Percutaneous Right Ventricular Assist Device as Support for Cardiogenic Shock due to Right Ventricular Infarction
- Volume 20 - Issue 7 - July, 2008
- Posted on: 8/1/08
- 0 Comments
- 9394 reads
Cardiogenic shock is a devastating complication of acute myocardial infarction (MI) with an in-hospital mortality between 40–76%.1,2 Cardiogenic shock from right ventricular infarction is uncommon, though it has a mortality rate equal to that of left ventricular shock.3,4 The TandemHeart (Cardiac Assist, Inc., Pittsburgh, Pennsylvania) is a peripheral ventricular assist device (PVAD) that can be inserted percutaneously to provide short-term mechanical support, primarily during high-risk percutaneous intervention or cardiogenic shock secondary to left ventricular dysfunction.5–11 We report the case of a patient with cardiogenic shock secondary to right ventricular dysfunction bridged to recovery with the TandemHeart as a right ventricular assist device (RVAD).
Case Report. A 57-year-old male with a history of Hodgkin’s disease and mediastinal radiation at age 15 presented with two episodes of syncope and severe back pain to a community hospital. He was noted to have ST elevations in leads II, III, aVF, and ST depressions in V1–3 on electrocardiography (a right-sided ECG was not obtained) and was given aspirin and intravenous unfractionated heparin. He developed bradycardia to 36 beats per minute with a blood pressure of 64/37 mmHg, which improved with intravenous fluids and an atropine bolus. He was then transferred to our institution for cardiac catheterization and further management.
Upon transfer, the patient underwent emergent coronary angiography, which revealed a completely occluded right coronary artery (RCA) at the ostium; the other coronary vessels showed only mild luminal irregularities, and an aortogram showed no dissection. He underwent percutaneous intervention with the placement of a Cypher™ stent (Cordis Corp., Miami Lakes, Florida) in the proximal RCA. Post intervention, there was TIMI 3 flow in the vessel with adequate perfusion of the right ventricular marginal branches. Because of persistent hypotension, an intra-aortic balloon pump (IABP) was placed.
The patient developed third-degree heart block with a slow escape rhythm and underwent temporary transvenous ventricular pacemaker insertion. The electrophysiology consultant felt that it would be difficult to place a right atrial lead due to dilation of the atrium and likely poor atrial capture in the setting of ischemia. In addition, given the severe hemodynamic derangements, the benefit of atrioventricular synchrony was thought to be marginal.
Immediately after catheterization, echocardiography showed akinesis of the entire inferior septum and basal posterior and inferior walls, with only mildly reduced global left ventricular function. There was akinesis of the basal two-thirds of the right ventricle with mild right ventricular dilation.
Throughout the first 24 hours, the patient remained hypotensive and required escalating doses of dopamine, dobutamine and vasopressin despite adequate volume resuscitation. A pulmonary artery catheter revealed elevated central venous pressure (25 mmHg), with only minimally elevated pulmonary artery pressures (34/24 mmHg) and low cardiac index (0.9 L/min/m2).
The decision was made to pursue mechanical support and, given prior mediastinal radiation, a TandemHeart device was inserted as an RVAD in the catheterization laboratory. An 8 Fr sheath had been previously placed in the right femoral vein, and this was removed over a J-tipped guidewire. After serial dilatations, a 17 Fr femoral venous catheter was positioned in the inferior vena cava. A 7 Fr balloon wedge catheter (Arrow International, Reading, Pennsylvania) was then placed through the 17 Fr catheter and advanced over a 0.035 inch angled glidewire to the pulmonary artery. The 17 Fr catheter was then advanced over the balloon-tipped catheter to the main pulmonary artery. Pulmonary angiography confirmed successful placement. An 18 Fr Fem-Flex cannula (Baxter Deutschland Gmb, Germany) was then advanced through the right internal jugular vein using a modified Seldinger technique to the right atrium (Figure 1) and de-airing of the inflow and outflow cannulae was completed. The outflow cannula was well visualized in the right ventricular outflow tract and the main pulmonary artery on transesophageal echocardiography. TandemHeart support was then initiated at the maximum speed of 7,500 rpm, which delivered an output of 3.4 L/minute.
Unfractionated heparin was used to maintain an activated clotting time (ACT) between 180–200 seconds, which led to moderate leakage of blood around the internal jugular cannula and necessitated transfusion of 2 units of packed red blood cells. Inhaled nitric oxide was administered and over the next 36 hours, the patient’s blood pressure stabilized and pressors were weaned. Transthoracic echocardiography showed that the middle-third of the right ventricle had regained function.
Forty-eight hours after the device was inserted, the patient was taken to the operating room to have the TandemHeart removed. Intraoperative transesophageal echocardiography demonstrated that the outflow cannula had dislodged from its prior position in the main pulmonary artery to below the pulmonic valve, likely secondary to movement of the patient’s leg the previous day. Both cannulae were removed and the vessels sutured closed to achieve complete hemostasis.
Over the course of the next nine days, the IABP was removed, inotropes and nitric oxide were weaned off and the patient was extubated. The patient was discharged home on hospital day 17. At 6-month follow-up, he was asymptomatic and walking 3 miles per day.
Discussion. Right ventricular infarction has high initial morbidity and mortality rates, but in those who survive the initial few days, there is often a rapid improvement in right ventricular function, with prompt early recovery and return to normal in 3–12 months.12–15 The early high morbidity rate in right ventricular infarction may be due to time to reperfusion, mechanical dysfunction or electrical abnormalities. Prompt reperfusion of the RCA is associated with earlier return of right ventricular function,16 though adequate flow in the major right ventricular marginal branches is also a strong predictor of hemodynamic improvement.17 Right ventricular infarction can lead to right ventricular dilation, increased pericardial pressure and bowing of the interventricular septum toward the left ventricle, reducing preload to the left ventricle with resultant cardiogenic shock, despite near-normal function of the left ventricle.18 In addition, the right ventricle becomes less compliant with poor diastolic relaxation. This, in turn, elevates left ventricular diastolic pressure through ventricular interdependence and septal bowing.17 In addition, elevated right ventricular pressure can increase intrapericardial pressures, further limiting biventricular filling. Proximal RCA occlusions may lead to right atrial ischemia and stiffening, which may further reduce flow into the right ventricle. If third-degree heart block occurs, the loss of an atrial “kick” may further worsen hemodynamic performance of the stiffened right ventricle and lead to increased tricuspid regurgitation.17 Atrioventricular sequential pacing may be a useful adjunct in this situation.19
The TandemHeart is a percutaneous VAD that may be a useful bridge to recovery from a right ventricular infarction. We have shown that it is feasible to use the device as an RVAD. Previous studies have described the use of the TandemHeart as a left ventricular assist device during high-risk percutaneous intervention or for short-term support during cardiogenic shock.5–11 The use of the TandemHeart as an RVAD may be safer than as an LVAD, given that it uses only venous access and, therefore, has a lower risk of bleeding and significant vascular complications. As there is no transseptal puncture, there is no risk of creating an atrial septal defect. There is the theoretical risk of a clot forming on the end of the outflow cannula leading to a pulmonary embolus, therefore, a therapeutic ACT was maintained throughout the duration of its insertion. The TandemHeart can be particularly beneficial in those with third-degree heart block, where loss of the “atrial kick” can be devastating, as seen in our patient.
PVADs can have a role in support of patients with cardiogenic shock due to right ventricular infarction.