Morning Report 7/31/07
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Transcript of Morning Report 7/31/07
3rd Degree AV blockJason Haag
Heart Block1st Degree AV Block
one-to-one relationship exists between P waves and QRS complexes, but the PR interval is longer than 200 ms
Heart Block2nd Degree Mobitz Type I AV Block
(Wenckebach)PR interval is prolonging with each P wave to
the point when the P wave is no longer conducted
Heart Block2nd Degree Mobitz Type II AV Block
PR interval is constant, but occasionally P waves are not followed by the QRS complexes
Heart Block3rd Degree Heart Block
More P waves than the QRS complexes exist and no relationship exists between them
3rd Degree Heart BlockBlock can be in AV node or infranodal
conduction systemAV node
2/3 escape rhythms have narrow QRS (junctional)Fascicular or bundle branches
Wide QRS (subjunctional)
Rate typically in low 40s
FrequencyIn the US: 0.02%Internationally: 0.04%.
Age: Bimodal peak, at infancy given congenital complete AV block and at advance d age due to progressive fibrosis and ischemia
HistorySyncope, near-syncope, and lightheadedness
Fatigue, dyspnea, and angina
Asymptomatic
Sudden cardiac death
PhysicalVital Signs (stable vs. unstable, always check
HR manually)Signs of heart failure – JVD, a waves,
Pulmonary edemaNew murmurs or gallopsTarget lesions (Lyme)Splinter hemm, Osler nodes, etc
(endocarditis)Neuromuscular changes (mytonic/muscular
dystrophy)
EtiologiesIdiopathic Progressive Cardiac Conduction Disease
½ of cases of AV blockLenegre’s disease
Progressive, fibrotic, sclerodegeneration of the conduction system
Younger individuals, may be hereditaryLev’s disease
Calcification extending from fibrous structures (aortic/mitral rings) into the conduction system
Older individuals, ? ESRDFibrosis NOS
Typically mitral and aortic rings Mitral narrow QRS Aortic wide QRS
Etiologies (cont.)Ischemic heart disease
40% of casesEither from chronic ischemia or acute MI
Acute MI AV blocks (20% of patients) 1st degree (8%) 2nd degree (5%) 3rd degree (6%)
LBBB/RBBB (10-20%)AV nodal block (narrow QRS) associated with inferior
wall MIBundle blocks (wide QRS) associated with anterior
wall MIDrugs
Calcium channel blockers, beta blockers, digoxin, amiodarone, adenosine, quinidine, procainamide
Etiologies (cont.)Infection
Lyme disease, endocarditis, Rheumatic fever, Chagas disease, myocarditis
Rheumatic diseaseAnkylosing spondylitis, Reiter syndrome,
relapsing polychondritis, rheumatoid arthritis, scleroderma
Infiltrative diseaseAmyloidosis, sarcoidosis, multiple myeloma,
hemachromatosis, Wilson’s disease
EtiologiesHyperthyroidismMetabolic
Hypoxia, hyperkalemiaNeuromuscular disease
Muscular dystrophy, dermatomyositis
TreatmentCorrect underlying problem – if you can
Correct K, stop AV blocking medications, etc.If unstable
Transcutaneous pacingIf stable
Plan for permanent pacemaker placement
Permanent PacemakerClass I - Conditions for which evidence
and/or general agreement exists that a given procedure or treatment is beneficial, useful, and effectiveThird-degree AV block and advanced second-
degree AV block at any anatomic level associated with any one of the following conditions: Bradycardia with symptoms, heart failure,
arrhythmias, pauses greater than 3 seconds, escape rate < 40 bpm
Permanent PacemakerClass IIa - Weight of evidence or opinion is in
favor of usefulness or efficacy Asymptomatic third-degree AV block at any
anatomic site with average awake ventricular rates of 40 bpm or faster, especially if cardiomegaly or left ventricular (LV) dysfunction is present
References Gregoratos G, Abrams J, Epstein AE, et al: ACC/AHA/NASPE 2002
guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2002 Oct 15; 106(16): 2145-61.
Kojic EM, Hardarson T, Sigfusson N, Sigvaldason H: The prevalence and prognosis of third-degree atrioventricular conduction block: the Reykjavik study. J Intern Med 1999 Jul; 246(1): 81-6.
McEnvoy GK, ed: AHFS Drug Information 2000. Bethesda, Md: American Society of Health-System Pharmacists; 2000: 1187-95.
Ostaner LD, Brandt RL, Kjelsberg MI, et al: Electrocardiographic findings among the adult population of a total natural community. 1965; 31: 888-98.
Rardon DA, Miles WM, Mitrani RD, et al: Electrocardiographic Recognition: Atrioventricular Block and Dissociation. In: Zipes DP, Jalife J, eds. Cardiac Electrophysiology From Cell to Bedside, 2nd ed. Philadelphia, Pa: WB Saunders; 1995.