Beyond the 100-bpm Dogma: A Physiology-Guided Approach to Early Postoperative Heart Rate Management After Heart Transplantation.

چکیده اصلی

Early postoperative heart rate (HR) management after heart transplantation (HTx) remains largely guided by historical haemodynamic concepts that support maintaining elevated HR to compensate for reduced stroke volume. This structured narrative review re-examines the physiological rationale and contemporary evidence underlying this approach, with the aim of refining perioperative chronotropic strategies. A comprehensive analysis of studies addressing early HR behavior, sinus node dysfunction (SND), pacing strategies, chronotropic therapies, and their association with clinical outcomes was performed. Classic studies from the 1970s described marked stroke-volume depression and a strong dependence of cardiac output on HR, forming the basis for maintaining HR around 90-100 bpm. However, contemporary evidence indicates a more heterogeneous early graft physiology, often with less pronounced stroke-volume limitation, and highlights potential adverse effects associated with excessive adrenergic stimulation, including renal dysfunction and worse mid-term outcomes. SND is common but typically transient, and atrial or atrioventricular-synchronous pacing can restore HR without the metabolic burden of β-adrenergic stimulation. In contrast, isoproterenol provides combined chronotropic and inotropic support but may increase myocardial oxygen consumption, shorten diastolic filling time, and impair right ventricular-pulmonary artery coupling when perfusion pressure is inadequate. Integration of perfusion markers, such as lactate and central venous oxygen saturation, with echocardiographic and invasive haemodynamic assessment is essential to determine whether HR augmentation improves oxygen delivery or instead increases metabolic stress. Early HR management after HTx should therefore be individualized and guided by integrated physiological assessment rather than fixed HR targets. Prospective studies are needed to define evidence-based chronotropic strategies.

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