1.Failure of the pump- In the most common situation, the cardiac muscle contracts weakly and the chambers cannot empty properly—so-called systolic dysfunction. In some cases, the muscle cannot relax sufficiently to permit ventricular filling, resulting in diastolic dysfunction.
2.Obstruction to flow- Lesions that prevent valve opening (e.g., calcific aortic valve stenosis) or cause increased ventricular chamber pressures (e.g., systemic hypertension or aortic coarctation) can overwork the myocardium, which has to pump against the obstruction.
3.Regurgitation flow- Valve lesions that allow backward flow of blood create conditions that add increased volume workload to the affected chambers with each contraction.
4.Shunted flow- Defects (congenital or acquired) that divert blood inappropriately from one chamber to another, or from one vessel to another, lead to pressure and volume overloads.
5.Disorders of cardiac conduction- Uncoordinated cardiac impulses or blocked conduction pathways can cause arrhythmias that reduce contraction frequency or diminish effective cardiac output.
6.Rupture of the heart or major vessel. Loss of circulatory continuity (e.g., gunshot wound through the thoracic aorta) leads to exsanguination, hypotensive shock, and death.
