A 53-year-old man with advanced heart failure because of a long-standing history of ischemic coronary artery disease with multiple myocardial infarctions and stent placements, chronic obstructive pulmonary disease, and diabetes mellitus type II was admitted with advanced cardiogenic shock in an outside hospital. A transthoracic echocardiogram showed 10% left ventricular ejection fraction, severely dilated atria, severely dilated right ventricle and left ventricle (LV) with reduced systolic function, moderate mitral regurgitation, and mild pulmonary hypertension. Despite multiple inotropic agents, the patient could only be stabilized using veno-arterial ECMO and intraaortic balloon pump. He was transferred to our center for further management and evaluation for left ventricular assist device (LVAD) implantation. He subsequently underwent an LVAD implantation procedure (HeartWare Ventricular Assist System, HeartWare Inc., Framingham, MA) as a bridge to cardiac transplantation. His early postoperative course was uneventful except for few episodes of ventricular tachycardia (VT) without significant drops in pump flow, which were successfully treated with IV Amiodarone. The patient was extubated the following day. All inotropic medications and vasopressors were weaned on the fifth postoperative day. A pump flow of 4–6 L/min was achieved using a pump speed of 2,800–3,000 rpm. He left the intensive care unit (ICU) 1 week postimplant. Two days later, he was readmitted to the ICU because of VT and low pump flow (2.5–3 L/min). These events did not respond to antiarrhythmia medications and appeared to be highly positional- and cough-dependent. A transesophageal echocardiogram (TEE) revealed moderately dilated LV with abnormal septal motion consistent with right ventricular volume overload and right ventricular dilation with moderately reduced systolic function. The aortic valve was closed. His central venous pressure (CVP) was >20 mm Hg, and IV inotropes (epinephrine and milrinone) were initiated to manage secondary right ventricular failure. Consequently, pump flow improved to 4.5 L/min, CVP dropped to 15 mm Hg, and his aortic valve started to open. However, the episodes of VT and suction events were more frequent. Because echocardiography was not conclusive regarding inflow cannula position, the patient underwent intracardiac echocardiography(ICE), which revealed that the tip of the inflow cannula was directed toward the septum (Figure 1) with direct contact between the cannula tip and the septum during systolic movement. We determined that the high flow caused shifting of the septum. As shown, an elevation of pump speed to 3,000 rpm caused a suctioning of the inflow cannula towards the septum (Figure 1). This effect was clearly reproducible. Under echocardiographic control using ICE and volume management, pump flow was successfully reduced to 2,700 rpm and further suction events were prevented. In the follow-up period, very few episodes of VT were observed. All inotropic agents were weaned, and the patient was discharged home after 10 days without further complications. He continues to be followed at our center and has been event-free for more than 6 weeks.
Intracardiac Echocardiography Procedure
An 8 French ultrasound catheter (Siemens Medical Solutions, Malvern, PA; frequency 5.5–10 MHz) was advanced percutaneously through a right femoral vein or through a right internal jugular vein into the right atrium and through the tricuspid valve into the right ventricle. The ICE was used for continuous real-time visualization of the left atrium, left atrial appendage, and left ventricle. In most patients, we observed displacement of the fossa ovalis to the left side, consistent with higher pressure in the right atrium compared with the left atrium. From the right ventricle, the interventricular septum was observed closer to the transducer, followed by the LV cavity and the left ventricular free wall. By rotating, withdrawing, or advancing the probe, we were able to visualize the anterior and inferior (posterior) walls of the LV, the mitral valve, the aortic valve, and the papillary muscles. The direction and location of the inlet cannula were determined (closer to the interventricular septum or to the free wall of the LV). The absence of LV thrombus was determined in each patient.
Left ventricular assist devices have become important in the management of patients with end-stage heart failure.1 This case describes ICE in a new application, which may be an important asset in the armamentarium of peri- and postoperative management of patients with LVADs. Variation of the inflow cannula position in the left ventricle may cause dead space inside the ventricle, which may lead to flow turbulance and low flow phenomena with subsequent intracavitary thrombus formation. Further septal deviation may result with relevant arrythmias with the potential for right heart failure and reduced cardiac output. Transthoracic echocardiogram, TEE, and 3D computed tomography (CT) scan have been used to visualize cannula position in the left ventricle after LVAD implantation and to exclude possible intracavity thrombus.2,3 Intracardiac echocardiography is an imaging technique that can be used as either an alternative to or in addition to TEE by using percutaneous access.4,5 It provides several advances compared with TEE or 3D CT, including improved image quality, no general anesthesia, less radiation exposure, and faster recovery time. Here a clinical scenario is described in which the improper position of the inflow cannula caused multiple suction events with VT episodes, subsequently leading to right heart failure in combination with higher left ventricular pressures. The application of ICE identified the major culprit by clearly assessing the inflow cannula position.
1. Slaughter MS, Rogers JG, Milano CA, et al.HeartMate II Investigators. Advanced heart failure treated with continuous-flow left ventricular assist device. N Engl J Med. 2009;361:2241–2251
2. Catena E, Milazzo F, Pittella G, et al. Echocardiographic approach in a new left ventricular assist device: Impella Recover 100. J Am Soc Echocardiogr. 2004;17:470–473
3. Dávila-Román VG, Barzilai B. Transesophageal echocardiographic evaluation of patients receiving mechanical assistance from ventricular assist devices. Echocardiography. 1997;14:505–512
4. Mitchell ARJ, Puwanarajah P, Timperley J, et al. The emerging role of intracardiac echocardiography -- Into the ICE Age. Br J Cardiol. 2007;14:31–36
5. Glassman E, Kronzon I. Transvenous intracardiac echocardiography. Am J Cardiol. 1981;47:1255–1259
intracardiac echocardiography; left ventricular assist device