Post-infarction conduction abnormalities

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hamid Parsa, MD.[2]

Synonyms and keywords:arrhythmias, ventricular septal defect, Supraventricular arrhythmias, ventricular arrhythmias, myocardial infarction, ischemic heart disease

Overview[edit | edit source]

Acute myocardial infarction (MI) remains the leading cause of mortality all over the world. Electrical conduction abnormalities commonly complicate acute myocardial infarction, leading to a further rise in long and short term morbidities and mortality rates. ^[1] Different types of conduction abnormalities can follow MI, with bradyarrhythmias and atrioventricular (AV) block representing the most common. Other post-MI conduction abnormalities include supraventricular arrhythmias and ventricular arrhythmias.

Historical Perspective[edit | edit source]

• The history of myocardial infarction (MI) diagnostics has gone through a continuous evolution over the past century, when several new discoveries have contributed to remarkably increase the number of patients appropriately diagnosed with this condition.^[2]
• For the time being, acute myocardial infarction represents a history of success concerning diagnose, management and treatment, whereas it was considered a fatal disease in the beginning of the 1900s.^[3]
• The evolution of the management of acute myocardial infarction (MI) has been one of the crowning achievements of modern medicine. At the turn of the twentieth century, MI was an often-fatal condition.^[4]

Classification[edit | edit source]

Bradyarrhythmia:

• Sinus bradycardia

Atrioventricular blocks:

• First degree AV block
• Second degree AV block
• Third degree AV block

Bundle branch blocks:

• Left bundle branch block (LBBB)
• Right bundle branch block (RBBB)
• Right bundle branch block(RBBB) with left anterior fascicular block (LAFB)
• RBBB with left posterior fascicular block (LPFB)
• Alternating bundle branch block
• Bifascicular block plus PR prolongation (trifascicular block)

Pathophysiology[edit | edit source]

Myocardial infarction is defined as sudden ischemic death of myocardial tissue. In the clinical context, myocardial infarction is usually due to thrombotic occlusion of a coronary vessel caused by rupture of a vulnerable plaque. Ischemia induces profound metabolic and ionic perturbations in the affected myocardium and causes rapid depression of systolic function. Prolonged myocardial ischemia activates a "wavefront" of cardiomyocyte death that extends from the subendocardium to the subepicardium. Mitochondrial alterations are prominently involved in apoptosis and necrosis of cardiomyocytes in the infarcted heart. The adult mammalian heart has negligible regenerative capacity, thus the infarcted myocardium heals through formation of a scar. Infarct healing is dependent on an inflammatory cascade, triggered by alarmins released by dying cells. Clearance of dead cells and matrix debris by infiltrating phagocytes activates anti-inflammatory pathways leading to suppression of cytokine and chemokine signaling. Activation of the renin-angiotensin-aldosterone system and release of transforming growth factor-β induce conversion of fibroblasts into myofibroblasts, promoting deposition of extracellular matrix proteins. Infarct healing is intertwined with geometric remodeling of the chamber, characterized by dilation, hypertrophy of viable segments, and progressive dysfunction. This review manuscript describes the molecular signals and cellular effectors implicated in injury, repair, and remodeling of the infarcted heart, the mechanistic basis of the most common complications associated with myocardial infarction, and the pathophysiologic effects of established treatment strategies. Moreover, we discuss the implications of pathophysiological insights in design and implementation of new promising therapeutic approaches for patients with myocardial infarction.^[5]

Causes[edit | edit source]

• The usual cause of sudden blockage in a coronary artery is the formation of a blood clot (thrombus).
• most common cause of a myocardial infarction is the rupture of an atherosclerotic plaque on an artery supplying heart muscle.
• spontaneous coronary artery dissection (SCAD) and atherosclerosis as the cause of acute myocardial infarction (AMI), especially in young females.^[6]
• A coronary artery embolism is an uncommon non-atherosclerotic cause of acute myocardial infarction.^[6]
• Coronary occlusion secondary to vasculitis.
• Ventricular hypertrophy
• Coronary trauma.

Differentiating myocardial infarction from other Diseases[edit | edit source]

MI must be differentiated from other diseases that cause chest pain such as :

• acute pericarditis
• Acute Mitral Regurgitation
• myocarditis
• Myopericarditis
• aortic stenosis
• aortic dissection
• Aortic Regurgitation
• Asthma
• Anxiety Disorders
• Cardiogenic Shock
• pulmonary embolism
• Mitral Valve Prolapse
• pneumonia
• pneumothorax

Epidemiology and Demographics[edit | edit source]

The incidence/prevalence of [disease name] is approximately [number range] per 100,000 individuals worldwide.

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In [year], the incidence/prevalence of [disease name] was estimated to be [number range] cases per 100,000 individuals worldwide.

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Patients of all age groups may develop [disease name].

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The incidence of [disease name] increases with age; the median age at diagnosis is [#] years.

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[Disease name] affects men and women equally.

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[Disease name] is a common/rare disease that tends to affect [patient population 1] and [patient population 2].

Risk Factors[edit | edit source]

• An abnormally high level of blood cholesterol (hypercholesterolemia)
• An abnormally low level of HDL (high-density lipoprotein), commonly called "good cholesterol"
• High blood pressure (hypertension)
• Diabetes
• Family history of coronary artery disease at an early age
• Cigarette smoking
• Obesity
• Physical inactivity (too little regular exercise)
• Age

Other Risk Factor:

• stress
• lack of exercise
• the use of certain illegal drugs, including cocaine and amphetamines
• a history of preeclampsia, or high blood pressure during pregnancy

Screening[edit | edit source]

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Natural History, Complications, and Prognosis[edit | edit source]

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Diagnosis[edit | edit source]

Diagnostic Study of Choice[edit | edit source]

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Laboratory Findings[edit | edit source]

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Electrocardiogram[edit | edit source]

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MRI[edit | edit source]

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Surgery[edit | edit source]

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References[edit | edit source]

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