Critical Care Medicine

Acute right heart syndromes (including PE), Acute right ventricular failure; acute cor pulmonale; acute right ventricular dysfunction; acute pulmonary hypertension; cor pulmonale; pulmonary arterial hypertension

Acute right heart syndromes

Synonyms

Acute right ventricular failure; acute cor pulmonale; acute right ventricular dysfunction; acute pulmonary hypertension; cor pulmonale; pulmonary arterial hypertension

Related Conditions

Right ventricular infarction; pulmonary embolism; thromboembolism; ARDS; acute respiratory distress syndrome; shock; pulmonary hypertension; pulmonary arterial hypertension; collagen vascular disease; scleroderma; post-operative; cardiac surgery; heparin-protamine; sickle crisis; acute chest syndrome

1. Description of the problem

What every clinician needs to know

Acute right heart syndromes are caused when pulmonary vascular resistance increases beyond the capacity of right ventricular function, most often seen with pulmonary embolism or ARDS or following cardiac surgery. Pulmonary artery pressure rises, impeding right ventricular ejection, and the right heart dilates. High transmural right ventricular systolic pressure combines with ventricular dilation to raise afterload.

At the same time, right ventricular perfusion is threatened by the rise in right ventricular wall tension and, often, a fall in systemic blood pressure. The right ventricle may become ischemic, leading to a tragic downward spiral of worsening function and more ischemia. When the right ventricle fails to produce sufficient output, the left heart is underfilled, a condition amplified by ventricular interdependence (left ventricular diastolic dysfunction as the septum shifts from right towards left). Cardiac output falls and shock may follow, often precipitously. Echocardiography is exceedingly useful in recognizing this problem.

Clinical features

  1. Shock

  2. Elevated right heart pressures, including central venous (right atrial) pressure, right ventricular pressure, and pulmonary artery pressure

  3. Echocardiographic signs of acute right heart syndrome, such as a dilated right ventricle (ratio of RV/LV end-diastolic area on the long axis view exceeding 0.6); poorly contracting RV; tricuspid regurgitation; or D-sign (interventricular septal shift on the short-axis view)

  4. Electrocardiographic clues such as right axis deviation; rightward axis shift; right bundle branch block; right precordial T-wave inversions; or an S1Q3T3 pattern

  5. Radiographic features include a distended azygous vein on plain radiography or RV dilation and septal shift on helical CT

  6. Several blood markers may also be abnormal, such as elevated brain natriuretic peptide (BNP), troponin, or D-dimer.

  7. Clinical circumstances that are associated with acute right heart syndromes, such as known ARDS, sickle cell crisis, pre-existing pulmonary hypertension; chronic lung disease; or following cardiac surgery

  8. Physical examination may reveal distended neck veins, a tender, pulsatile liver, a loud pulmonic component of the 2nd heart sound, or evidence of venous thrombosis.

Key management points

  1. Acute right heart syndromes may not be readily evident; rather, they may cause shock that overlaps with the presentation of left ventricular failure, cardiac tamponade, or sepsis.

  2. Echocardiography should be obtained urgently to confirm the diagnosis and seek treatable causes of shock.

  3. Treat specifically the underlying cause, when possible.

  4. Seek to avoid interventions that could precipitate worsening, such as hypoxemia; excessive lung distention; hypercapnia; unrestrained fluid loading; and systemic vasodilators.

  5. Support the circulation with inotropes and pulmonary vasodilators.

  6. Reduce the demand for cardiac output by sedation, mechanical ventilation, and treating fever.

2. Emergency Management

  1. Diagnose and treat the underlying cause of the acute right heart syndrome. For some, specific therapy may be life-saving, as in thrombolysis for acute pulmonary thromboembolism or percutaneous coronary intervention for acute right ventricular infarction.

  2. Secure vascular access -- for the sickest patients, this will include a central venous catheter for infusion of vasoactive drugs.

  3. Correct hypoxemia and, for ventilated patients, use lung protective ventilation.

  4. Monitor the circulation, often including venous oximetry (central or mixed venous) and an arterial catheter.

  5. Judge the adequacy of circulating volume. For most patients, this will involve a fluid challenge and discrete measures of effect, such as a rise in ScvO2 or thermodilution cardiac output. Most ICU patients with an acute right heart syndrome will not benefit from significant fluid infusion.

  6. For established shock, begin vasoactive therapy with dobutamine or an inhaled pulmonary vasodilator (nitric oxide or prostacyclin).

3. Diagnosis

Diagnosis of acute right heart syndromes is established by echocardiography or right heart catheterization. However, specific values for pulmonary artery pressure and echocardiographic parameters do not correlate well with the hemodynamic consequences. Rather, these results must be interpreted in light of the overall adequacy of perfusion, such as judged by blood pressure, central venous oxyhemoglobin saturation, lactic acid concentration or end-organ dysfunction.

Diagnostic tests and procedures

Pulmonary artery catheter: Pulmonary hypertension is defined as a mean pulmonary artery pressure (PAP) > 25 mmHg at rest. Acute cor pulmonale is unlikely to be present if the pulmonary artery systolic pressure is < 50 mmHg. Additional findings may include elevated right atrial pressure and low cardiac output and central (or mixed) venous oxyhemoglobin saturation.

Echocardiography: Findings include tricuspid regurgitant jet velocity > 3 m/s, corresponding to a systolic right ventricular pressure > 45 mmHg, and right ventricular enlargement, defined as an increase in the ratio of RV to LV end-diastolic areas in the long axis view to greater than 0.6. Septal dyskinesia results when RV systole lengthens (due to higher afterload) so that the RV is still contracting even while the LV begins to relax. This reversal of the normal pressure gradient at the onset of diastole creates the typical abnormal septal motion echocardiographically.

Occasionally the diagnosis may be made first from CT imaging.

How do I know this is what the patient has

An acute right heart syndrome is likely to be present when pulmonary hypertension is detected by PAC or echocardiography, combined with evidence of systemic hypoperfusion (for example, hypotension, lactic acidosis).

Differential diagnosis

The appearance of an acute right heart syndrome could be mimicked by chronic pulmonary hypertension with another form of shock, such as septic or hypovolemic shock. This is more likely in patients with known pulmonary hypertension, conditions that predispose to pulmonary hypertension (such as chronic left ventricular failure, sickle cell anemia, scleroderma, congenital heart disease, and others), or when there is echocardiographic or other evidence of right ventricular hypertrophy (implying chronically elevated right heart pressures).

Confirmatory tests

Echocardiography is the diagnostic test of choice. A pulmonary artery catheter is not necessary to confirm the presence of pulmonary hypertension; however, it can provide information (eg, mixed venous oxyhemoglobin saturation, cardiac output, pulmonary vascular resistance) that may aid assessment of severity or response to treatments.

4. Specific Treatment

First-Line Therapy:

1. Reduce pulmonary vascular resistance:

a. Reduce clot burden (thrombolysis, catheter embolectomy, surgical thromboembolectomy) when pulmonary embolism is the cause.

b. Avoid harmful ventilator settings, especially when ARDS is the cause:

i. Lung-protective tidal volumes (6 cc/kg predicted body weight), preferably with plateau airway pressure below 27 cmH2O

ii. Use the least PEEP that produces acceptable oxygenation.

iii. Monitor and minimize autoPEEP since autoPEEP, like PEEP, may raise pulmonary vascular resistance.

iv. Attempt to normalize arterial PCO2, since hypercapnia causes pulmonary vasoconstriction. Be aware, though, that normalizing PCO2 may produce autoPEEP or lung overdistention, which may be more harmful than hypercapnia.

c. Give inhaled nitric oxide (typical dose 35 ppm) or prostacyclin (begin with 1 ng/kg/min and escalate every 15 min).

2. Determine optimal intravascular volume:

a. Consider a judicious fluid challenge, using an objective measure of response (central venous oxyhemoglobin saturation or cardiac output).

b. Recognize that fluids are often not helpful in acute right heart syndromes and may be counterproductive.

c. Dynamic predictors of fluid responsiveness may help limit fluid administration to those most likely to be helped, but falsely positive pulse pressure variation has been described in patients with right ventricular dysfunction. Echocardiography (tissue Doppler tricuspid annular systolic velocity) can distinguish false positives.

3. Enhance right ventricular function:

a. Infuse dobutamine (2-5 mcg/kg/min). Higher doses (5-10 mcg/kg/min) are not often helpful and may produce undesired tachycardia.

b. Add norepinephrine (0.4 to 4 mcg/kg/min) if hypotension limits dobutamine infusion.

4. Reduce the demand for perfusion by mechanical ventilation, sedation, and control of fever.

Second-Line Therapy:

1. Consider alternative pulmonary vasodilators, such as bosentan or sildenafil;

2. Consider other inotropes, including milrinone and levosemindan.

3. Ventilate in the prone position, a strategy that does not appear to benefit groups of patients with ARDS, but aids alveolar recruitment, lowers PCO2, and has been demonstrated to unload the right ventricle.

Drugs and dosages

Dobutamine, 2-5 mcg/kg/min by continuous IV infusion

Norepinephrine 0.4-4 mcg/kg/min by continuous IV infusion

Bosentan, 62.5 mg bid, enterally

Sildenafil, 20 mg tid, enterally

Milrinone, 50 mcg/kg over 10 min intravenously, followed by 0.375-0.75 mcg/kg/min

Levosemindan, 0.05-0.6 mcg/kg/min by continuous IV infusion

Refractory cases

Extracorporeal life support (veno-arterial ECMO) unloads the right ventricle and supports the circulation, buying time for treatment or resolution of the underlying cause. Alternative approaches include insertion of a right ventricular assist device or balloon atrial septostomy, but there is little experience with these approaches in acute cor pulmonale.

5. Disease monitoring, follow-up and disposition

Expected response to treatment

In the most severely affected patients with shock due to acute right heart syndromes, successful treatment is heralded by improved systemic perfusion (rising venous oxyhemoglobin saturation and cardiac output, with resolving lactic acidosis). Blood pressure may rise, too, although this is probably not an accurate reflection of systemic perfusion. Failure to respond should prompt a reassessment of general supportive care, ventilator settings, intravascular volume status, and accuracy of diagnosis.

In those who respond with stabilization of hemodynamics and whose cause for acute cor pulmonale is treatable, the prognosis is very good. For example, in patients with massive pulmonary embolism and acute right heart syndrome who were stabilized with vasoactive therapy had an excellent prognosis (3% mortality), whereas those who were not stabilized with vasoactive therapy were much more likely to die (53% mortality).

Incorrect diagnosis

Failure to respond to therapy should prompt a reassessment of the diagnosis, especially if echocardiographic images were suboptimal.

Follow-up

Repeat echocardiographic imaging may assist withdrawal of vasoactive therapies.

Pathophysiology

Acute right heart syndrome result from an inability of the right ventricle to sustain flow through the pulmonary vascular bed. This can be due to depressed systolic RV function (as in right ventricular infarction) or to elevated pulmonary vascular resistance (or both). When the basis lies in the pulmonary vascular bed, the thin-walled right ventricle is unable to sustain large increases in afterload.

If pulmonary vascular resistance rises markedly (such as due to pulmonary embolism, ARDS, or acute sickle chest crisis), the right ventricle dilates and thins. Flow to the left heart falls, depressing stroke volume. As the septum shifts towards the left, left ventricular diastolic dysfunction may further impair LV filling.

At the same time that right ventricular oxygen demand rises (due to increased preload, afterload, and heart rate), oxygen supply may be crippled by systemic hypotension, hypoxemia, and a reduced period for coronary perfusion (as wall tension rises, the RV may no longer be perfused during systole). These factors combine to produce RV ischemia, initiating a downward spiral of worsened RV function and ischemia. Ultimately, shock ensues, threatening organ function and leading to arrhythmias.

Epidemiology

The incidence of acute cor pulmonale depends on the underlying cause. For patients admitted to an ICU with massive pulmonary embolism, roughly 2/3 will have an acute right heart syndrome and, in perhaps a third of those, hemodynamic instability unresponsive to vasoactive therapy. In those with ARDS, acute right heart syndromes were rather common before the era of lung-protective ventilation, but now less so. Perhaps one fourth of patients with ARDS will have RV dysfunction.

Prognosis

Prognosis depends strongly on the underlying cause of the acute right heart syndrome. In pulmonary embolism, prognosis is quite good if the patient can be stabilized hemodynamically, but very poor (> 50% mortality) if not. There is a modest incidence (< 10%) of long-term chronic thromboembolic pulmonary hypertension following massive acute PE. In ARDS, the prognosis is more guarded because ARDS itself has an expected mortality of 30 to 40%. It is likely that those with acute right heart syndromes are more likely to die than the average patient with ARDS.

Special considerations for nursing and allied health professionals.

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What's the evidence?

Description of the Problem

Woods, J, Monteiro, P, Rhodes, A. "Right ventricular dysfunction". Curr Opin Crit Care. vol. 13. 2007. pp. 532.

Brief overview of differential diagnosis, pathophysiology, evaluation, and treatment, with an emphasis on levosemindan.

Emergency Management

Mahjoub, Y, Pila, C, Friggeri, A. "Assessing fluid responsiveness in critically ill patients: false-positive pulse pressure variation is detected by Doppler echocardiographic evaluation of the right ventricle". Crit Care Med. vol. 37. 2009. pp. 2570.

Pulse pressure variation may falsely predict fluid responsiveness in patients with right ventricular dysfunction, but echocardiography with peak systolic velocity of tricuspid annular motion (Sta) was an accurate predictor.

Dell'Italia, LJ, Starling, MR, Blumhardt, R. "Comparative effects of volume loading, dobutamine, and nitroprusside in patients with predominant right ventricular infarction". Circulation. vol. 72. 1985. pp. 1327.

Classic study of right ventricular infarction demonstrating that fluid loading and nitroprusside are ineffective, whereas dobutamine raised cardiac index and improved right ventricular function.

Diagnosis

Engelke, C, Rummeny, EJ, Marten, K. "Acute pulmonary embolism on MDCT of the chest: prediction of cor pulmonale and short-term patient survival from morphologic embolus burden". AJR. vol. 186. 2006. pp. 1265.

A CT severity score was a significant predictor of cor pulmonale and short-term outcome.

Piazza, G, Goldhaber, SZ. "The acutely decompensated right ventricle: pathways for diagnosis and management". Chest. vol. 128. 2005. pp. 1836.

Comprehensive review, but with nice summaries of symptoms, physical examination findings, biomarkers, ECG, radiography, echocardiography, cardiac MRI, and pulmonary artery catheterization.

Specific Treatment

DeWet, CJ, Affleck, DG, Jacobsohn, E. "Inhaled prostacyclin is safe, effective, and affordable in patients with pulmonary hypertension, right heart dysfunction, and refractory hypoxemia after cardiothoracic surgery". J Thorac Cardiovasc Surg. vol. 127. 2004. pp. 1058.

Patients with pulmonary hypertension following cardiac surgery were treated with inhaled prostacyclin, showing it to be safe, effective, and far less expensive than inhaled nitric oxide.

Jardin, F, Vieillard-Baron, A. "Acute cor pulmonale". Curr Opin Crit Care. vol. 15. 2009. pp. 67.

Concise, sophisticated review focused on the impact of mechanical ventilation in patients with acute right heart syndromes.

Jardin, F, Vieillard-Baron, A. "Is there a safe plateau pressure in ARDS? The right heart only knows". Intensive Care Med. vol. 33. 2007. pp. 444.

Lung-protective ventilation has probably reduced the incidence of acute cor pulmonale in ARDS patients.

Khan, TA, Schnickel, G, Ross, D. "A prospective, randomized, crossover pilot study of inhaled nitric oxide versus inhaled prostacyclin in heart transplant and lung transplant recipients". J Thorac Cardiovasc Surg. vol. 138. 2009. pp. 1417.

Inhaled NO and prostacyclin had similar effects on pulmonary artery and central venous pressures, cardiac index, and mixed venous oxyhemoglobin saturation.

Kerbaul, F, Rondelet, B, Demester, J-P. "Effects of levosemindan versus dobutamine on pressure load-induced right ventricular failure". Crit Care Med. vol. 34. 2006. pp. 2814.

Levosemindan has similar inotropic effects as dobutamine but with additional pulmonary vasodilating capability in an animal model of RV failure.

Kerbaul, F, Rondelet, B, Motte, S. "Effects of norepinephrine and dobutamine on pressure load-induced right ventricular failure". Crit Care Med. vol. 32. 2004. pp. 1035.

Dobutamine is superior to norepinephrine in an animal model of RV failure.

Lahm, T, McCaslin, CA, Wozniak, TC. "Medical and surgical treatment of acute right heart failure". J Am Coll Cardiol. vol. 56. 2010. pp. 1435.

Thorough review of therapy, drawing especially on data from patients with chronic pulmonary arterial hypertension.Disease Monitoring, follow-up, and disposition

Pathophysiology

Cecconi, M, Johnston, E, Rhodes, A. "What role does the right side of the heart play in circulation?". Critical Care. vol. 10. 2006. pp. S5.

Emphasizes normal physiology and contrasts between the left and right heart, as well as the acute effects of increased right ventricular afterload. Reviews also treatment and monitoring.

Mebazza, A, Karpati, P, Renaud, E. "Acute right ventricular failure -- from pathophysiology to new treatments". Intensive Care Med. vol. 30. 2004. pp. 185.

Thorough review of all aspects of acute cor pulmonale, with an emphasis on pathophysiology and diagnosis.

Zamanian, RT, Haddad, F, Doyle, R. "Management strategies for patients with pulmonary hypertension in the intensive care unit". Crit Care Med. vol. 35. 2007. pp. 2037.

Complete review of acute cor pulmonale, but with an especially detailed section on pharmacologic therapy.

Epidemiology

Mekontso Dessap, A, Leon, R, Habibi, A. "Pulmonary hypertension and cor pulmonale during severe acute chest syndrome in sickle cell disease". Am J Respir Crit Care Med. vol. 177. 2008. pp. 646.

Large series of acute sickle chest syndrome, including detailed echocardiographic characterization.

Prognosis

Kline, JA, Steuerwald, MT, Marchick, MR. "Prospective evaluation of right ventricular function and functional status 6 months after acute submassive pulmonary embolism". Chest. vol. 136. 2009. pp. 1202.

Patients with baseline echocardiography at the time of submassive PE were studied again 6 months later. At diagnosis, 38% had right ventricular systolic pressure > 40 mmHg, but at 6 months only 7% did. Nevertheless, the right ventricular systolic pressure at 6 months was higher than the baseline value in 27% of those treated initially with heparin only.
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