The ProtekDuo Cannula for Acute Right Ventricular Support in Thyrotoxicosis

ABSTRACT

A 25-year-old female was presented with acute right heart failure (aRHF) and cardiogenic shock secondary to thyrotoxicosis with concomitant acute respiratory failure. A ProtekDuo cannula was placed to provide temporary percutaneous right ventricular assistance and extracorporeal membrane oxygenation (ECMO) in venopulmonary (V-P) configuration, which provided both decompression of the right ventricle (RV) and oxygenation. With treatment of the underlying thyrotoxicosis, the RV function improved and respiratory failure resolved. She was discharged home in good condition. This case details alternative ECMO management with ProtekDuo compared to the gold standard of venoarterial (V-A) ECMO.

INTRODUCTION

Hyperthyroidism occurs due to a number of primary conditions and has an estimated prevalence of 1.2% in the U.S.[1] Women are affected by hyperthyroidism more than men with some degree of lab or clinical abnormalities occurring in 4% to 21% of women, compared to 3% to 16% of men, in one study.[2] The effects of excessive thyroid hormone on the cardiovascular system have been well described and include increased heart rate and left ventricular contraction, as well as reduced systemic vascular resistance, which can lead to “high output” heart failure. Hyperthyroidism may also lead to increased pulmonary vascular resistance, which can cause right ventricular failure, in some cases occurring without left ventricular dysfunction.[3]

The ProtekDuo is a single site, double-lumen cannula that may be used in a multitude of settings. It has mainly been described for its original function as temporary percutaneous right ventricular assist device (RVAD) or in V-P ECMO configuration (also called oxyRVAD).[4] Several other options of use exist, such as left ventricular assist device (LVAD), a drainage cannula on cardiopulmonary bypass, veno-venopulmonary (V-VP) ECMO, or venopulmonary arterial (VP-A) ECMO as described in detail elsewhere.[5,6]

CASE HISTORY

A 25-year-old female patient with a history of diffuse toxic goiter and non-adherence to antithyroid medication presented to our ECMO service with acute symptoms of thyrotoxicosis, cardiogenic shock, and acute respiratory failure. Her transthoracic echocardiogram (TTE) showed severely enlarged RV with severely reduced systolic and diastolic function, paradoxical septal motion, severely dilated right atrium (RA), severe tricuspid regurgitation, and dilation of the inferior vena cava indicative of aRHF. She had to be intubated and mechanically ventilated for hypoxic respiratory failure. A diagnostic computed tomography pulmonary angiography ruled out pulmonary embolism but demonstrated RV dilation and paradoxical interventricular septal bowing suggestive of RV strain. Her labs were obtained and remarkable for thyroid stimulating hormone <0.01 micro-IU/mL (Ref 0.4–5.5 micro-IU/mL), free thyroxine 2.3 ng/dL (Ref range 0.8–1.8 ng/dL), T3 resin uptake 49% (Ref range 22–25%), and total thyroxine of 5.0 mcg/dL (Ref range 5.1–11.9 mcg/dL). This patient had the uncommon diagnosis of aRHF secondary to thyrotoxicosis and required high doses of inotropes and vasopressors to maintain hemodynamic stability. Using fluoroscopy, we inserted a ProtekDuo cannula through the right internal jugular vein (RIJV) in the V-P position [Figure 1]. The cannula was connected to an ECMO circuit with oxygenator for respiratory support. Once on mechanical circulatory support (MCS), we were able to rapidly wean vasopressors and inotropes. A post-cannulation TTE demonstrated decompression of the right heart chambers. The patient was treated with methimazole 40 mg daily for ten days, and free thyroxine level decreased to <0.3 ng/dL. Methimazole was resumed 11 days later at a dose of 20 mg daily due to rising free thyroxine levels, with peak of 6.5 ng/dL. The patient was treated with that dose for 12 days, and the dose was then reduced to 10 mg daily. The patient was supported with ProtekDuo for seven days. With improvement of her endocrine function, she also showed cardiac recovery with improving RV and respiratory function. The membrane oxygenator was removed after three days, leaving the ProtekDuo cannula as an RVAD for four days. She was extubated on day 8, required nine days in the ICU, and was discharged home on hospital day 26. A follow-up TTE demonstrated normal RV cavity size and function.

Figure 1.

AP chest x-ray demonstrating placement of ProtekDuo cannula

DISCUSSION

Isolated aRHF is an uncommon manifestation of thyrotoxicosis. If isolated aRHF occurs, its most common manifestations are pulmonary hypertension, tricuspid regurgitation, and constrictive pericarditis. The pathophysiology of thyrotoxicosis-induced isolated aRHF is unclear, but several mechanisms have been proposed.[3] Machado et al.[7] proposed increased blood volume that may increase pulmonary arterial pressure and dilate the RV. Additionally, excess thyroid hormone may cause a form of stunned myocardium predominantly involving the RV, and thyroid autoantibodies may injure the pulmonary vascular endothelium, further contributing to pulmonary hypertension. Finally, McDonough and colleagues hypothesized hyperthyroid-induced vasospasm as a rare but clinically relevant diagnostic dilemma of thyrotoxicosis.[3]

Placement of the ProtekDuo cannula can be performed in the operating room, cardiac catheterization lab, or intensive care unit using ultrasound, fluoroscopy, and transesophageal echocardiography (TEE). The modified Seldinger technique is used to place an 8-Fr introducer in the RIJV, and then a balloon-tipped catheter is “floated” into the wedge position within the PA. Under fluoroscopic guidance, a 0.035-inch/260-cm Lunderquist® Extra Stiff Wire Guide (Cook Medical, Bloomington, IN, USA) or Amplatz Super Stiff™ (Boston Scientific, Malborough, MA, USA) is placed into the right PA through the balloon-tipped catheter, which is carefully removed while taking great care to ensure the wire remains in appropriate position. After serial dilation, the cannula can be advanced over the guidewire under continuous fluoroscopic guidance until the distal tip of the cannula is in the main PA, which can be verified with TEE. The drainage and return cannulas are connected to an extracorporeal pump, and MCS is initiated. If respiratory support is needed in addition to RV support, a membrane oxygenator can be interposed in the circuit, a configuration commonly referred to as oxy-RVAD or dual lumen (dl) venopulmonary (V-P) ECMO.[5] Available in two sizes (29- and 31-French), the ProtekDuo cannula can be used with most commercially available centrifugal extracorporeal circulatory support pumps using standard 3/8-inch blood circuit tubing and is capable of blood flow rates between 4 and 5 liters per minute (LPM). See Figure 2.

Figure 2.

(a) ProtekDuo cannula, (b) ProtekDuo cannula placed as temporary percutaneous RVAD, (c) ProtekDuo cannula with interposed oxygenator in V-P configuration for ECMO. From: Condello I. Percutaneous right ventricular assist device, rapid employment in right ventricular failure during septic shock. Crit Care. 2020;24:674

There is no universal approach to weaning from V-VP ECMO for cardiorespiratory failure. In most cases, out approach is to first wean the respiratory support component, beginning with a gradual reduction of the FiO2 and sweep gas support until the patient is “off blender.” At that point, the oxygenator is removed from the circuit, leaving only a non-ECMO or non-oxygenated temporary percutaneous RVAD. RVAD support is gradually reduced in small increments (0.25 to 0.5 LPM) until the total flow is approximately 2 to 2.5 LPM and hemodynamic stability is maintained for up to 24 h. When appropriate, further weaning is performed to assess liberation readiness by administering a bolus dose of an anticoagulant such as unfractionated heparin followed by reduction of the flow in a series of small increments until the circuit is clamped and a “zero flow” state is achieved. An echocardiogram is used to measure chamber size and qualitatively assess RV function during each step down in flow. A balloon wedge catheter may also be used to monitor hemodynamics during weaning, as we did in this patient.

Our rescue “gold standard” for patients with cardiogenic shock is peripheral V-A ECMO; however, in aRHF the use of the ProtekDuo can result in rapid RV decompression and reduction of inotropes and vasopressors, which is a phenomenon that is commonly observed following initiation of V-A ECMO.[8] Peripheral V-A ECMO has a high risk for complications related to the arterial access including vascular injury, limb ischemia, and bleeding. In addition, arterial repair and embolectomy may be necessary at the time of decannulation. In cases of isolated aRHF, arterial access may be avoided altogether when using the ProtekDuo cannula since it only requires right internal jugular vein access.[8]

We have performed a systematic literature search on the ProtekDuo cannula,[9,10] and to the best of our knowledge, our group is the first to report use of the ProtekDuo cannula for isolated aRHF secondary to thyrotoxicosis. The patient discussed in this case report developed aRHF and hypoxic respiratory failure because of a reversible acute endocrine disorder. In cases where isolated aRHF and respiratory failure are present, the use of the ProtekDuo cannula in a V-P ECMO configuration as an oxy-RVAD represents an excellent alternative to V-A ECMO.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.