, and Derrick Faison; NBA players Reggie Lewis, Jason Collier, and Kevin Duckworth; NHL player Sergei Zholtok; baseball pitcher Joe Kennedy; long distance runner Ryan Shay; Loyola Marymount basketball star Hank Gathers; Kansas State football player Anthony Bates; OHL Windsor Spitfires player Mickey Renaud; and Russian hockey star Alexei Cherepanov.

On December 10, 2008, NBA player Cuttino Mobley announced his retirement due to worsening HCM.[36]

Famous British comedy actor Leonard Rossiter died from hypertrophic cardiomyopathy in 1984 while waiting to go onstage at the Lyric Theatre, London.

Jesse Marunde, an American strongman, died of HCM in 2007 after a workout at his gym.

[edit] Fictional characters

In the CW television show One Tree Hill, characters Dan and Lucas Scott have HCM.

Vivian Johnson on Without a Trace also has HCM.

On the TV series Scrubs, in the first episode involving Jordan, Dr. Kelso tells JD to run tests to check her for HCM.

One of the players in Glory Road was benched with HCM.

The main character of the 1997 film The Sixth Man, Antoine Taylor, played by actor Kadeem Hardison, died from HCM.

In the Australian TV series Love My Way, Frankie and Charlie's daughter, Lou, dies suddenly from HCM.

In an episode of Eli Stone (10/21/2008) the character Grace Fuller played by Katie Holmes has HCM.

[edit] References

  1. ^ Richardson P, McKenna W, Bristow M, et al (Mar 1996). "Report of the 1995 World Health Organization/International Society and Federation of Cardiology Task Force on the Definition and Classification of cardiomyopathies". Circulation 93 (5): 841–2. PMID 8598070. http://circ.ahajournals.org/cgi/content/full/93/5/841. 
  2. ^ a b c d e f Maron BJ (Mar 2002). "Hypertrophic cardiomyopathy: a systematic review". JAMA 287 (10): 1308–20. doi:10.1001/jama.287.10.1308. PMID 11886323. http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=11886323. 
  3. ^ a b c d Sherrid MV, Chaudhry FA, Swistel DG (Feb 2003). "Obstructive hypertrophic cardiomyopathy: echocardiography, pathophysiology, and the continuing evolution of surgery for obstruction". Ann Thorac Surg. 75 (2): 620–32. doi:10.1016/S0003-4975(02)04546-0. PMID 12607696. 
  4. ^ Wigle ED, Sasson Z, Henderson MA, et al (1985). "Hypertrophic cardiomyopathy. The importance of the site and the extent of hypertrophy. A review". Prog Cardiovasc Dis. 28 (1): 1–83. doi:10.1016/0033-0620(85)90024-6. PMID 3160067. http://linkinghub.elsevier.com/retrieve/pii/0033-0620(85)90024-6. 
  5. ^ a b c d Wigle ED, Rakowski H, Kimball BP, Williams WG (Oct 1995). "Hypertrophic cardiomyopathy. Clinical spectrum and treatment". Circulation 92 (7): 1680–92. PMID 7671349. http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=7671349. 
  6. ^ a b Maron BJ, McKenna WJ, Danielson GK, et al (Nov 2003). "American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines". J Am Coll Cardiol 42 (9): 1687–713. PMID 14607462. http://linkinghub.elsevier.com/retrieve/pii/S0735109703009410. 
  7. ^ Maron BJ, Thompson PD, Puffer JC, et al (Aug 1996). "Cardiovascular preparticipation screening of competitive athletes. A statement for health professionals from the Sudden Death Committee (clinical cardiology) and Congenital Cardiac Defects Committee (cardiovascular disease in the young), American Heart Association". Circulation 94 (4): 850–6. PMID 8772711. http://circ.ahajournals.org/cgi/content/full/94/4/850. 
  8. ^ Rivera-Diaz J, Moosvi AR (Jul 1996). "Apical hypertrophic cardiomyopathy" ([dead link] – Scholar search). South Med J 89 (7): 711–3. PMID 8685759. http://www.sma.org/smj/96jul12.htm. 
  9. ^ Doolan G, Nguyen L, Chung J, Ingles J, Semsarian C (Aug 2004). "Progression of left ventricular hypertrophy and the angiotensin-converting enzyme gene polymorphism in hypertrophic cardiomyopathy". Int J Cardiol 96 (2): 157–63. doi:10.1016/j.ijcard.2004.05.003. PMID 15314809. 
  10. ^ Marian AJ, Yu QT, Workman R, Greve G, Roberts R (Oct 1993). "Angiotensin-converting enzyme polymorphism in hypertrophic cardiomyopathy and sudden cardiac death". Lancet 342 (8879): 1085–6. doi:10.1016/0140-6736(93)92064-Z. PMID 8105312. http://linkinghub.elsevier.com/retrieve/pii/0140-6736(93)92064-Z. 
  11. ^ a b c d e f Jiang L, Levine RA, King ME, Weyman AE (Mar 1987). "An integrated mechanism for systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy based on echocardiographic observations". Am Heart J. 113 (3): 633–44. doi:10.1016/0002-8703(87)90701-0. PMID 3825854. 
  12. ^ a b c d e Sherrid MV, Gunsburg DZ, Moldenhauer S, Pearle G (Oct 2000). "Systolic anterior motion begins at low left ventricular outflow tract velocity in obstructive hypertrophic cardiomyopathy". J Am Coll Cardiol. 36 (4): 1344–54. doi:10.1016/S0735-1097(00)00830-5. PMID 11028493. http://linkinghub.elsevier.com/retrieve/pii/S0735-1097(00)00830-5. 
  13. ^ a b c d e f Sherrid MV, Chu CK, Delia E, Mogtader A, Dwyer EM (Sep 1993). "An echocardiographic study of the fluid mechanics of obstruction in hypertrophic cardiomyopathy". J Am Coll Cardiol. 22 (3): 816–25. PMID 8354817. 
  14. ^ a b c d Levine RA, Vlahakes GJ, Lefebvre X, et al (Feb 1995). "Papillary muscle displacement causes systolic anterior motion of the mitral valve. Experimental validation and insights into the mechanism of subaortic obstruction". Circulation 91 (4): 1189–95. PMID 7850958. http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=7850958. 
  15. ^ a b c Messmer BJ (Aug 1994). "Extended myectomy for hypertrophic obstructive cardiomyopathy". Ann Thorac Surg. 58 (2): 575–7. PMID 8067875. 
  16. ^ a b c Schoendube FA, Klues HG, Reith S, Flachskampf FA, Hanrath P, Messmer BJ (Nov 1995). "Long-term clinical and echocardiographic follow-up after surgical correction of hypertrophic obstructive cardiomyopathy with extended myectomy and reconstruction of the subvalvular mitral apparatus". Circulation 92 (9 Suppl): II122–7. PMID 7586394. 
  17. ^ Klues HG, Maron BJ, Dollar AL, Roberts WC (May 1992). "Diversity of structural mitral valve alterations in hypertrophic cardiomyopathy". Circulation 85 (5): 1651–60. PMID 1572023. 
  18. ^ Henry WL, Clark CE, Griffith JM, Epstein SE (Mar 1975). "Mechanism of left ventricular outlfow obstruction in patients with obstructive asymmetric septal hypertrophy (idiopathic hypertrophic subaortic stenosis)". Am J Cardiol. 35 (3): 337–45. doi:10.1016/0002-9149(75)90025-9. PMID 1167730. 
  19. ^ Schwammenthal E, Levine RA (Jul 1996). "Dynamic subaortic obstruction: a disease of the mitral valve suitable for surgical repair?". J Am Coll Cardiol. 28 (1): 203–6. doi:10.1016/0735-1097(96)00213-6. PMID 8752815. http://linkinghub.elsevier.com/retrieve/pii/0735-1097(96)00213-6. 
  20. ^ Bonow R, Braunwald E, Zipes DP, Libby P (2005). "The Cardiomyopathies". Braunwald's heart disease: a textbook of cardiovascular medicine (7th ed.). Philadelphia: WB Saunders. ISBN 1-4160-0014-3. 
  21. ^ Maron BJ, Cecchi F, McKenna WJ (Dec 1994). "Risk factors and stratification for sudden cardiac death in patients with hypertrophic cardiomyopathy". Br Heart J 72 (6 Suppl): S13–8. doi:10.1136/hrt.72.6_Suppl.S13. PMID 7873317. PMC: 1025670. http://heart.bmj.com/cgi/pmidlookup?view=long&pmid=7873317.  and the Task Force on Sudden Cardiac Death of the European Society of Cardiology link Note: Guideline withdraw
  22. ^ a b Sherrid MV, Barac I, McKenna WJ, et al (Apr 2005). "Multicenter study of the efficacy and safety of disopyramide in obstructive hypertrophic cardiomyopathy". J Am Coll Cardiol. 45 (8): 1251–8. doi:10.1016/j.jacc.2005.01.012. PMID 15837258. 
  23. ^ Wynne J, Braunwald E (1997). "Hypertrophic cardiomyopathy". in Braunwald E. Heart disease: a textbook of cardiovascular medicine (5th ed.). Philadelphia: Saunders. ISBN 0-7216-5666-8. 
  24. ^ Morrow AG (Oct 1978). "Hypertrophic subaortic stenosis. Operative methods utilized to relieve left ventricular outflow obstruction". J Thorac Cardiovasc Surg. 76 (4): 423–30. PMID 581298. 
  25. ^ Nakatani S, Schwammenthal E, Lever HM, Levine RA, Lytle BW, Thomas JD (Feb 1996). "New insights into the reduction of mitral valve systolic anterior motion after ventricular septal myectomy in hypertrophic obstructive cardiomyopathy". Am Heart J. 131 (2): 294–300. doi:10.1016/S0002-8703(96)90357-9. PMID 8579024. http://linkinghub.elsevier.com/retrieve/pii/S0002-8703(96)90357-9. 
  26. ^ a b Balaram SK, Sherrid MV, Derose JJ, Hillel Z, Winson G, Swistel DG (Jul 2005). "Beyond extended myectomy for hypertrophic cardiomyopathy: the resection-plication-release (RPR) repair". Ann Thorac Surg. 80 (1): 217–23. doi:10.1016/j.athoracsur.2005.01.064. PMID 15975370. 
  27. ^ McIntosh CL, Maron BJ, Cannon RO, Klues HG (Nov 1992). "Initial results of combined anterior mitral leaflet plication and ventricular septal myotomy-myectomy for relief of left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy". Circulation 86 (5 Suppl): II60–7. PMID 1424035. 
  28. ^ Brilakis ES, Nishimura RA (Jul 2003). "Severe pulmonary hypertension in a patient with hypertrophic cardiomyopathy: response to alcohol septal ablation". Heart 89 (7): 790. doi:10.1136/heart.89.7.790. PMID 12807862. PMC: 1767712. http://heart.bmj.com/cgi/pmidlookup?view=long&pmid=12807862. 
  29. ^ Heldman AW, Wu KC, Abraham TP, Cameron DE (Jan 2007). "Myectomy or alcohol septal ablation surgery and percutaneous intervention go another round". J Am Coll Cardiol. 49 (3): 358–60. doi:10.1016/j.jacc.2006.10.029. PMID 17239718. 
  30. ^ Ommen SR, Nishimura RA, Squires RW, Schaff HV, Danielson GK, Tajik AJ (Jul 1999). "Comparison of dual-chamber pacing versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy: a comparison of objective hemodynamic and exercise end points". J Am Coll Cardiol 34 (1): 191–6. doi:10.1016/S0735-1097(99)00173-4. PMID 10400010. http://linkinghub.elsevier.com/retrieve/pii/S0735109799001734. 
  31. ^ Kittleson M, Meurs K, Munro M, Kittleson J, Liu S, Pion P, Towbin J (1999). "Familial hypertrophic cardiomyopathy in Maine coon cats: an animal model of human disease". Circulation 99 (24): 3172–80. PMID 10377082. 
  32. ^ Cat Fancier's Association, Special Report to the Winn Feline Foundation: Feline Hypertrophic Cardiomyopathy: Advice for Breeders
  33. ^ Meurs K, Sanchez X, David R, Bowles N, Towbin J, Reiser P, Kittleson J, Munro M, Dryburgh K, Macdonald K, Kittleson M (2005). "A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy". Hum Mol Genet 14 (23): 3587–93. doi:10.1093/hmg/ddi386. PMID 16236761. 
  34. ^ Veterinary Cardiac Genetics Laboratory of the College of Veterinary Medicine
  35. ^ Meurs KM, Norgard MM, Ederer MM, Hendrix KP, Kittleson MD (2007). "A substitution mutation in the myosin binding protein C gene in Ragdoll hypertrophic cardiomyopathy". Genomics 90 (2): 261-264. PMID 17521870. 
  36. ^ http://sports.espn.go.com/nba/news/story?id=3762828

[edit] External links

v • d • e
Cardiovascular disease: heart disease · Circulatory system pathology (I00-I52, 390-429)
Ischaemic
Active ischemia
Layers
Valves
Conduction/
arrhythmia
Premature contraction
Flutter/fibrillation
Other/ungrouped
Other
Retrieved from "http://en.wikipedia.org/wiki/Hypertrophic_cardiomyopathy"
Personal tools