Treatment of complications of myocardial infarction

Acute revascularisation measures, within hours or days after myocardial infarction, have an increased operation risk. This is also the case for emergency surgery after failed percutaneous balloon dilatation, e.g. after iatrogenic occlusion or dissection of coronary arteries. However, myocardial infarction cannot be prevented in all cases. A large defect in the ventricular septum can develop within days as a result of acute infarction. Such a life-threatening infarction-induced ventricular septal defect (VSD) can often be treated only by high-risk emergency cardiac surgery to close the VSD by means of a synthetic patch.

However, sudden mitral insufficiency with subsequent cardiac instability of the patient can also occur as a result of necrosis of a papillary muscle, particularly with a posterior infarct. Imminent cardiac shock can then be averted only by emergency mitral valve replacement.

A ventricular aneurysm develops after large infarcts involving all layers of the heart wall. The thin scar bulges out like a balloon due to the systolic pressure. The cause is usually an anterior infarct due to proximal occlusion of the left anterior descending artery, with the posterior wall affected more rarely. Ventricular aneurysms are usually asymptomatic initially and the heart becomes weaker later because of reduced pump function. Embolism (because of blood clots dislodged from the aneurysm sac) is not uncommon. The cardiac surgeon must therefore make a longitudinal opening in the cardioplegic heart in the region of the aneurysm sac, using ECC to arrest the heart whose pump function is markedly impaired. The scar tissue is removed almost to the edge of the intact muscle. The resulting large opening in the left ventricle is closed with a continuous suture over plastic strips. Alternatively, the defect can be closed with a Dacron® patch.

After one major or several myocardial infarctions, if there is massively disturbed pump function (severe heart failure, ejection fraction (EF) <20%), an intra-aortic balloon pump (IABP) can be inserted in the intensive care unit or mechanical circulatory support systems (assist devices) can be employed as a temporary life-saving measure and bridging until cardiac transplantation if the cardiogenic shock persists despite complex modern therapy. Implantation of a defibrillator or cardiac pacemaker may be necessary for severe arrhythmias such as ventricular fibrillation and conduction blocks that can no longer be controlled medically and occur repeatedly. In end-stage heart failure due to diffuse CHD with high-grade impairment of ventricular function (= decompensated heart failure) or even after implantation of an assist device, the patient’s long-term survival and quality of life can only be secured by a heart transplant as a last resort.