2 The procedure
2.1.1 Endoaortic balloon occlusion is performed to achieve temporary obstruction of the aorta during cardiac surgery, including mitral valve repair or replacement and coronary artery bypass grafting.
2.1.2 Occlusion of the aorta is required in a number of cardiac operations. This is normally achieved by external application of an aortic cross-clamp, either during conventional open surgery or during minimally invasive cardiac procedures.
2.2.1 This procedure is usually employed during minimally invasive cardiac operations (also known as port-access surgery) that require endovascular aortic occlusion, cardioplegia and left ventricular decompression.
2.2.2 A balloon catheter is inserted through the skin into an artery (normally the femoral artery in the groin) and manipulated towards the aortic root. The balloon at the tip of the catheter is filled with saline to occlude the aorta and prevent blood flow. Various devices can be used for this procedure.
2.2.3 Continuous transoesophageal echocardiographic monitoring is used to detect balloon migration along with other forms of monitoring such as radial arterial pressure monitoring and direct monitoring of the surgical field, as necessary.
Sections 2.3 and 2.4 describe efficacy and safety outcomes which were available in the published literature and which the Committee considered as part of the evidence about this procedure. For more details, refer to the Sources of evidence.
2.3.1 There were no outcomes reported in the literature that related directly to the efficacy of endoaortic balloon occlusion alone.
2.3.2 The Specialist Advisers considered key efficacy outcomes to include efficiency of cardioprotection, reduced length of hospital stay, duration of cardiac arrest and avoidance of the use of a cross-clamp from outside.
2.4.1 In a case series of 306 patients treated with endoaortic balloon occlusion, the 30-day mortality rate was 1% (3/306) and the rate of late deaths (mean follow-up 20 months) was 2% (6/306). A case series comparing 117 patients treated with endoaortic balloon occlusion with 117 matched controls treated with conventional aortic cross-clamping reported one perioperative death in each group. In four case series, 5% (11/209), 4% (6/151), 1% (1/127) and 25% (13/52) of patients who were treated with endoaortic balloon occlusion died in hospital.
2.4.2 The three case series of 306, 209 and 117 patients treated with endoaortic balloon occlusion all reported aortic dissection in 1% (3/306, 3/209, and 1/117) of patients. One aortic dissection in the case series of 151 patients was judged by the authors to be unrelated to the endoaortic balloon occlusion device. In the case series that described 58, 120 and 127 patients, no aortic dissections occurred.
2.4.3 In a case series of 449 patients, there were no significant differences in the incidences of arrhythmias, pulmonary dysfunction, bleeding, renal failure or low cardiac output between those treated with endoaortic balloon occlusion and those treated with transthoracic clamping. However, the rates of neurological complications were higher in patients who had endoaortic balloon occlusion (p < 0.05; absolute numbers not given). (Neurological complications were defined as stroke and transient hemiplegia.)
2.4.4 In five case series, stroke or transient ischaemic attack was reported in 4% (2/52), 2% (2/127), 0.4% (1/306), 1% (1/117) and 1% (1/151) of patients.
2.4.5 In seven case series, re-exploration for bleeding or tamponade was required in 10% (6/60), 9% (26/306), 7% (14/209), 6% (9/151), 4% (5/117), 4% (1/23) and 2% (3/127) of patients treated with endoaortic balloon occlusion.
2.4.6 In the case series of 306 and 151 patients, myocardial infarction was reported in 1 and 2 patients, respectively.
2.4.7 The Specialist Advisers reported anecdotal adverse events including aortic dissection, balloon puncture, balloon migration, damage to aortic intima, device movement causing loss of occlusion, femoral artery damage, difficulty positioning the balloon, death due to failure to deliver cardioplegia, and inability to complete planned surgery due to occlusion failure. Additional theoretical adverse events noted by the Advisers were stroke, inadequate myocardial protection and cerebral ischaemia due to balloon misplacement and arterial embolism. The Advisers noted that this procedure has the potential to reduce stroke risk in patients who have a very calcified aorta.