Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 18 Disorders of Cardiac Function
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Disorders That Affect the Whole Heart Pericardial disorders Coronary heart disease Myocardial diseases These disorders can cause symptoms of both right- and left-sided heart failure
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Pericardium Surrounds the Heart
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Pericarditis Inflammation of the pericardium causes: –Pain –Exudate ºSerous pericardial effusion Cardiac tamponade: rapid accumulation of exudate compresses the heart ºFibrous friction rub; adhesions –ECG changes
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Pericarditis (cont.) Inflammation of the pericardium may restrict the heart’s movement due to: –Serous exudate filling the pericardial cavity (pericardial effusion) –Fibrous scar tissue making the pericardium stick to the heart (constrictive pericarditis)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Consequences of Pericardial Effusion fluid in pericardial cavity restricts heart expansion left ventricle cannot accept enough blood decreased cardiac output decreased blood pressure and shock right ventricle cannot accept enough blood increased venous pressure; jugular distension
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question What is the immediate treatment for severe cardiac tamponade? a.Oxygen b.Cardiac drugs c.Surgery d.Pericardiocentesis (removal of fluid from the sac with a needle)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer d.Pericardiocentesis (removal of fluid from the sac with a needle) Rationale: In severe cardiac tamponade, there is so much fluid in the pericardial sac compressing the heart that its function declines rapidly. The fluid must be removed quickly by inserting a needle into the pericardial space and aspirating the accumulated fluid.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Pulsus Paradoxus On inhaling, the right ventricle fills with extra blood Because the heart cannot expand fully when the right ventricle is overfilled, the left ventricle is compressed and cannot accept much blood On the next heartbeat, the left ventricle does not send out much blood: systolic BP drops
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Coronary Heart Disease Atherosclerosis blocks coronary arteries Ischemia may cause: –Angina –Heart attack –Cardiac arrhythmias –Conduction deficits –Heart failure –Sudden death
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Chronic Ischemic Heart Disease Imbalance in blood supply and the heart’s demands for oxygen –Less blood ºAtherosclerosis ºVasospasm ºThrombosis –Higher oxygen demand ºStress ºExercise ºCold
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Kinds of Angina Stable angina –Pain when heart’s oxygen demand increases Variant angina –Pain when coronary arteries spasm Silent myocardial ischemia –Myocardial ischemia without pain
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Acute Coronary Syndromes ECG changes –T-wave inversion –ST-segment depression or elevation –Abnormal Q wave Serum cardiac markers –Proteins released from necrotic heart cells ºMyoglobin, creatine kinase, troponin
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. Chronic ischemic heart disease is more likely to result in stable angina than acute coronary syndromes.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True Rationale: Ischemic heart disease is characterized by stable angina, which is associated with plaques that are fixed obstructions. Unstable angina is characterized by plaques with platelets stuck to them (these are likely to form a thrombus)—they cause a range of acute coronary syndromes.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Acute Myocardial Infarction Chest pain –Severe, crushing, constrictive, OR like heartburn Sympathetic nervous system response –GI distress, nausea, vomiting –Tachycardia and vasoconstriction –Anxiety, restlessness, feeling of impending doom Hypotension and shock –Weakness in arms and legs
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins An Acute MI (AMI) Leaves Behind an Area of Yellow Necrosis
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Complications of AMI Heart failure Cardiogenic shock Pericarditis Thromboemboli Rupture of the heart Ventricular aneurysms
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Malfunctioning Heart Muscle Malfunctioning heart muscle can cause heart failure if: –Ventricles are unusually thick so there is not a normal amount of room for blood inside them (hypertrophic cardiomyopathy) –Ventricles are too stiff to stretch (restrictive cardiomyopathy) –Ventricles are too weak to pump out the blood that is in them (MI, myocarditis, dilated cardiomyopathy)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Myocardial Disorders Myocarditis Cardiomyopathies –Dilated cardiomyopathies –Hypertrophic cardiomyopathies –Restrictive cardiomyopathies –Peripartum cardiomyopathy
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Hypertrophic Cardiomyopathy Defects in their contractile proteins make cells too weak They hypertrophy to do the same amount of work as normal cells Need more oxygen and perform less efficiently, so the person is prone to heart failure and may suffer sudden death during exertion
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Which type of cardiomyopathy is characterized by weakened ventricles? a.Dilated cardiomyopathy b.Hypertrophic cardiomyopathy c.Restrictive cardiomyopathy d.Peripartum cardiomyopathy
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer a.Dilated cardiomyopathy Rationale: In dilated cardiomyopathy, the ventricles are too weak to pump blood, resulting in a diminished cardiac output (CO). The other types listed are caused by thick ventricles, stiff ventricles, or LV dysfunction in late pregnancy or postpartum, respectively.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Valvular Disorders and Heart Defects By interfering with normal blood flow, these often cause the signs and symptoms of left- or right- sided heart failure right heart lungs left heart body
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Endocardial Structures The endocardial structures lining the heart can cause heart failure –If the AV valves leading into the ventricles do not work (mitral or tricuspid problems) –If the semilunar valves leading out of the ventricles do not work (aortic or pulmonary problems)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Cardiac Cycle Discussion: Arrange these steps in the proper order: – Ventricles relax– First heart sound – Systole– Semilunar valves open – Diastole– AV valves close – AV valves open– Semilunar valves close – Ventricles contract– Second heart sound
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Valve Defects Each of the four valves can be defective Stenosis: valve will not open all the way; it is harder to force blood through it Regurgitation: valve will not close all the way; it leaks when it should be closed
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Question Tell whether the following statement is true or false. Mitral valve regurgitation results in a diminished stroke volume.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Answer True Rationale: If the mitral valve does not close as it should, a portion of the stroke volume (amount of blood ejected by the ventricle/beat) leaks back into the left atrium, decreasing the amount of blood that is ejected during that beat (SV).
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Discussion Defects in which valves might cause: Severe dependent edema? Paroxysmal nocturnal dyspnea? Congested liver? Distended jugular veins? Productive cough with frothy sputum?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Identifying Defective Valves The blood going through the valve makes a noise These are called heart murmurs You can identify them by: –Where they are—which valve are they near? –How they sound—high- or low-pitched? –When they happen—systole or diastole?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins When Will You Hear Murmurs? If a valve is stenotic, you will hear a murmur of blood shooting through the narrow opening when the valve is open If a valve is regurgitant, you will hear a murmur of blood leaking back through when the valve should be closed
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Left-sided Valvular Disorders Mitral valve disorders –Mitral valve stenosis –Mitral valve regurgitation –Mitral valve prolapse Aortic valve disorders –Aortic valve stenosis –Aortic valve regurgitation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Congenital Heart Defects Atrial septal defects Ventricular septal defects Endocardial cushion defects Patent ductus arteriosus Pulmonary stenosis Tetralogy of Fallot Transposition of the great vessels Coarctation of the aorta
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Shunts A shunt is an opening or connection that lets blood move from one side of the circulation to the other Most shunts occur in the heart and move blood either from the left to the right or from the right to the left Because the left side is stronger, blood is usually pushed from the left to the right side
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Shunts (cont.) Shunts are normal before birth Foramen ovale –Lets blood go from the right atrium to the left atrium to bypass the lungs Ductus arteriosus –Lets blood go from the pulmonary trunk to the aorta to bypass the lungs Ductus venosus –Lets blood go from the visceral veins to the vena cava, bypassing the liver
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Left-to-right Shunt Less blood goes to body More blood goes to lungs Blood moves from left to right right heart lungs left heart body
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Right-to-left Shunt Deoxygenated blood goes to body Less blood goes to lungs Blood moves from right to left right heart lungs left heart body
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Discussion Show how the diagram would look for: Patent ductus arteriosus Transposition of the great vessels Tetralogy of Fallot right heart lungs left heart body