Masked Hypotension due to Elevated Venous Pressure in a Patient with Complex Adult Congenital Heart Disease

Abstract

An adult with surgically corrected Tetralogy of Fallot presented with profoundly elevated central venous pressure (CVP) and acute renal dysfunction thought secondary to acute on chronic right heart failure. Treatment with dopamine promoted diuresis and a stabilization of renal function. Repeated attempts to wean the patient from dopamine were associated with hypotension and worsening renal failure. Invasive hemodynamic assessment unexpectedly demonstrated high cardiac output with low systemic vascular resistance (SVR). In retrospect, the markedly elevated CVP had concealed the impact of reduced SVR on blood pressure. After reversible causes of low SVR state were excluded, the patient was successfully managed with oral alpha-adrenergic agents. While typically negligible under physiologic conditions, elevated CVP can artificially increase mean arterial pressure. We have coined the term "masked hypotension" to describe this unique pathophysiological phenomenon.

Figure 1

Electrocardiogram on presentation. The patient was noted to be in sinus rhythm with a first-degree AV block with a prolonged PR interval of 223 msec and a stable right bundle branch block that had been present for many years.

Figure 2

Plot of serum creatinine and weight over the 30 days after initial presentation. Shaded areas represent time periods where the patient received treatment with intravenous vasopressor agents. Dopamine was used as the vasopressor on days 1-8 and 16-23 while intravenous phenylephrine was used on days 27-29 with the patient being transitioned to oral phenylephrine thereafter. Note that despite correction of volume status by day 10, and the relative stability of weight thereafter, the patient still developed renal failure (second shaded area) supporting a pathophysiologic role for distributive shock in the face of high-output cardiac failure.

Figure 3

Simultaneous left and right ventricle hemodynamic monitoring with left ventricular pressure shown in yellow and right ventricular pressure shown in green. Red lines added to highlight the concordance between right ventricular and left ventricular pressure with respiration. Concordance between right ventricular and left ventricular pressures with respiration is suggestive of restrictive physiology.