title: Uncommon causes of hemodynamic instability during myocardial revascularization without cardiopulmonary bypass.
abstract: OBJECTIVE
  Myocardial revascularization (MR) in patients with ventricular hypertrophy and/or dysfunction is frequently performed without cardiopulmonary bypass (CB), since it can be difficult to wean those patients off CB. Intraoperative control demands strict hemodynamic adjustment, as well as partial clamping of the aorta to minimize hemodynamic changes. The objective of this study was to report two cases of hemodynamic instability during MR without CB after partial clamping of the aorta.
  
  
  METHODS
  The first case is a female patient, whose aortic diameter was slightly reduced (2.8 cm); the second case refers to a patient with left ventricular ejection fraction (LVEF) of 24% on the echocardiogram. In both cases, significant hypotension and increase in pulmonary blood pressure were observed immediately after clamping of the aorta. The surgical teams were informed of the problem, and in both cases the hemodynamic instability was reverted after unclamping of the aorta. Afterwards, smaller areas of the aorta were clamped and proximal anastomoses were performed without intercurrence.
  
  
  CONCLUSIONS
  Although cardiac manipulation and changes in ventricular preload represent the most common causes of hemodynamic instability during MR without CB, in the cases presented here, hypotension and pulmonary hypertension were most likely secondary to a reduction in cardiac output due to the increase in afterload in patients with a relatively small aortic diameter or ventricular dysfunction even with partial clamping. Adequate intraoperative monitoring and immediate correction of the hemodynamic changes can minimize surgical morbidity and mortality.
authors.affiliation: Serviço de Anestesiologia, HC, FMUSP, Ribeirão Preto. maria.carmona@incor.usp.br
authors.forename: Luciana Moraes dos
authors.initials: LM
authors.lastname: Santos
authors.forename: Maria José Carvalho
authors.initials: MJ
authors.lastname: Carmona
authors.forename: Silvia Minhye
authors.initials: SM
authors.lastname: Kim
authors.forename: Ricardo Ribeiro
authors.initials: RR
authors.lastname: Dias
authors.forename: José Otávio Costa
authors.initials: JO
authors.lastname: Auler
mesh_terms: D001013:Aorta, Thoracic; D002303:Cardiac Output, Low / Q000209:etiology*; D003250:Constriction; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009204:Myocardial Revascularization; D018487:Ventricular Dysfunction, Left / Q000209:etiology*