Left ventricular hypertrophy
Encyclopedia
Left ventricular hypertrophy (LVH) is the thickening of the myocardium (muscle) of the left ventricle
of the heart
.
occurs naturally as a reaction to aerobic exercise
and strength training
, it is most frequently referred to as a pathological reaction to cardiovascular disease
, or high blood pressure.
While LVH itself is not a disease, it is usually a marker for disease involving the heart. Disease processes that can cause LVH include any disease that increases the afterload
that the heart has to contract against, and some primary diseases of the muscle of the heart.
Causes of increased afterload that can cause LVH include aortic stenosis, aortic insufficiency
, and hypertension
. Primary disease of the muscle of the heart that cause LVH are known as hypertrophic cardiomyopathies
, which can lead into heart failure.
, which the thickness of the muscle of the heart can be measured. The electrocardiogram
(ECG) often shows signs of increased voltage from the heart in individuals with LVH, so this is often used as a screening test to determine who should undergo further testing.
. If the myocardium is more than 1.1 cm thick, the diagnosis of LVH can be made.
The Sokolow-Lyon index:
The Cornell voltage criteria for the ECG diagnosis of LVH involve measurement of the sum of the R wave in lead aVL and the S wave in lead V3. The Cornell criteria for LVH are:
The Romhilt-Estes point score system ("diagnostic" >5 points; "probable" 4 points):
Other voltage-based criteria for LVH include:
Left ventricle
The left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
.
Causes
While ventricular hypertrophyVentricular hypertrophy
Ventricular hypertrophy is the enlargement of ventricles in the heart. Although left ventricular hypertrophy is more common, enlargement can also occur in the right ventricle, or both ventricles.- Physiology :...
occurs naturally as a reaction to aerobic exercise
Aerobic exercise
Aerobic exercise is physical exercise of relatively low intensity that depends primarily on the aerobic energy-generating process. Aerobic literally means "living in air", and refers to the use of oxygen to adequately meet energy demands during exercise via aerobic metabolism...
and strength training
Strength training
Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction...
, it is most frequently referred to as a pathological reaction to cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...
, or high blood pressure.
While LVH itself is not a disease, it is usually a marker for disease involving the heart. Disease processes that can cause LVH include any disease that increases the afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
that the heart has to contract against, and some primary diseases of the muscle of the heart.
Causes of increased afterload that can cause LVH include aortic stenosis, aortic insufficiency
Aortic insufficiency
Aortic insufficiency , also known as aortic regurgitation , is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle....
, and hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
. Primary disease of the muscle of the heart that cause LVH are known as hypertrophic cardiomyopathies
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is a disease of the myocardium in which a portion of the myocardium is hypertrophied without any obvious cause...
, which can lead into heart failure.
Diagnosis
The principal method to diagnose LVH is echocardiographyEchocardiography
An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
, which the thickness of the muscle of the heart can be measured. The electrocardiogram
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
(ECG) often shows signs of increased voltage from the heart in individuals with LVH, so this is often used as a screening test to determine who should undergo further testing.
Echocardiography
Two dimensional echocardiography can produce images of the left ventricle. The thickness of the left ventricle as visualized on echocardiography correlates with its actual mass. Normal thickness of the left ventricular myocardium is from 0.6 to 1.1 cm (as measured at the very end of diastoleDiastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
. If the myocardium is more than 1.1 cm thick, the diagnosis of LVH can be made.
ECG criteria for LVH
There are several sets of criteria used to diagnose LVH via electrocardiography. None of them is perfect, though by using multiple criteria sets, the sensitivity and specificity are increased.The Sokolow-Lyon index:
- S in V1 + R in V5 or V6 (whichever is larger) ≥ 35 mm (≥ 7 large squares)
- R in aVL ≥ 11 mm
The Cornell voltage criteria for the ECG diagnosis of LVH involve measurement of the sum of the R wave in lead aVL and the S wave in lead V3. The Cornell criteria for LVH are:
- S in V3 + R in aVL > 28 mm (men)
- S in V3 + R in aVL > 20 mm (women)
The Romhilt-Estes point score system ("diagnostic" >5 points; "probable" 4 points):
| ECG Criteria | Points |
Voltage Criteria (any of):
|
3 |
ST-T Abnormalities:
|
3 1 |
| Negative terminal P mode in V1 1 mm in depth and 0.04 sec in duration (indicates left atrial enlargement Left atrial enlargement Left atrial enlargement or left atrial dilation is a form of cardiomegaly.In the general population, obesity appears to be the most important risk factor for LAE. Also, a study found that LAE can occur as a consequence of atrial fibrillation , although another study found that AF by itself does... ) |
3 |
| Left axis deviation (QRS of -30° or more) | 2 |
| QRS duration ≥0.09 sec | 1 |
| Delayed intrinsicoid deflection Intrinsicoid deflection In the electrocardiogram, the time of the onset of the intrinsicoid deflection, also referred to as the R wave peak time, is measured from the beginning of the QRS complex to the peak of the R wave... in V5 or V6 (>0.05 sec) |
1 |
Other voltage-based criteria for LVH include:
- Lead I: R wave > 14 mm
- Lead aVR: S wave > 15 mm
- Lead aVL: R wave > 12 mm
- Lead aVF: R wave > 21 mm
- Lead V5: R wave > 26 mm
- Lead V6: R wave > 20 mm