Cardiovascular System Disorders PDF

CARDIOVASCULAR SYSTEM DISORDERS DR MUMANGA C (BSc Micro, BSc HB, MBChB, Cert med education) JRMO Kanyama General Hospital 1. HEART FAILURE The long term consequences of all major CVS disorders is HEART FAILURE Heart failure occurs when the heart is unable to pump eno...

CARDIOVASCULAR SYSTEM DISORDERS DR MUMANGA C (BSc Micro, BSc HB, MBChB, Cert med education) JRMO Kanyama General Hospital 1. HEART FAILURE The long term consequences of all major CVS disorders is HEART FAILURE Heart failure occurs when the heart is unable to pump enough blood (CO) to meet the metabolic demands/needs of the body Heart failure occurs as a clinical syndrome characterised by dyspnoea, fatigue and signs of volume overload caused by circulatory and neurohormonal responses to the underline cardiac dysfunction. Causes of heart failure are both functional and structural in nature Causes of heart failure Main causes (world wide) Ischaemic heart disease(CAD) (35–40%) – Commonest in western countries (whites) Dilated Cardiomyopathy (30–34%) Hypertension (15–20%) – Commonest in Zambia GENERAL causes of CCF Cardiomyopathy: Dilated, hypertrophic, restrictive (amyloidosis, sarcoidosis) Valvular heart disease (mitral, aortic, tricuspid), Rheumatic, Endocarditis Congenital heart disease (ASD, VSD, TOF) Alcohol and drugs (chemotherapy – trastuzumab, imatinib) Hyperdynamic circulation (anaemia, thyrotoxicosis, haemochromatosis, Paget's disease) Right heart failure (right ventricular infarct, pulmonary hypertension, pulmonary embolism, COPD) Arrhythmias (atrial fibrillation, bradycardia (complete heart block, sick sinus syndrome – sinus node dysfunction) Pericardial disease (constrictive pericarditis, pericardial effusion, tamponade) Infections – myocarditis (mainly by viruses), infectious endocarditis (mainly by bacteria) Pathophysiology of heart failure When the heart fails, considerable changes affect the heart and peripheral vascular system in response to the haemodynamic changes associated with heart failure These physiological changes are compensatory and maintain cardiac output and peripheral perfusion. However, as heart failure progresses, these mechanisms are overwhelmed and become pathophysiological Factors involved are venous return, outflow resistance, contractility of the myocardium, and salt and water retention. Classification of heart failure acute heart failure (AHF) vs Chronic heart failure Heart failure that presents suddenly is termed acute heart failure (AHF), Chronic heart failure presents more insidiously Systolic vs Diastolic dysfunction - Left ventricular systolic dysfunction (LVSD) or heart failure and a reduced (R) ejection fraction (HFREF) is commonly caused by ischaemic heart disease but can also occur with valvular heart disease and hypertension. - Diastolic heart failure is a syndrome consisting of symptoms and signs of heart failure with preserved (P) left ventricular ejection fraction (HFPEF) >45–50%. There is increased stiffness in the ventricular wall and decreased left ventricular compliance, leading to impairment of diastolic ventricular filling and hence decreased cardiac output. Echocardiography may demonstrate an increase in left ventricular wall thickness, increased left atrial size and abnormal left ventricular relaxation with normal or near-normal left ventricular volume.  Diastolic heart failure is more common in elderly hypertensive patients but may occur with primary cardiomyopathies (hypertrophic, restrictive, infiltrative). Right ventricular systolic dysfunction (RVSD) may be secondary to chronic LVSD but can occur with primary and secondary pulmonary hypertension, right ventricular infarction, arrhythmogenic right ventricular cardiomyopathy and adult congenital heart disease. New York Heart Association (NYHA) Functional Classification of Heart Failure Class I: heart disease present but ordinary physical activity does not cause symptoms of HF (dyspnoea) Class II: comfortable at rest, ordinary physical activity results in symptoms Class III: marked limitation of ordinary activity; less than ordinary physical activity results in symptoms Class IV: inability to carry out any physical activity without discomfort; symptoms may be present at rest Investigations in heart failure Blood tests. - Full blood count, urea and electrolytes, liver biochemistry, cardiac enzymes (in acute heart failure), BNP or NT-proBNP, and thyroid function Chest X-ray - cardiomegaly, pulmonary congestion with upper lobe diversion, fluid in fissures, Kerley B lines (LVF) and pulmonary oedema. Electrocardiogram - Identify ischaemia, hypertension or arrhythmia. Echocardiography - cardiac chamber dimension, systolic and diastolic function, regional wall motion abnormalities, valvular disease and cardiomyopathies. Stress echocardiography - Assess viability in dysfunctional myocardium – dobutamine identifies contractile reserve in stunned or hibernating myocardium.  Nuclear cardiology - Radionucleotide angiography (RNA) can quantify ventricular ejection fraction; SPECT or PET can demonstrate myocardial ischaemia and viability in dysfunctional myocardium. Cardiac MRI (CMR) - Assess cardiac structure and function and viability in dysfunctional myocardium with the use of dobutamine for contractile reserve or with gadolinium for delayed enhancement (‘infarct imaging’). Cardiac catheterization - This technique is employed for the diagnosis of ischaemic heart failure (and suitability for revascularization) and for measurement of pulmonary artery pressure, left atrial (wedge) pressure, left ventricular end- diastolic pressure.  Cardiac biopsy - This is used for diagnosis of cardiomyopathies, such as amyloid, and for follow-up of transplanted patients to assess rejection. Cardiopulmonary exercise testing - Peak oxygen consumption (VO2) is predictive of hospital admission and death in heart failure. A 6-minute exercise walk is an alternative. Ambulatory 24-hour ECG monitoring (Holter). This is used in patients with suspected arrhythmia, and may be used in those with severe heart failure or inherited cardiomyopathy to determine whether a defibrillator is appropriate (non-sustained ventricular tachycardia). Diagnosis of heart failure The diagnosis of heart failure remains clinical; there is no single diagnostic investigation that can be considered a gold standard. ECHO cardiography is an excellent method of identifying LV systolic dysfunction, ventricular hypertrophy and valvular dysfunction TREATMENT OF HEART FAILURE Disease – modifying therapy Symptomatic therapy Other pharmacological therapy Non-pharmacological therapy and life style modification Device therapy Surgical options Disease – modifying therapy ACE inhibitors - Consider in all those with left ventricular systolic dysfunction; improves symptoms and decreases mortality - If cough is a problem, an angiotensin receptor blocker (ARB) may be substituted Beta blockers - (eg carvedilol) decrease mortality in heart failure These benefits appear to be additional to those of ACE-i in patients with heart failure due to LV dysfunction Aldosterone antagonists - Spironolactone (25mg/24h PO) reduces mortality by 30% when added to conventional therapy. Angiotensin II receptor Antagonists or blockers – alternative to ACE - i Hydralazine and nitrates (isosorbide nitrate) SYMPTOMATIC RELIEF Diuretics - Give loop diuretics to relieve symptoms of fluid overload, e.g furosemide 40mg/24h PO or bumetanide 1–2mg/24h PO. Increase dose as necessary - Monitor U&E and add K+-sparing diuretic (eg spironolactone) if K+