Hypertrophic cardiomyopathy overview

https://https://www.youtube.com/watch?v=8RnkKB8xvwA%7C350}}

Hypertrophic Cardiomyopathy Microchapters
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Hypertrophic Cardiomyopathy from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Diagnostic Study of Choice
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
X Ray
Echocardiography and Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Interventions
Surgery
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Hypertrophic cardiomyopathy overview On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Hypertrophic cardiomyopathy overview
CDC on Hypertrophic cardiomyopathy overview
Hypertrophic cardiomyopathy overview in the news
Blogs on Hypertrophic cardiomyopathy overview
Directions to Hospitals Treating Hypertrophic cardiomyopathy
Risk calculators and risk factors for Hypertrophic cardiomyopathy overview

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Soroush Seifirad, M.D.[2]

Overview

Historical Perspective

The first case of hypertrophic cardiomyopathy (HCM) was described by in 1869 Henri Liouville in the Gazette Medecine Paris. In 1907 Dr. A. Schmincke, a German pathologist, described two hearts with left ventricular hypertrophy; both came from women in their mid-fifties. Levy and von Glahn in 1944, from Colombia University in New York, published a series of cases which resembles HCM. In 1949, William Evans, a London cardiologist, described familial occurrence of cardiac hypertrophy in a series of patients which were similar to those described in the paper by Levy and von Glahn. In 1961 Paré et al. reported thirty members of five generations of a French Canadian family in Quebec in whom the condition was inherited in an autosomal dominant manner. In 1958 Teare, an English pathologist, described eight cases of asymmetric cardiac muscle hypertrophy, he thought that they might be benign cardiac tumors. Seven of these caused sudden death in young adults. Teare named the condition “Asymmetrical Hypertrophy of the Heart.” In 1959 Sir Russell Brock described a young man with angina and a subaortic stenosis and a subaortic intraventricular pressure gradient. Morrow and Braunwald published their first report in the same year, followed by several other reports. The sudden cardiac deaths of 387 young American athletes (under age 35) were analyzed in a 2003 medical review, and HCM was the leading cause of sudden cardiac death in athletes. In 1961, Morrow described a surgical procedure to relieve the obstruction, which is still the most widely used method of surgical treatment. In 1962, with respect to the observed intensification of obstruction in HCM with the beta-adrenergic agonists, Braunwald suggested the use of newly developed beta-blockers. In 1964, Braunwald reported beta-blockers beneficial hemodynamic effects. 1967, the clinical benefits of treatment with beta blockers in patients with HCM has been proved to the scientific society.

Classification

Pathophysiology

Causes

Differentiating Hypertrophic Cardiomyopathy from Other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications, and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X-ray

Echocardiography and Ultrasound

CT scan

MRI

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Interventions

Surgery

Primary Prevention

Secondary Prevention

Overview

Hypertrophic cardiomyopathy, or HCM, is a disease of the myocardium (the muscle of the heart) in which a portion of the myocardium is hypertrophied (thickened) without any alternate cause such as hypertension, amyloid or aortic stenosis. Although HCM has gained notoriety as a leading cause of sudden cardiac death in young athletes, it should be noted that HCM is a cause of sudden cardiac death in any age group and may be associated with cardiac morbidity and disabling cardiac symptoms as well.

Variants

There are two variants of hypertrophic cardiomyopathy: an obstructive variant, and a non-obstructive variant. A non-obstructive variant of HCM is known as apical hypertrophic cardiomyopathy ,which is also known as nonobstructive hypertrophic cardiomyopathy and Japanese variant hypertrophic cardiomyopathy or the Yamaguchi variant (since the first cases described were all in individuals of Japanese descent).

Pathophysiology

In hypertrophic cardiomyopathy (HCM), the sarcomeres (contractile elements) in the heart replicate causing heart muscle cells to increase in size, which results in the thickening of the heart muscle. In addition, the normal alignment of muscle cells is disrupted, a phenomenon known as myocardial disarray. Myosin heavy chain mutations are associated with development of familial hypertrophic cardiomyopathy. HCM also causes disruptions of the electrical functions of the heart.

Genetics

Hypertrophic cardiomyopathy is most commonly due to a mutation in one of 14 sarcomeric genes that results in a mutated protein in the sarcomere, the primary component of the myocyte (the muscle cell of the heart).

Epidemiology and Demographcs

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

Screening

HCM is frequently asymptomatic until sudden cardiac death, and for this reason some suggest routinely screening certain populations for this disease.

Diagnosis

Studies which have used heart ultrasound (echo) to check people in the general population have found HCM in approximately 1 in every 500 people (0.2% of the general population). Only 15% of HCM patients have been diagnosed, which means the majority of patients with HCM are undiagnosed.

Symptoms

The symptoms associated with hypertrophic cardiomyopathy are quite variable and range from no symptoms, to the development of heart failure, to the occurrence of sudden cardiac death. The symptoms may vary tremendously from individual even within a family. The timing of symptom onset is quite variable as well and may range from infancy to adulthood. Symptoms may include:

• Chest pain,
• Dizziness,
• Fainting, especially during exercise
• Heart failure (in some patients)
• High blood pressure (hypertension)
• Light-headedness, especially with or after activity or exercise, or when standing up suddenly
• Sensation of feeling the heart beat (palpitations)
• Shortness of breath
• Fatigue
• Reduced activity tolerance
• Shortness of breath when lying down (orthopnea)

Treatment

Medical Therapy

The medical management of the patient with hypertrophic cardiomyopathy involves minimizing diastolic dysfunction, reducing left ventricular outflow tract obstruction, optimizing heart failure management, maintaining normal sinus rhythm, rate control and anticoagulation in the presence of atrial fibrillation, and implantation of an automatic implantable cardiac defibrillator in those patients who survive sudden cardiac death.

Management During Pregnancy

Women with hypertrophic cardiomyopathy should be managed by a skilled cardiovascular specialist and a high-risk obstetrician during pregnancy. Among HCM patients who chronically have mild symptoms, pregnancy is generally well tolerated . Although pregnancy causes vasodilation which should exacerbate the outflow gradient, pregnancy also causes fluid retention and an increase in plasma volume which increases preload and offsets the reduction in afterload. In a series of 100 HCM patients, only one of 28 asymptomatic patients developed NYHA Class III or IV heart failure.

Epidural Anesthesia Should Be Avoided due to the potential for venous pooling. Bleeding should be minimized. Blood should be crossed and typed in case a transfusion is needed for bleeding, which can exacerbate outflow obstruction. Although both beta blockers and verapamil may improve symptoms in the mother, the dosing should be limited to minimize the risk of fetal bradycardia, growth retardation and hypoglycemia. There is more experience with the use beta blockers during pregnancy. Home delivery without IV access is not preferred. Vaginal delivery is usually successful.

References