静脉注射美托洛尔对肥厚型心肌病左心室功能的影响

目的:应用频谱多普勒超声心动图技术,定量观测肥厚型梗阻性心肌病和肥厚型非梗阻性心肌病患者经静脉注射美托洛尔前后左心室功能和左心室流出道压力阶差的变化,并观察血流动力学的变化,探讨静脉注射美托洛尔对肥厚型心肌病左心室功能的影响。方法:应用PHILIPS-SONOS7500型彩色多普勒超声诊断仪,测量用药前和用药后10分钟肥厚型梗阻性心肌病组(n=33)和肥厚型非梗阻性心肌病组(n=26)患者左心室功能各指标,并监测用药过程中的血流动力学变化。结果:肥厚型梗阻性心肌病组患者用药后较用药前左心室舒张功能明显改善,左心室流出道(LVOT)明显增宽(P<0.05),左心室流出道压力阶差(LVOTPG)明显下降(P<0.05),EF值无明显变化(P>0.05);肥厚型非梗阻性心肌病组患者用药后较用药前上述各指标无明显变化(P>0.05)。两组的心率、收缩压、舒张压用药后较用药前均明显降低(P<0.05),有显著差异。结论:静脉注射美托洛尔能够快速改善肥厚型梗阻性心肌病组患者的左心室舒张功能,改善临床症状,明显减轻左心室流出道梗阻,降低压力阶差,明显降低两组的血压、心率,影响其血流动力学;而对肥厚型非梗阻性心肌病组患者无明显作用,对两组的收缩功能均无明显影响。     

Altered autonomic cardiac control in hypertrophic cardiomyopathy: Role of outflow tract obstruction and myocardial hypertrophy

Aim The goal of this study was to investigate the role of leftventricular outflow tract obstruction and myocardial hypertrophyon autonomic cardiac function in patients with hypertrophiccardiomyopathy. Methods and results The sympatho-vagal function was evaluatedby spectral analysis of heart rate variability in 28 patientswith hypertrophic obstructive cardiomyopathy, 22 patients withhypertrophic non-obstructive cardiomyopathy, 12 with systemichypertension and left ventricular hypertrophy and 28 healthysubjects. Left ventricular outflow tract pressure gradient inpatients with hypertrophic cardiomyopathy was evaluated by echo-Dopplermethods and the quantitative assessment of left ventricularhyper-trophy was based on an echocardiographic index. At rest,patients with hypertrophic non-obstructive cardiomyop-athy showednormal spectral patterns, while in patients with hypertrophicobstructive cardiomyopathy and in patients with systemic hypertensionwe observed, respectively, a significant reduction and increasein the low frequency component relative to the control (P<0·05).During tilt, the physiological increases in the low frequencycomponent, and in the low to high frequency ratio were markedlyblunted, or even reverted, only in patients with hypertrophicobstructive cardiomyopathy. In these patients, the heart rateincrease during tilt was delayed in comparison to the othergroups. Finally, in the hypertrophic obstructive cardiomyopathygroup, the impairment of sympathetic activation (lack of increasein the low frequency component during tilt) was significantlycorrelated to the echocardiographic index of left ventricularhypertrophy (r=–0·800,P<0·001) ratherthan to the left ventricular outflow tract pressure gradient(r=0·295,P: ns). Conclusion Among patients with hypertrophic cardiomyopathy,only those with outflow tract obstruction show spectral signsof altered autonomic cardiac control. Within this group, theautonomic dysfunction appears to be correlated to myocardialhypertrophy rather than to left ventricular outflow tract obstruction.     

Left ventricular remodeling in patients with hypertrophic obstructive cardiomyopathy treated with percutaneous alcohol septal ablation: an echocardiographic study

INTRODUCTION: In patients with hypertrophic obstructive cardiomyopathy, obstruction in the left ventricular outflow tract may generate more hypertrophy. Our aim was to evaluate the impact of reducing ventricular outflow tract obstruction on left ventricular hypertrophy and remodeling after alcohol septal ablation. PATIENTS AND METHOD: 20 patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation were included. Doppler echocardiography was performed in all patients at baseline, immediately after alcohol septal ablation, and at 3 and 12 months' follow-up. Left ventricular diameters and wall thickness and pressure gradients in the ventricular outflow tract were determined. RESULTS: Immediately after alcohol septal ablation, ventricular outflow tract pressure gradient decreased from 63.0 27.7 to 28.2 24.7 mmHg (p < 0.001), without significant changes in left ventricular dimensions. However, after 12 months we observed an increase in left ventricular end-diastolic (from 47.1 4.9 to 50.8 4.5 mm) and end-systolic diameter (from 27.1 3.0 to 33.7 4.6 mm), as well as a reduction in septal (from 19.5 4.0 to 15.5 2.7 mm) and posterior wall thickness (from 14.0 2.2 to 12.9 1.3 mm) (p < 0.01 in all cases). Left ventricular end-diastolic and end-systolic volumes increased (from 106.4 26.9 to 123.1 28.7 ml and from 50.2 17.3 to 56.7 18.3 ml, respectively, p < 0.01 in both cases), without changes in left ventricular ejection fraction. The reduction in ventricular outflow tract pressure gradient at 12 months' follow-up correlated significantly with the increase in left ventricular end-systolic diameter (r = 0.63; p < 0.01). CONCLUSIONS: In patients with hypertrophic obstructive cardiomyopathy who underwent alcohol septal ablation, relief of ventricular outflow tract obstruction is associated with an increase in left ventricular chamber diameters and volume. These findings suggest that middle- and long-term ventricular remodeling and regression of hypertrophy occur in these patients, which may contribute to their clinical improvement.     

Left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy: increase in gradient after exercise.

To define alterations in the magnitude of the left ventricular outflow tract gradient during supine exercise, 10 patients with hypertrophic obstructive cardiomyopathy were studied under basal conditions and during exercise and recovery with simultaneous invasive hemodynamic measurements, particularly of the peak to peak systolic pressure gradient across the left ventricular outflow tract. Basal outflow pressure gradient ranged from 0 to 89 mm Hg (average 37.4 +/- 9.6). No increase was observed during 5 min of exercise (average 29.6 +/- 10 mm Hg, range 0 to 91; p = NS), even though arterial blood pressure, heart rate and cardiac index increased significantly in association with a decrease in peripheral vascular resistance. However, a rapid and highly significant increase in left ventricular outflow gradient occurred after exercise was completed (average 83.5 +/- 11.4 mm Hg, range 10 to 130; p less than 0.001), while arterial blood pressure, heart rate and cardiac index closely approached basal levels and total peripheral vascular resistance increased. In contrast to previous assumptions regarding the behavior of the outflow gradient in hypertrophic cardiomyopathy, obstruction to left ventricular outflow increases after rather than during supine exercise. Rapid changes in preload during recovery represent the most likely explanation for the postexercise development of outflow obstruction. New considerations regarding the mechanisms of sudden cardiac death and the therapeutic approach in patients with hypertrophic cardiomyopathy may result from this pathophysiologic observation.     

Investigation of a hemodynamic basis for syncope in hypertrophic cardiomyopathy. Use of a head-up tilt test.

BACKGROUND. Syncope and sudden death in hypertrophic cardiomyopathy may have a hemodynamic basis. The presence of a small ventricular cavity with high intracavity pressures may activate left ventricular baroreceptors and cause reflex hypotension as described in other populations with syncope. METHODS AND RESULTS. To investigate this potential mechanism of syncope in hypertrophic cardiomyopathy, we studied 17 patients with a history of syncope (syncopal), 19 without syncope (nonsyncopal), and nine normal control subjects by using a head-up tilt test. Head-up tilt at 60 degrees for 45 minutes was followed by 10-minute tilts during incremental doses of isoprenaline. Heart rate, blood pressure, and two-dimensional and Doppler echocardiography were monitored throughout. On tilting, hypertrophic cardiomyopathy patients showed a decline in mean arterial pressure of -5 +/- 6 mm Hg (p less than 0.001) compared with no change in control subjects (0.2 +/- 6 mm Hg, p = 0.9). Left ventricular outflow tract velocity decreased on tilting in control subjects (-8 +/- 6 cm/sec, p = 0.004) but increased in the syncopal and nonsyncopal patients (20 +/- 50 cm/sec, p = 0.05). Reflex hypotension with or without bradycardia, associated with syncope or presyncope, was induced in seven syncopal patients, two nonsyncopal patients, and two control subjects (p = 0.05). The early response to tilt in these subjects was characterized by maintenance of blood pressure but a greater increase in left ventricular fractional shortening than in the other subjects (10 +/- 8% versus 1 +/- 1%, p = 0.002). The onset of hypotension was associated with a trend toward further decreases in left ventricular diameters, outflow tract velocity, and transmitral flow velocities. In the remaining patients who had a negative test, transient hypotension (systolic pressure less than 100 mm Hg) occurred in seven syncopal patients and three nonsyncopal patients compared with none of the control subjects (p = 0.01). In total, hypotension was demonstrated in 82% of syncopal patients compared with 26% of nonsyncopal patients and 22% of control subjects (p = 0.001). CONCLUSIONS. Patients with hypertrophic cardiomyopathy and a history of syncope frequently display hypotension during head-up tilt. In some cases, sudden hypotension occurs and is usually associated with bradycardia and a reduced cavity size, findings compatible with activation of a ventricular baroreflex. In other cases, transient hypotension occurs and could be explained by an impairment of baroreceptor function. These mechanisms may contribute to the occurrence of syncope in daily life.     

Evolution of the surgical strategy in hypertrophic cardiomyopathy: case studies of eight patients

INTRODUCTION: Hypertrophic cardiomyopathy is an inherited disease characterized by a left ventricular hypertrophy, a diastolic dysfunction and rhythm troubles with risk of sudden death. There was an evolution in the surgical strategy to treat the patients who present a left ventricular outflow tract gradient. MATERIALS AND METHODS: A retrospective study was conducted: We selected eight cases who presented an hypertrophic cardiomyopathy and operated on. Pre and post operative echocardiographic data were analysed. Follow up was obtained by call or mail to the cardiologist. RESULTS: The patients were classified in four groups: isolated left ventricular outflow tract obstruction, left ventricular outflow tract obstruction and associated lesions, obstructive hypertrophic cardiomyopathy and endocarditis, post operative complications of the hypertrophic cardiomyopathy surgery. We observed a significant decrease of the left ventricular outflow tract mean gradient in the post operative period and at four years. CONCLUSION: Surgical management of obstructive hypertrophic cardiomyopathy remain an important option in young patients, in case of failure of the ethanol septal ablation or in patients who present other surgical lesions. The dual chamber stimulation remain indicated in old patients.     

Long-term effects of dual chamber pacing in patients with hypertrophic cardiomyopathy without outflow tract obstruction at rest

BACKGROUND: Atrioventricular-synchronous pacing is beneficial in patientswith hypertrophic obstructive cardiomyopathy. The effects ofpacing in patients without significant left ventricular outflowtract obstruction at rest are, however, less well explored.This study compares the long-term outcome of pacing patientswith and without significant left ventricular outflow tractobstruction at rest. METHODS: Forty-one patients with hypertrophic obstructive cardiomyopathywere studied, 19 with a left ventricular outflow tract gradient<40 mmHg at rest, but exceeding 50 mmHg during provocationwith isoproterenol (group A), and 22 with a left ventricularoutflow tract obstruction >40 mmHg at rest (group B). Beforethe implantation of a permanent pacemaker, the patients werestudied according to a temporary pacing protocol. This includedgraded isoproterenol provocation of the left ventricular outflowtract obstruction, which was assessed by echo Doppler. Followingpermanent pacemaker implantation, the patients were regularlyfollowed up with echo Doppler, exercise testing and monitoringof the clinical condition. RESULTS: Isoproterenol provocation was reproducible and the techniquedid not cause any clinically important side effects. Left ventricularoutflow tract gradient reduction after chronic pacing did notdiffer between the two groups. In group A, it decreased from98±30 mmHg in sinus rhythm to 42±26 mmHg duringpacing. The corresponding values in group B were 87±40mmHg to 36±24 mmHg. The clinical condition improved similarlyin the two groups. Exercise capacity increased significantlyand perceived dyspnoea and angina pectoris were significantlylower at submaximal levels of exercise after 6 months of pacing. CONCLUSION: Hypertrophic obstructive cardiomyopathy patients who only exhibitsignificant left ventricular outflow tract obstruction duringprovocation benefit as much from pacemaker treatment as do patientswho already have significant obstruction at rest. Isoproterenolis a safe and reproducible method for pre-pacing evaluationof hypertrophic obstructive cardiomyopathy patients.     

左室流出道肌性梗阻的外科治疗

本文观察了8例肥厚性梗阻型心肌病患者经手术治疗前后的血液动力学变化,其中5例术中经食管超声检查。结果表明,对肥厚性梗阻型心肌病患者施行室间隔部分切除术后,左室流出道明显增宽,压力阶差明显降低,二尖瓣反流程度减轻,晕厥及心力衰竭症状明显改善,无手术死亡。术中经食管超声心动图技术对手术准确切除肥厚的室间隔以及解除左室流出道梗阻是有帮助的。     

Nonsurgical septal reduction therapy for hypertrophic obstructive cardiomyopathy: one-year follow-up

OBJECTIVE: The objective of this study is to evaluate the one-year outcome of the first 50 patients who underwent nonsurgical septal reduction for symptomatic hypertrophic obstructive cardiomyopathy at our institution. BACKGROUND: Left ventricular outflow tract obstruction is an important determinant of clinical symptoms in patients with hypertrophic obstructive cardiomyopathy. Nonsurgical septal reduction is a new therapy that has been shown to result in left ventricular outflow tract gradient reduction and resolution of symptoms immediately after the procedure and on midterm follow-up. METHODS: Fifty patients with hypertrophic obstructive cardiomyopathy who underwent nonsurgical septal reduction at our institution and completed 1-year follow-up are described. Complete history, physical examination, two-dimensional echocardiography with Doppler and exercise treadmill testing have been analyzed. RESULTS: The mean age of the study group was 53 +/- 17 years. All patients had refractory symptoms before enrollment. Ninety-four percent had class III or IV New York Heart Association class symptoms at baseline compared to none at 1 year (p < 0.001). The exercise duration increased by 136 s at 1 year (p < 0.021). Only 20% of patients were either receiving beta-blockers or calcium-channel blockers on follow-up. The resting left ventricular outflow tract gradient decreased from 74 +/- 23 mm Hg to 6 +/- 18 mm Hg (p < 0.01) and from 84 +/- 28 mm Hg to 30 +/- 33 mm Hg (p < 0.01) in patients with dobutamine-provoked gradient at one year. These changes are associated with decreased septal thickness and preserved systolic function. CONCLUSION: Nonsurgical septal reduction therapy is an effective therapy for symptomatic patients with hypertrophic obstructive cardiomyopathy with persistence of the favorable outcome up to one year after the procedure.     

Hypertrophic obstructive cardiomyopathy: hemodynamic improvement with intravenous verapamil

We report the reduction in left ventricular outflow tract gradient following the intravenous administration of verapamil to two pediatric patients with hypertrophic obstructive cardiomyopathy. Traditional therapy with beta adrenergic antagonists was relatively contraindicated in both patients. In a 15-year-old patient, the left ventricular outflow tract gradient decreased from 160 torr, at rest, to 45 torr during the verapamil infusion. In a 3-year-old boy, there was a reduction in the left ventricular outflow tract gradient from 60 torr, under basal conditions, to 10 torr during the intravenous verapamil infusion. We believe that verapamil may be effective in reducing the left ventricular outflow tract gradient in some pediatric patients with hypertrophic obstructive cardiomyopathy and may be useful in treating selected patients with this disorder.     

Dynamic left ventricular outflow tract obstruction in a patient with pheochromocytoma

Symmetric left ventricular hypertrophy or asymmetric septal hypertrophy associated with pheochromocytoma simulating hypertrophic obstructive cardiomyopathy have been rarely reported. In this report, we present a case with pheochromocytoma that had dynamic left ventricular outflow tract obstruction without asymmetric septal hypertrophy. A surface echo revealed resolution of the systolic anterior motion of the mitral valve and all Doppler evidence of left ventricular outflow tract obstruction following removal of the tumor. Dynamic left ventricular outflow tract obstruction seen in this patient was probably due to excessive secretion of cathecolamines by the tumor.     

Acute mitral regurgitation due to ruptured chordae tendineae in a patient with hypertrophic obstructive cardiomyopathy: a case report

A 63-year-old woman had been followed up for hypertrophic obstructive cardiomyopathy with 85 mmHg of left ventricular outflow tract pressure gradient over 7 years. She was hospitalized because of acute dyspnea and syncope. On admission, echocardiography revealed severe mitral regurgitation with ruptured chordae tendineae at the medial scallop of the posterior mitral leaflet. Mitral valve replacement was successfully performed and her symptoms improved to 28 mmHg of left ventricular outflow tract pressure gradient. In patients with hypertrophic obstructive cardiomyopathy, elevated left ventricular systolic pressure and systolic anterior motion of the mitral leaflets may lead to mucoid degeneration in the chordae tendineae. Rupture of the mitral chordae tendineae should be considered in the differential diagnosis of acutely deteriorated mitral regurgitation in patients with hypertrophic obstructive cardiomyopathy, because this is a rare but critical complication.     

Left Ventricular Outflow Tract Obstruction Following Mitral Valve Replacement with Carpentier-Edwards Prosthesis

Left ventricular outflow tract (LVOT) obstruction is a rare complication of mitral valve replacement. In this article, we describe three patients in whom left ventricular outflow tract obstruction occurred following Carpentier-Edwards porcine mitral valve replacement. All three patients presented with symptomatic mitral regurgitation (angiographic grade 3–4) requiring mitral valve replacement. Preoperatively there was no evidence of hypertrophic obstructive cardiomyopathy by physical exam, echocardiography, or by cardiac catheterization. At the time of surgery all three were shown to have severe mitral valve prolapse. The native anterior mitral leaflet was left intact and pledgeted to the mitral annulus. Following surgery a new systolic murmur was appreciated. Echocardiographic exam visualized obstruction of the left ventricular outflow tract by the prosthetic strut in two cases and by a flail anterior leaflet in one case. Continuous-wave Doppler measured a calculated peak gradient of 72 to 81 mmHg across the left ventricular outflow tract. In one case simultaneous Doppler and cardiac catheterization confirmed the diagnosis and severity of left ventricular outflow tract obstruction. Mechanisms of left ventricular outflow tract obstruction following Carpentier-Edwards porcine mitral valve replacement are discussed. These three cases highlight the importance of echo-Doppler techniques in understanding the mechanism of newly detected systolic murmurs following mitral valve replacement.     

Systolic and diastolic flow abnormalities in elderly patients with hypertensive hypertrophic cardiomyopathy

Seventeen patients with clinical and echocardiographic features of hypertensive hypertrophic cardiomyopathy of the elderly were studied to more completely characterize left ventricular systolic and diastolic function in this group. Measurements of left ventricular structure and systolic and diastolic function were made in the study patients and compared with those of age-matched control subjects. The study group had significantly greater left ventricular mass, wall thickness, shortening fraction and relative wall thickness than did the control subjects. Left ventricular end-diastolic dimension was smaller and left atrial size was not different in study patients compared with control subjects. Left ventricular filling was characterized by an increased peak atrial velocity and reduced ratio of peak early to peak atrial velocity in the study group. Left ventricular outflow velocities were elevated in 14 of the 17 study patients with peak velocities ranging from 1.2 to 5.0 m/s corresponding to a peak intraventricular gradient of 16 to 100 mm Hg. The velocity waveforms in these patients were late-peaking, similar to those described in hypertrophic obstructive cardiomyopathy. The elevated velocities were localized to the left ventricular outflow tract. These findings imply a pathophysiologic state in these elderly patients with long-standing hypertension, very similar to that in hypertrophic obstructive cardiomyopathy, and provide further support for the use of pharmacologic agents with negative inotropic properties or positive lusitropic properties in this group.     

A case of hypertrophic cardiomyopathy with right ventricular outflow obstruction manifested during three-year follow-up study

A case is reported of a 55-year-old female with idiopathic hypertrophic cardiomyopathy, which was accompanied with outflow obstruction in the right ventricle developed during the previous 3 years without lesion of the left ventricle. In 1984, she was admitted to our hospital to be examined for cardiac murmurs and abnormal electrocardiogram including ST depression and inverted T. The findings of echocardiography and cardiac catheterization revealed non-obstructive hypertrophic cardiomyopathy. She had been treated with sympathetic beta-blockade and calcium antagonist for 3 years until she complained of dyspnea on exertion, and she was readmitted to our hospital in 1987. Echocardiographic findings showed protrusion of the ventricular septum toward the right ventricle and systolic turbulent flow along the right ventricular outflow tract (by pulsed Doppler technique). A pressure gradient of 20 mmHg across the protrusion was detected by the examination of the cardiac catheter. However, neither protrusion nor pressure gradient was observed in the left ventricular outflow tract as well as that in 1984. Idiopathic hypertrophic cardiomyopathy has been described as involving both ventricles, and outflow obstruction is the usual hemodynamic finding in the left ventricle. However, right ventricular outflow obstruction is the usual hemodynamic finding in the left ventricle. However, right ventricular outflow obstruction with the left ventricular outflow tract intact has been very rare. In addition, in this case, the change of hemodynamic characteristics from non-obstructive to obstructive hypertrophic cardiomyopathy, and the development of these changes only in the right ventricle were observed during the last 3 years.     

The significance of increased left ventricular outflow tract velocities in the elderly measured by continuous wave Doppler

Forty-four elderly patients (mean age 80 +/- 7 years) with elevated left ventricular outflow tract velocities and corresponding outflow tract gradients documented by continuous wave Doppler are reported (mean peak gradient 50 +/- 28). They had severe left ventricular hypertrophy, small left ventricular end-diastolic dimensions, and supernormal ejection fractions. Thirty-nine percent had a history of hypertension. They were predominantly female, had uniform concentric left ventricular hypertrophy, and had a high incidence of congestive heart failure. Diastolic function was found to be reduced in the elderly group compared to young patients with hypertrophic cardiomyopathy and to age- and sex-matched normal controls. It is concluded that most elderly patients with increased left ventricular outflow tract velocities are etiologically distinct from young patients with hypertrophic cardiomyopathy.     

Noninvasive assessment of left ventricular diastolic function by pulsed Doppler echocardiography in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a primary myocardial disease in which symptoms may frequently result from impaired left ventricular relaxation, filling and compliance. In the present investigation, Doppler echocardiography was utilized to measure transmitral flow velocity and thereby assess left ventricular diastolic performance noninvasively in a group of 111 patients representative of the broad clinical spectrum of hypertrophic cardiomyopathy. In patients with hypertrophic cardiomyopathy, all Doppler indexes of diastolic relaxation and filling differed significantly (p less than 0.001) from those obtained in 86 control subjects without heart disease, namely, prolongation of isovolumic relaxation (94 +/- 24 versus 78 +/- 12 ms) and of the early diastolic peak of flow velocity (244 +/- 55 versus 220 +/- 28 ms), as well as slower deceleration (3.4 +/- 1.4 versus 4.9 +/- 1.3 m/s2) and reduced maximal flow velocity in early diastole (0.5 +/- 0.2 versus 0.6 +/- 0.1 m/s). As an apparent compensation for impaired relaxation and early diastolic filling, the atrial contribution to left ventricular filling was increased, as shown by increased late diastolic flow velocity (0.4 +/- 0.3 versus 0.3 +/- 0.1 m/s) and reduced ratio of maximal flow velocity in early diastole to that in late diastole (1.4 +/- 0.8 versus 2.1 +/- 0.9). The vast majority of patients with hypertrophic cardiomyopathy (91 [82%] of 111) showed evidence of impaired left ventricular diastolic performance, as assessed from the Doppler waveform. Abnormal Doppler diastolic indexes were identified with similar frequency in patients with (78%) or without (83%) left ventricular outflow obstruction, as well as in patients with (84%) or without (80%) cardiac symptoms. However, patients with nonobstructive hypertrophic cardiomyopathy showed more severe alterations in the Doppler indexes of diastolic function than did patients with obstruction. Thus, abnormal diastolic performance as assessed by Doppler echocardiography was apparent in the vast majority of the study patients with hypertrophic cardiomyopathy, independent of the presence or absence of cardiac symptoms or a subaortic pressure gradient. The high frequency with which diastolic abnormalities are identified in asymptomatic patients with hypertrophic cardiomyopathy suggests that impaired diastolic performance may be present at a time in the natural history of the disease when functional limitation is not yet evident.     

Echocardiographic assessment of right ventricular obstruction in hypertrophic cardiomyopathy.

Echocardiography was used to evaluate the incidence, flow dynamics and morphological characteristics of right ventricular obstruction in 91 patients with hypertrophic cardiomyopathy. Color flow mapping was used to define the sites of obstruction in the left and right ventricles. Ventricular obstruction was considered to be present if the flow velocity was less than 2.0 m/s as measured by continuous wave Doppler. The thickness of both the right ventricular free wall and anterior ventricular septum was measured to assess the magnitude and extent of hypertrophy. Right ventricular obstruction was present in 14 patients of whom 6 (43%) had left ventricular obstruction also. The right ventricular obstructions were found in the outflow tract (9 patients), mid-base septal bulge (2 patients) and apical trabecular region (3 patients). Doppler waveform was confined to systole in all patients with obstruction in the outflow tract and in one of the patients with mid-base septal bulge. Moreover, the flow wave persisted into early diastole in 4 patients, including 2 with apical trabecular obstruction. The thickness of both the right ventricular free wall and anterior ventricular septum suggested that these hypertrophied regions were the sites of right ventricular obstruction. Thus, echocardiography was useful in evaluating right ventricular obstruction 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 assessing 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 catheterization. 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 less than 0.0001) and during provocative maneuvers (r = 0.89; p less than 0.0001). In 26 of the 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.     

Fixed left ventricular outflow tract obstruction mimicking hypertrophic obstructive cardiomyopathy: pitfalls in diagnosis

We present a case series that highlights the diagnostic challenges with left ventricular hypertrophy (LVH) and left ventricular outflow tract obstruction (LVOTO). Fixed structural lesions causing LVOTO with secondary LVH may mimic hypertrophic obstructive cardiomyopathy (HOCM). Management of these two entities is critically different. Misdiagnosis and failure to recognize fixed left ventricular outflow tract (LVOT) lesions may result in morbidity as a result of inappropriate therapy and delay of definitive surgical treatment. It is thus necessary to identify the correct type and level of obstruction in the LVOT by careful correlation of clinical examination, Doppler evaluation, and advanced imaging findings.