Treatment of cardiogenic shock with left ventricular assist device combined with cardiac resynchronization therapy: a case report

Management of cardiogenic shock: a narrative review

Cardiogenic shock (CS) is characterized by low cardiac output and sustained tissue hypoperfusion that may result in end-organ dysfunction and death. CS is associated with high short-term mortality, and its management remains challenging despite recent advances in therapeutic options. Timely diagnosis and multidisciplinary team-based management have demonstrated favourable effects on outcomes. We aimed to review evidence-based practices for managing patients with ischemic and non-ischemic CS, detailing the multi-organ supports needed in this critically ill patient population.

Impact of Cardiac Resynchronization Therapy on Left Ventricular Unloading in Patients with Implanted Left Ventricular Assist Devices

Cardiac resynchronization therapy (CRT) and left ventricular assist devices (LVADs) are common heart failure therapies; however, little is known regarding the concomitant use of these devices. We aim to evaluate unloading differences in LVAD patients with and without active biventricular pacing. Left ventricular assist device patients with and without CRT prospectively underwent ramp hemodynamic/echocardiographic testing. Patients with >95% biventricular pacing comprised the active CRT pacing group; all others (no device, implantable cardioverter defibrillator only, CRT without biventricular pacing) were categorized into the non-CRT pacing group. Invasive hemodynamics and echocardiographic characteristics (left ventricular end-diastolic/systolic diameter and valvular regurgitation) were measured at baseline and at incremental speed changes. Unloading slopes were calculated using linear regression modeling for individual hemodynamics and echocardiographic characteristics across speeds. Among 62 LVAD patients (age 59.6 ± 11.4 years, 60% male), 25 had active CRT pacing. There was no significant difference in echocardiographic or hemodynamic characteristics at baseline or final set speeds between CRT groups. Similarly, no significant differences were noted in the unloading characteristics. In LVAD patients, active biventricular pacing is unlikely to improve echocardiographic or hemodynamic characteristics.

Usefulness of Cardiac Resynchronization Therapy in Patients With Continuous Flow Left Ventricular Assist Devices

The benefit of cardiac resynchronization therapy in patients supported by a left ventricular assist device (LVAD) is unknown. There are currently no guidelines regarding the continuation, discontinuation or pacemaker (PM) settings post-LVAD implant. The aim of the study was to assess the hemodynamic benefit of biventricular (BiV) pacing in LVAD patients. We studied 22 patients supported by LVADs (age 62 ± 9, 21 males) who had received a BiV PM before LVAD implant. A total of 123 complete sets of hemodynamics were obtained during BiV pacing (n = 54), right ventricular (RV) pacing (n = 54), and intrinsic rhythm (n = 15). There were no significant differences in right atrial (RA) pressure, mean pulmonary artery pressure (mPA), PCWP, cardiac output, PA saturation (PASat) and right ventricular stroke work index between BiV and RV pacing. Hemodynamics obtained during intrinsic rhythm in 15 non-PM-dependent patients were not significantly different compared with those obtained during BiV or RV pacing. Furthermore, hemodynamics were similar at different heart rates ranging 50 to 110 beats/min. Right ventricular stroke work index was significantly lower at the highest heart rate compared with baseline and lowest heart rates suggesting decreased RV performance at higher heart rate. In conclusion, BiV pacing does not have any acute hemodynamic benefit compared with RV pacing or intrinsic rhythm in LVAD patients. A lower heart rate may confer better RV performance.

Computational Prediction of the Combined Effect of CRT and LVAD on Cardiac Electromechanical Delay in LBBB and RBBB

Two case reports showed that the combination of CRT and LVAD benefits the end-stage heart failure patients with prolonged QRS interval significantly. In one of the reports, the patient had the LVAD removed due to the recovery of the heart function. However, the quantification of the combined devices has yet to be conducted. This study aimed at computationally predicting the effects of CRT-only or combined with LVAD on electromechanical behaviour in the failing ventricle with left bundle branch blocked (LBBB) and right bundle branch blocked (RBBB) conditions. The subjects are normal sinus rhythm, LBBB, RBBB, LBBB with CRT-only, RBBB with CRT-only, LBBB with CRT + LVAD, and RBBB with CRT + LVAD. The results showed that the CRT-only shortened the total electrical activation time (EAT) in the LBBB and RBBB conditions by 20.2% and 17.1%, respectively. The CRT-only reduced the total mechanical activation time (MAT) and electromechanical delay (EMD) of the ventricle under LBBB by 21.3% and 10.1%, respectively. Furthermore, the CRT-only reduced the contractile adenosine triphosphate (ATP) consumption by 5%, increased left ventricular (LV) pressure by 6%, and enhanced cardiac output (CO) by 0.2 L/min under LBBB condition. However, CRT-only barely affects the ventricle under RBBB condition. Under the LBBB condition, CRT + LVAD increased LV pressure and CO by 10.5% and by 0.9 L/min, respectively. CRT + LVAD reduced ATP consumption by 15%, shortened the MAT by 23.4%, and shortened the EMD by 15.2%. In conclusion, we computationally predicted and quantified that the CRT + LVAD implementation is superior to CRT-only implementation particularly in HF with LBBB condition.

Electrical devices for left ventricular dysfunction and heart failure: do we need revised guidelines?

Three recent trials have demonstrated the benefit of cardiac resynchronization therapy (CRT) in the New York Heart Association (NYHA) class II patients with heart failure (HF) with ischemic or nonischemic cardiomyopathy as well as in NYHA class I (asymptomatic) patients mostly with ischemic cardiomyopathy. Earlier intervention with CRT in asymptomatic or minimally symptomatic patients improves survival and reduces HF hospitalizations. The reduction or the prevention of HF hospitalizations is of paramount importance because the HF episodes seem to alter the natural history of disease and are associated with deterioration of left ventricular (LV) function and a marked increase in mortality. The CRT benefit is greatest in patients with a QRS ≥ 150 ms. At this time, it would seem prudent to consider CRT-D (D = ICD) therapy for class I NYHA patients with a QRS ≥ 150 ms and an LV ejection fraction ≤ 30% regardless of etiology. Although the data for NYHA class I patients with nonischemic cardiomyopathy are scanty, the recommendation for class I patients is justified because CRT achieves a much greater degree of LV reverse remodeling in nonischemic compared to ischemic patients. With regard to lone ICDs, there is no evidence that they prevent sudden cardiac death more efficiently in symptomatic than in asymptomatic patients. Cardiomyopathy should be the primary target for device therapy regardless of symptoms for both CRT and lone ICD therapy. New guidelines are needed to address the role of CRT in hospitalized NYHA class IV HF patients or those who depend on inotropic therapy or an LV assist device because randomized CRT trials have not included these patients. CRT in these patients remains controversial. The mortality of such patients even with CRT is very high despite the occasional positive response. The role of CRT in patients waiting for cardiac transplantation also needs guidelines. With the expansion of CRT indications to minimally symptomatic or asymptomatic patients, the benefit of device therapy must be carefully weighed against the potential risk of lifelong device complications.