Heart failure monitoring with a cardiac resynchronization therapy device-based cardiac contractility sensor: a case series

The expanding role of implantable devices to monitor heart failure and pulmonary hypertension

The epidemics of heart failure and, to a lesser extent, of pulmonary arterial hypertension continue unabated worldwide and are extremely costly in terms of loss of life and earnings, as well as the burden of health-care expenditure due to repeated hospitalization. The effectiveness of newly discovered therapies for the two conditions depends on their timely application. To date, symptoms have been used to guide the application and timing of therapy. Compelling evidence now exists that symptoms are preceded by several metabolic and haemodynamic changes, particularly a rise in intravascular pressures during exercise. These observations have stimulated the development of several implantable devices for the detection of impending unstable heart failure or pulmonary arterial hypertension, necessitating admission to hospital. In this Review, we summarize the rationale for monitoring patients with heart failure or pulmonary arterial hypertension, the transition from noninvasive to implantable devices and the current and anticipated clinical uses of these devices.

Impact of haemodynamic SonR sensor on monitoring of left ventricular function in patients undergoing cardiac resynchronization therapy

Aims

The haemodynamic SonR sensor is able to measure myocardial contractility. The isometric effort is useful in quantifying left ventricular (LV) performance. We investigated the amplitude changes in SonR signal over time and during static exercise according to the recovery of the left ventricle.

Methods and results

Twenty five patients [18 male, 70 ± 8 years, LV ejection fraction (LVEF) 29 ± 5%, in sinus rhythm] underwent biventricular SonR implantable cardioverter defibrillator implant. After procedure and at 6 months, each patient underwent detection of SonR signal and continuous measurement of blood pressure, at rest and during isometric effort. During evaluation at baseline device was programmed in VVI at 40 bpm while in DDD at 60 bpm at follow-up. At 6 months, LV reverse remodelling was investigated. Cardiac resynchronization therapy patients were considered responders when an absolute improvement in LV ejection fraction ≥ 5% occurred. At 6 months, 14 (56%) patients were responders and 11 (44%) non-responders (mean LVEF 40 ± 10% vs. 27 ± 6%, respectively). In responders, SonR value did not significantly change at follow-up compared to baseline (P = 0.894). At follow-up, SonR value was not significantly different between two groups (P = 0.651). SonR signal significantly increased during isometric effort in responders (P = 0.002) while it slightly decreased in non-responders at follow-up (P = 0.572). No differences were observed in response to isometric effort between two groups at baseline (P = 0.182, P = 0.069, respectively).

Conclusions

The absolute SonR amplitude provides limited information on the status of LV performance. The variation in SonR signal during static exercise is more likely to identify responders at follow-up.

Comparison of hemodynamic effects of biventricular versus left ventricular only pacing in patients receiving cardiac resynchronization therapy: A before-after clinical trial

Background

Biventricular (BiV) pacing is the most common mode of delivering cardiac resynchronization therapy (CRT). However, initial clinical studies have indicated that left ventricular (LV) pacing is not inferior to BiV pacing. This study was conducted to address whether LV only pacing can provide the same hemodynamic response as BiV pacing.

Methods

This before–after clinical trial was conducted at Ekbatan Hospital, from July 2012 to November 2014. Patients with a LV ejection fraction ≤35% and a QRS duration ≥0.12 s who had a standard indication for ventricular pacing were enrolled. The CRT devices of all patients had already been set for BiV pacing. Therefore, their CRT devices were set for LV only pacing for 3 months. The hemodynamic status of the patients was assessed by echocardiography before setting the CRT device to LV only pacing (as a control) and 3 months after (as an intervention).

Results

There was no statistically significant difference between the effect of BiV pacing and LV only pacing on the hemodynamic responses including LV ejection fraction, LV end diastolic and systolic volume, and velocity time integral of the aortic valve. Moreover, no significant difference was seen between men and women either.

Conclusions

LV only pacing is not inferior to BiV pacing, and the hemodynamic response was similar in the two groups. However, the LV mode has a number of advantages over the BiV mode. More evidence, based on large clinical trials, is needed to confirm our results.

Lumbar multifidus muscle changes in unilateral lumbar disc herniation using magnetic resonance imaging

OBJECTIVE

To assess multifidus muscle asymmetry using the cross-sectional area (CSA) and perpendicular distance of the multifidus muscle to the lamina (MLD) measurements in patients with nerve compression due to lumbosacral disc hernia.

MATERIALS AND METHODS

In total, 122 patients who underwent microdiscectomy for unilateral radiculopathy caused by disc herniation, diagnosed by magnetic resonance imaging (MRI), were evaluated retrospectively. Posterolateral or foraminal disc herniation at only one disc level, the L3-4, L4-L5, or L5-S1 region, was confirmed using MRI. Subjects were divided by symptom duration: 1-30 days, (group A), 31-90 days (group B), and > 90 days (group C). There were 48 cases in group A, 26 in group B, and 48 in group C.

RESULTS

In groups A, B, and C, the median MLD differed significantly between the diseased and normal sides (P < 0.05). The MLD increased on the diseased side with symptom duration by lumbar disc herniation. The diseased side MLD was 5.1, 6.7, and 7.6 mm in groups A, B, and C, respectively (P < 0.05). The cut-off values for the MLD measurements were 5.3 mm (sensitivity = 62.3%, specificity = 55.5%; P < 0.05). In groups A, B, and C, the median CSA of the multifidus muscle was not significantly different between the diseased and the normal side (P > 0.05).

CONCLUSIONS

The MLD measurement correlated significantly with multifidus asymmetry in patients with lumbar disc herniation.