Shock is traditionally classified according to its primary etiology—septic, hypovolemic, obstructive, or cardiogenic—yet these syndromes frequently converge on a common feature: disturbances of cardiac performance, ventricular loading, and tissue perfusion. Despite distinct initiating mechanisms, altered preload and afterload, ventricular interdependence, vascular dysfunction, maladaptive neurohormonal responses, and, in selected states, impaired myocardial contractility may ultimately reduce effective forward flow and tissue perfusion. Echocardiography provides a rapid, noninvasive bedside tool for characterizing these evolving cardiovascular effects. It enables assessment of left and right ventricular function, cardiac filling, preload responsiveness, pulmonary and systemic venous congestion, fluid tolerance, and broader hemodynamic profiles while facilitating recognition of reversible causes such as cardiac tamponade, acute pulmonary embolism, or severe hypovolemia. This allows clinicians to move beyond static etiologic classifications toward a physiology-based assessment of shock. Beyond diagnosis, echocardiography can inform fluid resuscitation and vasoactive or inotropic therapy. Serial assessment also permits evaluation of therapeutic response and evolving hemodynamic phenotypes. This review synthesizes the mechanisms of cardiac involvement across shock syndromes and highlights echocardiography as a unifying tool for their evaluation and management. By integrating pathophysiology, bedside imaging, and hemodynamic treatment, we propose a physiology-based framework that complements traditional shock classification and may improve diagnostic precision and individualized management in critically ill patients.