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Definition
1 - The acute complications a - Disorder of the rhythm and of the cardiac conduction: - Slowing of the heart (bradycardia) and increase of the cardiac frequency (tachycardia). Bradycardia is very frequent notably in the acute stage in case of lower myocardial infarction. The vasovagal malaise is characteristic: hypotension, sweats, nauseas, vomiting, yawning. The treatment calls on the atropine in the subcutaneous dose of 0.5mg or by i.v. The tachycardia is a bad prognosis if it persists beyond the painful stage: it is often a sign of a left cardiac failure. - The disorders of the ventricle rhythm They directly witness the myocardial infarction. They are precocious or even inaugural and exacerbated by the discharge of adrenaline in the original stage. + The ventricular premature beats are frequent and sometimes precede more serious ventricular rhythm disorders. The heralding signs are their number (superior to 5/minute), their polymorphous character, and their association in doublets (bigeminy) or in “triplets”, or their situation close to the T wave. The physician’s interest is then to treat them by lidocaine in the dose of 1200 with 1600mg/24h while controlling the potassium rate. + Ventricular tachycardias are regular tachycardias. They impose an immediate treatment, because of the risk of evolution toward a ventricular, generally lethal fibrillation. In one case, the ventricular tachycardia witnesses the reperfusion of the cardiac muscle; in another case it proves a decay of the heart muscle. If the ventricular tachycardia is well tolerated by the patient, the physician can attempt a pharmacological reduction by 2mg/kg Lidopaine in bolus or 150mg amiodarone. In case of intolerance or failure, the external electric shock under Valium is indicated, relieved by a preventive antiarrhythmic treatment of the relapses.
+ The ventricular fibrillation is sometimes inaugural (sudden death), precocious (primary ventricular fibrillation with a good prognosis), sometimes late (secondary ventricular fibrillation) then coming with a bad prognosis aneurysm of the left ventricle. The only treatment is the external electric shock, the resuscitation and a vigorous antiarrhythmic treatment sometimes associating 2 antiarrhythmic drugs. - The disorders of the heart electric conduction If they are precocious and frequent, they are generally transient. + The atrio-ventricular blocks of the posterior-lower myocardial infarction reveal an attack of the atrio-ventricular node. Their rhythm is generally fast and does not systematically require a pacemaker. + The atrio-ventricular blocks of the previous myocardial infarctions are brutal and complete, inducing a slow cardiac rhythm. The apparition of the slightest conduction disorder in case of previous myocardial infarction imposes the implantation of a transient pacemaker. + The other disorders of the cardiac rhythm occur more seldom. The premature beats of the auricle are banal and can be the signs of an evolution into an atrial fibrillation. The atrial fibrillation, or more seldom the atrial flutter, sometimes comes with a previous myocardial infarction and precipitates the patient into a left cardiac failure. It can also be the consequence of the constitution of a pericarditis. Their reduction under amiodarone and digitalis requires 24 to 48 hours: meanwhile, a pulmonary oedema treatment is therefore systematically associated. b - Acute cardiac failure: 1rst mortality cause in the myocardial infarction - Left cardiac failure The acute pulmonary oedema (APO) accompanies the extended previous myocardial infarction. Obstinate tachycardia or even shortening of breath in lying position are the heralding signs. - Right cardiac failure: it often comes with the posterior-lower myocardial infarction (see specific question). c - Mechanical complications, due to the modifications of the heart tissues features. - The rupture of the heart wall (free wall rupture) It is a rare possibility. The picture is the most often brutal with the stop of the heart, or progressive with the creation of an effusion in the tissue enveloping the heart, the pericardium. The heart scan confirms the presence of blood in the pericardium. The patient must be quickly referred to the surgeon. - The communication between the two ventricles (“inter-ventricular communication” and rupture of the interventricular septum) When the infarct involves the wall between the two ventricles, a perforation of this wall (the inter-ventricular septum) can cause an inter-ventricular communication. This communication comes with a global cardiac failure or a cardiovascular shock state. The echocardiography, a haemodynamic and angiographic check-up precede the surgical closing. - The rupture of a mitral pillar (rupture of a papillary muscle) Filaments that the physicians call cordskeep the mitral valve, situated between the auricle and the left ventricle. These cords are indispensable to prevent the mitral valve from regurgitating. These cords are kept to the heart muscle by pillars (papillary muscle).
The rupture of a mitral pillar is a rare but extremely serious possibility. Only inserting a prosthetic cardiac valve in emergency along with a new vascularisation of the damaged area of the heart muscle permits a hope for survival. d - Anatomical evolution of the infarct (recurrent ischemia and infarction) Sometimes, in spite of a medical or instrumental well-conducted treatment, the size of the infarct can nevertheless increase. e - The other complications of the precocious stage of the myocardial infarction * The clots formed in the heart are more frequent in case of aneurysm of the left ventricle (dilation of the left ventricle forming a pocket), well visible on echocardiography. * Venous thrombo-embolism and pulmonary embolism are avoided by the passive mobilization of the members, wearing support stockings and a heparin treatment. * The occurrence of a pericarditis is frequent in case of an extended myocardial infarction. Its treatment calls on the non-steroid anti-inflammatory drugs and to dividing heparin doses in 2. 2 - The late complications of the myocardial infarction * The recurrentischaemia is only symptomatic once out of 2. The exercise electrocardiogram must sometimes be carried out under treatment and meet 75% at the utmost of the maximal theoretical frequency: - A positive electrocardiogram in the myocardial infarction territory proves an incomplete permeability that can benefit from a re-vascularization. - A positivity in another territory reveals a bi - or tri-truncal lesion and the indication of coronarography is brought - Negativity must lead to a new exam later and reach thetheoretical maximal frequency * The recurrent ischemia and infarction can occur in situ or on another territory: it is anyway pejorative. One then distinguishes the threat of recidivation and extension syndrome respectively. They require restarting the heavy treatment of the myocardial infarction (aspirin, heparin, nitrate, powerful antisludge drugs). Recurent ischemia can be painless. The most indicated radical treatment is in one case angioplasty and in the other one surgery. * The secondary ventricular fibrillation is more frequent in case of aneurysm of the left ventricle or evolved myocardial decay. It is detected by the EKG Holter and is treated by antiarrhythmic drugs. * The aneurysm of the left ventricle exposes to the cardiac failure and rhythmic and thromboembolic complications. A perceivable systolic expansion associated to a B4, a ST over-gap beyond 15 days occurring in a previous myocardial infarction are heralding signs. Echocardiography and angiography make the diagnosis. It justifies a surgical exeresis when it is possible. * The Dressler syndrome has an immunological nature. From the 15th day, it associates a pericardial or even pleural reaction to a febrile inflammatory syndrome. It gives up with non-steroid anti-inflammatory drugs. File last reviewed on dec 18, 2011 |
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