Role of Echocardiography in the Intensive Care Unit: Overview of the Most Common Clinical Scenarios

The intensive care unit (ICU) is among the more important settings in which echocardiography plays a pivotal role. The ease of use, speed of execution, and completeness of information on heart anatomy and function that echocardiography is able to provide makes this tool the perfect diagnostic technique in patients for whom exhaustive information must be quickly obtained by physicians who sometimes lack specific skills in cardiovascular imaging. However, the clinical entities encountered by ICU clinicians are often difficult to distinguish and patient symptoms may not be obvious. This brief review describes three common clinical scenarios that benefit from echocardiography in the ICU, based on symptoms frequently claimed by patients admitted to the ICU. For each symptom we describe the most likely clinical possibilities, underlining the fundamental role that echocardiography plays in the differential diagnosis, and the echocardiographic elements most relevant to obtain the correct diagnosis and to guide treatment.

Impairment of elastic properties of the aorta in bicuspid aortic valve: relationship between biomolecular and aortic strain patterns

Aims

Bicuspid aortic valve (BAV) is associated with aortic wall alterations. We aimed to detect any correlation between aortic elasticity and genetic and biomolecular patterns of elastin.

Methods and results

Forty-nine BAV patients (mean age: 38 ± 17.05) were prospectively enrolled. A blood sample was drawn for analysis of a single nucleotide polymorphism of elastin gene (ELN rs2071307) responsible for misfolding of elastin, and for the amount of elastin soluble fragments (ESF) in the plasma. Aortic dimensions and elastic properties were determined by echocardiography, aortic stiffness (AS) by M-mode analysis, and longitudinal strain (LS) of the ascending aorta (AA) by speckle-tracking echocardiography; values of aortic strain were compared with 45 age-matched subjects (mean age: 33 ± 9.67) with tricuspid aortic valve (TAV). BAV patients had greater aortic dimensions [Valsalva sinus (P = 0.004), sinotubular junction (P = 0.013), AA (P < 0.001)] and stiffness (P = 0.002) but lower LS (P = 0.04) than those with TAV. Results from comparisons of mutated genotype patients (AA, n = 10) with heterozygous (GA, n = 21) and wild-types ones (GG, n = 16) revealed that the presence of mutation was associated with increased ESF (P = 0.010 GG vs. GA; P = 0.035 GA vs. AA), larger AA (P = 0.019 GG vs. GA; P = 0.001 GG vs. AA), and lower LS (P = 0.032 GG vs. AA). Patients with a dilated AA showed greater ESF (P < 0.001), greater AS (P = 0.007), and lower LS of the AA (P = 0.002) than those with a normal AA. The same parameters were not significantly different comparing patients with moderate or severe aortic valve disease and patients with less than moderate valve disease.

Conclusions

Our results show a close correlation between genetic and biomolecular patterns of elastin and mechanical properties of the aorta in patients with BAV.

Takotsubo cardiomyopathy: queries of the current era

: Takotsubo cardiomyopathy (TTS), also known as left ventricular apical ballooning syndrome, is an acute, usually reversible heart failure syndrome that most often affects postmenopausal women experiencing an emotionally stressful event. It is characterized by sudden left ventricular dysfunction and wall motion abnormalities involving the apical and mid segments. TTS has been increasingly recognized in recent years, and more and more information about the pathophysiology, diagnosis, and treatment of these patients has been reported. However, much is still unknown. TTS has a wide variety of clinical subtypes and has been described in several clinical contexts. Moreover, TTS simulates ST-segment elevation myocardial infarction and acute myocarditis, and it can be difficult to obtain a certain diagnosis. As a result, clinical decisions are challenging, and many patients currently receive an inappropriate management strategy. The aim of this review is to critically analyze the evidence about this disease reported in the literature, with particular focus on the pathophysiological processes, the diagnostic elements that can help the clinician differentiate it from other diseases, and the best management of these patients.

Arterial stiffness and mitral regurgitation in arterial hypertension: an intriguing pathophysiological link

BACKGROUND

We examined the relative impact of arterial stiffness on the presence and/or severity of chronic mitral regurgitation (MR) in hypertensive patients.

METHODS

We prospectively enrolled 141 untreated hypertensive patients (mean age 56.6 ± 11.5 years): 94 with MR, 47 without MR. As a measure of arterial stiffness, pulse wave velocity (PWV) was assessed by applanation tonometry. Assessment of MR severity was obtained through calculation of effective regurgitant orifice area (EROA) and vena contracta by standard two-dimensional transthoracic echocardiography.

RESULTS

PWV appears to progressively increase according to the presence and severity of MR (no MR = 7.3 ± 1.1 m/s, mild MR = 7.9 ± 1.3 m/s, moderate MR = 9.0 ± 1.7 m/s, severe MR = 13.3 ± 4.1 m/s; P < 0.001 for all comparisons). EROA was positively correlated with age (P = 0.011), left atrial volume index (P = 0.023), PWV (P < 0.001) and augmentation index (P < 0.001), and negatively correlated with left ventricular ejection fraction (P = 0.002) and heart rate (HR) (P = 0.018). On stepwise multivariate logistic regression analysis, only PWV (OR = 2.87, 95% CI 1.750-4.738, P < 0.001) and HR (OR = 0.94, 95% CI 0.895-0.994, P = 0.02) appeared to be independent predictors of severe MR. Receiver operating characteristic curves showed that a cutoff of 9 m/s for PWV provided the best sensitivity/specificity for predicting both the presence of any degree of MR (sensitivity 73%, specificity 87%, AUC = 0.863; P < 0.001) and MR severity (sensitivity 100%, specificity 81%, AUC = 0.954; P < 0.001).

CONCLUSION

Reduced arterial elasticity because of increased stiffness may be an important marker for the presence and severity of MR in hypertensive patients.

Visually guided TEE probe insertion, making a case based on anatomic variation: A cadaveric study

AIMS

The variations in upper esophageal anatomy currently are unknown. This study was carried out to evaluate this variation and assess its impact on transesophageal echocardiography probe insertion.

METHODS

We included 9 consecutive cadavers studied at the University of Maryland School of Medicine's Clinical Surgical Laboratory. Each cadaver was first intubated blindly by an echocardiographer (KAA) and then under direct vision with a UE Medical VL 400 video laryngoscope (Newton, MA) by an anesthesiologist (JD).

RESULTS

The visually guided method took a shorter average time (19.4 ± 13.4 seconds) and fewer passes (2.4 ± 2.1 passes) than blind insertion (30.3 ± 19.1 seconds, 5.3 ± 3.3 passes). None of the cadavers had the esophagus located directly posterior to the trachea. The esophageal hiatus was posterior and to the right of the trachea in most (n = 6); in these, the traditional "forward" jaw thrust helped to open the esophageal hiatus. Two cadavers had the esophagus and trachea located almost side by side, and in these the "forward" jaw thrust method failed. Instead, the jaw needed to be pulled to the left in order to advance the probe.

CONCLUSION

This is the first study to describe anatomic variations in the location of and relationship between the upper esophageal sphincter and the larynx for the purpose of transesophageal echocardiography probe insertion. Awareness of the side-by-side anatomic variation can help to improve esophageal intubation by prompting the use of a new "pull to the side" technique instead of the traditional "forward" jaw thrust.

Diastolic dysfunction evaluated by cardiac magnetic resonance: the value of the combined assessment of atrial and ventricular function

OBJECTIVES

We sought to evaluate the role of cardiac magnetic resonance imaging (CMR) in the evaluation of diastolic function by a combined assessment of left ventricular (LV) and left atrial (LA) function in a cohort of subjects with various degrees of diastolic dysfunction (DD) detected by echocardiography.

METHODS

Forty patients with different stages of DD and 18 healthy controls underwent CMR. Short-axis cine steady-state free precession images covering the entire LA and LV were acquired. Parameters of diastolic function were measured by the analysis of the LV and LA volume/time (V/t) curves and the respective derivative dV/dt curves.

RESULTS

At receiver operating characteristic (ROC) curve analysis, the peak of emptying rate A indexed by the LV filling volume with a cut-off of 3.8 was able to detect patients with grade I DD from other groups (area under the curve [AUC] 0.975, 95% confidence interval [CI] 0.86-1). ROC analysis showed that LA ejection fraction with a cut-off of ≤36% was able to distinguish controls and grade I DD patients from those with grade II and grade III DD (AUC 0.996, 95% CI 0.92-1, p < 0.001). The isovolumetric pulmonary vein transit ratio with a cut-off of 2.4 allowed class III DD to be distinguished from other groups (AUC 1.0, 95%CI 0.93-1, p < 0.001).

CONCLUSIONS

Analysis of LV and LA V/t curves by CMR may be useful for the evaluation of DD.

KEY POINTS

• Combined atrial and ventricular volume/time curves allow evaluation of diastolic function. • Atrial emptying fraction allows distinction between impaired relaxation and restrictive/pseudo-normal filling. • Isovolumetric pulmonary vein transit ratio allows distinction between restrictive and pseudo-normal filling.

Hypertrophic cardiomyopathy with aortic dilation: a novel observation

Aims

Our goal was to identify the prevalence of aortic dilation in patients with hypertrophic cardiomyopathy (HCM), the most prevalent (0.2%) heritable, genetic cardiovascular disease. Aortic dilation also represents a spectrum of familial inheritance. However, data regarding the prevalence of aortic dilation in HCM patients is lacking.

Methods and results

This is an observational retrospective study of all patients referred to our HCM centre. Aortic dilation was defined based on recent American Society of Echocardiography and European Association of Cardiovascular Imaging published guidelines. Of the 201 HCM patients seen between Jan. 1, 2011 and March 31, 2014, 18 (9.0%) met the definition of aortic dilation. Mean age was 56.3 ± 9.3 years, 77.8% were male, mean ascending aorta diameter was 4.0 ± 0.4 cm in males and 3.8 ± 0.2 cm in females, mean sinuses of Valsalva diameter was 4.2 ± 0.2 cm in males and 3.8 ± 0.4 cm in females, and 13 (72.2%) had left ventricular outflow tract obstruction. HCM patients with dilated aorta were more likely males, less likely hypertensive and had larger left ventricle diameter and more aortic valve regurgitation; remaining characteristics were similar.

Conclusion

We report a novel observation with 9.0% prevalance of dilated aorta in HCM patients. Further studies are needed to help define the genetic and pathophysiologic basis as well as the clinical implications of this association in a larger group of HCM patients.

Left atrial volume and strain parameters using echocardiography in a black population

Aims

Left atrial (LA) volume is an important predictor of morbidity and mortality in cardiovascular disease. Left atrial strain is a feasible technique for assessing LA function. The EchoNoRMAL study recently highlighted the possibility that ethnic-based differences may exist in LA size. There is a paucity of data regarding LA parameters in an African population. We sought to establish normative values for LA volumetric and strain parameters in a black population.

Methods and results

This cross-sectional study comprised 120 individuals between 18 and 70 years of age. Left atrial volumes were measured by biplane Simpson's method, and strain parameters were measured using Philips QLAB 9 (Amsterdam, The Netherlands) speckle-tracking software. The mean age was 38.7 ± 12.8 years (50% male). Maximum LA volume indexed (LAVi), pre-atrial LAVi, and minimum LAVi were 19.7 ± 5.9, 12.2 ± 4.4, and 7.7 ± 3.2 mL/m2, respectively. Females had a higher LAVi compared with males (20.9 ± 6.3 vs. 18.6 ± 5.3 mL/m2, P = 0.04). Peak global longitudinal strain in the reservoir phase (ɛR) was 39.0 ± 8.3%, and the peak LA strain in the contractile phase (ɛCT) was -2.7 ± 2.5%. No gender differences were noted in ɛR. Body surface area, age, and weight were the main determinants of ɛR on multivariate linear regression analysis.

Conclusion

The data reported in this study establish the normal reference values for phasic LA volumes and strain in a normal black population and serve as a platform for future studies.

Transthoracic echocardiography is adequate for intraprocedural guidance of transcatheter aortic valve implantation

Background

While transcatheter aortic valve implantation (TAVI) has traditionally been supported intraprocedurally by transoesophageal echocardiography (TOE), transthoracic echocardiography (TTE) is increasingly being used. We evaluated echocardiographic imaging characteristics and clinical outcomes in patients who underwent TTE during TAVI (TTE-TAVI).

Methods and results

A select team of dedicated sonographers and interventional echocardiographers performed TTE-TAVI in 278 patients, all of whom underwent TAVI through transfemoral access. We implanted the Medtronic EVOLUT R valve in 258 patients (92.8%). TTE images were acquired immediately pre-procedure by a dedicated sonographer in the cardiac catheterization laboratory with the patient in the supine position. TTE was then performed post deployment of TAVI. In the procedure, TTE image quality was fair or better in 249 (89.6%) cases. Color-flow Doppler was adequate or better in 275 (98.9%) cases. In 2 cases, paravalvular regurgitation (PVL) could not be assessed confidently by echocardiography due to poor image quality; in those cases, PVL was assessed by fluoroscopy, aortic root injection and invasive hemodynamics. Both TTE and invasive hemodynamics were used in the assessment of need for post-deployment stent ballooning (n = 23, 8.3%). TTE adequately recognized new pericardial effusion in 3 cases. No case required TOE conversion for image quality. There was only 1 case of intraprocedural TTE failing to recognize moderate PVL, without clinical implication. In 99% of patients, TTE-TAVI adequately assessed PVL compared with 24-h and 1-month follow-up TTE.

Conclusions

With the current generation of TAVI, TTE-TAVI is adequate intraprocedurally when performed by specialized sonographers and dedicated cardiologists in a highly experienced TAVI center.