Pressure Gradient In Hypertrophic Cardiomyopathy Research Articles

PS-C14-9: DIFFERENTIAL DIAGNOSIS OF HYPERTROPHIC CARDIOMYOPATHY AND HYPERTENSIVE HEART DISEASE

Objective: To conduct a differential diagnosis of hypertrophic cardiomyopathy and hypertensive heart. Material and Methods: The study included 40 patients with hypertrophic cardiomyopathy without left ventricle outflow tract obstruction, mean age 57.3 ± 9.5 years, 26 women and 30 patients with hypertensive heart, mean age 49.0 ± 8.7 years, 21 men. Results: The diagnosis of hypertrophic cardiomyopathy was established on the basis of clinical and anamnestic data, electrocardiography and echocardiography, genetics, upon detection of left ventricle myocardial hypertrophy with a maximum wall thickness of > 15 mm without dilatation of its cavity in the absence of other heart diseases. Hypertensive heart was diagnosed in patients with left ventricle myocardial hypertrophy > 12 mm due to hypertension. Hypertonic disease was detected according to the data of 24 hour blood pressure monitoring when systolic blood pressure > 135 mm Hg was recorded during wakefulness, diastolic > 85 mm Hg. The patients of both groups were comparable in terms of gender and age. Left ventricle myocardial mass index, interventricular septum thickness in diastole in patients with hypertrophic cardiomyopathy significantly exceeded those in patients with hypertensive heart. The thickness of the posterior wall of the left ventricle was almost the same in both groups. The maximum pressure gradient in hypertrophic cardiomyopathy at a load of 9 to 22 mm Hg. According to blood pressure monitoring data, arterial hypertension was detected in 65% of patients with hypertrophic cardiomyopathy. The degree of arterial hypertension was higher in patients with hypertensive heart. Exercise tolerance in patients with hypertension was higher than 111.0 ± 22.2. The maximum systolic blood pressure at the peak of physical activity in hypertrophic cardiomyopathy was significantly lower than in hypertensive heart 159.6 ± 21.1 and 196 ± 7.9 mmHg. Dyspnea as a reason for discontinuation of the test was more often observed in hypertrophic cardiomyopathy, 39% and 5%. In 26% of patients with hypertrophic cardiomyopathy, frequent ventricular extrasystole occurred at the height of the load, and no rhythm disturbances were recorded in patients with hypertensive heart. Conclusion: According to echocardiography data, there was no significant difference; systolic blood pressure at the height of the load in patients with hypertensive heart was significantly higher. Despite the above differences between patients with hypertrophic cardiomyopathy and hypertensive heart, it is not possible to single out an absolute sign that allows for a differential diagnosis. Important is the history of the disease, complaints and genetic analysis to identify mutations in hypertrophic cardiomyopathy.

Utility of continuous wave doppler echocardiography in the noninvasive assessment of left ventricular outflow tract pressure gradient in patients with hypertrophic cardiomyopathy

Subaortic obstruction is an important determinant of the clinical presentation of and therapeutic approach to patients with hypertrophic cardiomyopathy. Therefore, assessment of the presence and magnitude of the intraventricular pressure gradient is paramount in the clinical evaluation of these patients. To establish the utility of continuous wave Doppler echocardiography in a sessing the pressure gradient in hypertrophic cardiomyopathy, 28 patients representing the wide hemodynamic spectrum of this disease underwent simultaneous determination of the subaortic gradient by continuous wave Doppler ultrasound and cardiac calheterization.With use of the modified Bernoulli equation, the Doppler-estimated gradient showed a strong correlation with the maximal instantaneous pressure difference measured at catheterization, both under basal conditions (r = 0.93; p < 0.0001) and during provocative maneuvers (r = 0.89; p < 0.9001). In 26 of she 28 patients, all assessments of the subaortic gradient were in agreement within 15 mm Hg (average difference 5 ± 3 mm Hg). In the other two patients there were substantial differences between these measurements (under basal conditions in one patient and after provocation in another), although the Doppler technique predicted the presence of marked subaortic obstruction in each. In both patients the erroneous interpretation was due to superimposition of the mitral regurgitation signal on that of left ventricular outflow.Doppler waveforms from the left ventricular outflow tract showed variability in contour among different patients and in individual patients. Hence, continuous wave Doppler echocardiography is a useful noninvasive method for estimating the subaortic gradient in patients with hypertrophic cardiomyopathy. However, technical factors such as contamination of the outflow tract jet with that of mitral regurgitation and variability in waveform configuration may importantly influence such assessments of the subaortic gradient.

Left ventricular ejection dynamics and outflow obstruction in hypertrophic cardiomyopathy

Despite more than 25 years of investigation, the physiologic and clinical significance of the systolic pressure gradient measured across the left ventricular outflow tract in many patients with hypertrophic cardiomyopathy remains a subject of controversy and seemingly endless debate. This controversy appears destined to continue into the foreseeable future. Several aspects of the complex interplay between left ventricular morphologic and functional abnormalities during systolic ejection in hypertrophic cardiomyopathy have been scrutinized and debated. These include the high velocity of blood ejected in early systole by the hyperdynamic left ventricle, the anatomic narrowing of the outflow tract and the importance of systolic anterior motion of the mitral valve leaflets in the genesis of the gradient. At the core of this debate, however, are the timing and completeness of left ventricular ejection; whether the left ventricle ejects against a true impediment to emptying (l-3), with forward flow continuing for the duration of systole (and for the duration of the pressure gradient), or whether the pressure gradient arises from cavity obliteration after the superejecting left ventricle has emptied its contents very rapidly in early systole, with continued isovolumic contraction during the remainder of systole (4-7). Relation between the pressure gradient and ejection time. The findings of Sasson et al. (8) reported in this issue of the Journal provide additional compelling data in support of the concept that the pressure gradient in hypertrophic cardiomyopathy represents a true obstruction to left ventricular ejection. These investigators demonstrated highly significant correlations between the magnitude of the pressure gradient and prolongation of left ventricular ejection time under conditions at rest and during drug interventions to raise or

Doppler echocardiographic determination of the pressure gradient in hypertrophic cardiomyopathy

The continuous wave Doppler ultrasound signal across the left ventricular outflow tract in hypertrophic cardiomyopathy has a characteristic pattern that is in keeping with the dynamic nature of the pressure gradient in this condition. To determine the accuracy and reliability of the peak Doppler flow velocity signal for measuring the peak pressure gradient in this condition, 340 beats were analyzed from five consecutive patients studied with simultaneous continuous wave Doppler ultrasound and dual catheter pressure recordings across the left ventricular outflow tract. Each patient was studied at steady state and during physiologic and pharmacologic manipulations of the pressure gradient. Peak velocity and calculated peak gradient were determined by two independent observers who did not know the catheter measurements. In addition, 18 beats with well defined flow velocity envelopes were digitized for analysis of the magnitude, timing and contour of the instantaneous Doppler ultrasound and catheter gradients throughout systole.Peak catheter gradient in the 340 beats ranged from 12 to 245 mm Hg. The correlations between the Doppler-derived and catheter peak gradients were close (r = 0.96, SEE = 4 mm Hg for Observer 1 and r = 0.97, SEE = 11 mm Hg for Observer 2). Interobserver variability for measurement of peak flow velocity was small (mean ± SD 0.16 ± 0.15 m/s). An interobserver difference >0.3 m/s occurred in 25 of the 340 beats analyzed. By retrospective analysis, this was due to contamination of the outflow tract signal by mitral regurgitation.The peak flow velocity and characteristic pattern of the continuous wave Doppler ultrasound signal accurately reflect the peak magnitude as well as the timing and contour of the dynamic pressure gradient across the left ventricular outflow tract in hypertrophic cardiomyopathy. Although the Interobserver variability of the peak flow velocity measurement is small, substantial error may occur when even a minimal signal of mitral regurgitation is superimposed on a seemingly well defined outflow tract contour.