Bedside Ultrasound of Internal Jugular Vein for Right Ventricular Function Assessment

Abstract

<h3>Purpose</h3> Assessing right ventricular (RV) function is important in critically ill heart failure patients and candidacy for mechanical circulatory support options. In addition, diastolic heart failure and fluid overload are the earliest manifestations of rejection and coronary vasculopathy in heart transplant (HTx) recipients. Echocardiographic measurements can be difficult to obtain due to body habitus and poor ultrasound windows. Using ultrasound (POCUS) to assess dynamic changes in internal jugular vein (IJV) dimension could be a quick and reproducible method for bedside RV function assessment. <h3>Methods</h3> Patients scheduled to undergo right heart catheterization (RHC) as their standard of care were prospectively enrolled. While supine, the IJV was imaged at the apex of the sternocleidomastoid. Using M-mode on a portable ultrasound machine, maximum (Dmax) and minimum (Dmin) anteroposterior diameters were measured during normal breathing. Respiratory variation in diameter (RVD) was then calculated using the following equation [(Dmax - Dmin)/Dmax] and expressed as a percentage. RHC was then performed within one hour. <h3>Results</h3> A total of 92 heart failure patients were enrolled with mean age 58 and mean BMI 30.3. IJV dimensions could be assessed in all patients irrespective of BMI. Poor right ventricular (RV) function (right ventricular stroke work index -RVSWI) of <5 g/m/beat/m² was associated with low RVD (16% vs 34%, p = 0.001). An IJV RVD of < 15% had 82% specificity for RVSWI < 5 (ROC AUC 0.774). When using pulmonary artery pulsatility pressure (PAPi), an RVD of <15% had 79% specificity for a PAPi ≤ 2. When combined with a Dmin of 1cm, the specificity increased to 87% (Odds ratio 3.75, p=0.016). 21 of these assessments were in HTx patients, showing similar correlation. A Dmax >1.1cm or RVD <20% individually had specificity of 80% for RAP >=10 mmHg (both with ROC AUC > 0.800). Again, RVSWI <5 was associated with low RVD (19% vs 41%, p = 0.02). In the 14 biopsies performed in HTx patients, 4 were noted with >= 2R acute cellular rejection and all 4 of these had an RAP >=8mmHg, Dmax >1cm and RVD <20% (p<0.01). <h3>Conclusion</h3> Less dynamic IJV diameter variation on POCUS correlates with poor RV function and may be an early indicator of rejection in HTx patients. This assessment can be easily done at bedside regardless of body habitus, with great specificity and can be helpful in the diagnostic management of these patients.