Is the right ventricle (RV) more sensitive to hypotension?

Right Ventricular Sensitivity to Hypotension

Yes, the right ventricle (RV) is significantly more sensitive to hypotension than the left ventricle due to its unique physiological characteristics and response to changes in afterload. 1

Physiological Basis for RV Sensitivity

Anatomical and Functional Differences

• The RV has a thinner wall and different geometry compared to the left ventricle (LV)
• The RV requires only one-sixth the energy expenditure of the LV 1
• RV coronary perfusion occurs during both systole and diastole, unlike the predominantly diastolic perfusion of the LV 1, 2

Afterload Response

• The RV has a shallower end-systolic pressure-volume relationship than the LV 1
• Minor increases in afterload cause large decreases in stroke volume 1
• As shown in Figure 4 of the AHA scientific statement, the RV demonstrates a steep decline in stroke volume with increases in pressure compared to the LV 1

Clinical Implications of RV Sensitivity to Hypotension

RV Ischemia and Dysfunction

• During hypotension, RV coronary perfusion decreases significantly 1
• Elevated RV end-diastolic pressure further reduces coronary blood flow, potentially inducing subendocardial ischemia 1
• The pressure-overloaded RV is at increased risk for ischemia due to decreased perfusion pressure and increased RV intramural pressure 1

Ventricular Interdependence

• RV dysfunction from hypotension leads to RV dilation 1
• This promotes tricuspid regurgitation and exacerbates RV dilation 1
• Mechanical flattening with leftward shift of the interventricular septum impedes LV diastolic filling 1
• This ventricular interdependence further contributes to systemic hypoperfusion 1

Management Considerations for RV Hypotension

Volume Management

• Unlike LV failure, RV failure often requires careful volume loading 3
• Avoid inappropriate preload reduction with nitrates and diuretics in RV infarction 3
• In RV infarction, factors that reduce preload (volume depletion, diuretics, nitrates) can have profoundly adverse hemodynamic effects 1

Vasopressor and Inotrope Selection

• In severe hypotension (systolic BP <80 mmHg), intravenous norepinephrine should be administered until systolic arterial pressure rises to at least 80 mmHg 1
• Once arterial pressure reaches 90 mmHg, transition to dopamine (5-15 μg/kg/min) and consider adding dobutamine 1
• Vasopressors and inotropes, rather than fluid boluses, are often required to augment cardiac output and reduce the risk of exacerbating RV ischemia 4

Mechanical Support

• Consider initiating intra-aortic balloon counterpulsation in cardiogenic shock 1
• Early consultation with specialists and transfer to tertiary care centers with invasive monitoring and mechanical support capabilities is advised for severe RV failure 4

Pitfalls in Managing RV Hypotension

• Misdiagnosis due to the complex geometry of the RV 3
• Overlooking RV dysfunction can lead to poor outcomes 3
• The right coronary circulation is more sensitive than the left to α-adrenergic-mediated constriction, which may increase vulnerability to coronary vasoconstriction during administration of α-adrenergic receptor agonists 2
• Declining pulmonary artery pressure in the setting of high pulmonary vascular resistance is an ominous clinical finding 1

In conclusion, the RV's unique physiology makes it particularly vulnerable to hypotension, with significant implications for clinical management. Understanding these differences is crucial for appropriate treatment of patients with RV dysfunction.