Heart
Authors: Flaherty, Alice W.; Rost, Natalia S.
Title: Massachusetts General Hospital Handbook of Neurology, The, 2nd Edition
Copyright 2007 Lippincott Williams & Wilkins
> Table of Contents > Medicine > Heart
Heart
A. Cardiac code calls
What you need: Call code team; bag-valve ventilator, 12-lead EKG; cardiac and oxygen monitor; large-bore IV access; stat blood gas, electrolytes, and CBC; defibrillator and code cart. Arrange for an ICU bed.
Basic life support: For all cases, two initial breaths, then compressions 80-100 per minute.
One rescuer: 15:2 ratio of compressions to ventilations.
Two rescuers or pediatric: 5:1 ratio of compressions to ventilations.
Advanced cardiac life support: See Figures 31 and 32.
B. Neurological complicaions of heart dz
Embolic stroke, global hypoxia. MIs are RFs for stroke and vice versa. A fib, mechanical valves, and LV thrombus are all reasons for anticoagulation to prevent stroke.
P.204
 |
Figure 31. Bradycardia ACLS protocol. |
 |
Figure 32. Tachycardia ACLS protocol. |
P.205
 |
Figure 33. Pulseless ACLS protocols. |
C. Arrhythmia
See also: Electrocardiogram, p. 207.
H&P: Is pt. symptomatic during arrhythmia? What drugs is pt. on? Freq, duration, what triggers and stops rhythm.
Tests: EKG (compare with old), electrolytes, Ca, Mg, TSH, ABG, drug levels, CXR.
Atrial fibrillation (A fib):
Causes: Ischemia, PE, thyroid, drugs, conduction system problem, alcohol binge, post heart surgery.
EKG: Absent P waves. If QRS is wide, consider V tach.
Rx of new A fib: Consider cardiology consult if unable to control rate. Unstable pts. may require immediate cardioversion.
Diltiazem: Bolus 20 mg IV over 2 min; may repeat in 15 min. Consider verapamil or -blockers (i.e., metoprolol 5 mg IV q5min 3). Always give oral dose once rate controlled, as IV dosing wears off quickly.
Digoxin: 0.5 mg IV, then 0.25 mg PO q8h 2, then 0.125-0.25 mg qd. Takes time for effect not always the first-line agent. See Digoxin, p. 168.
Contraindications to A fib drugs:
Wide QRS complex: May actually be V tach, in which Ca channel blockers may be lethal. Consider adenosine. Treat like V tach: 75 mg lidocaine, cardiovert.
Hypotension.
Plan for DC cardioversion: Digoxin may make cardioversion dangerous.
DC cardioversion: Emergent if there is angina, low BP, CHF.
Anticoagulation: See Anticoagulants, p. 160.
P.206
AV block:
1st degree = Long PR. Do not treat unless bradycardic. Consider digoxin toxicity as cause.
2nd degree:
Mobitz I (Wenckebach): Above bundle of His.
EKG: Gradual PR lengthening, narrow QRS, RR gradually shorter.
Rx: Usually benign. If pt. is symptomatic or if there is bundle branch block, give atropine or pace.
Mobitz II: The lesion is usually below the bundle of His. May go to complete heart block.
EKG: PR constant; usually wide QRS; occasional nonconducted P wave.
Rx: Cardiology consult. Needs pacer even if pt. is asymptomatic. In the mean time, if symptomatic, use atropine, isoproterenol, or external pacing.
3rd degree: Complete heart block. Treat as Mobitz II, but more urgently.
Bradycardia: See Cardiac code calls, p. 203.
Junctional rhythm:
EKG: Narrow QRS but no P waves.
Rx: Treat underlying condition (ischemia, dig toxicity). Treat paroxysmal junctional tach like SVT, but carotid massage does not work as well.
Premature beats: (PACs, PVCs). Usually treat only if pt. is symptomatic, but check with cardiology some PVCs are malignant.
Supraventricular tachycardia (SVT, AKA PSVT):
DDx: V tach; rapid A fib, sinus tach.
EKG: Narrow-complex tachycardia always preceded by P waves. Tachycardia can cause ST depression and T wave inversion, without ischemia, even after tachycardia has resolved.
Rx: See Cardiac code calls, p. 203. Consult cardiology.
Adenosine if narrow-complex tachycardia.
Dosing: Run rhythm strip; give 6-12-12 mg rapid bolus through peripheral IV (3-6-6 if central line) q1-2min.
Complications: Watch for bronchospasm and low BP. If pt. is on theophylline, adenosine may not work.
Specific conditions: Okay to use in Wolff-Parkinson-White (WPW). In A fib/flutter, adenosine will uncover a string of nonconducted Ps.
Cardioversion if pt. has angina, hypotension, or CHF.
Carotid sinus massage Valsalva maneuver. Need IV access and EKG monitoring. Rule out bruits first. Massage carotids only one side at a time: 10 sec on R; if no response, then 10 sec on L. This may convert A flutter to A fib.
Nodal blockers:
Contraindications: Avoid in wide-complex tachycardia, hypotension.
Verapamil: 5-10 mg IV over 2-3 min.
Beta-block: Propranolol 0.15 mg/kg at 1 mg/min, or esmolol if h/o asthma.
Digoxin: 0.5-0.75 mg IV/PO, then 0.25 mg q2h as needed.
P.207
Torsades de pointes:
Causes: Things that lengthen QT interval, e.g., bradycardia, antiarrhythmics; phenothiazines; low K, Mg, or Ca; cerebral hemorrhage, ischemia, cardiomyopathy, congenital long QT, erythromycin + Seldane.
EKG: QRS height varies sinusoidally, HR 160-180. Long QTc.
Rx: Consult cardiology. Stop offending drugs. Give magnesium. Treat drug or metabolic imbalance. Consider lidocaine, phenytoin, isoproterenol (cautious if CAD), overdrive pacing.
Ventricular fibrillation (V fib): Call a code. see p. 203.
Ventricular tachycardia (V tach):
DDx: Aberrantly conducted SVT (15%, usually with RBB), tachycardic A fib. When in doubt, treat as V tach.
Causes: Ischemia, MI recovery (especially with post-MI aneurysm), cardiomyopathy, prolonged QT, mitral valve prolapse, drug toxicity, metabolic disturbance.
EKG: >6 wide QRSs at 100-200 bpm. ST and T changes in direction opposite to major QRS deflection. LAD (compared with axis in sinus). AV dissociation. Monophasic or biphasic RBBB QRSs with LAD and R/S <1 in V6.
Rx:
Sustained V tach: Call a code. see p. 203.
Nonsustained V tach: Consult cardiology immediately. Treat V tach if pt. is symptomatic during V tach or if runs are increasing in frequency or length (this has high risk of V fib).
Varying rhythm:
Identical Ps: Suggests sinus arrhythmia; observe.
Changing Ps: Suggests wandering atrial pacemaker or multifocal atrial tachycardia.
Causes: COPD, hypoxia, digoxin toxicity, mitral regurgitation, myocard. scar.
Rx: Correct hypoxia, electrolytes; try verapamil or diltiazem, beta-block (not if COPD), consider Ia antiarrhythmics, amiodarone. Avoid digoxin.
No P waves: Suggests A fib.
D. Electrocardiogram
Compare all EKGs to old ones.
Heart rate: Normally 60-100. One box = 0.04 sec.
Rhythm: Look at both Ps and QRSs. If there is arrhythmia (see Arrhythmia, p. 205), ask:
What is relation between P and QRS? Ps best seen in leads II and V1. Should be upright there.
Wide or narrow QRS?
QRS regular or irregular?
Intervals:
PR: 3-5 boxes. <0.12 sec suggests WPW; >0.2 sec = AV block.
QRS: >3 boxes (0.12) suggests ventricular arrhythmia or bundle branch block (BBB). Look in widest QRS, usually V1, V5.
QT: 7-10 boxes (0.28-0.40 sec) for normal rate.
QTc = QT/(RR interval)1/2. Less than 0.42 for men, 0.43 women.
DDx: Drugs (quinidine, procainamide, TCAs, phenothiazines), hypothermia, electrolyte abnormality, pentamidine, idiopathic.
P.208
Axis: Normal if upright in I, F (or, more liberally, if -30 to +90).
P waves: Best seen in II and VI.
Absent Ps: Atrial fibrillation (q.v. p. 205).
Inverted Ps in II, III, or F: Low atrial or junctional pacemaker.
Figure 34. EKG axes.
QRS waves:
Q wave = significant when more than 1 box wide or deep, or more than 1/3 of the following R wave. Normal in III, or small isolated Q in I, L, F, V4-V6. Q in III can also suggest PE.
Poor R-wave progression (PRWP): DDx = anterior MI, LBBB.
Too-good RWP (R in V1-V2 larger than in V3): Posterior MI, RV infarct, lateral MI, RBBB, RV hypertrophy, WPW.
LV hypertrophy: S in V1 + R in V5 >35 mm. LAD, wide QRS, and T slants down slowly and returns rapidly.
ST segments: Compare voltages to TP segment, not PR.
ST elevation: Nl <1 mm limb leads; <2 mm chest.
DDx: Acute MI, LBBB, J point elevation (concave, upsloping ST in young people).
Persistent ST elevations: DDx: persistent ischemia, LV aneurysm, pericarditis (concave, widespread, or anterior).
ST depression: DDx: ischemia, digoxin (upsloping), exercise, strain, PE (especially lead II).
T waves: Can be down in III, L, F, V1-V2. Brain injury can cause nonspecific T wave changes, but this is a diagnosis of exclusion.
Peaked (hyperacute) T waves: Ischemia, high K. Ts should be <5 mm in limb leads; <10 mm in chest leads.
T wave flattening: Ischemia, post MI, low K.
T wave inversion (TWI): Ischemia, post MI, BBB (should be in opposite direction), strain (biphasic and asymmetric in V5-V6), sometimes just from tachycardia. Normally inverted in R.
Pseudonormalized Ts: I.e., formerly inverted, now flat or upright. Suggests ischemia.
T wave axis: Should be <50 from QRS axis.
U waves: Low K, low Mg.
E. Miscellaneous EKG syndromes
Beta-blockers: Bradycardia, AV block.
Bundle branch block (BBB): If QRS >0.12. Left BBBs can have fixed ST elevations not associated with MI, but always worry if the elevations change.
Calcium:
Calcium channel blockers: Sinus arrest, AV block.
High Ca: Short QT, tachycardia.
Low Ca: Long QTc.
Digoxin toxicity: Upsloping ST depressions, tachycardia, AV block, junctional rhythms, bradycardic junctional escape, V tach, V fib.
Potassium:
High K: In sequence as K rises, see peaked T (esp. V2-V4), ST depression, decreased R waves, PR lengthening, flat P, wide QRS, long QT, torsades.
Low K: Flat T and U wave, ST depression, SVT, A fib, long QT.
Pulmonary embolus: Often nonspecific sinus tachycardia, sometimes SI-QIII-TIII (big S in I, Q, and TWI in III), right axis deviation and right BBB.
P.209
F. Coronary artery dz
Acute MI:
DDx of chest pain: Aortic dissection, peri- or myocarditis, PE, PTX, perforated ulcer, cholecystitis, pancreatitis, rupture of the esophagus, musculoskeletal pain.
Tests: See Rule Out MI Protocol, p. 209.
Rx: Emergency cardiology or medicine consult.
Reduce cardiac work:
But beware low BP if carotid dz, renovascular dz, aortic stenosis, RV infarct, big anterior MI, tamponade.
Nitroglycerine: SL and IV to increase coronary perfusion.
Beta-blocker: IV metoprolol.
Loading metoprolol: 5 mg IVP over 2 min 3 doses to lower heart rate, while SBP >100, HR >50, PR <0.24. Then 50 bid, and titrate up, with hold parameters.
Beware of PO BP drugs that cannot reverse fast.
Use cautiously in COPD, CHF, inferoposterior or big anterior MI.
Morphine: 2-5 mg IV. Reduces pain, preload. Watch BP.
Treat clot: Have pt. chew aspirin, IV heparin; consider lysis, angioplasty, bypass.
Heparin: For unstable angina, ST depressions, or chest pain with a baseline BBB.
Consider thrombolysis: For ST elevations. Absolute contraindications = recent surgery, stroke, GI or brain bleed.
Complications of MI:
Arrhythmias: Cardiac monitor.
Hypotension: Suspect right ventricle infarct in anyone with hypotension during an inferoposterior MI.
Congestive heart failure: see p. 210.
Rule Out MI Protocol:
Cardiology consult.
Drugs: Aspirin, heparin SC or IV (for unstable angina, needs several days of heparin to cool off), O2, IV access, colace, sucralfate,
P.210
nitropaste q4h (see Admission Orders, p. 13, for doses; adjust if carotid dz or longstanding HTN).Labs: CPK/troponin q8min 3, profile 7, PTT (bid if IV hep), Ca/Mg/phos, CBC, LFTs, lipids, drug levels, EKG qAM 3; consider echocardiogram, ETT with thallium (make pt. NPO after midnight) or Persantine- or adenosine-thallium scan (no caffeine or theophylline before scan).
Orders: Bed rest, check orthostatic BP, guaiac stools, I/Os, daily wts, low-salt and low-cholesterol diet, cardiac monitor (pt. may travel without), old chart to floor quickly.
Chest pain orders: Check vitals, EKG during pain, nitroglycerine SL q5min 3 if SBP >90, O2 2 L/min, call resident, post-pain EKG. Consider Mylanta, morphine.
G. Preoperative cardiac evaluation
If pt. has any of the following CAD markers, consider pre-op cardiology consult: Age >70, prior angina or MI, prior CHF or ventricular arrhythmia, DM, positive stress test.
H. Congestive heart failure (CHF)
Systolic failure:
H&P: Ask about SOB, check rales, JVP, edema.
DDx: Lung dz, noncardiac edema.
Rx: Goal = decreased preload.
Acute: Sit pt. up with legs dangling. Oxygen, morphine 2-5 mg IV, nitroglycerine SL or IV, furosemide 40 mg IV.
Severe: Consider digoxin, CPAP (helps LV pump, but bad if preload is low), dobutamine, intubation.
Orders: R/O MI orders, fluid restrict, low salt, daily weights.
Labs: Digoxin level, repeat K and CXR after diuretics, consider echocardiogram.
Drugs: Digoxin, furosemide, captopril (or isosorbide dinitrate + hydralazine).
Diastolic dysfunction: Goal is maintained preload, decreased afterload, and decreased contractility. Nitrates and diuretics are okay acutely, but try verapamil long term.
I. Blood pressure
Hypertension:
Causes: MI, stroke, cerebral bleed, drug withdrawal or overdose, renal, endocrine, anxiety, aortic dissection or coarct, eclampsia.
Hypertensive crisis: Usually DBP >130 or SBP >250, with evidence of end-organ damage: heart, brain, renal, fundi.
Rx: Arterial line + IV nitroprusside or labetalol. see p. 172.
Contraindications to Nipride: Cerebral edema or coronary ischemia.
Avoid: SL nifedipine, which can drop BP too fast.
Time course: Decrease BP gradually, by 25% in the following intervals:
If cerebral hemorrhage, in 6-12 h.
If papilledema, in 3-6 h.
If CHF, LV failure, dissection, in 15 min.
Antihypertensive drugs: Consider nifedipine 10 mg SL (danger of hypotension), or metoprolol 50 mg PO. For IV blood pressure control, see p. 172.
Aortic aneurysm: Use labetolol (lowers HR as well as BP) unless there is CHF.
CHF: Use ACE-I, diuretics, 1-blockers. Avoid -blockers, diltiazem, verapamil.
CAD: Use -blockers, Ca channel blockers, ACE-I. Avoid diuretics, hydralazine.
Cerebral bleed or stroke: Use -blockers, then -blockers, then ACE-I.
COPD: Use Ca blockers, ACE-I, diuretics. Avoid -blockers.
DM: Use ACE-I, 1-blockers, Ca blockers. Avoid -blockers, diuretics.
Diastolic dysfunction: Use -blockers or Ca blockers.
Heart block/bradycardia: Avoid -blockers, verapamil.
Hyperlipidemia: Use 1-blockers, Ca blockers. Avoid -blockers, diuretics except indapamide.
Peripheral vascular dz: Use Ca blockers, ACE-I, diuretics. Avoid -blockers.
Renal failure: Use loop diuretics, Ca blockers, ACE-I (especially for DM or nephrotic syndrome, but use very cautiously). Avoid -blockers, K-sparing diuretics.
Sexual dysfunction: Use ACE-I, Ca blockers. Avoid -blockers, central -blockers, diuretics.
P.211
Hypotension:
Causes: Heart rate, pump, or volume problem: drug effect, blood loss, dehydration, sepsis, third-spacing, adrenal insufficiency, tension PTX.
Tests: EKG, ABG, orthostatics, chem. 20, cultures, CXR.
Rx:
Trendelenburg position: Head of bed down 10 degrees. Of short-term benefit only; increases risk of aspiration.
If bradycardic: Correct rate before giving fluid or pressor.
Normal saline IV: Be careful if CHF.
Hold offending drugs.
Blood: For volume (be careful if CHF).
Oxygen: Especially if anemic (be careful if COPD, because of risk of CO2 retention).
Take cultures: If febrile.
Pressors: Oral rx: fludrocortisone 0.1 mg qd or midodrine 10 mg tid. For IV pressors, see p. 172.
J. Cholesterol emboli syndrome
Causes: Often after arterial catheterization, vascular surgery.
Sx: Necrotic foot lesions, conjunctival petechiae, renal failure, depression and dementia, nausea and anorexia.
Rx: Symptomatic.
K. Pulmonary artery catheter (Swann-Ganz catheter)
Alternatives: Green dye cardiac output (requires arterial line and central line); noninvasive cardiac output (NICO) monitor, echocardiography, a better physical exam .
Indications: Note there is no evidence that Swanns improve outcome. They may worsen it. They are useful for telling cause of shock (e.g., septic vs. cardiogenic); cause of pulmonary edema (e.g., cardiogenic vs. increased permeability); monitoring the effects of fluids, inotropes, pressors, afterload agents, and vasodilators; and optimizing oxygen transport.
Relative contraindications: Coagulopathy, thrombocytopenia, endocardial pacemaker, severe pulmonary hypertension, ventricular arrhythmias, left bundle branch block (have external pacer ready in case of complete heart block), prosthetic right heart valve.
Complications: Include these risks on the consent form.
During puncture: Arterial puncture, pneumo- or hemothorax, air embolism, nerve injury, thrombosis.
During advancement of catheter: Arrhythmias, cardiac perforation and tamponade, bundle branch block.
During maintenance of catheter: Pulmonary artery rupture, mural thrombus, infection, valve damage, pulmonary infarction.
Normal values:
CVP: Central venous pressure, 5-8 mm Hg.
RA: Right atrial pressure, 0-8 mm Hg.
RV: Right ventricular pressure, (15-30)/(0-4) mm Hg.
PA: Pulmonary artery pressure, (15-30)/(6-12) mm Hg.
PCWP: Pulmonary capillary wedge pressure, 1-10 mm Hg.
LVP: Left ventricular pressure, (100-140)/(3-12) mm Hg.
CO: Cardiac output, 4-8 L/min (= HR stroke volume).
CI: Cardiac index, 2.5-4.2 L/min/m2.
SVR: Systemic vascular resistance, 770-1500 dynes/sec/cm5.
PVR: Pulmonary vascular resistance, 20-120 dynes/sec/cm5.
MAP: Mean art. pressure, 70-105 mm Hg = 1/3 (SBP - DBP) + DBP.
P.212
EAN: 2147483647
Pages: 109