Myocardial Infarction
Definition
MI
Is death of the cardiac muscle due to occlusion of the coronary arteries or their branches
The dead or necrosed part is replaced by scar tissue
Pathophysiology
One or all the coronary arteries or their branches get occluded by a plaque
The affected part becomes ischaemic - pain - dies - replaced by scar
According to the area of involvement : anterior, inferior, posterior or lateral wall MI
ECG identifies the location and ECG with history identifies the time.
Causes
Vasospasm of a coronary artery
Decreased oxygen supply (eg. acute blood loss, anemia, or low blood pressure)
Increased demand for oxygen e.g., rapid heart rate, thyrotoxicosis, ingestion of cocaine)
- a profound imbalance exists between myocardial oxygen supply supply and demand
Signs and Symptoms
of an acute myocardial Infarction or Acute Coronary Syndrome (ACS)
Chest pain / discomfort
Palpitations
Shortness of breath, dyspnea, tachypnea, crepitations due to pulmonary edema
nausea, vomiting
decreased urinary output due to cardiogenic shock
cold clammy skin, pallor
Anxiety, restlessness, light headedness
Fear of impeding death
Heart sounds S3,S4 and new onset of a murmur
Increased jugular venous distension
BP may be elevated or decreased
Pulse deficit may indicate atrial fibrillation
Diagnosis
ECG : to be taken within 10 mts - changes seen in the leads that face the involved wall of the heart
Pathological Q wave
ST segment elevation of more than one small square
T wave inversion
MI classified as Q-wave infarction and non-Q-wave infarction
Q wave develops in 1 to 3 days
Echocardiogram
evaluates ventricular function
Lab tests :
CK-MB raised - if negative repeat after 3 hours - another negative test confirms that pt did not have an MI
Troponin - a protein in the myocardium, serum level increases and remains elevated for upto 3 weeks.
cannot be used to identify subsequent extension of an MI
Medical Management
Minimize myocardial damage - Thrombolytic medications or PTCA - reduce myocardial oxygen demand - increase oxygen supply
by medicines, O2 administration and bed rest
Analgesics
ACE inhibitors
Beta blocker
Thrombolytics
Contraindicated after major surgery, stroke
Done as early as possible
Streptokinase
Alteplase
Reteplase Anistreplase
Analgesics
Morphine sulphate
Emergent Percutaneous Coronary Intervention
Like angioplasty - to be done within 60 minutes
Cardiac Rehabilitation
Risk reduction by education
Individual and group support
Physical activity
Insurance programmes
Nursing Process
Assessment
Forms a baseline
Deviations from normal recorded
Priorities fixed
Initial symptoms and signs recorded
Aggravating events noted
Nursing Diagnosis
Ineffective perfusion related to coronary blood flow
Gas exchange impairments due to fluid overload from left ventricular dysfunction
Peripheral tissue perfusion
Anxiety
Knowledge Deficiency
Collaborative problems/ potential complications
Acute pulmonary edema
Heart failure
Cardiogenic Shock
Dysrrhythmias
Pericardial effusion and tamponade
Myocardial rupture
Planning and Goals
Relief of pain or ischemic signs and symptoms (ST - segment changes)
Prevention of further myocardial damage
Absence of respiratory dysfunction
Maintenance of adeqquate tissue perfusion
Reducing anxiety
Recognition of complications
Nursing Interventions
Relieve pain and other signs/symptoms of ischemia - revascularization with thrombolytic therapy or PCI
Aspirin
IV betablockers
Nitroglycerine
GPIIb/IIIa agent or heparin
Morphine
O2 - 2 to 4 lit/mt
Vital signs monitored
Reduce abdominal contents to increase tidal volume
Reduce venous return to decrease preload
Strict attention to fluid volume balance
Deep breathing
Change of position to reduce pooling of blood in one part of the lung
Promote tissue perfusion - rest - maintain body temperature - O2
Reduce anxiety - encourage the pt to share his fears and thoughts
Monitor closely for changes in cardiac rate and rhythm, heart sounds, blood pressure, chest pain, respiratory status, urinary output, skin color, temperature, sensorium, ECG changes, Lab values
Promoting Home and Community-based care
Teach self care
Evaluation
Expected Patient Outcomes
Relief of angina
No signs of respiratory difficulties
Adequate tissue perfusion
Decreased anxiety
Adherence to a self-care program
Absence of complications
