PROCESSES AND PATHWAYS

Thinning and geometry change of the left ventricular wall to a more circular appearance with ventricular enlargement and systolic dysfunction

What is the primary pathophysiological hallmark of dilated cardiomyopathy?

Impaired forward flow or pump failure due to systolic dysfunction

What is the main hemodynamic problem that leads to congestive symptoms in dilated cardiomyopathy?

Asymmetric left ventricular hypertrophy, dynamic left ventricular outflow tract obstruction, and increased stiffness of the hypertrophied muscle

What are the three core features that characterize hypertrophic cardiomyopathy?

Increased stiffness of the hypertrophied muscle leading to impaired ventricular filling

What is the primary cause of diastolic dysfunction in hypertrophic cardiomyopathy?

Decreased preload or decreased afterload

What hemodynamic changes intensify the dynamic left ventricular outflow tract pressure gradient in hypertrophic cardiomyopathy?

Endomyocardial scarring or myocardial infiltration resulting in restriction to left and right ventricular filling

What is the defining pathophysiology of restrictive cardiomyopathy?

Abnormal diastolic dysfunction with preserved systolic function in early stages, progressing to impaired systolic function in late stages

What is the clinical hallmark and progression of restrictive cardiomyopathy?

Loss of functional myocardium and interspersion of fibrosis into the muscle area

What structural changes in restrictive cardiomyopathy lead to impaired systolic function in late stages?

Fibrofatty replacement of the right ventricular myocardium, leading to right ventricular dilatation, aneurysms, and failure

What is the pathophysiology of arrhythmogenic right ventricular cardiomyopathy?

Transient apical ballooning with contraction restricted to the bases, typically triggered by intense emotional or physical stress

What is the pathophysiology of Takotsubo cardiomyopathy?

Cardiac myocytes are hypertrophied with variable size, enlarged nuclei, and significant fibrosis interspersed in between

What are the microscopic and histologic findings in a myocardial biopsy of dilated cardiomyopathy?

Widened angle of the carina of the bronchus to ninety degrees or more

What chest radiograph sign indicates left atrial enlargement in a patient with dilated cardiomyopathy?

Obliteration of the retrosternal sternal space on the lateral view

How is right ventricular enlargement visualized on a chest radiograph of a dilated cardiomyopathy patient?

Low voltage on limb leads, conduction defects, and atrial fibrillation

What are the characteristic electrocardiogram findings in amyloidosis restrictive cardiomyopathy?

Inspiration causes diaphragm descent, creating negative intrathoracic pressure that sucks jugular venous blood into the compliant right ventricle

What is the normal physiological mechanism of jugular venous pressure changes during inspiration?

The heart is non-compliant or stiff, preventing the expected increase in right ventricular filling and causing a paradoxical rise in the jugular vein during inspiration

What is the physiological mechanism behind Kussmaul's sign in restrictive cardiomyopathy or constrictive pericarditis?

Symmetrically thickened left ventricular walls with dilated atria, normal or slightly reduced ventricular and systolic functions

What are the typical echocardiographic and Doppler findings in restrictive cardiomyopathy?

A dip-and-plateau or square root configuration of the diastolic portion of the ventricular pressure curve

What pathognomonic hemodynamic sign is seen during cardiac catheterization in restrictive cardiomyopathy?

Myocardial inflammation simulating an acute coronary syndrome with chest pain, ST-segment abnormalities, and elevated troponin despite normal coronary arteries

What is the pathophysiology of acute myocarditis?

A preceding viral upper respiratory febrile illness, flu-like syndrome, viral nasopharyngitis, or tonsillitis

What clinical history typically precedes the development of viral myocarditis?

Direct viral injury, immune-mediated cytotoxicity, and inflammatory cytokine release leading to focal or diffuse myocardial necrosis

What mechanism leads to myocardial damage during acute coxsackievirus myocarditis?

Exaggerated host immune activation and severe systemic inflammation triggering severe acute myocardial injury and dysfunction

What is the mechanism of SARS-CoV-2 induced myocarditis?

Hypersensitivity reaction characterized by eosinophilic myocardial infiltration, often triggered by drugs like clozapine, sulfonamides, or penicillins

What is the pathogenesis of drug-induced hypersensitivity myocarditis?

Loss of functional cardiac myocytes from an index event followed by compensatory neurohormonal activation that initially restores homeostasis but eventually drives adverse remodeling

What is the general pathway of progression in dilated cardiomyopathy?

Attenuating or damping of the heart's electrical signals due to increased fluid or tissue distance between the myocardium and electrodes

What is the cause of low voltage on the electrocardiogram of patients with amyloidosis or dilated cardiomyopathy?

Dynamic systolic anterior motion of the mitral valve where the anterior leaflet is sucked into the outflow tract during systole

What mechanism causes the left ventricular outflow tract obstruction in hypertrophic cardiomyopathy?

Asymmetric septal hypertrophy where the interventricular septum is significantly thicker than the posterior free wall

What is the classic structural defect of the septum in hypertrophic cardiomyopathy?

A sarcomeric protein mutation, most commonly involving beta-myosin heavy chain or myosin-binding protein C

What genetic etiology is responsible for familial hypertrophic cardiomyopathy?

Genetic mutation in the giant sarcomeric protein titin, representing fifteen to twenty percent of inherited cases

What is the most common genetic cause of familial dilated cardiomyopathy?

Duchenne muscular dystrophy where a deficiency of dystrophin leads to progressive cardiomyocyte membrane instability and necrosis

What neuromuscular pathway is a well-known genetic cause of dilated cardiomyopathy?

Visceral epicardium is a monocellular layer intimately attached to the heart, while the parietal pericardium is a tough fibrous layer producing pericardial fluid

What are the structural and functional differences between the visceral and parietal pericardium?

Compressive effect of pericardial fluid decreases diastolic volume, collapsing the right atrium first, then the right ventricle, and finally the left ventricle

What is the sequential mechanical pathway of acute cardiac tamponade?

Decreased diastolic filling reduces ventricular preload, which decreases stroke volume, leading to a fall in cardiac output

What is the pathophysiology linking ventricular compression to cardiogenic shock in tamponade?

Sympathetic surge triggering tachycardia and peripheral vasoconstriction to maintain systemic blood pressure in response to low cardiac output

What is the first compensatory reflex activated in early cardiac tamponade?

Hypotension, distended neck veins, and muffled heart sounds

What are the three clinical signs of Beck's triad and why do they occur in cardiac tamponade?

Stage I shows concave upward ST-segment elevation in all leads except V1 and aVR with PR-segment depression; Stage II shows ST return to baseline and T-wave flattening; Stage III shows T-wave inversion; Stage IV shows ECG normalization

What is the four-stage electrocardiogram evolutionary process in acute pericarditis?

Rapid accumulation of fluid can compress the heart and cause tamponade before the pericardial sac has time to stretch and enlarge the cardiac shadow

Why can a chest radiograph show a completely normal cardiac size in acute, critical cardiac tamponade?

Echocardiography showing right atrial free wall diastolic collapse, right ventricular free wall diastolic collapse, and a dilated inferior vena cava without inspiratory collapse

What are the key diagnostic findings that confirm cardiac tamponade on a two-dimensional echocardiogram?

Cytology, cell count, protein, lactate dehydrogenase, glucose, and bacterial or tuberculosis cultures

What fluid examinations are performed on a pericardial aspirate to establish the etiology of acute pericarditis?

Acute pericarditis causes pericardial effusion, leading to fibrin deposition, pericardial organization, chronic fibrotic scarring, and calcification

What is the step-by-step process of development of chronic constrictive pericarditis?

Thickened, fibrotic, calcified, inelastic, and fused visceral and parietal pericardium restricts ventricular expansion, impeding normal diastolic filling

What is the core pathophysiology of chronic constrictive pericarditis?

Limited diastolic filling of the right ventricle decreases stroke volume and cardiac output, causing easy fatigability and exertional dyspnea

What is the physiological cause of exercise limitation in constrictive pericarditis?

Impeded right ventricular filling elevates right atrial pressure and central venous pressure to ten to thirty mmHg, causing systemic venous congestion

What mechanism leads to hepatomegaly, ascites, and peripheral edema in constrictive pericarditis?

A high-frequency heart sound produced by the sudden, premature cessation of ventricular filling early in diastole against the rigid pericardial sac

What is the pathophysiological mechanism behind a pericardial knock?

Left-sided trans-mitral velocity decreases significantly, while right-sided trans-tricuspid velocity increases during inspiration

What is the respiratory variation in ventricular inflow velocities seen on Doppler echocardiography in constrictive pericarditis?

High-resolution computed tomography scan and fast magnetic resonance imaging

What are the preferred imaging modalities for accurately measuring pericardial thickness and diagnosing constrictive pericarditis?

Vena cava dilatation, hepatic vein dilatation, right atrial dilatation, hepatosplenomegaly, and ascites

What computed tomography findings suggest impaired right ventricular filling in constrictive pericarditis?

Dissecting the parietal pericardium off the epicardium from phrenic nerve to phrenic nerve, and from left to right pulmonary arteries, prioritizing ventricular freeing

What is the surgical pathway and priority of a pericardiectomy?

Prophylactic pericardiectomy is recommended because acute tuberculous pericarditis invariably progresses to chronic constriction

What is the surgical recommendation for an established case of tuberculous pericarditis in the Philippines?

Malignant tumors have already spread beyond the cardiac structures, making surgical resection non-curative and carrying a poor prognosis

Why is surgical excision not attempted for primary malignant cardiac tumors with extra-cardiac spread?

A benign, slow-growing polypoid mass covered by epithelium, possessing a one to two centimeter stalk attached to the atrial septum

What is the structural pathology of a cardiac myxoma?

The tumor mass is sucked into the mitral orifice during diastole, obstructing left ventricular inflow and mimicking mitral stenosis

What is the mechanism of diastolic obstruction in a left atrial myxoma?

Fragmentation of the gelatinous tumor mass or dislodgement of surface thrombi that travel into the systemic arterial tree

What mechanism leads to stroke or acute limb ischemia in left atrial myxoma?

A tumor plop heart sound heard early in diastole as the pedunculated tumor falls across the mitral valve

What is the characteristic auscultatory finding of a mobile left atrial myxoma?

Metastatic cardiac neoplasms occur in four to twelve percent of cancer deaths, whereas primary cardiac tumors are extremely rare

What is the relative prevalence of primary versus metastatic cardiac neoplasms?

Direct tumor invasion, hematogenous spread, lymphatic spread, or venous extension through the vena cava into the right atrium

What are the pathways through which metastatic cancers reach the heart?

Angiosarcoma, which has a predilection for the right atrium

What is the most common primary malignant tumor of the heart and its typical location?

Rhabdomyoma, which is strongly associated with tuberous sclerosis

What is the most common primary benign cardiac tumor in infants and children?

Systemic embolization, intracardiac obstruction, and constitutional symptoms like fever, weight loss, and elevated ESR

What is the classic clinical triad of presentations in a patient with a cardiac myxoma?

Metastatic tumors involve the pericardium and myocardium but spare the cardiac valves, whereas myxomas arise from the endocardium

What structural tissue boundaries help differentiate metastatic cardiac neoplasms from primary myxomas?

Hypertension, coronary artery disease, and valvular heart disease

What are the three most common cardiovascular diseases that serve as predisposing pathways to heart failure?

A clinical syndrome characterized by structural or functional cardiac impairment that leads to reduced cardiac output and/or elevated intracardiac pressures

What is the definition of heart failure according to the universal guidelines?

Inability of the ventricle to stretch and accept blood due to a stiff, non-compliant wall

What is the pathophysiology behind heart failure with an impaired ability of the ventricle to fill?

Impaired myocardial contractility preventing the ventricle from effectively pumping blood out into the circulation

What is the pathophysiology behind heart failure with an impaired ability of the ventricle to eject?

Fatigue, fluid retention, breathlessness, ankle swelling, and easy fatigability

What are the cardinal clinical manifestations of heart failure?

Elevated jugular venous pressure, pulmonary crackles, and peripheral edema

What are the primary objective physical signs of heart failure?

Rapid decompensation of pre-existing chronic heart failure or new-onset dysfunction triggered by acute coronary syndrome, acute valvular disease, or hypertensive urgency

What is the pathogenesis of acute decompensated heart failure?

Myocardial infarction survivors live longer due to modern reperfusion therapies, but eventually progress to chronic ventricular remodeling and heart failure

Why is the prevalence of heart failure increasing with aging populations?

Myocardial damage or coronary artery disease

What is the leading cause of heart failure with a reduced ejection fraction?

Depressed left ventricular ejection fraction of forty percent or less

What defines the HFrEF phenotype?

Preserved left ventricular ejection fraction of fifty percent or more

What defines the HFpEF phenotype?

Ejection fraction between forty-one and forty-nine percent

What defines the HFmrEF phenotype?

Initial left ventricular ejection fraction of forty percent or less that improves to over forty percent following guideline-directed medical therapy

What defines the HFrecEF phenotype?

Younger age, shorter duration of heart failure, non-ischemic etiology, small left ventricular volume, and absence of myocardial fibrosis

What are six clinical and structural predictors of successful ejection fraction recovery in heart failure?

Loss of functional cardiac myocytes leads to an initial decline in pumping capacity, activating neurohormonal pathways that initially support cardiac output but ultimately cause adverse remodeling

What is the pathophysiological pathway of heart failure progression?

Baroreceptor dysfunction in the left ventricle, carotid sinus, and aortic arch decreases afferent inhibitory vagal tone, triggering a massive sympathetic surge

What is the first neurohormonal process activated in response to decreased cardiac output in heart failure?

Sustained sympathetic stimulation increases heart rate, myocardial contractility, and systemic vasoconstriction, raising myocardial oxygen demand and promoting arrhythmia

What is the cause-and-effect relationship of chronic sympathetic activation in heart failure?

Angiotensin II stimulates myocytes to hypertrophy, fibroblasts to deposit collagen, and triggers aldosterone release, promoting myocardial fibrosis and remodeling

What is the molecular pathway of angiotensin II-induced ventricular remodeling?

Renal underperfusion stimulates juxtaglomerular cells to secrete renin, converting angiotensinogen to angiotensin I, which is converted by ACE to angiotensin II, stimulating aldosterone secretion

What is the sequence of the renin-angiotensin-aldosterone system activation in heart failure?

Sustained aldosterone secretion promotes sodium reabsorption and water retention in the distal nephron, expanding blood volume to increase cardiac preload

What is the renal mechanism of volume retention in heart failure?

High atrial and ventricular wall stretch due to volume overload stimulates the synthesis and release of atrial and brain natriuretic peptides

What triggers the release of natriuretic peptides in heart failure?

Promote systemic vasodilation, inhibit renal sodium and water reabsorption, suppress renin and aldosterone release, and blunt baroreceptor activity

What are the counter-compensatory effects of endogenous vasodilatory hormones in heart failure?

The enzyme neprilysin rapidly degrades ANP, BNP, and bradykinin, shortening their beneficial vasodilatory and natriuretic actions

What enzymatic process limits the effectiveness of the body's vasodilatory peptide response in heart failure?

Decreased cardiac output impairs renal arterial perfusion and induces systemic venous congestion, which raises renal venous pressure and activates the hepato-renal reflex to cause renal vasoconstriction

What is the pathophysiological pathway of cardiorenal syndrome in heart failure?

Left ventricular apical PMI is displaced inferiorly and laterally to the fifth or sixth intercostal space, representing ventricular dilation and remodeling

What anatomical change is reflected by a displaced point of maximal impulse on physical exam of a heart failure patient?

Rapid ventricular filling during early diastole into an already volume-overloaded, non-compliant ventricular cavity

What physiological event produces an S3 third heart sound in heart failure?

Atrial contraction pushing blood into a stiff, non-compliant ventricle during late diastole

What physiological event produces an S4 fourth heart sound in heart failure?

Estimated right atrial pressure is calculated by measuring the height of the jugular venous column above the sternal angle in centimeters and adding five centimeters

What is the step-by-step method for quantifying jugular venous pressure?

Sustained pressure on the abdomen for ten to thirty seconds forces venous blood back to the heart, distending the internal jugular vein if the right ventricle is non-compliant

What is the physiological mechanism of the abdominojugular reflux test?

Mitral and tricuspid annular dilation due to progressive ventricular remodeling prevents normal leaflet coaptation, producing functional valvular regurgitation

What mechanism causes secondary mitral or tricuspid regurgitation in advanced heart failure?

Accumulation of bradykinin due to ACE inhibitor-mediated blockade of its degradation pathways

What biochemical pathway is responsible for the development of dry cough during enalapril therapy?

Loop diuretics inhibit the Na-K-2Cl cotransporter in the thick ascending limb of Henle, promoting rapid sodium and water excretion to relieve congestion

What is the mechanism of action of furosemide in heart failure?

High-dose diuretics cause excessive volume depletion, severe electrolyte abnormalities, worsening cardiorenal syndrome, and are linked to increased mortality

Why should high doses of loop diuretics be avoided in chronic heart failure?

Block the beta-one receptor to prevent chronic adrenergic-mediated toxicity, decrease heart rate to prolong diastole, and slow the progression of ventricular remodeling

What is the mechanism of action of beta-blockers in heart failure?

ACE inhibitors block angiotensin converting enzyme to prevent angiotensin II synthesis, while ARBs block the angiotensin II type one receptor directly

What are the mechanisms of action of ACE inhibitors and ARBs in heart failure?

Sacubitril is a prodrug that inhibits neprilysin to prevent the breakdown of ANP and BNP, while valsartan blocks the AT1 receptor to prevent remodeling

What is the dual mechanism of action of an angiotensin receptor-neprilysin inhibitor?

Competitive antagonism of the mineralocorticoid receptor blocks aldosterone-mediated sodium reabsorption, potassium excretion, and myocardial fibrosis

What is the mechanism of action of spironolactone in heart failure?

Inhibit SGLT2 in the proximal renal tubule to prevent glucose and sodium reabsorption, promoting osmotic diuresis and natriuresis to improve preload and afterload

What is the mechanism of action of SGLT2 inhibitors in heart failure?

Hydralazine relaxes arterial smooth muscle to reduce afterload, but without RAAS-blocking activity, left ventricular remodeling proceeds unimpeded

Why do HFrEF patients treated with hydralazine alone have a poorer long-term prognosis than those on RAAS blockers?

Administer loop diuretics to decongest the patient, then initiate SGLT2 inhibitors, followed by RAAS blockers, then beta-blockers once stable, and finally MRAs

What is the recommended clinical sequencing pathway for initiating HFrEF medications?