Cardiology Week 6 Summary

Question 26

How is wide pulse pressure defined and what are the causes?

Wide pulse pressure is defined as:
Pulse pressure more than 50% of systolic blood pressure
i.e. (BP systolic & BP diastolic) >50% BP systolic

Extremely wide pulse pressure can be seen in conditions with high stroke volume, such as:

1. Aortic insufficiency
2. Hyperthyroidism
3. Beriberi
4. Pregnancy
5. Fever
6. Anemia
7. Patient ductus arteriosus
8. Severe Paget’s disease with extensive arteriovenous shunting through the diseased bone
9. Severe exfoliative dermatitis with shunting through the diseased skin

N.B. If widened pulse pressure only seen in one limb, one should search for an arteriovenous fistulas in that limb.

Question 27

How is narrow pulse pressure defined and what are the causes?

Narrow pulse pressure is defined as:
Pulse pressure less than 25% of the systolic blood pressure
i.e. (BP systolic & BP diastoic) <25% BP systolic

1. Decreased stroke volume
2. Pericardial tamponade
3. Constrictive pericarditis
4. Tachycardia
5. Aortic stenosis
6. Artificially produced in severely heightened vasomotor tone with increased peripheral vascular resistance, e.g. cardiogenic shock

Question 28

What are the criteria for left ventricular hypertrophy (LVH) on a 12-lead ECG? What are the causes?

Criteria:

1. S in V1 + R in V5 or V6 >35 mm above age 40,
   (>40 mm for age 31-40, >45 mm for age 21-30)
2. R in aVL >11 mm
3. 3. R in I + S in III >25 mm
4. 4. R in V6 >26 mm
5. Additional criteria:
   • LV strain pattern (ST depression and T wave inversion in leads I, aVL, V4-V6)
   • Left atrial enlargement

Differential includes:

1. LV Mass increase & hypertension, hypertrophic cardiomyopathy
2. LV Pressure overload – aortic stenosis, hypertrophic cardiomyoathy with obstruction
3. LV Volume overload & aortic insufficiency, mitral regurgitation

Question 29

What are the criteria and differential for right ventricular hypertrophy (RVH) on a 12-lead ECG? What are the causes?

Criteria:

1. Right axis deviation (>=100 degree)
2. Tall R in V1 (R/S ratio>1)
3. Additional criteria:
   • RV Strain pattern with ST depression & T wave inversion V1-V4
   • Right atrial enlargement favours the diagnosis

Differential includes:

• RV mass approaches or exceeds LV mass
• chronic lung disease
• primary pulmonary hypertension
• congenital pulmonary stenosis
• Tetralogy of Fallot

Question 30

In assessing patients who present with chest pain, how does one characterize and classify the chest pain?

Typical angina:

• Steady retrosternal chest pain
• Provoked by exertion or emotional stress
• Relieved by rest or nitroglycerine

Atypical angina: 2 out of 3 criteria

Non-anginal chest pain: 1 out of 3 criteria

Reference: Diamond GA Forrester JS Analysis of probability as an aid in the clinical diagnosis of coronary-artery disease.
NEJM 1979 300:1350-8