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Chapter 3: Cardiology

Marina Fomina-Nazarova

DIAGNOSTIC TESTING

Physical Exam

Pulses

Table 3.1 addresses causes of ↑ and ↓ pulses.

Table 3.1Alterations in Normal Pulses
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Table 3.1 Alterations in Normal Pulses
  INCREASED DECREASED NOTES
Peripheral Aortic regurgitation, persistent ductus arteriousus, ↑ cardiac output (sepsis, hyperthyroid) Peripheral vascular disease, low cardiac output Water-hammer: Radial rapid rise/fall, seen in aortic regurgitation
Central   Delayed and weak in aortic stenosis Pulsus bisferien: Two pulse peaks, seen in aortic regurgitation and large patent ductus arteriosus
Jugular venous Distention with volume overload, tamponade    

Heart Murmurs

See the Child and Adolescent Medicine chapter for a discussion of heart murmurs. Sites for auscultation of the heart are shown in Figure 3.1.

Figure 3.1

Common heart murmurs and where best to hear them. (Reproduced with permission from USMLE-Rx.com.)

A diagram shows the locations that are best for hearing different types of heart murmurs.
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Heart Sounds

  • S1: Closure of the mitral and tricuspid valves. ↓ with LV systolic dysfunction and mitral regurgitation. See Figure 3.2 for the relation of heart sounds to other parts of the cardiac cycle.

  • S2: Closure of the aortic and pulmonary valves. Normally, the aortic component (A2) precedes the pulmonic component (P2).

    • Physiologic splitting: ↑ time between A2 and P2 with inspiration. P2 is delayed during inspiration as negative intrathoracic pressure pulls more blood volume into right side of the heart. Normalizes when the breath is held.

    • Wide splitting: Early closing of A2 or delayed P2. Causes include right bundle branch block (RBBB), pulmonic stenosis, pulmonary embolism (PE), or pulmonary hypertension (HTN).

    • Paradoxical splitting: A2 comes after P2 so ↑ splitting with expiration. Causes include aortic stenosis (AS), left bundle branch block (LBBB), use of a pacemaker, and left ventricular (LV) systolic dysfunction.

    • Fixed splitting: Time between A2 and P2 does not vary with breath. Caused by atrial septal defect (ASD).

  • S3: Low-pitched sound after S2 as ↑ blood volume flows into dilated ventricle. Best heard with the bell at the apex. Suggests ventricular enlargement and LV systolic dysfunction such as heart failure (HF) and dilated cardiomyopathy.

  • S4: Low-pitched sound preceding S1 as atrial contraction forces blood into a stiff ventricle.

Figure 3.2

Wiggers diagram. Diagram shows the aortic, atrial, and ventricular pressures during the cardiac cycle and their relation to the ECG signal. (Reproduced with permission from USMLE-Rx.com.)

Examples of the waveforms for heart sounds, E C G, ventricular volumes and cardiac-related pressures.
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Cardiac Testing

Electrocardiography

The key elements of an ECG are shown in Figure 3.3.

Figure 3.3

Normal elements of an ECG. (Reproduced with permission from USMLE-Rx.com.)

A tracing is marked to show the elements of a typical E C G.
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