The Effect of Hemodialysis on Left Ventricular Outflow Tract Gradient

Left ventricular basal muscle bundle in hypertrophic cardiomyopathy: insights into the mechanism of left ventricular outflow tract obstruction

AIMS 

Many factors cause left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM). Previous studies reported that left ventricular basal muscle bundle (BMB) may be associated with LVOTO. We aimed to evaluate the role of BMB in LVOTO by echocardiography.

METHODS AND RESULTS 

Two hundred fifty-six patients diagnosed with HCM were recruited. The morphologic characteristics of left ventricular outflow tract (LVOT) were analysed. BMB was detected in 178 (69.5%) patients by echocardiography. Patients were separated by a resting or provocative LVOT gradient ≥30 mmHg or not. Compared to patients without LVOTO, patients with LVOTO had a significantly thicker basal septum, elongated anterior mitral leaflet (AML), shorter distance between the AML-free margin and the septum or BMB (M-sept/bundle), larger angle between the plane of the mitral valvular orifice and the ascending aorta (MV-AO angle), and higher prevalence of BMB (P < 0.05). According to multivariate analysis, the independent predictors of LVOTO were the presence of BMB, a large basal septum thickness, a short M-sept/bundle, a large MV-AO angle, and a large AML [odds ratio (95% confidence interval): 5.207 (1.381-19.633), 1.386(1.141-1.683), 0.615(0.499-0.756), 1.113(1.054-1.176), and 1.343(1.076-1.677), respectively, P < 0.05]. Of the 256 included patients, 139 underwent surgical myectomy. The transthoracic echocardiography, compared with surgical specimen, showed: sensitivity 98.3%, specificity 82.3%, positive predictive value 97.6%, negative predictive value 87.5%, and accuracy 96.4% to detect BMB.

CONCLUSIONS

BMB is common in HCM. BMB is a risk factor for LVOTO.

Point-of-care ultrasound in end-stage kidney disease: beyond lung ultrasound

PURPOSE OF REVIEW

Following the miniaturization of ultrasound devices, point-of-care ultrasound (POCUS) has been proposed as a tool to enhance the value of physical examination in various clinical settings. The objective of this review is to describe the potential applications of POCUS in end-stage renal disease patients (ESRD).

RECENT FINDINGS

With basic training, the clinician can perform pulmonary, vascular, cardiac, and abdominal POCUS at the bedside of ESRD patients. Pulmonary ultrasound can be used to quantify pulmonary congestion and for the differential diagnosis of dyspnea. Ultrasound of the inferior vena cava combined with simple cardiac ultrasound can be used to promptly investigate the mechanism of hemodynamic instability. Vascular ultrasound can be used for troubleshooting of arteriovenous fistula problems and for catheter installation. Multiple potential applications of POCUS in the ESRD population are reviewed, including areas of future research.

SUMMARY

Acquiring basic skills in POCUS may improve patient care through the rapid identification of threats, improved diagnostic abilities for common symptoms, and safer procedures. The adoption of POCUS in undergraduate, internal medicine and nephrology training curriculums will likely lead to a gradual introduction of this technology in the care of ESRD patients.

Patient after renal transplantation with syncope: Role of echocardiography in upright position

In Doppler echocardiography, testing left ventricular outflow tract (LVOT) gradient in the supine position (as is done in everyday practice) does not reflect the pathophysiology of this dynamic abnormality during the daily activities that trigger the symptoms (eg, syncope). LVOT obstruction is a dynamic phenomenon, strongly dependent on the left ventricular cavity size, geometric configuration of hypertrophy, load variability, contractility, and mitral apparatus abnormalities. LVOT gradient may develop not only in hypertrophic cardiomyopathy but also in various heart diseases. Recent investigations show that LVOT gradient should be measured also in the standing position. Here, we report the case of patient after renal transplantation, who developed LVOT gradient during orthostatic test. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:616-620, 2017.

Need for a standardized protocol for stress echocardiography in provoking subaortic and valvular gradient in various cardiac conditions

(Semi) supine exercise testing has an established role in the evaluation of patients with valvular heart disease and can help clinical decision making. Stress echocardiography has the advantages of its wide availability, low cost, and versatility for the assessment of disease severity. However, exercise-induced changes in valve hemodynamics, left ventricular outflow obstruction and pulmonary artery pressure depended on load variation. Changing position from supine to upright rapidly decreases load conditions for the ventricles. Therefore several cardiac centers have proposed exercise stress echocardiography in the upright position with gradient monitoring sometimes also in post-exercise recovery. Doppler measurement of subaortic gradient has been a very helpful and informative examination in several heart diseases (especially in hypertrophic cardiomyopathy, valve heart diseases, prosthesis dysfunction).

Orthostatic stress echocardiography as a useful test to measure variability of transvalvular pressure gradients in aortic stenosis

The aim of the study was to assess the influence of the orthostatic stress test on changes in aortic pressure gradients in patients with aortic stenosis (AS).

METHODS

The orthostatic stress test was performed in 56 AS patients. The maximum aortic gradient was compared between the supine and the upright position (using Doppler echocardiography from the apical window). The left hand of each patient was kept on top of their head for both readings. 21 patients were excluded from the study for three reasons: 1) atrial fibrillation (significant beat-to-beat variability of measured gradient), 2) suboptimal Doppler signal during the orthostatic test, and 3) aortic gradient significantly higher in suprasternal or right parasternal windows than in apical window (different direction of stenosed blood jets) in the supine examination. The last limitation (#3) is methodologically important because during the orthostatic examination, only the transapical measurement was used. We were able to analyze 35 AS patients (20 males, 15 females, mean age 74.8 ± 9.2 years).

RESULTS

The wide range of severity of AS was examined (maximal aortic gradient in the supine position from 30 to 146 mmHg). With regard to statistical trends, the mean value of the maximum aortic gradient significantly decreased after orthostatic stress (from 87.5 ± 28.6 to 75.8 ± 23.7 mmHg), p > 0.01). In 7 patients (increasing responders) the peak aortic gradient slightly increased during the stress test. Five of the seven only increased by a few percent. The other two patients increased by nearly 10%. In contrast, the remaining 28 AS patients' gradient decreased by as much as 40% (decreasing responders).

CONCLUSIONS

The orthostatic position test frequently generated a decrease of "theoretically fixed at rest" valvular gradient in AS. The combination of the stiffened stenotic valve apparatus and a reduced LV preload may be responsible for this decreasing response.

Standing position alone or in combination with exercise as a stress test to provoke left ventricular outflow tract gradient in hypertrophic cardiomyopathy and other conditions

Measuring left ventricular outflow tract (LVOT) gradient by echocardiography in decubitus position, which is used in routine clinical practice, does not reflect the pathophysiology of this dynamic abnormality during daily activities, which trigger the symptoms. LVOT obstruction is dynamic and greatly dependent upon the left ventricular cavity size, geometric configuration of hypertrophy, load, contractility and mitral apparatus abnormalities, including systolic anterior motion of mitral leaflet. Importantly, LVOT gradient may develop not only in hypertrophic cardiomyopathy, but also in other heart diseases. Recent studies show that LVOT gradient should be measured both in a standing position and during exercise.