Pathophysiological background and prognostic implication of systolic aortic root motion in non-ischemic dilated cardiomyopathy

Aortic annular plane systolic excursion in cats with hypertrophic cardiomyopathy

BACKGROUND

Impairment of left ventricular (LV) longitudinal function is an early marker of systolic dysfunction in hypertrophic cardiomyopathy (HCM). Aortic annular plane systolic excursion (AAPSE) is a measure of LV longitudinal function in people that has not been evaluated in cats.

HYPOTHESIS

Aortic annular plane systolic excursion is lower in cats with HCM compared to control cats, and cats in stage C have the lowest AAPSE.

ANIMALS

One hundred seventy-five cats: 60 normal, 61 HCM stage B and 54 HCM stage C cats.

MATERIALS

Multicenter retrospective case-control study. Electronic medical records from 4 referral hospitals were reviewed for cats diagnosed with HCM and normal cats. HCM was defined as LV wall thickness ≥6 mm and normal cats ≤5 mm. M-mode bisecting the aorta in right parasternal short-axis view was used to measure AAPSE.

RESULTS

Aortic annular plane systolic excursion was lower in HCM cats compared to normal cats (3.9 ± 0.9 mm versus 4.6 ± 0.9 mm, P < .001) and was lowest in HCM stage C (2.4 ± 0.6 mm, P < .001). An AAPSE <2.9 mm gave a sensitivity of 83% (95% CI 71%-91%) and specificity of 92% (95% CI 82%-97%) to differentiate HCM stage C from stage B. AAPSE correlated with mitral annular plane systolic excursion (r = .6 [.4-.7], P < .001), and atrial fractional shortening (r = .6 [.5-.7], P < .001), but showed no correlation with LV fractional shortening.

CONCLUSIONS AND CLINICAL IMPORTANCE

Aortic annular plane systolic excursion is an easily acquired echocardiographic variable and might be a new measurement of LV systolic performance in cats with HCM.

Correlation of Aortic Root Movement with Left Ventricular Function

Objectives:

The motion of structures of the heart is the basis for cardiac function. Factors such as low image quality and low signal-to-noise ratio create hindrances in the adequate valuation of left ventricular (LV) systolic and diastolic function. Even in cases with poor image quality, the aorta being a large structure is well visualized. One of the unorthodox approaches to the assessment of heart function is the study of aortic root movement.

Materials and Methods:

We studied patients who came to the Nizam Institute of Medical Sciences. The ethics committee of the institute approved our study. We studied 85 patients who came to the emergency or outpatient department with or without various cardiovascular problems. We have included patients who presented with myocardial infarction, arrhythmia, and heart failure, cerebrovascular accident. We measured the constants pertaining to the aortic root motion and LV function with the standard parameters of echocardiography. Then, we aimed to check for a correlation between aortic root movement parameters and the LV function of the heart. Patients filling the inclusion criteria were enrolled in the study after taking informed consent. The data from the participants were collected prospectively. We recorded the echocardiography according to the standard guidelines. We used the Vivid E9 scanner (GE Vingmed Ultrasound AS) with the M5S-D (1.7–3.3 MHz) cardiac probe to acquire the data. We studied the echocardiographic 2D images and Doppler parameters. We used the parasternal long axis view as well as the parasternal short axis view to measure the aortic movement.

Results:

We included a total number of 85 patients as per the defined criteria among which 22 (25.88%) are females and 63 (74.11%) are males. The average age of enrolled participants was 56.30 years (±14.95 years). The mean age of the patients was 56.3 ± 14.9. About 75% of the subjects had LV dysfunction and the remaining had normal lv function. Sixty-five patients had LV dysfunction either due to ischemic or non-ischemic cardiomyopathy. We, then, checked for the relationship between the aortic root constants and the LV function parameters. We found the mean value of aortic root diastolic distance (ARDD) as 2.59 ± 0.43 cm and. The aortic root maximal diastolic velocity (ARDV) was 10.8 ± 2.4 cm/s. The aortic root systolic distance (ARSD) was 2.71 ± 0.65 cm. The aortic root maximal systolic velocity (ARSV) was 7.92 ± 2.26 cm/s. Mean aortic root excursion was 4.3 mm. Aortic root systolic excursion (ARSE) showed a parallel relation with LV function (r up to 0.7). We found ARSD and ARSV correlating weakly with systolic Doppler parameters, such as ejection fraction (EF), maximum annular plane systolic excursion (MAPSE), and s' medial. ARSE was an exception that it showed a good correlation with s’medial r = 0.746 (P < 0.001), EF r = 0.807 (P < 0.001), and MAPSE r = 0.68 (P < 0.001). The ARDD and ARDV related poorly with LV diastolic parameters such as e' mean, e' medial, e' lateral, E/A, and E/e’. E velocity, E/A, and E/e’mean showed a negative correlation with ARDV. ARDD (r up to 0.02) and ARSD (all r values < 0.40) did not correlate with the LV Doppler measurements. ARDV correlated (r up to 0.51) with some LV diastolic Doppler parameters and ARSV correlated in moderate range only with mitral annulus plane systolic excursion (r = 0.31). In fact, we found that ARDD is related better than ARDV with Doppler measurements.

Conclusion:

In our study, we included subjects with cardiovascular diseases and we conclude that systolic aortic root motion correlates significantly with systolic LV function, the most essential being the aortic root systolic velocity. We found that the diastolic root motion parameters correlated weakly with the diastolic LV function. In patients with poor echo windows, aortic root motion may be helpful in predicting LV function in patients with or without LV dysfunction.

Ventricular Dysfunction in Obese and Nonobese Rats with Metabolic Syndrome

Obesity and dyslipidemias are both signs of metabolic syndrome, usually associated with ventricular arrhythmias. Here, we tried to identify cardiac electrical alteration and biomarkers in nonobese rats with metabolic syndrome (MetS), and these findings might lead to more lethal arrhythmias than obese animals. The MetS model was developed in Wistar rats with high-sucrose diet (20%), and after twenty-eight weeks were obtained two subgroups: obese (OMetS) and nonobese (NOMetS). The electrocardiogram was used to measure the ventricular arrhythmias and changes in the heart rate variability. Also, we measured ventricular hypertrophy and its relationship with electrical activity alterations of both ventricles, using micro-electrode and voltage clamp techniques. Also, we observed alterations in the contraction force of ventricles where a transducer was used to record mechanical and electrical papillary muscle, simultaneously. Despite both subgroups presenting long QT syndrome (0.66 ± 0.05 and 0.66 ± 0.07 ms with respect to the control 0.55 ± 0.1 ms), the changes in the heart rate variability were present only in OMetS, while the NOMetS subgroup presented changes in QT interval variability (NOMetS SD = 1.8, SD2 = 2.8; SD1/SD2 = 0.75). Also, the NOMetS revealed tachycardia (10%; p < 0.05) with changes in action potential duration (63% in the right papillary and 50% in the left papillary) in the ventricular papillary which are correlated with certain alterations in the potassium currents and the force of contraction. The OMetS showed an increase in action potential duration and the force of contraction in both ventricles, which are explained as bradycardia. Our results revealed lethal arrhythmias in both MetS subgroups, irrespectively of the presence of obesity. Consequently, the NOMetS showed mechanical-electrical alterations regarding ventricle hypertrophy that should be at the NOMetS, leading to an increase of CV mortality.

Aortic root movement correlation with the function of the left ventricle

Echocardiographic assessment of systolic and diastolic function of the heart is often limited by image quality. However, the aortic root is well visualized in most patients. We hypothesize that the aortic root motion may correlate with the systolic and diastolic function of the left ventricle of the heart. Data obtained from 101 healthy volunteers (mean age 46.6 ± 12.4) was used in the study. The data contained sequences of standard two-dimensional (2D) echocardiographic B-mode (brightness mode, classical ultrasound grayscale presentation) images corresponding to single cardiac cycles. They also included sets of standard echocardiographic Doppler parameters of the left ventricular systolic and diastolic function. For each B-mode image sequence, the aortic root was tracked with use of a correlation tracking algorithm and systolic and diastolic values of traveled distances and velocities were determined. The aortic root motion parameters were correlated with the standard Doppler parameters used for the assessment of LV function. The aortic root diastolic distance (ARDD) mean value was 1.66 ± 0.26 cm and showed significant, moderate correlation (r up to 0.59, p < 0.0001) with selected left ventricular diastolic Doppler parameters. The aortic root maximal diastolic velocity (ARDV) was 10.8 ± 2.4 cm/s and also correlated (r up to 0.51, p < 0.0001) with some left ventricular diastolic Doppler parameters. The aortic root systolic distance (ARSD) was 1.63 ± 0.19 cm and showed no significant moderate correlation (all r values < 0.40). The aortic root maximal systolic velocity (ARSV) was 9.2 ± 1.6 cm/s and correlated in moderate range only with peak systolic velocity of medial mitral annulus (r = 0.44, p < 0.0001). Based on these results, we conclude, that in healthy subjects, aortic root motion parameters correlate significantly with established measurements of left ventricular function. Aortic root motion parameters can be especially useful in patients with low ultrasound image quality precluding usage of typical LV function parameters.

Effects of pimobendan on left atrial transport function in cats

BACKGROUND

Arterial thromboembolism is a sequela of hypertrophic cardiomyopathy (HCM) in cats related to left atrial (LA) enlargement and dysfunction.

HYPOTHESIS

Pimobendan improves LA transport function in cats.

ANIMALS

Twenty-two client-owned cats with HCM and 11 healthy cats.

METHODS

Prospective, double-blind, randomized, placebo-controlled clinical cohort study. Cats were randomized to receive either pimobendan (0.25 mg/kg PO q12h) or placebo for 4 to 7 days. Nineteen echocardiographic variables of LA size and function were evaluated. Statistical comparisons included t tests, analysis of variance, and multivariable analyses.

RESULTS

Peak velocity of left auricular appendage flow (LAapp peak; mean ± SD, 0.85 ± 0.20 vs 0.71 ± 0.22 m/s; P = .01), maximum LA volume (P = .03), LA total emptying volume (P = .03), peak velocity of late diastolic transmitral flow (A peak velocity; 0.77 ± 0.12 vs 0.62 ± 0.17 m/s; P = .05), and A velocity time integral (A VTI; 3.05 ± 0.69 vs 3.37 ± 0.49; P = .05) were increased after pimobendan. Mean change after pimobendan was larger in cats with HCM compared to healthy cats for LA fractional shortening (2.1% vs -2.1%; P = .05), A VTI (0.58 vs 0.01 cm; P = .01), LAapp peak (0.20 vs 0.02 m/s; P = .02), LA kinetic energy (3.51 vs -0.10 kdynes-cm; P = .05), and LA ejection force (1.93 vs -0.07 kdynes; P = .01) in the multivariable model. The stronger effect of pimobendan in cats with HCM was independent of LA size.

CONCLUSIONS AND CLINICAL IMPORTANCE

We identified positive, albeit minor, effects of pimobendan on LA function in cats with HCM. Whether or not treatment with pimobendan decreases the risk of cardiogenic embolism deserves further study.