~uncomfortable sensations in the chest associated w/ a wide range of dysrythmias

~commonly caused by extra atrial or ventricular systoles.

~Do not necessarily indicate serious heart disease

(Black, p. 1360)

Electrocardiogram (ECG/EKG)

Normal sinus rhythm findings

~Rate: 60-100 bpm

~P waves: one preceding each QRS

~PR Interval: 0.12-0.20 seconds

~QRS: 0.04-0.10 seconds

~Regular P-P and R-R intervals

Essentials of Dysrhythmia Interpretation

~Determine rate

~Regularity/Irregularity

~Atrial activity? (presence of P-waves)

~Normal ventricular activity? (width of QRS)

~Relationship b/w atrial & ventricular activity:

-Coordination b/w P-wave & QRS?

-Is P-wave conducting QRS?

Conduction pathway of the heart

Initiation of impulse @ SA node (upper R atrium) → AV node (lower R atrium) → 

Bundle of His (upper intravent. septum)→ 

L & R Bundle Branches (intravent. septum) →

Purkinje fibers (ventricular walls)

ECG/EKG Interpretation:

Time increments

~Small squares = 0.04 seconds

~Large squares = 0.20 seconds

~Segments b/w small notches = 1 second

~Segments b/w larger notches = 3 seconds

♦To determine rate: count QRS's in 6-second segment & multiply by 10♦

ECG/EKG Interpretation: meaning of waves

~P-wave = atrial depolarization

~QRS = ventricular depolarization

~T-wave = ventricular repolarization

~Vertical axis = voltage (large box = .5 mV)

~Horizontal axis = time (sm box=.04, lrg=.2 sec)

ECG/EKG: Uses

~Evaluation of rhythm

~Indications of myocardial ischemia

~Dx of abnormalities of impulse formation & conduction

~Determine area of infarct in MI

ECG/EKG: Types

~12 Lead: Standard ECG/EKG, has 6 limb leads & 6 precordial leads

~Telemetry: 3-5 leads, used to constantly monitor heart's electrical activity

~Has positive (+) & negative (-) leads

~Impulses traveling towards positive lead show as upward deflection

~Impulses traveling away from (+) lead show as downward deflections

Murmurs:

Best place to hear aortic stenosis

(R) sternal border during systole

Murmurs:

Best place to hear mitral regurgitation

~5th intercostal space @ mid-clavicular line ~during diastole

Definition: pulsus paradoxus

SBP drop >10 mmHg during inspiration, sign of pericardial effusion & cardiac tamponade

Mitral regurgitation (insufficiency)

=Incomplete closure of valve r/t scarring & retraction of leaflets

•Results: dilation & hypertropy of L atrium, hypertrophy of L ventricle, eventual LV failure, pulmonary HTN, eventual R-sided HF

•Causes: mitral valve prolapse, myocardial ischemia, rheumatic heart disease, cardiomyopathy, valve calcification

Mitral Stenosis

=narrowing of mitral valve r/t thickened leaflets, fusion of leaflets, etc.

•Leads to: dilation of L atrium, LV failure, pulmonary HTN, tricuspid & pulmonary valve incompetence, secondary R-sided HF

~s/sx: (insidious onset) ↓activity tolerance, dyspnea, orthopnea, paroxysmal nocturnal dyspnea

Also: A-fib, hemoptysis, thrombi in atria→ emboli into systemic circulation

Mitral prolapse

=bulging of valve's leaflets into atrium during systole, usually congenital & not assoc. w/ other diseases

~not very serious, many pts asymptomatic

~possible manifestations: tachy, light-headedness, syncope, fatigue, weakness, dyspnea, palpitations, etc. 

TX of Mitral stenosis

~Prevent infective endocarditis w/ antibx prophylaxis

~Aggressively treat anemia & infections

~Anticoag tx to avoid thromi & pulm emboli

~Dig for A-fib & beta blockers to ↓HR

~when CO becomes inadequate even w/ medical mgmt→surgical replacement of valve

Tx of Mitral regurge

~restriction of physical activities that produce fatigue & dyspnea

~reduce Na intake & promote Na excretion

~Nitrates, dig, and ACE inhibs for hemodynamic improvement & symptom relief

Important in all valvular disease & cardiomyopathies

Prevention of infective endocarditis w/ prophylactic antibx before invasive and dental procedures

Aortic Stenosis

Causes: congenital defects, or degenerative processes (1. calcification of valve in older adults, 2. retraction & stiffening from rheumatic fever)

Manifestations: Angina (66% of pts), Syncope upon exertion, exertional dyspnea, NOC dyspnea, pulmonary edema, palpitations, fatigue

Tx for HF manifestations, prevention of infections, early surgical intervention for optimum prognosis

Aortic Regurge

Causes: infectious processes(rheumatic fever, syphilis, infective endocarditis) or connective tissue disorders

S/sx: Palpitations, widened pulse pressure (SBP-DBP), prominent neck pulsations

Tx: same as for aortic stenosis

3 types of Cardiomyopathy

1. Dilated(most common): ventricular dilation & contractile dysfunction→HF

2. Hypertrophic: significantly thickened intraventricular septum & wall rigidity

3. Restrictive(least common): fibrosed ventricles impair diastolic filling

In both Dilated & Hypertrophic Cardiomyopathy...

...alcohol consumption should be avoided!

In hypertrophic cardiomyopathy...

...sudden death is frequently the first clinical manifestation of the disease (most often in pts < 30 y/o).