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Commentary on "protective effect of pulmonary hypertension against right-sided tamponade in pericardial effusion".

Cardiac tamponade is a life-threatening condition requiring urgent detection to provide effective treatment. The diagnosis of cardiac tamponade is based upon clinical and echocardiographic findings, which often can be subtle. Classic physical examination findings include the Beck triad (hypotension, distended neck veins, and muffled heart sounds) and tachycardia and pulsus paradoxicus 910 mm Hg. Echocardiographic findings include right atrial systolic collapse, right ventricular diastolic collapse, paradoxical septal motion, respiratory reduction in mitral inflows, and inferior vena cava dilation. The rapid recognition of these findings is critical in establishing the diagnosis of cardiac tamponade and providing emergency therapy. Pulmonary arterial hypertension (PAH) results in hemodynamic changes, predominantly in the right side of the heart, which can interferewith signs for identifying cardiac tamponade. Elevated right heart pressures resist the compressive effects of increased pericardial pressure in the effusion, reducing the degree of right atrial and right ventricular collapse. Chronic PAH also can result in structural changes to the right ventricular and right atrial myocardium, which further resist the effects of elevated pericardial pressure. Subsequent reduction in ventricular interdependence can reduce respiratory variations in left ventricular filling, further impairing signs of cardiac tamponade. The structural and hemodynamic effects of PAH on the right heart may result in atypical presentations of cardiac tamponade, with isolated left ventricular diastolic collapse relativelymore likely in this setting. Isolated left-sided tamponade can lead to systemic hypotension as a result of impaired left ventricular fillingwithout the classic right-sided physical examination and echocardiographic findings that are typical of cardiac tamponade. Numerous case reports have documented absent or impaired physical examination findings of cardiac tamponade in patients with PAH. Moreover, Plotnick et al demonstrated in a blinded prospective study that the presence of PAH reduced the predictive accuracy of echocardiographic findings in diagnosing cardiac tamponade by 8% to 32%. As such, isolated left-sided cardiac tamponade in the setting of PAH is more insidious in its presentation and more difficult to recognize than classic cardiac tamponade. In this issue of the Southern Medical Journal, Khan and Khouzam describe the impact of PAH on the diagnosis and management of cardiac tamponade. Their review is a cogent summary of the acute and chronic pathophysiologic effects of pulmonary hypertension on the right heart chambers and the mechanisms by which PAH may impair the recognition and treatment of cardiac tamponade. They appropriately caution against the rapid lowering of pulmonary artery pressure in the presence of a significant pericardial effusion because this may enhance the pressure difference between the pericardium and right-sided chambers, thereby precipitating the rapid development of an underlying cardiac tamponade. Although this mechanism has been described in case reports, it is not likely to be studied in a large-scale clinical trial because of the rarity of this condition and its severe consequences. Nevertheless, the concerns expressed by the authors are based on sound hemodynamic principles and are clinically reasonable. These concerns also are of more than just theoretical significance, because many conditions that cause PAH also result in pericardial effusions. Shimony et al reported a prevalence of pericardial effusion of 44% in a 2-year period in patients with PAH; therefore, heightened awareness of the coexistence of these conditions is warranted. Furthermore, prophylactic pericardial drainage in advance of treating PAH is not a desirable option, because therapeutic pericardiocentesis generally is not indicated in the absence of cardiac tamponade. Medical personnel involved in the management of PAH or Invited Commentary