"The non-ischemic repair" as a safe alternative method for repair of anterior post-infarction VSD

The rupture of the interventricular septum after myocardial infarction constitutes a severe mechanical complication of the coronary artery disease with very high surgical mortality (19-50%) and morbidity [1, 2]. Many factors contribute to an unfavourable surgical outcome such as the emergency, the coexisting 3-vessel coronary artery disease, the posterior rupture, the "non-complete revascularization" operation, the "intractable" shock and the secondary organ-failure (mainly renal) [2, 3]. The adequate myocardial protection during the operation is considered to be the cornerstone for a better outcome postoperatively [4, 5]. The classic method of systemic hypothermia, aortic occlusion, and intermittent administration of cold blood cardioplegic solution is a well established method for the reconstruction of the post-infarction VSD [1–4, 6]. Nevertheless, cardioplegic arrest is related to perioperative myocardial injury, which is considered as a severe determinant of postoperative haemodynamic condition, and therefore of clinical outcome [7, 8]. This is the reason of suggestions by some authors for other alternative methods as that of using continuous myocardial perfusion after aortic occlusion, or by using intermittent ventricular fibrillation, or by administration of normothermic cardioplegia [9, 10]. We propose another alternative method of myocardial protection during surgical repair of the anterior or apical cases of ruptures of the ventricular septum, and we recommend this as simple, safe and efficient.

Patient's myocardium with post-infarction VSD is characterized by severe dysfunction [2, 3]. Many unfavourable factors such as the recent infarction, the shock condition, the increased tissue (myocardial) edema, the inotropic support, the increased endogenous produced catecholamines, as well as the coexisting hypoxia due to pulmonary congestion are causing severe malfunction of the rest "rescued" myocardium. The additional ischemia to this myocardium, due to aortic occlusion and systemic and local hypothermia, entails significant postoperative functional deterioration and finally, possible unfavourable outcome. The methodology of myocardial protection using obligatory aortic occlusion, continuous or even intermittent, which was applied from the beginning of the surgical treatment of the post myocardial infarction mechanical complications, is still consider to be by many authors "inevitable" [1–3, 5, 6]. Even Gummert et al [6] in their chapter about the use of beating heart methodology in patients with acute myocardial infarction, state: "ventricular septal defect, acute mitral regurgitation, and myocardial free wall rupture following acute myocardial infarction require reparative surgery under cardioplegic arrest, and therefore will not be discussed any further in this chapter". The attempt to avoid systematic hypothermia, aortic occlusion and cardioplegia infusion is aiming to avoid cardiac arrest and to nullify the ischemic time. Our methodology has a series of significant advantages, especially important in our opinion for the early and also the late postoperative results: a) it does not aggravate the myocardium with the "toxic influence" of the ischemia - reperfusion process, b) additionally it does not have the adverse effect of the systemic hypothermia, c) it allows to the left ventricle to contract empty of volume on extracorporeal circulation, condition which consider to be the most favorable from the energy consumption point of view ("... the oxygen consumption of the beating, empty heart -as on cardiopulmonary bypass- is less than under any other condition.") [11], d) it significantly reduces the CPB time, another important detrimental factor, mainly because it avoids the hypothermia but also because we don't use any other catheter for cardioplegia infusion etc., e) it precludes possible complications from the cardioplegic infusion such as injury to the coronary vessels, coronary embolism, myocardial oedema etc., f) it allows easier distinction of the excision borders of the non-viable septum up to the point of the viable bleeding tissue, g) it secures safer "palpable feeling" for the proper setting and above all correct riveting of the sutures in a contracting not arrested myocardium which keeps the natural muscular tone (it avoids crushing the arrested myocardium), h) it can be applied in the anterior and apical ruptures which are the majority of the ruptures representing 60-80% of all cases [3], and finally ι) it allows seasonably control and correction of any local bleeding point in the ventriculotomy suture line during the phase of the passive lung expansion, and the temporary left ventricle overloading. Our method's disadvantage is that it can not be applied in the cases of inferior septal ruptures, unless they are either small or chronic, and the temporarily produced aortic regurgitation can be well tolerated by the patient. We have to note that there is no risk of aortic embolism during the maneuvers, because the existence of continuously positive intra-aortic pressure and patient's Trendelenburg position. Up today we have used the method in 3 patients with anterior rupture ascertaining the previous mentioned advantages in emergent setting. We observed a better global cardiac function during the early postoperative phase. It has been observed an amelioration of about 10% of the left ventricle ejection fraction. Two of the patients survived without complications and discharged after 13 and 17 days respectively from hospital, but unfortunately, the third one died 28 days postoperatively in intensive care unit (ICU) from multiple organ failure (MOF). The small number of our patients does not allow us to randomly compare the haemodynamic and clinical results, but we greatly believe that the complete abolition of the ischemic-time improves the safety conditions of the operation, the early results, as well as the survival in these patients. However, further multicenter randomized trials are necessary in order to establish the superiority of this method.