The Effect of Dobutamine Stress on Left Ventricular Outflow Tract Gradients in Hypertensive Patients with Basal Septal Hypertrophy

Sitting maneuver to uncover latent left ventricular outflow tract obstruction in patients without hypertrophic cardiomyopathy

BACKGROUND

Left ventricular outflow tract obstruction [LVOTO; pressure gradient (PG) ≥30 mmHg] is observed in some patients without hypertrophic cardiomyopathy (HCM), and it may develop especially in older patients without HCM (non-HCM). The aim of this study is to investigate if the Valsalva or an upright sitting maneuver can unveil latent LVOTO in patients with non-HCM.

METHODS

A total of 33 non-HCM patients with a late peaking or dagger-shaped pulsed Doppler waveform of the LVOT and PG <30 mmHg were included. The Doppler flow velocity of the LVOT was measured at rest, after the Valsalva and a sitting maneuver. Peak PG of ≥30 mmHg after either maneuver was defined as latent LVOTO. The angle between the left ventricular septum and the aorta in the parasternal long-axis view and the apical three-chamber view was measured.

RESULTS

Twenty (61 %) of the 33 patients (mean age 74 ± 9 years) were diagnosed with latent LVOTO. Of these, five (25 %) patients were diagnosed after both the Valsalva and sitting maneuver, and 15 (75 %) were diagnosed only after the sitting maneuver. The latent LVOTO group had a significantly smaller angle than the no-LVOTO group between the ventricular septum and the aorta in the parasternal long axis views (107 ± 8° vs. 117 ± 8°, p < 0.01).

CONCLUSION

The sitting maneuver is better than the Valsalva maneuver in unveiling latent LVOTO in older, non-HCM patients.

Stress and Heart in Remodeling Process: Multiple Stressors at the Same Time Kill

Myocardial remodeling is developed by increased stress in acute or chronic pathophysiologies. Stressed heart morphology (SHM) is a new description representing basal septal hypertrophy (BSH) caused by emotional stress and chronic stress due to increased afterload in hypertension. Acute stress cardiomyopathy (ASC) and hypertension could be together in clinical practice. Therefore, there are some geometric and functional aspects regarding this specific location, septal base under acute and chronic stress stimuli. The findings by our and the other research groups support that hypertension-mediated myocardial involvement could be pre-existed in ASC cases. Beyond a frequently seen predominant base, hyperkinetic tissue response is detected in both hypertension and ASC. Furthermore, hypertension is the responsible factor in recurrent ASC. The most supportive prospective finding is BSH in which a hypercontractile base takes a longer time to exist morphologically than an acutely developed syndrome under both physiologic exercise and pressure overload by transaortic binding in small animals using microimaging. However, cardiac decompensation with apical ballooning could mask the possible underlying hypertensive disease. In fact, enough time for the assessment of previous hypertension history or segmental analysis could not be provided in an emergency unit, since ASC is accepted as an acute coronary syndrome during an acute episode. Additional supportive findings for SHM are increased stress scores in hypertensive BSH and the existence of similar tissue aspects in excessive sympathetic overdrive like pheochromocytoma which could result in both hypertensive disease and ASC. Exercise hypertension as the typical form of blood pressure variability is the sum of physiologic exercise and pathologic increased blood pressure and results in increased mortality. Hypertension is not rare in patients with a high stress score and leads to repetitive attacks in ASC supporting the important role of an emotional component as well as the potential danger due to multiple stressors at the same time. In the current review, the impact of multiple stressors on segmental or global myocardial remodeling and the hazardous potential of multiple stressors at the same time are discussed. As a result, incidentally determined segmental remodeling could be recalled in patients with multiple stressors and contribute to the early and combined management of both hypertension and chronic stress in the prevention of global remodeling and heart failure.

Basal Septal Hypertrophy as the Early Imaging Biomarker for Adaptive Phase of Remodeling Prior to Heart Failure

Hypertension plays a dominant role in the development of left ventricular (LV) remodeling and heart failure, in addition to being the main risk factor for coronary artery disease. In this review, we focus on the focal geometric and functional tissue aspects of the LV septal base, since basal septal hypertrophy (BSH), as the early imaging biomarker of LV remodeling due to hypertensive heart disease, is detected in cross-sectional clinic studies. In addition, the validation of BSH by animal studies using third generation microimaging and relevant clinical observations are also discussed in the report. Finally, an evaluation of both human and animal quantitative imaging studies and the importance of combined cardiac imaging methods and stress-induction in the separation of adaptive and maladaptive phases of the LV remodeling are pointed out. As a result, BSH, as the early imaging biomarker and quantitative follow-up of functional analysis in hypertension, could possibly contribute to early treatment in a timely fashion in the prevention of hypertensive disease progression to heart failure. A variety of stress stimuli in etiopathogenesis and the difficulty of diagnosing pure hemodynamic overload mediated BSH lead to an absence of the certain prevalence of this particular finding in the population.

Hemodynamic stress and microscopic remodeling

BACKGROUD

Heart responds to physiologic and pathologic conditions and sympathetic drive plays an important role. It has been documented that LV base is more dominantly affected by sympathetic drive compared to the other regions. LV base is more dominantly exposed to wall stress in the initial period of remodeling due to pressure-overload, since LV cavity is the largest at base. Basal septal hypertrophy (BSH) in cross-sectional data is associated with the early phase of hypertensive heart disease. BSH was confirmed by 3rd generation microscopic ultrasound in small animals. BSH as the closest location to increased afterload could be detected in variety of stress stimuli and result in a huge septal hypertrophy in advance cases possibly related to earlier exposure of hemodynamic stress to septal wall.

CONCLUSION

Effective geometric and functional evaluation of initial remodeling due to hemodynamic stress is important according to both human and animal data. These findings possibly contribute to early recognition of adaptive phase of hypertensive remodeling and more effective management in a timely fashion.

Left ventricular outflow tract obstruction in ICU patients

PURPOSE OF REVIEW

Left ventricular (LV) outflow tract (LVOT) obstruction (LVOTO) is not unusual in ICU patients particularly with septic shock.

RECENT FINDINGS

LVOT was first described in patients with hypertrophic cardiomyopathy and was defined as LV wall thickness at least 15 mm. LVOT is usually because of systolic anterior motion of the mitral valve. By convention, LVOTO is defined as an instantaneous peak Doppler LVOT pressure gradient at least 30 mmHg at rest or during physiological provocation such as Valsalva maneuver. Recently, it has been demonstrated that LVOT can be present in patients with severe hypovolemia or hyperkinesia with or without LV hypertrophy and can lead to hemodynamic compromise. LVOT is because of a combination of precipitating factors, which may or may not be associated with anatomical abnormalities. Decreased preload because of hypovolemia or decreased afterload because of septic shock, increased heart rate, and LV hyperkinesis produced by dobutamine infusion can induce a change of LV shape and induce LVOTO.

SUMMARY

LVOTO is not uncommon in ICU patients and can be observed at the early phase of septic shock. Treatment should include discontinuation of dobutamine infusion and fluid infusion. β blockers can be useful in this clinical situation.

Could early septal involvement in the remodeling process be related to the advance hypertensive heart disease?

BACKGROUND

Quantitative imaging analyses showed an earlier septal wall involvement in hypertension. We planned to determine the effect of hypertension on regional myocardial performance index (MPI) in a hypertensive patient population.

METHODS

We evaluated 119 hypertensive patients who were divided into gr. I: 57 patients without left ventricular hypertrophy (LVH), (53.1 ± 10 years), and gr. II: 62 patients with LVH (55.1 ± 9 years) using conventional and tissue doppler imaging. They were compared with gr. III, a sex-age-matched normal control group (37 subjects, 53.0 ± 10 years).

RESULTS

We detected basal septal and basal lateral contraction time (CT), isovolumetric CT and relaxation time (IVRT) and MPI. EF was 68 ± 5 % in gr. I, 69 ± 5 % in gr. II, 69 ± 4 % in gr. III. LV mass index was 122 ± 11 g/m2 in gr. I, 148 ± 13 g/m2 in gr. II and 118 ± 13 g/m2 in gr. III. Concentric LVH was detected in gr. II (relative wall thickness = 0.49 ± 0.8). LV septal and lateral MPI were abnormal in both hypertensive groups (p < 0.0001). Septal MPI was correlated moderately with septal wall thickness (r = 0.447, p < 0.001).

CONCLUSIONS

LV diastolic dysfunction becomes more severe in septal wall than lateral wall in hypertensive LVH. Septal myocardial performance is more dominantly affected by hypertension possibly due to earlier septal involvement in disease course. Septal MPI is correlated moderately with septal wall thickness.

Basal septal hypertrophy

A significant clinical problem is patients presenting with exercise-limiting dyspnoea, sometimes with associated chest pain, in the absence of detectable left ventricular (LV) systolic dysfunction, coronary artery disease, or lung disease. Often the patients are older, female, and have isolated basal septal hypertrophy (BSH), frequently on a background of mild hypertension. The topic of breathlessness in patients with clinical heart failure, but who have a normal ejection fraction (HFNEF) has attracted significant controversy over the past few years. This review aims to analyse the literature on BSH, identify the possible associations between BSH and HFNEF, and consequently explore possible pathophysiological mechanisms whereby clinical symptoms are experienced.

Stress induced hypertensive response: should it be evaluated more carefully?

Various diagnostic methods have been used to evaluate hypertensive patients under physical and pharmacological stress. Several studies have shown that exercise hypertension has an independent, adverse impact on outcome; however, other prognostic studies have shown that exercise hypertension is a favorable prognostic indicator and associated with good outcome. Exercise hypertension may be encountered as a warning signal of hypertension at rest and future hypertensive left ventricular hypertrophy. The results of diagnostic stress tests support that hypertensive response to exercise is frequently associated with high rate-pressure product in hypertensives. In addition to the observations on high rate-pressure product and enhanced ventricular contractility in patients with hypertension, evaluation of myocardial contractility by Doppler tissue imaging has shown hyperdynamic myocardial function under pharmacological stress. These recent quantitative data in hypertensives suggest that hyperdynamic myocardial function and high rate-pressure product response to stress may be related to exaggerated hypertension, which may have more importance than that it has been already given in clinical practice.

Stress-induced regional features of left ventricle is related to pathogenesis of clinical conditions with both acute and chronic stress

Tako-tsubo cardiomyopathy is a relatively newly described acute and reversible left ventricular (LV) dysfunction triggered by emotional stress. The disease is associated with excessive sympathetic stimulation, microvascular dysfunction and abnormal myocardial tissue metabolism. Recently, we have pointed out that tako-tsubo cardiomyopathy may be associated with particular LV features which are also described by quantitative echocardiographic methods in hypertensive heart disease. The patients with acute or chronic stress can be presented clinically by stress-induced LV hypercontractility of LV base, relevant LV outflow tract obstruction and narrowed cavity. Recent observations also have confirmed the possibility of association of both acute and chronic conditions in a clinical presentation of the patients. Therefore, we believe that the presence of both resistance and hypercontractile response of LV base to stress induction compared with midapical region in clinical conditions with acute or chronic stress is important in the disease process.

Mechanism and correlated factors of SAM phenomenon after aortic valve replacement

To investigate the mechanism and correlated factors of systolic anterior motion (SAM) phenomenon after aortic valve replacement, 48 patients with severe aortic valvular stenosis were studied. Tested by echo-Doppler one week after aortic valve replacement, the patients were divided into two groups: SAM group and non-SAM group. The data of the left ventricular end-diastolic diameters, the left ventricular end-systolic diameters, the left ventricular outflow diameters, the thickness of the interventricular septum, the posterior wall of left ventricle, the blood velocities of left ventricular outflow and intra-cavitary gradients were recorded and compared. The results showed that no patients died during or after the operation. The blood velocities of left ventricular outflow was increased significantly in 9 patients (>2.5 m/s), and 6 of them developed SAM phenomenon. There was significant difference in all indexes (P<0.05 or P<0.01) except the posterior wall of left ventricle (P>0.05) between two groups. These indicated that the present of SAM phenomenon after aortic valve replacement may be directly related to the increase of blood velocities of left ventricular outflow and intra-cavitary gradients. It is also suggested that smaller left ventricular diastolic diameters, left ventricular systolic diameters, left ventricular outflow diameters and hypertrophy of interventricular septum may be the anatomy basis of SAM phenomenon.

Dynamic left ventricular outflow tract obstruction without basal septal hypertrophy, caused by catecholamine therapy and volume depletion

Hypertrophic cardiomyopathy (HCM) with hypertrophy of the basal septum is the most common etiology of left ventricular outflow tract (LVOT) obstruction. In this article, we report the case of a patient with a structurally normal heart who developed hemodynamic deterioration due to severe LVOT obstruction following treatment with catecholamines. Hypovolemia accompanied with a hyperdynamic condition, resulting from catecholamine treatment, may cause dynamic LVOT obstruction due to the systolic anterior motion of the mitral valve leaflet. The solution for this is early recognition and correction of aggravating factors such as, withdrawal of catecholamine therapy and volume replacement.

Acute myocardial ischemia associated with latent left ventricular outflow tract obstruction in the absence of left ventricular hypertrophy

Left ventricular outflow tract obstruction (LVOTO) is a recognized feature in hypertrophic cardiomyopathy, but can occur in other clinical scenarios such as acute myocardial ischemia. In some patients, LVOTO may only be detectable with provocation testing such as exercise stress. Accurate and timely diagnosis, therefore, relies on recognizing an echocardiographic substrate in which LVOTO may occur, such as ventricular hypertrophy. The investigators describe two cases of latent LVOTO, presenting with acute myocardial ischemia in the absence of obstructive coronary artery disease, in which the diagnosis was delayed because of the absence of hypertrophy, or other recognizable substrate, on the resting echocardiographic study, but became evident during exercise echocardiography.

Effect of dobutamine stress on basal septal tissue dynamics in hypertensive patients with basal septal hypertrophy

Left ventricular outflow tract (LVOT) obstruction has been classically observed in hypertrophic cardiomyopathy in which the LVOT obstruction is associated with asymmetric septal hypertrophy producing a systolic pressure gradient across the LVOT. Basal septal hypertrophy (BSH) with hypertension may result in dynamic LVOT obstruction as well. It was suggested that regional hypertrophy may be related to enhanced ventricular dynamics.

Dynamic left ventricular outflow tract obstruction secondary to catecholamine excess in a normal ventricle

Hypertrophic cardiomyopathy (HCM) is the most common cause of left ventricular outflow tract (LVOT) obstruction. The LVOT obstruction is a consequence of the asymmetric septal hypertrophy and the mitral systolic anterior motion (SAM), causing both of them a dynamic gradient in LVOT. LVOT obstruction has been observed also in other conditions like hypertensive hypertrophy, dehydration, sepsis, vasodilatation, excessive sympathetic stimulation, pericardial tamponade, and after mitral valve repair and aortic valve replacement for aortic stenosis. We report in this document the case of two patients who developed a significant gradient at LVOT in the context of amine treatment during their admission into the intensive unit care. In both, cases there were no gradient, significant hypertrophy or SAM at baseline cardiac evaluation. We have met only one case reported in the literature matching those conditions. In order to treat this type of patients properly, it is essential to take in consideration this pathology.