Ventricular Hypertrophies

Question 1

Ventricular Hypertrophy

Answer 1

ventricles having to increase force in response to increase stress

Question 2

Left Ventricular Hypertrophy causes

Answer 2

Thickening of the left ventricular myocardium.

This can be as a result of ;
1.Hypertension. -increased resistance to Vasoconstriction of arterioles in hypertension -> increases the resistance against which the LV is pumping

2.Aortic stenosis and / or mitral regurgitation - increased resistance to LV systole -> increased force therefore hypertrophy
LV dilates to accommodate SV and regurgitant volume -> stretch activates Frank Starling to maintain output so increased workload -> hypertrophy

These conditions cause the left ventricle to perform more work than usual, resulting in an increase in muscle mass

Question 3

ECG Criteria LVH

Answer 3

The thickened myocardium gives rise to increased force of depolarization and therefore a longer intrinsic deflection time.
I.e. ventricular activation time.

1. V1 & V2 - deep S waves >30mm
2. V4, V5, V6, I, AVL - tall R waves >26mm
3. The sum of the S wave in V1+ the R wave in V5 or V6 should be >35mm
4. Left axis deviation
5. Ventricular activation time >0.12secs

Question 4

Strain pattern LVH

Answer 4

A reflection of the state of the myocardium.

May be seen in the leads looking at the LV; I, AVL, V5, V6.

1. Depressed, convex ST segment depression.
2. Inverted T waves.

Question 5

Right Ventricular Hypertrophy

Answer 5

Thickening of the right ventricular myocardium.

Occurs in
1. Pulmonary hypertension, COPD
2. Congenital heart disease, when the right ventricle becomes dominant.

As with hypertrophy of the left ventricle, increased right ventricular workload causes an increase in muscle mass.
The force of depolarization of the right ventricle is greatly increased.

Question 6

ECG criteria for RVH

Answer 6

R wave in leads looking at RV increase in magnitude - V1, V2, V3, V4.
The most diagnostic feature is a dominant R wave in V1

2. S wave in V5/V6.
3. Right axis deviation ( RVH is the most common cause of RAD ).

If the RVH is of a moderate degree, there will be R wave dominance in V1, V2.

If the RVH is severe, there will be R wave dominance in leads V1 to V4.
R/S ratio >1, >7mm R wave in V1, >7mm S wave in V6 R/S <1.
R in V1 + S in V5/V6 = 10.5mm

Question 7

Bi-Ventricular Hypertrophy

Answer 7

This is difficult to diagnose from the ECG.

The increased forces of activation may cancel each other out,
giving rise to a normal QRS complex in amplitude.

The duration however, may still be increased.

If either ventricle is more dominant,
the hypertrophy in the dominant ventricle
will be more evident on the ECG.

Question 7

RVH with strain pattern

Answer 7

Seen in the leads looking at the right ventricle.

1. Depressed, convex ST segment.
2. Inverted T waves in these leads.

Question 8

ECG criteria for BiVentricular Hypertrophy

Answer 8

1. It may exist without ECG change.
2. QRS duration may be prolonged.
3. T wave inversion may be present in precordial ( chest ) leads.
4. ECG criteria for LVH with a QRS axis of +90°( right axis deviation )
   is suggestive, but not diagnostic of bi-ventricular hypertrophy.
5. Occasionally RVH with left axis deviation is seen.

Question 9

Clinical Significance of BiVentricular Hypertrophy

Answer 9

1. Aortic valve disease + pulmonary hypertension.
2. Cardiomyopathy.
3. Congenital heart disease ( occasionally )