Apical suction leads to severe ischemia of the ventricular apex

Objective: Apical suction devices allow displacement of the heart in off-pump coronary artery surgery. However, high vacuum pressure may injure the suctioned myocardium. It has been demonstrated that partial pressure of oxygen in the myocardium (ptiO 2 ) is a sensitive and rapid indicator of myocardial ischemia. The purpose of this study is to evaluate the effect of apical suction on the ptiO 2 as an indirect measure of myocardial perfusion of the ventricular apex. Methods: Twenty-six patients undergoing elective off-pump coronary surgery were studied. Intramyocardial ptiO 2 was continuously measured using a flexible catheter microprobe (Licox® GMS mbH, Kiel, Germany). Patients were divided into two groups. In one group (Group A; n = 14), the microprobe was intraoperatively inserted into the myocardium of the left ventricular apex. In the second group (Group B; n = 12), the probe was inserted in the anterior wall of the left ventricle. Intramyocardial ptiO 2 monitoring was made with the heart in the resting position and after placing the apical suction device. Results: In Group A, basal ptiO 2 was 15.3 ± 7.4 mmHg. One minute after placing the apical suction device, the ptiO 2 significantly decreased to 2.3 ± 1 mmHg (p < 0.001). A progressive increase of ptiO 2 was observed immediately after the Xpose™ suction device was removed. ptiO 2 was 13.6 ± 9.1 mmHg 5 min after releasing the suction cup and increased to 27.2 ± 12.6 mmHg 20 min later. In Group B, basal ptiO 2 was 17 ± 10.3 mmHg. No significant changes were observed in Group B after placing and removing the suction cup. Conclusions: Apical suction devices lead to severe ischemia of the suctioned myocardium. Collapse of coronary vessels due to vacuum pressure is a possible mechanism. Reperfusion occurs immediately after removing the suction cup and a significant reactive hyperemia is observed.