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Acute Myocardial Infarction

Cardiac Enzymes

Arrhythmias

Hypertensive Crisis

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Acute MI

 

Diagnosis (2 of following 3 should be present):

1-     Typical Chest Pain

2-     EKG changes

3-     Elevation in serum markers

 

Management:

 

            Ischemic chest pain:

                        Give 160-325 mg ASA

                        EKG (within 5min)

History, Physical, risks, Oxygen, BP in both arms(dissection), IV while awaiting EKG                     

                        Baseline cardiac enzymes

 

            If EKG shows ST elevation OR new BBB:

                        Look for contraindications to thrombolysis

                        Antiischemic therapy

If in pain start IV NTG (start at 5-10ug/min. Increase by 5ug Q5min to max 200ug/min)

Morphine IV if still in pain

IV metoprolol / atenolol in 5mg boluses Q2min x 3 to achieve HR <70 followed by PO metoprolol (25-50mg BID) or atenolol (50-100mg QD)

MgSO4 only in elderly and those not fit for reperfusion {8mmol (192mg) IV over 10min, than 64mmol(1536mg) IV over 24hr. Reduce dose in renal patients}

                        Reperfusion

                                    PTCA preferable if available in <60min

                                    Thrombolysis (should be started within 30min of presentation)

                                                Streptokinase = 1.5MU in 30-60min (allergic)

                                                Alteplase = 100mg in 90min (non-allergic)

                        Anticoagulation

Heparin: only indicated if large anterior or apical thrombus to prevent mural thrombus)

Warfarin:

            INR 2-3. For 1-3 months

Indicated only if risk of embolization as in

            - LV thrombus or aneurysm

            - EF < 30%

            - Heart failure

            - Past Medical History of thromboembolisim

            - Atrial Fibrillation (continue indefinitely)

                       

 

Anti-Platelets

            Aspirin: 75mg QD indefinitely

Clopidogrel (Plavix) 75mg QD, Ticlopidine 250mg BID or Dipyridamole if true ASA allergy

                        ACE

Within 24hr in Acute MI with ST elevation in 2 or more anterior leads or heart failure (SBP should be >100)

Later in pts with MI+LVEF <40 or MI+CHF from sys dysfunction

Drugs: Captopril (50mg TID) or Ramipril (5mg TID)

 

If pain or ST elevation persist 60-90min after initial thrombolysis or PTCA, consider repeat thrombolysis or rescue PTCA.

           

            If EKG shows ischemic ST depression or T inversion:

                        Admit

                        Antiischemic therapy

                        Consider ACE

                        Pain goes away: conservative treatment

                        Pain persist: PTCA

 

            If EKG normal or non-diagnostic:

                        Repeat EKG Q15min x 2

                        FU cardiac enzymes

                        2D Echo

                        No Ischemia: DC home

                        Ischemia: Thrombolysis or PTCA if ST elevation develops

                       

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Cardiac Enzymes

 

Troponin I:

Onset: 4-6hrs

Peak: 18-24hrs

Duration: 10 days

Use: useful for rapid diagnosis as rises early

Drawback: difficult to assess time since MI if already elevated (10days)

Sampling schedule: once > 12hrs

 

CK-MB:

Onset: 4-12hrs

Peak: 18-24hrs

Duration: 2 days

Use: indicates that MI is recent

Drawback: remains only for 48hrs

Sampling schedule: Q12H x 3

 

LDH:

Onset: 6-12hrs

Peak: 24-48hrs

Duration: 8 days

Sampling schedule: once > 24 hrs

 

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Arrhythmias

 

SUPRAVENTRICULAR ARRHYTHMIAS

 

  1. Sinus Arrhythmia:
    1. No significance

 

  1. Sinus Bradycardia:
    1. < 50
    2. Normal children, athletes, elderly, sleep
    3. Many causes including MI, BB, CCB, digoxin
    4. CC: weakness, confusion, syncope
    5. At Risk Of: Atrial & vent. Ectopic arrhythmias
    6. Treatment:

Ø      In acute MI: atropine

Ø      Drugs: alternative

Ø      Chronic: atrial or DDI pacemaker

 

  1. Sinus Tachycardia:
    1. > 100 (usually <160)
    2. Normally exercise, emotion, pain, fever
    3. Hyperthyroidism, shock, anemia, PE, MI, COPD, CHF, nicotine, caffeine, alcohol, alcohol withdrawal,
    4. Onset & termination gradual (vs. SVT)
    5. Inappropriate Sinus Tachycardia:

Ø      persistent or episodic for years

Ø      symptomatic

Ø      can cause LV sys dysfunction

Ø      Treatment: B-blocker or Radiofrequency ablation

 

  1. Atrial Premature Beats or Complexes (APCs)
    1. ectopic focus in atria firing before SA
    2. EKG:

Ø      different P than SA nodal P

Ø      RR length unchanged or slightly longer

Ø      Normal QRS (aberrant if early APC)

Ø      Noncompensatory pause

    1. Almost always in Normal hearts
    2. Sometimes in MVP, MI, MS, CMP, smoking, coffee, alcohol
    3. CC: sense of skipped beat
    4. Treatment: only if symptomatic

Ø      Reassure & ask to stop smoking, alcohol, coffee, stress

Ø      B-blockers

Ø      IA, IC, III

 

 

  1. Paroxysmal SVT
    1. Commonest paroxysmal tachycardia
    2. Starts & stops abruptly
    3. No structural heart disease
    4. HR 140-240
    5. Regular
    6. Mechanism: Reentry

Ø      AV nodal reentry tachycardia (AVNRT)

Ø      Accessory AV reentry tachycardia (AVRT)

    1. CC:

Ø      awareness of fast HR

Ø      mild CP, SOB when prolonged

    1. Treatment:

Ø      Mechanical: vasalva, cough, breath holding

Ø      Carotid sinus massage (1st R for 20 sec, than L)

Ø      IV Adenosine: 6mg, 12mg(after 2min), 12mg. Give half dose if thru central line

Ø      IV Diltiazem: 0.25mg/kg over 2 min. 0.35mg/kg if no response after 1st. Than drip at 5-15mg/hr

Ø      IV Verapamil: 2.5mg bolus. Than 2.5-5mg every 3min up to total of 20mg

Ø      Oral Verapamil: 80-120mg Q4-6H if stable pt

Ø      IV Esmolol: 500ug/kg over 1min. Than 25-200ug/kg drip

Ø      IV Digoxin: 0.5-0.75mg IV over 20min. Than 0.125-0.25mg every 2-4hrs to a total of 1-1.25mg

Ø      Procainamide (give only after dig, verapamil or a B-blocker as it can initially increase HR)

Ø      DC Cardioversion: start with 100J. Only if pt. hemodynamically stable & adenosine/verapamil ineffective. If dig toxicity avoid it.

    1. Prevention:

Ø      Radiofrequency ablation

Ø      Digoxin (1st choice)

Ø      Verapamil (2nd choice)

Ø      IA, IC, III

 

  1. Lown-Ganong-Levine (LGL) syndrome (Pre-Excitation syndrome):
    1. SVT due to accessory fibers (Mahaim fibers) wholly or partially within AV node-so narrow QRS
    2. Normal QRS & short PR interval
    3. CC: palpitations

 

  1. WPW syndrome / Wolf-Parkinson-White Syndrome (Pre-Excitation syndrome):
    1. SVT due to a direct connection b/w atria and vent (Kent)-so wide QRS
    2. Short PR but wide, slurred QRS (delta wave)

 

 

    1. Orthodromic tachycardia:

Ø      antegrade thru AV, retrograde thru Kent-narrow QRS

Ø      initiated by APCs or PVCs

Ø      150-250

Ø      QRS alternans or ST depression(sometimes)

    1. Antedromic tachycardia:

Ø      antegrade thru Kent, retro thru AV-wide QRS

Ø      initiated by APCs or PVCs

Ø      250

    1. Permanent Junctional Reentrant tachycardia:

Ø      Usually Children

Ø      120-200

Ø      normal QRS

Ø      present with LV dysfunction

Ø      orthodromic

    1. Other: AV nodal reentrant tachycardia, AF, Vfib, VT, sudden death
    2. Treatment:

Ø      Only if palpitation, lightheadedness, syncope

Ø      Radiofrequency ablation: (esp. those with RR <220ms, as at risk of sudden death)

Ø      Drugs for Acute Orthodromic: vagal maneuvers (as for SVT).

IV Verapamil (5mg every 3 min. up to 15mg)-1st choice

IV adenosine (can precipitate AF)

Procainamide, metoprolol, esmolol, digoxin, amiodarone (all IV)

Ø      Drugs for Orthodromic prevention:

Propafenone (1st choice)

B-blocker, CCB, Digoxin, amiodarone

Ø      Drugs for Acute Antedromic:

IV procainamide (1st choice)

B-blocker, CCB, Digoxin (all only if sure of Diagnosis, otherwise VFib)

Avoid adenosine (cause AFib)

Ø      Drugs for Chronic Antedromic:

Propofenone & flecainide (1st choice)

Procainmide, amiodarone

B-blocker, CCB, Digoxin (all contraindicated)

Ø      Acute AFIB:

IV procainamide or propafenone

B-blocker, Dig, CCB, Adenosine (all contraindicated)

Ø      Chronic AFIB:

Propafenone, procainamide, amiodarone

 

                                               

 

  1. Atrial Fibrillation:
    1. Commonest chronic rhythm
    2. HTN (commonest cause)
    3. Rheumatic heart, CAD, HCMP, DCMP, ASD, pericarditis, PE, thyrotoxicosis, CABG, MVP, familial, theophylline, B-agonist, alcohol intoxication & withdrawal, holiday heart (even small alcohol), lone AF
    4. Lone Afib (30%): paroxysmal or constant. No structural heart defect.
    5. Very irregular rhythm.
    6. Atrial rate 400-600
    7. Vent rate 80-180
    8. Pulse deficit (less time for LV to fill up)
    9.  Aim of Treatment: (i)NSR, (ii) maintenance of NSR, (iii)rate control in ch. AF, (iv)prevent embolization
    10. Acute Treatment:

Ø      Pt. unstable or ischemia – DC cardioversion

Ø      Pt stable – two options:

Ø      Rate control & cardioversion later (if precipitating factor unresolved or

>48hrs). in later case anti-caog for 3-4wks or atrial thrombus excluded by TEE.

Initially IV metoprolol or esmolol, IV diltiazem, IV verapamil, IV digoxin

Ø      Cardioversion: if < 48hrs DC(100-200j, than 360) OR Ibutilide (IV 1mg over 10min, than 1mg 10min later if no effect) OR Procainamide (500-1000mg IV, @ 20mg/min), OR Propafenone (PO 300-600mg), OR Sotalol (PO 160-320mg)

    1. If AF return after Treatment:

Ø      Choose b/w NSR or ch anti-coag with rate control

Ø      Infrequent recur: Pt takes Propafenone (300-600mg) or Flecainide (200-400mg) immediately

Ø      Frequent recur with no structural defect: as above but regularly

Ø      Frequent recur with structural defect: Amiodarone (less proarrhytmic)

    1. Chronic AFib Treatment:

Ø      Rate control: Verapamil, diltiazem, digoxin, B-blocker (add amiodarone to anyone if less effective or AV radiofrequency modification)

Ø      Embolization (stroke 20%/yr esp. if MVDz, aged, LV dysfunction, HF, HTN, DM): <70yrs Warfarin-INR 2-3 (check monthly). ASA 325 in >70yrs due to bleed risk.

Ø      Lone Afib: if <60, no DM or HTN- no anti-coag (may give ASA 325)

Ø      Maze procedure

 

 

 

9.    Ventricular Tachycardia:

  1. Acute VT:
    1. If causes hypotension, MI, heart failure – DC cardioversion
    2. If stable – IV procainamide (20mg/min IV, than 20-80ug/kg/min)

OR Amiodarone (150mg over 10min, than 1mg/min for 6hrs, than maintain at 0.5mg/min for 18-42hrs) OR Bretylium (5mg/kg IV over 3-5min, than 1-2mg/min drip)

    1. Magnesium sulp 1g IV may help
    2. Ventricular overdrive pacing (for recurrent)

 

  1. Chronic Recurrent Sustained VT:
    1. If LV dysfunction – ICD
    2. Preserved LV function – amiodarone + B-blocker
    3. Arising from LV outflow tract (appear as LBBB with inf. axis – radiofrequency ablation)

 

  1. Chronic Recurrent Non-Sustained VT:
    1. LV function normal + no or mild symptoms – B-blocker
    2. LV dysfunction – B-blocker 

 

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Hypertensive Crisis

 

Hypertensive Urgency

 

Diastolic BP > 130

Asymptomatic (i.e., no headache, focal neurological signs, encephalopathy, etc)

 

Treatment:       BP reduction to 160/110 over 3-6hrs

            Rest in a quiet room

            Lasix 20mg PO + Isradipine 5mg PO / Felodipine 5mg PO

            Captopril 12.5mg PO if not adequate response

            DC home on anti HTN meds

 

Hypertensive Emergency

 

Malignant Hypertension

 

SBP >210, DBP >130

Headache, Blurred vision, focal neurological signs

O/E:     retinal hge, papilledema,

            ARF, hematuria, protienuria from malignant nephrosclerosis

            Intracerebral hge, SAH, lacunar infarcts

            HTN encephalopathy (Nausea, vomiting, confusion, restless, seizure, coma)

 

Treatment:       Rapidly lower DBP to 100-105 in 2-6hrs

 

Labetalol:20mg IV bolus. Than 20-80mg IV Q10min to total of 300mg.

OR start as 0.5-2mg/min drip to a max. of 300mg.

Nitroprusside:   Initially 0.25-0.5ug/kg/min drip (max. 8-10ug/kg/min)

 

Once DBP 100-105. Start on PO. Reduce DBP to 85-90 over 2-3 months

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 Please contact Irfan A. Khan, MD for suggestions and corrections.

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