chapter 24 cardiomyopathy

primary cardiomyopathies

(genetic, nongenetic, and acquired), which are focused primarily on the heart muscle,

HCM

A patient may have pathology representing more than one of these classifications, such as a patient with ___ with restrictive physiology.

inherited storage disease

An __ that can lead to RCM is hemochromatosis, in which iron deposits in the heart lead to cardiac stiffness.

infiltrative disease

An example of an ___ that may cause RCM is amyloidosis, in which amyloid, a misfolded protein, is deposited between cardiomyocytes.

arrhythmogenic cardiomyopathy (ACM)

Because of this typical pathologic progression, there is a move to change the name of this cardiomyopathy to a more general term of ___ to recognize the left ventricular involvement. In patients with ARVC/D, palpitations or syncope may develop between 15 and 40 years of age. Sudden cardiac death may also be the first presentation. Diagnosis is made based on the ECG, echocardiogram, cardiac MRI, and family history. Since this is a genetic disorder, patients that are diagnosed are referred to a genetic counselor for testing. Patients affected by arrhythmias may benefit from having an implantable cardioverter defibrillator (ICD) placed

hypertrophied

Cardiac muscle cells normally lie parallel to and end to end with each other. The ___ cardiac muscle cells are disorganized, oblique, and perpendicular to each other, decreasing the effectiveness of contractions.

endomyocardial

Certain cancer treatments, such as radiation and use of various chemotherapeutic agents (e.g., anthracyclines) can cause ___ damage that leads to RCM. Often, endomyocardial biopsy is needed to determine the etiology; treatment is then directed at the underlying cause.

bleeding disorders, hemorrhage, thromboemboli, hemolysis, infection, kidney injury, right-sided heart failure, multisystem failure, and mechanical failure

Complications of VADs and TAHs include:

hypertrophy and systolic dysfunction

DCM is distinguished by significant dilation of the ventricles without simultaneous ___. The ventricles have elevated systolic and diastolic volumes but a decreased ejection fraction. Microscopic examination of the muscle tissue shows diminished contractile elements (actin and myosin filaments) of the muscle fibers and diffuse necrosis of myocardial cells. The result is poor systolic function. The structural changes decrease the amount of blood ejected from the ventricle with systole, increasing the amount of blood remaining in the ventricle after contraction. Less blood is then able to enter the ventricle during diastole, increasing end-diastolic pressure and eventually increasing pulmonary and systemic venous pressures. Altered valve function, usually regurgitation, can result from an enlarged stretched ventricle. Poor blood flow through the ventricle may also cause ventricular or atrial thrombi, which may embolize to other locations in the body.

biventricular

Each VAD is used to support one ventricle, although in some instances, two VAD pumps may be used for ___ support.

left ventricular noncompaction and stress-induced (Takotsubo) cardiomyopathy

Examples of unclassified cardiomyopathies can include:

biventricular pacing

For some patients with DCM, ___ (also known as cardiac resynchronization therapy or CRT) increases the ejection fraction and reverses some of the structural changes in the myocardium

left ventricular outflow tract (LVOT)

HCM can lead to obstruction of the ___ if there is systolic anterior motion of the mitral valve that abuts the mitral valve against the hypertrophied septum during systole.

positive

If genetic testing is ___ for known HCM genetic mutations, first-degree relatives should also be tested for the genetic mutation found in the patient.

myocardium

In HCM, the coronary arteriole walls are thickened, which decrease the internal diameter of the arterioles. The narrow arterioles restrict the blood supply to the ___, causing numerous small areas of ischemia and necrosis. The necrotic areas of the myocardium ultimately fibrose and scar, further impeding ventricular contraction and possibly increasing the risk of arrhythmias such as ventricular tachycardia and ventricular fibrillation

ECG, physical examination and echocardiogram

In patients that have positive genetic testing, but are asymptomatic for cardiomyopathy, annual screening with an ____ should be done, as the likelihood of clinical progression increases with increasing age. The phenotype typically manifests sometime between adolescence and the fifth decade of life

low sodium diet

It is also important to ensure that the patient receives or chooses food selections that are appropriate for a ___.

DCM

Many patients with ___ find that sitting up with their legs down is more comfortable than lying down in a bed. This position is helpful in pooling venous blood in the periphery and reducing preload.

pregnancy, hypertension, heavy alcohol intake, viral infection (e.g., influenza), chemotherapeutic medications (e.g., daunorubicin, doxorubicin), thyrotoxicosis, myxedema, persistent tachycardia, and Chagas disease.

More than 75 conditions and diseases may cause DCM, including:

syncope, ventricular arrhythmias, dyspnea, and heart failure

Obstruction of the LVOT can lead to ___.

SynCardia TAH

Only one TAH has been approved by the U.S. Food and Drug Administration (FDA) as a bridge to transplant, the ___, and it requires the removal of the patient's heart for implant.

mechanical heart assistance

Patients who cannot be weaned from cardiopulmonary bypass and patients in cardiogenic shock may benefit from a period of ___. The most commonly used device is the intra-aortic balloon pump. This pump decreases the work of the heart during contraction but does not perform the actual work of the heart.

beta-blockers

Patients with HCM should avoid dehydration and may need ___ to maintain cardiac output and minimize the risk of LVOT obstruction during systole. Anticoagulants are no longer routinely prescribed.

HCM, ARVC/D, or RCM

Patients with ___ must avoid strenuous activity, isometric exercises, and competitive sports.

genetic testing

Patients with a suspected diagnosis of HCM should undergo ___; if negative, the diagnosis is not completely ruled out.

Assessment and Diagnostic Findings of CMO

Physical examination at early stages may reveal tachycardia and extra heart sounds (e.g., S3, S4). Patients with DCM may have diastolic murmurs, and patients with DCM and HCM may have systolic murmurs. With disease progression, examination also reveals signs and symptoms of heart failure (e.g., crackles on pulmonary auscultation, jugular vein distention, pitting edema of dependent body parts, hepatomegaly [i.e., enlarged liver]). Diagnosis is usually made from findings disclosed by the patient history and by ruling out other causes of heart failure such as myocardial infarction. echocardiogram, Cardiac MRI, ECG, chest x-ray, Cardiac catheterization, coronary CT, or stress testing Endomyocardial biopsy

Heart failure Ventricular arrhythmias Atrial arrhythmias Cardiac conduction defects Pulmonary or cerebral embolism Valvular dysfunction

Potential complications may include the following:

noninfiltrative

Scleroderma is a ___ connective tissue disorder that can cause RCM.

axial and centrifugal pumps

The ___ have lower rates of pump thrombus formation and are of smaller device sizes.

heavy alcohol intake, recent illness or pregnancy, family history of sudden death or history of the disease in immediate family members

The nurse identifies possible etiologic factors for CMO, such as:

age dependent

The phenotypic expression of the disease is ___. HCM is the leading cause of sudden death in adolescents and young adults, particularly in athletes. 12-lead ECGs, physical examinations, and echocardiograms are used to screen for the disease.

Vital signs Calculation of pulse pressure and identification of pulsus paradoxus Current weight and any weight gain or loss Detection by palpation of the point of maximal impulse, often shifted to the left Cardiac auscultation for a systolic murmur and S3 and S4 heart sounds Pulmonary auscultation for crackles Measurement of jugular vein distention Assessment of edema and its severity

The physical assessment focuses on signs and symptoms of heart failure. The baseline assessment includes key components such as:

Hydration, beta-blockers, calcium channel blockers, and lifestyle modification

The presence of a systolic ejection murmur can be indicative of LVOT, and echocardiography is then indicated to confirm its presence. ___ can be used to minimize LVOT obstruction. In particular, patients should avoid activities that can cause rapid alterations to preload (e.g., hot tubs, saunas, prolonged hot showers). However, patients that do not respond to medical therapy should be considered for surgical myectomy or alcohol septal ablation to decrease the size of the hypertrophied septum and thereby eliminate LVOT obstruction.

the presence of orthopnea, PND, and syncope or dyspnea with exertion

The review of systems includes:

cardiopulmonary bypass

The use of ___ in cardiovascular surgery and the possibility of performing heart transplantation in patients with end-stage cardiac disease, as well as the desire for a treatment option for patients who are not transplant candidates, have increased the need for mechanical assist devices.

infiltrative disease, storage disease, noninfiltrative, and endomyocardial

There are four general categories for the causes of RCM:

pneumatic, electric or electromagnetic, axial flow, and centrifugal

There are four types of VADs:

ventricular assist devices

These more sophisticated ___ can circulate as much blood per minute as the heart, if not more. There are short- and long-term devices available, depending on the indication.

primary cardiomyopathies and secondary cardiomyopathies

Under this classification system, cardiomyopathies are divided into two major groups based on predominant organ involvement. These include:

pulsatile or continuous

VADs may be external, internal (i.e., implanted) with an external power source, or completely internal, and they may generate a ___ blood flow.

a "bridge to recovery" for patients who require temporary assistance for reversible ventricular failure, a "bridge to transplant" for patients with end-stage heart failure until a donor organ becomes available for transplant, and "destination therapy" for patients with end-stage heart failure who are not candidates for or decline heart transplantation and have the VAD implanted for permanent use

VADs may be used as:

Surgical Management for CMO

When heart failure progresses and medical treatment is no longer effective, surgical intervention, including heart transplantation, is considered. In some cases, a VAD is implanted to support the failing heart until a suitable donor heart becomes available.

myectomy (sometimes referred to as a myotomy-myectomy or the Morrow procedure)

When patients with HCM and LVOT obstruction become symptomatic despite optimal medical therapy or cannot tolerate medical therapy, surgery is considered. The most common procedure done is a ___ , in which some of the heart tissue is excised. Septal tissue approximately 1 cm wide and deep is cut from the enlarged septum below the aortic valve. The length of septum removed typically extends to the papillary muscles. Possible complications include complete heart block and subsequent pacemaker dependence, ventricular septal defects, or failure to adequately alleviate the obstruction.

idiopathic DCM

When the causative factor cannot be identified, the diagnosis is ___ which accounts for 20% to 30% of nonischemic DCM cases

Increased thickness

__ of the heart muscle reduces the size of the ventricular cavities and causes the ventricles to take a longer time to relax after systole. During the first part of diastole, it is more difficult for the ventricles to fill with blood. The atrial contraction at the end of diastole becomes critical for ventricular filling and systolic contraction.

Centrifugal

___ VADs are nonpulsatile devices that consist of a single moving impeller that is suspended in the pump housing by a combination of magnetic and hydrodynamic forces. The impeller rotates and pulls blood into the pump housing and ejects the blood out to the systemic circulation.

Electric or electromagnetic

___ VADs are similar to pneumatic VADs, but instead of using pressurized air to return the blood to the circulation, one or more flat metal plates are pushed against the reservoir.

Axial flow

___ VADs use a rotary mechanism (an impeller) to create nonpulsatile blood flow. The impeller spins rapidly within the VAD, creating a vacuum that pulls blood into the VAD and then pushes the blood out into the systemic circulation—the process is similar to a fan spinning in a tunnel, pulling air in one end of the tunnel and pushing it out the other.

Familial DCM

accounts for approximately 30% to 50% of all DCM cases and approximately 40% of familial DCM cases have a definitive genetic etiology

Total artificial hearts

are designed to replace both ventricles.

Unclassified Cardiomyopathies

are different from or have characteristics of more than one of the previously described types and are caused by fibroelastosis, noncompacted myocardium, systolic dysfunction with minimal dilation, and mitochondrial diseases.

Pneumatic VADs

are external or implanted pulsatile devices with a flexible reservoir housed in a rigid exterior. The reservoir usually fills with blood drained from the atrium or ventricle. The device then forces pressurized air into the rigid housing, compressing the reservoir and returning the blood to the circulation, usually into the aorta.

Signs and symptoms of RCM

are similar to constrictive pericarditis and include dyspnea, nonproductive cough, and chest pain. Arrhythmias and conduction disturbances are common. Echocardiography may be useful in differentiating between these two conditions. Generally, RCM is either due to an inherited or acquired disease that may be systemic.

RCM is characterized by

diastolic dysfunction caused by rigid ventricular walls that impair diastolic filling and ventricular stretch. A rigid ventricle alters the curve in the Frank-Starling law and leads to the rapid rise of filling pressures despite only small increases in blood volume. However, chamber size and systolic function are usually normal.

clinical manifestations of CMO

dilated or restrictive cardiomyopathy is first diagnosed when the patient presents with signs and symptoms of heart failure (e.g., DOE, fatigue, PND, cough [especially with exertion or at night], orthopnea, peripheral edema, early satiety, nausea.) The patient also may experience chest pain, palpitations, dizziness, nausea, and syncope with exertion.

LVOT obstruction

is a dynamic process that is dependent on both the volume of blood in the left ventricle as well as the ability of the myocytes to contract. Approximately one third of patients with HCM have LVOT obstruction at rest that worsens with provocation, another one third do not have obstruction at rest, but can get obstruction with provocation (e.g., exercise or the Valsalva maneuver), and roughly one third of patients have no LVOT obstruction even with provocation.

The pathophysiology of all cardiomyopathies

is a series of events that culminate in impaired cardiac output. Decreased stroke volume stimulates the sympathetic nervous system and the renin-angiotensin-aldosterone response, resulting in increased systemic vascular resistance and increased sodium and fluid retention, which place an increased workload on the heart. Often, the decrease in cardiac output can be seen on echocardiogram as a decrease in ejection fraction, expressed as a percentage of the end-diastolic blood volume ejected from the ventricle with each heartbeat. These alterations can lead to heart failure.

Ischemic cardiomyopathy

is a term frequently used to describe an enlarged heart caused by coronary artery disease, which is usually accompanied by heart failure.

Hypertrophic Cardiomyopathy

is an autosomal dominant genetic disorder that leads to increased heart muscle size and mass, especially along the septum but can involve other areas of the heart.

ARVC/D

is an uncommon form of inherited heart muscle disease. occurs when the myocardium is progressively infiltrated and replaced by fibrous scar and adipose tissue. Infiltration of fibrous and adipose tissue leads to ventricle dilatation, poor contractility, and arrhythmias. Initially, only localized areas of the right ventricle are affected, but as the disease progresses, the entire heart is affected.

Medical management for CMO

is directed toward identifying and managing possible underlying or precipitating causes; correcting the heart failure with medications, a low sodium diet, and an exercise/rest regimen and controlling arrhythmias with antiarrhythmic medications and possibly with an implanted electronic device, such as an ICD. If the patient has signs and symptoms of congestion, fluid intake may be limited to 2 L each day.

Cardiomyopathy

is disease of the heart muscle that is associated with cardiac dysfunction. It is classified according to the structural and functional abnormalities of the heart muscle: dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), and unclassified cardiomyopathy.

RCM

is the least common type of cardiomyopathy

DCM

is the most common form of cardiomyopathy

extracorporeal membrane oxygenation (ECMO)

some VADs can be combined with an oxygenator; the combination is called ___. The oxygenator-VAD combination is used for the patient whose heart cannot pump adequate blood through the body or when the lungs fail to oxygenate the blood despite supplemental oxygen or ventilation.

secondary cardiomyopathies

which show myocardial involvement secondary to the influence of a vast list of disease processes that include, but are not limited to, amyloidosis, Fabry disease, sarcoidosis, and scleroderma