Pulmonary Hypertension: The 'RV Protection' Plan

If you're like me, the patient with pulmonary hypertension presenting for non-cardiac surgery is the case that makes you want to have a very long pre-op conversation with the cardiologist before anyone turns on an anesthetic. The right ventricle is the fragile pump in this picture — it is not built for the afterload burden that pulmonary hypertension imposes, and it has very little reserve when things go wrong. On the anesthesiology oral boards, pulmonary hypertension tests your understanding of RV physiology, PVR modulators, and the "death spiral" that connects RV failure to systemic circulatory collapse.

The common board scenario: a patient with known pulmonary arterial hypertension (PAH) on home pulmonary vasodilator therapy requires surgery for an unrelated condition — orthopedic, general surgery, or obstetric. The question is how you manage a patient whose right heart is already working at maximum capacity.

The Core Logic

The right ventricle is a thin-walled, low-pressure pump optimized for volume, not pressure. In pulmonary hypertension, the RV faces persistently elevated pulmonary vascular resistance. Over time it hypertrophies and adapts, but it remains vulnerable to acute PVR increases. When PVR rises acutely — from hypoxia, hypercarbia, acidosis, pain, N2O, or high airway pressures — the RV cannot maintain forward flow. Right heart failure develops: dilated RV, elevated right atrial pressure, decreased RV output, and eventually leftward septal shift (D-sign on echo) that impairs LV filling. Systemic hypotension follows. Coronary perfusion to the RV drops, RV ischemia worsens the failure — the death spiral is now self-perpetuating.

The management strategy: maintain PVR low (avoid all vasoconstrictors of the pulmonary vasculature), maintain SVR adequate (to preserve coronary perfusion pressure to the RV), maintain preload (the RV depends on adequate filling), and use selective pulmonary vasodilators if PVR rises intraoperatively.

How the Examiner Tests This

Classic scenario: 42-year-old woman with PAH on sildenafil and ambrisentan requires an appendectomy. "What are your anesthetic concerns and how do you prepare?" Pre-op: ensure pulmonary vasodilators are continued right up to surgery (sildenafil, bosentan, ambrisentan — stopping abruptly can cause rebound PVR elevation). Have inhaled nitric oxide (iNO) or inhaled epoprostenol available in the OR. Arterial line before induction. Avoid all triggers of PVR rise: prevent hypoxia, maintain normocapnia, prevent acidosis, minimize pain-related sympathetic activation.

Intraoperative crisis probe: "During the case the patient develops sudden hypotension and the anesthesiologist notes a dilated RV on TEE with D-sign. What do you do?" This is acute RV failure. Immediate actions: 100% O2 (reduces hypoxic vasoconstriction), treat any hypercarbia or acidosis, start inhaled nitric oxide or epoprostenol to lower PVR selectively, start vasopressin for SVR support (vasopressin does not increase PVR), avoid inodilators that drop SVR further. Notify cardiac surgery if ECMO may be needed.

The Board Trap

The phenylephrine trap: using phenylephrine for intraoperative hypotension in a pulmonary hypertension patient. Phenylephrine raises SVR — which sounds good — but it also increases RV afterload indirectly by increasing left heart filling pressures, and it can worsen already-elevated PVR. Vasopressin is the preferred systemic vasopressor in this population because it works predominantly on systemic V1 receptors without increasing PVR.

The "hold the home medications" trap: instructing the patient to hold sildenafil or bosentan on the morning of surgery. These drugs have short half-lives and abrupt cessation causes rebound PVR elevation. They must be continued right up to surgery. If the patient is NPO, many pulmonary vasodilators can be given with a small sip of water or have IV equivalents. Consult pulmonology before making changes to the home regimen.

Lead-In Phrases

• "My primary goals in this pulmonary hypertension patient are: avoid PVR triggers (hypoxia, hypercarbia, acidosis, high airway pressures, N2O), maintain adequate RV preload, and support SVR with vasopressin if needed — all while keeping the patient's home pulmonary vasodilators uninterrupted."
• "I will have inhaled nitric oxide or inhaled epoprostenol immediately available — if PVR rises intraoperatively, I need a selective pulmonary vasodilator that will not cause systemic hypotension."
• "For vasopressor support, I will use vasopressin as my first choice — it maintains SVR without increasing PVR, unlike phenylephrine or norepinephrine."
• "My induction will be careful and slow — I will avoid histamine-releasing agents (atracurium, morphine), maintain ventilation to prevent hypercarbia, and ensure adequate analgesia to prevent sympathetic activation from pain."
• "I will place a TEE or consider invasive monitoring with PA catheter depending on the severity of the pulmonary hypertension — I need real-time data on RV function and preload if this patient decompensates."

FAQs

Is neuraxial anesthesia safe in pulmonary hypertension?

Spinal anesthesia causes rapid, uncontrolled sympathectomy — this can dramatically drop SVR and precipitate the RV death spiral in a patient with already-elevated PVR. Epidural anesthesia, titrated slowly, is more controllable and can be appropriate for lower-risk PAH patients. The key is controlled, gradual sympathectomy with immediate vasopressor backup. For high-risk patients, general anesthesia with careful hemodynamic management may be safer than the unpredictable sympathectomy of spinal.

What drugs increase PVR that I should avoid?

Nitrous oxide increases PVR — avoid it in PAH patients. High doses of inhalation agents can cause pulmonary vasoconstriction in susceptible patients. Protamine (used for heparin reversal) causes pulmonary vasoconstriction and can cause acute RV failure — this is particularly relevant in cardiac surgery. Histamine-releasing drugs (atracurium, morphine) can also increase PVR. The safest anesthetic technique is TIVA or low-dose volatile with careful monitoring.

When do I need an ECMO plan?

Any patient with severe PAH (mean PAP above 40-45 mmHg, RV dysfunction on pre-op echo, WHO functional class III-IV) presenting for intermediate-to-high-risk surgery should have ECMO discussed pre-operatively with cardiac surgery. VA-ECMO can rescue severe RV failure that is unresponsive to pharmacologic management. Having this conversation before the case — not during the crisis — is the correct approach.

Pulmonary hypertension cases require more preparation than almost any non-cardiac surgery. Know the physiology, have the inhaled vasodilators ready, keep the home medications going, and practice the RV failure recognition-to-rescue sequence in Boards Bot until vasopressin and iNO are your automatic responses to acute RV decompensation.