Congestive Heart Failure - PDF

congestive heart failure LEARNING OBJECTIVES Enumerate the compensatory mechanisms during HF Differentiate between systolic HF (HFrEF) and diastolic HF (HFpEF) List the causes of HFrEF and HFpEF Identify the precipitating factors for decompensated HF Explain the classes of...

congestive heart failure LEARNING OBJECTIVES Enumerate the compensatory mechanisms during HF Differentiate between systolic HF (HFrEF) and diastolic HF (HFpEF) List the causes of HFrEF and HFpEF Identify the precipitating factors for decompensated HF Explain the classes of HF according to NYHA staging system Enumerate the pharmacologic treatment of HF including the newer drugs Introduction and pathophysiology: Heart failure (HF) arises from the inability of the ventricle to efficiently pump blood throughout the circulation. As HF evolves, changes in vascular function, blood volume, and neurohumoral status occur throughout the body. These changes serve as compensatory mechanisms to help maintain cardiac output (primarily by the Frank-Starling mechanism) and arterial blood pressure (by systemic vasoconstriction). However, these compensatory changes over time can worsen cardiac function. In summary, Compensatory mechanisms during HF include: 1. Cardiac: Frank-Starling mechanism, tachycardia, ventricular dilatation. 2. Neuro-Hormonal: a. Increased sympathetic adrenergic activity, reduced cardiac vagal activity. b. Activation of RAAS (Renin Angiotensin Aldosterone System) with renal sodium retention and Extracellular volume (ECV) expansion, increased vasopressin, catecholamines, and natriuretic peptides. Figure showing bad sequele of compensatory mechanisms HF classification: In clinical practice, HF is classified into: (Ejection fraction is used to determine the systolic function of the left ventricle, mainly by echo. It is calculated as the percentage of blood ejected in systole from the total amount that filled the Lv in diastole. Normally it should be above 50% i.e. the LV ejects more than 50% of blood that filled it) A.Systolic HF (also known as heart failure with reduced EF [HFrEF]): o Caused by a loss of contractile strength of the myocardium with ventricular dilatation. 64  o Accompanied by a decrease in normal ventricular emptying (EF 50%) o Examples include hypertensive heart disease and the infiltrative cardiomyopathies. Recently, a new class called heart failure with mildly reduced ejection fraction (HFmrEF) was introduced, requires the presence of symptoms and/or signs of HF, and a mildly reduced EF (41-49%) Causes: HF may occur because of most causes of heart disease, but ischemic heart disease is responsible for over 70% of all cases in the western world. Other common causes include hypertensive heart disease, the cardiomyopathies (idiopathic, alcohol related, etc.), and valvular and congenital heart diseases. The causes can be groups into 3 categories: Diseased myocardium, abnormal loading (preload or afterload) and arrhythmias (See table) Clinical presentation of CHF: Congestive HF indicates a clinical syndrome of dyspnea and fatigue as well as evidence of features of circulatory congestion (peripheral edema, elevated JVP). Decompensated HF or exacerbation of HF denotes worsening of symptoms and clinical findings in pre-existing HF. This can be due to precipitating factors such as: ✓ Nonadherence with medication regimen ✓ Acute myocardial ischemia ✓ Uncorrected high blood pressure ✓ AF and other arrhythmias ✓ Pulmonary embolus ✓ Recent addition of negative inotropic drugs (e.g., verapamil, diltiazem) 65  ✓ Initiation of drugs that increase salt retention (e.g., steroids, thiazolidinediones, NSAIDs) ✓ Excessive alcohol or illicit drug use ✓ Endocrine abnormalities (e.g., DKA, thyrotoxicosis) ✓ Concurrent infections (e.g., pneumonia, viral illnesses) ✓ Additional acute cardiovascular disorders (e.g., valve disease endocarditis, myopericarditis, aortic dissection) Note: In evaluating patients with CHF, it is important to exclude precipitating factors. Symptoms of HF: Left sided failure → dyspnea, orthopnea, paroxysmal nocturnal dyspnea Right sided failure → LL swelling and abdominal discomfort (hepatomegaly, ascites) Low cardiac output → fatigue, dizziness The severity of heart failure is commonly classified by using The New York Heart Association Functional Classification (NYHA staging system) that depends on symptoms ONLY: (very important) Class I: No limitation of activity; they suffer no symptoms from ordinary activities Class II: Mild limitation of activity; they are comfortable with rest or with mild exertion Class III: Marked limitation of activity; they are comfortable only at rest Class IV: Any physical activity brings on discomfort and symptoms occur at rest Physical findings in HF: Left sided failure → Pulmonary rales/edema, in HFrEF (displaced apical impulse, Third heart sound and gallop, Mitral regurge murmur) Right sided failure → LL edema, Ascites, Hepatomegaly, Jugular venous distention Low cardiac output → hypotension, impaired capillary filling ACC/AHA Stages of HF: The ACC/AHA stages of HF recognize that both risk factors and abnormalities of cardiac structure are associated with HF whereas the NYHA classes focus on exercise capacity and the symptomatic status of the disease.. Stage A: patients at high risk of HF but without structural heart disease or symptoms e.g. Hypertension, dyslipidemia, obesity, DM,.. Stage B: patients with structural heart disease but without HF symptoms or signs e.g., MI, LVH, LV dysfunction, valvular heart diseases, (These can be in NYHA I) Stage C: Patients with structural heart disease with prior or current HF symptoms (these can be in any NYHA class) Stage D: Patients with refractory heart failure (NYHA IV) Therapeutic interventions in each stage aimed at modifying risk factors (stage A), treating structural heart disease (stage B), and reducing morbidity and mortality (stages C and D). Investigations: 1- Chest x-ray: It may show cardiomegaly, vascular redistribution, Kerley B-lines, or interstitial edema. It is also important to detect alternative cardiac, pulmonary, and other diseases that may cause or contribute to the patient’s symptoms 2- ECG: may identify ventricular hypertrophy, the presence of ischemia, arrhythmias. 66 3- Brain natriuretic peptide (BNP) (or type B natriuretic peptide) and NT-pro BNP (N- terminal pro BNP): see clinical pathology section Remember that they have very high sensitivity (97% sensitivity): almost always elevated in patients with decompensated HF (except obesity, where BNP can be falsely low) but low specificity (elevated in many cardiac and non-cardiac conditions e.g. AF, cardiac surgery, pericardial diseases, pneumonia, pulmonary hypertension, sepsis, renal failure and old age) thus best used for ruling out HF 4- Echocardiogram: determine ejection fraction (EF) and classify the type, and to identify valvular heart disease and other cardiac problems (dilated ventricle, ……). 5- Other non-invasive imaging may be needed e.g. to rule out ischemia, to assess myocardial viability, or to diagnose some aetiological causes (infiltration,..) 6- Invasive procedures are sometimes needed: o Monitoring with a pulmonary artery catheter in patients with respiratory distress or impaired systemic perfusion when clinical assessment is inadequate o Coronary arteriography when ischemia may be contributing to HF o Endomyocardial biopsy can be useful in patients with HF when a specific diagnosis is suspected that would influence therapy e.g. amyloidosis Treatment of HFrEF: Treatment goals in HF are to improve hemodynamics, relieve symptoms, and prolong survival. A. Non-pharmacologic treatment: o Reduction of salt/fluid intake. o Specific education to facilitate HF self-care such as daily weighing and medication adherence o Moderation or stopping alcohol o Exercise training/cardiac rehabilitation: Exercise training in patients with HF is safe and has numerous benefits. Meta-analyses show that cardiac rehabilitation may reduce mortality; improves functional capacity, exercise duration, and quality of life and reduces hospitalizations. Other benefits include improved endothelial function, blunted catecholamine spillover, increased peripheral oxygen extraction, and reduced hospital admission. B. Pharmacologic treatment: (see details in pharmacology section): Essential drugs (for all patients with HFrEF) The Four Pillars 1. ACE inhibitors or ARNI (angiotensin receptor-neprilysin inhibitor): 2. Beta blockers 3. Sodium-glucose transport protein 2 (SGLT2) inhibitors dapagliflozin or empagliflozin 4. Aldosterone antagonists: Spironolactone and eplerenone and…… Loop Diuretics: for relief of fluid retention Other drugs: ✓ ARBs if ACEI or ARNI are contraindicated ✓ Isosorbid dinitrate + Hydralazine if ACEI or ARNI are contraindicated ✓ Digitalis ✓ Ivabradine 67  C. Cardiac Devices for HFrEF: After medical management has been initiated (at least for 3 months), several mechanical devices may be added to further improve symptoms and/or prognosis in HF. Automatic implantable cardioverter/defibrillator (ICD) is a standard therapy for severe ischemic and nonischemic dilated cardiomyopathy (EF