This is a disorder where the tricuspid valve fails to close properly, allowing backward flow of blood. Other structural defects which lead to RVH include tetralogy of Fallot, ventricular septal defects, pulmonary valve stenosis, and atrial septal defects. RVH is also associated with abdominal obesity, elevated fasting blood glucose, high systolic blood pressure, and fractional shortening of the left ventricular mid-wall.Other risk factors for RVH include smoking, sleep apnea, and strenuous activity. These increase the risk of heart and lung disease and hence RVH. Pathophysiology
Right ventricular hypertrophy can be both a physiological and pathophysiological process. It becomes pathophysiological (damaging) when there is excessive hypertrophy. The pathophysiological process mainly occurs through aberrant signalling of the neuroendocrine hormones; angiotensin II, endothelin-1 and the catecholamines (e.g. noradrenaline). Angiotensin-II and endothelin-1
Angiotensin-II and endothelin-1 are hormones that bind to the angiotensin (AT) and endothelin (ET) receptors. These are G-protein coupled receptors that act via internal signalling pathways. Through several intermediates, these pathways directly or indirectly increase reactive oxygen species (ROS) production causing accumulation in myocardial cells. This can subsequently induce necrotic cell death, fibrosis, and mitochondrial dysfunction.This has been demonstrated in animal studies. Protein Kinase C (PKC) is an intermediate molecule in the signalling pathway and mice lacking PKC shown resistance to heart failure compared to mice overexpressing PKC which shown heart dysfunction.Targeting the renin–angiotensin (RAAS) system (using angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers) are a well-recognized clinical approach for reversing maladaptive cardiac hypertrophy independently of blood pressure. Catecholamines
Catecholamines levels increase due to increased sympathetic nervous system activity.
The normal thickness of a right ventricular free wall ranges from 2-5 millimetres, with a value above 5 mm considered to be hypertrophic. Treatment
It is important to understand that right ventricular hypertrophy in itself is not the main issue, but what right ventricular hypertrophy represents is. Right ventricular hypertrophy is the intermediate stage between increased right ventricular pressure (in the early stages) and right ventricle failure (in the later stages). As such, management of right ventricular hypertrophy is about either preventing the development of right ventricular hypertrophy in the first place, or preventing the progression towards right ventricle failure. Right ventricular hypertrophy in itself has no (pharmacological) treatment. Treating the cause
Since the main causes of right ventricular hypertrophy is tricuspid regurgitation or pulmonary hypertension (discussed above), management involves treatment of these conditions. Tricuspid regurgitation is typically treated conservatively by aiming to treat the underlying cause and following up the patient regularly. Surgery is considered in more serious situations where the patient is severely symptomatic. Surgical options include either: replacement of the valve or repair of the valve (termed annuloplasty). When it comes to replacement, there is a choice between a bioprosthetic valve or a mechanical valve, depending upon the specific patient characteristics. Mechanical valve has greater durability, but requires anti-coagulation to reduce the risk of thrombosis. Treatment of pulmonary hypertension will depend on the specific cause of the pulmonary hypertension. On top of this, the following may also be considered: diuretic, oxygen and anti-coagulant therapy.