Chapter 9Heart

Review of Structure and Function

• The heart is divided into the systemic (left) and pulmonary (right) systems– The pulmonary system has low vascular

resistance, thus the right side is less muscular

– Each side has an atrium and a ventricle, separated by valves

Review of Structure and Function

• Cardiac muscle is highly dependent on a large oxygen supply, supplied by the right and left coronary arteries

• The flow of electricity through the heart is what produces contraction

Review of Structure and Function

• The Sinoatrial (SA) node is the pacemaker for the heart

• The SA node then sends the signal to the Atrioventricular (AV) node, and finally down the Bundle of His to stimulate the ventricles to contract

Most Frequent and Serious Problems

• Atherosclerosis is the most common cause of death in the United States– Leads to cardiac dysfunction by interrupting

the delivery of oxygen to the muscle– This can cause myocardial infarction (heart

attack) or arrhythmias (abnormal heart beats)

Most Frequent and Serious Problems

• Angina pectoris and congestive heart failure (CHF) are the major causes of disability from heart dysfunction

Most Frequent and Serious Problems

• Hypertensive heart disease

• Rheumatic heart disease

• Cor pulmonale

• Sudden cardiac death

Symptoms, Signs, and Tests

• Myocardial infarcts– Patients can present with chest pain that

radiates to the left shoulder, arm, neck, or jaw

– Women will present with atypical symptoms– Diagnosed with electrocardiography (ECG)

and laboratory exams

Symptoms, Signs, and Tests

• Congestive heart failure– As fluid backs up, it can flood the alveoli,

causing decreased gas exchange and shortness of breath

– Physical exam identifies jugular venous distension, crackles in the lungs, and dullness to percussion over lung fields

Symptoms, Signs, and Tests

• Congestive heart failure– Diagnosed through physical exam, chest x-

ray, ECG, echocardiogram, and laboratory exams

• The ultimate test is cardiac catheterization

Specific Diseases

• Genetic/Developmental Diseases– Bicuspid aortic valve

• Instead of three cusps, only two or present, this allows for the valve to become scarred

Specific Diseases

• Genetic/Developmental Diseases– Atrial and Ventricular Septal Defects

(ASD/VSD)• VSD is more serious due to the larger

pressures present in the ventricles• The heart must pump the same blood

more than once, which can potentially lead to heart failure

Specific Diseases

• Tetralogy of Fallot– A cyanotic disease, actually caused by four

defects• Pulmonary stenosis• Right ventricular hypertrophy• Overriding aorta—both ventricles empty

into it• VSD

Specific Diseases

• Coarctation of the Aorta– Narrowing of the thoracic aorta– Can result in left ventricular hypertrophy

and heart failure

Specific Diseases

• Hypertrophic Cardiomyopathy– Caused by a genetic mutation that affects

the proteins that promote contraction– The interventricular septum becomes so

large it affects ventricular filling, thus decreasing stroke volume

Specific Diseases

• Inflammatory/Degenerative Diseases– The major cause of morbidity and mortality

in the United States

Specific Diseases

• Coronary Artery Atherosclerosis– In some patients, plaque formation is

gradual, which allows for collateral blood vessel formation

– However, in some patients, a single larger plaque in a strategic location may prove fatal

Specific Diseases

• Coronary Artery Atherosclerosis– If coronary artery insufficiency does occur,

the end result could be arrhythmias or infarcts

– One symptom of coronary insufficiency is angina pectoris, which becomes worrisome when the patient begins having unstable angina—or chest pain at rest

Specific Diseases

• Coronary Artery Atherosclerosis Treatment– Angioplasty

• A catheter with a balloon on the tip is inserted to the area of narrowing, then it is inflated, compressing the plaque out of the way

• A stent can be placed to maintain patency• Coronary artery bypass graft (CABG)—open

heart surgery, uses segments of other veins to bypass blockages

Specific Diseases

• Aneurysms– Weakening of the heart or vessels, leads to

impaired ventricular function

• Rheumatic heart disease– Can occur following streptococcal

infections, resulting in myocarditis or valvulitis

Specific Diseases

• Infective Endocarditis– Caused by an organism living on a heart

valve, producing an inflammatory response

• Hypertensive heart disease– Causes an increased workload for the heart,

which can lead to hypertrophy and eventually failure

Specific Diseases

• Cor Pulmonale– Pulmonary hypertension caused by chronic

lung disease leads to an increased workload on the right heart and eventually failure

Specific Diseases

• Cardiomyopathy– Disease intrinsic to the cardiac muscle

• Dilated• Hypertrophic• Restrictive

Specific Diseases

• Atrial Fibrillation– The atria quiver rather than contract– This allow for blood to pool, potentially

developing clots– This also does not allow for complete

ventricular filling, which can result in decreased cardiac output

Organ Failure

• Cardiogenic Shock– Perfusion of tissues is inadequate to meet

the metabolic demand of those tissues– In the case of cardiogenic shock, it is the

result of inadequate contractility

Organ Failure

• Congestive Heart Failure– The heart is unable to pump the blood that

is returned to it, resulting in the blood backing up into the pulmonary system