Dual chamber pacing in hypertrophic cardiomyopathy: long-term effects on diastolic function

To assess the effects of chronic dual chamber pacing (DDD) on LV diastolic function in obstructive hypertrophic cardiomyopathy (HCM), 21 patients with obstructive HCM paced for refractory symptoms were studied at baseline and at 3 and 12 months. HCM patients were matched to 21 patients with obstructive HCM on conventional treatment. Left atrial fractional shortening was calculated by M-mode echocardiography; this index reflects LV end-diastolic pressure. LV outflow tract gradient decreased 65 +/- 21% with DDD pacing and the NYHA class improved (P = 0.033). Left atrial fractional shortening worsened with DDD pacing (P < 0.001). Patients with abnormal baseline left atrial fractional shortening (< 16%) were older, had a higher NYHA class, and had more severe mitral regurgitation. In this subgroup, left atrialfractional shortening did not worsen with DDD pacing and the NYHA class improved more than in patients with normal left atrialfractional shortening (P = 0.033). In conclusion, chronic DDD pacing reduces obstruction but impairs diastolic function in HCM. In patients with normal diastolic function, the untoward effects of pacing on diastolic function are more evident than in patients with abnormal diastolic function at baseline. This suggests that DDD pacing might be beneficial in a subgroup of patients with obstructive HCM and abnormal diastolic function.     

The importance of ventricular septal morphology in the effectiveness of dual chamber pacing in hypertrophic obstructive cardiomyopathy

It has been reported that older patients with hypertrophic obstructive cardiomyopathy (HOCM) benefited the most from dual chamber (DDD) pacing. Since in older patients the distribution of septal hypertrophy and left ventricular (LV) cavity shape differs from that in younger patients, we decided to study the efficacy of DDD pacing on the reduction of LV outflow tract (LVOT) gradient in different patterns of septal hypertrophy. We compared HOCM patients with nonreversed septal curvature, thus preserving the elliptical LV cavity contour (common in the elderly), (group I) versus patients with reversed septal curvature, deforming the LV cavity to a crescent shape (common in the young), (group II). Eighteen HOCM patients were studied (11 patients in group I and 7 patients in group II). After implantation of a DDD pacemaker, the LVOT gradient was measured using Doppler echocardiography at various programmed AV delay intervals to determine the maximal percentage decrease of LVOT gradient from baseline. The measurement was repeated after at least a 6-month follow-up (chronic DDD pacing). The baseline LVOT gradient was comparable between groups (79 +/- 28 vs 81 +/- 25 mmHg, P = 0.92). The LVOT gradient reduction at acute DDD pacing was significantly greater in group I than group II (61 +/- 18% vs 23 +/- 10%, P = 0.0001). This difference in favor of the patients from group I was maintained at midterm follow-up (69 +/- 17% vs 40 +/- 17% P = 0.0076). In conclusion, patients with normal septal curvature and preserved elliptical LV cavity shape had a greater reduction of LVOT gradient after DDD pacing than patients with reversed septal curvature deforming LV cavity. The proposed criterion assessing the septal curvature may be useful to predict the efficacy of DDD pacing in the reduction of LVOT gradient.     

Pacing-induced electrophysiological remodeling in hypertrophic obstructive cardiomyopathy--observations on cardiac memory

BACKGROUND: Hypertrophic cardiomyopathy carries an increased risk for sudden cardiac death. While pacing therapy reduces the left ventricular outflow tract gradient and improves symptoms in a subgroup of hypertrophic obstructive cardiomyopathy (HOCM) patients, its electrophysiological consequences are unknown and were therefore assessed in this prospective study. METHODS AND RESULTS: Fifteen consecutive HOCM patients were studied and compared with 14 patients without HOCM paced because of sinus bradycardia. ECG intervals were measured before pacemaker implantation and after > or =3 months of DDD pacing in HOCM patients and > or =5 weeks in controls. Both groups showed similar ECG signs of cardiac memory development. In HOCM patients, with baseline QTc 447 +/- 33 ms, cardiac memory development was not associated with any significant changes in ECG intervals. In contrast, baseline repolarization in control patients was significantly prolonged by 6% (QTc 429 +/- 33 vs 454 +/- 46 ms; P < 0.05). Furthermore, in HOCM patients repolarization was 7% shorter during DDD pacing compared to sinus rhythm (JTc 329 +/- 25 vs 353 +/- 21 ms; P < 0.05), despite a significantly prolonged ventricular activation time (QRS duration 155 +/- 16 vs 91 +/- 9 ms; P < 0.01). CONCLUSIONS: Importantly, the development of cardiac memory-induced different repolarization responses depending on baseline structure and electrophysiology. In HOCM patients repolarization was shorter during right ventricular apical pacing than during normal activation despite prolonged activation time.     

Systolic and diastolic ventricular function in the normal and extra-embryonic venous clipped chicken embryo of stage 24: a pressure-volume loop assessment.

OBJECTIVES: Fluid mechanical forces affect cardiac development. In the chicken embryo, permanent obstruction of the right lateral vitelline vein by clipping reduces the mechanical load on the embryonic myocardium, which has been shown to induce a spectrum of outflow tract anomalies. Insight into the effects of this intervention on the mechanical function of the developing myocardium could contribute to a better understanding of the relationship between hemodynamics and cardiac morphogenesis. We aimed to explore the effects of clipping on intrinsic systolic and diastolic ventricular function at stage 24 in the chicken embryo METHODS: Cardiac pressure-volume relationships enable load-independent quantification of intrinsic ventricular systolic and diastolic properties. We determined ventricular function by pressure-volume loop analysis of in-ovo stage-24 chicken embryos (n = 15) 2 days after venous obstruction at 2.5 days of incubation (stage 17, venous clipped embryos). Control embryos (n = 15) were used for comparison. RESULTS: End-systolic volume was significantly higher in clipped embryos (0.36 +/- 0.02 microL vs. 0.29 +/- 0.02 microL, P = 0.002). End-systolic and end-diastolic pressure were also increased compared with control animals (2.93 +/- 0.07 mmHg vs. 2.70 +/- 0.08 mmHg, P = 0.036 and 1.15 +/- 0.06 mmHg vs. 0.82 +/- 0.05 mmHg, P < 0.001, respectively). No significant differences were demonstrated for other baseline hemodynamic parameters. Analysis of pressure-volume relationships showed a significantly lower end-systolic elastance in the clipped embryos (slope of end-systolic pressure-volume relationship: 2.91 +/- 0.24 mmHg/microL vs. 7.53 +/- 0.66 mmHg/microL, P < 0.005) indicating reduced contractility. Diastolic stiffness was significantly increased in the clipped embryos (slope of end-diastolic pressure-volume relationship: 1.54 +/- 0.21 vs. 0.60 +/- 0.08, P < 0.005), indicating reduced compliance. CONCLUSION: Venous obstruction apparently interferes with normal myocardial development, resulting in impaired intrinsic systolic and diastolic ventricular function. These changes in ventricular function may precede morphological derangements observed in later developmental stages.     

Relationship of basal-septal fibrosis with LV outflow tract obstruction in hypertrophic cardiomyopathy: insights from cardiac magnetic resonance analysis

Myocardial fibrosis is frequently observed and may be associated with the prognosis in patients with hypertrophic cardiomyopathy (HCM); however, the clinical pathophysiological features, particularly in terms of fibrosis, of hypertrophic obstructive cardiomyopathy (HOCM) remain unclear. This study aimed to determine a role of local fibrosis in HOCM using cardiac magnetic resonance (CMR). 108 consecutive HCM patients underwent CMR. HOCM was defined as a left ventricular outflow tract (LVOT) pressure gradient ≥30 mmHg at rest. Myocardial mass and fibrosis mass by late gadolinium-enhancement CMR (LGE-CMR) were calculated and the distribution/pattern was analyzed using the AHA 17-segment model. LV ejection fraction (LVEF) was significantly higher in patients with HOCM (n = 19) than in those with nonobstructive HCM (n = 89) (P < 0.05). Both total myocardial and fibrosis masses in LV were similar in the two groups (P = 0.385 and P = 0.859, respectively). However, fibrosis in the basal septum was significantly less frequent in the HOCM group than in the nonobstructive HCM group (P < 0.01). The LVOT pressure gradient was significantly higher in the basal-septal non-fibrosis group than in the fibrosis group (23.6 ± 37.3 vs. 4.8 ± 11.4 mmHg, P < 0.01). Multivariate analysis revealed that basal-septal fibrosis was an independent negative predictor of LVOT obstruction in addition to the local wall thickness and LVEF as positive predictors in HCM patients. In conclusion, a significant association was observed between LVOT obstruction and basal septal fibrosis by LGE-CMR in HCM patients. In addition to negative impact of basal-septal fibrosis, basal-septal hypertrophy and preserved global LV contractility may be associated with the pathophysiological features of LVOT obstruction.     

Dynamics of left ventricular ejection in obstructive and nonobstructive hypertrophic cardiomyopathy.

The purpose of this study was to examine the dynamics of left ventricular ejection in patients with obstructive and nonobstructive hypertrophic cardiomyopathy (HCM). 30 patients with HCM and 29 patients with no evidence of cardiovascular disease were studied during cardiac catheterization. Using a single multisensor catheter, electromagnetically derived ascending aortic flow velocity and high fidelity left ventricular and aortic pressures were recorded during rest (n = 47) and provocative maneuvers (n = 23). Dynamic ventricular emptying during rest was also analyzed with frame-by-frame angiography (n = 46). Left ventricular outflow was independently derived from both flow velocity and angiographic techniques. The HCM patients were subdivided into three groups: (I) intraventricular gradients at rest (n = 9), (II) intraventricular gradients only with provocation (n = 12), and (III) no intraventricular gradients despite provocation (n = 9). During rest, the percentage of the total systolic ejection period during which forward aortic flow existed was as follows (mean +/- 1 SD): group I, 69 +/- 17% (flow), 64 +/- 6% (angio); group II, 63 +/- 14% (flow), 65 +/- 6% (angio); group III, 61 +/- 16% (flow), 62 +/- 4% (angio); control group, 90 +/- 5% (flow), 86 +/- 9% (angio). No significant difference was observed between any of the HCM subgroups, but compared with the control group, ejection was completed much earlier in systole independent of the presence or absence of intraventricular gradients. These results suggest that "outflow obstruction," as traditionally defined by the presence of an abnormal intraventricular pressure gradient and systolic anterior motion of the mitral valve, does not impede left ventricular outflow in HCM.     

Single versus dual chamber pacing in the young: noninvasive comparative evaluation of cardiac function

The advantages of atrial synchrony over asynchronous ventricular pacing remain unclear in the young, chronically right ventricular (RV) - paced patient. This is in contrast to the older patient with inherent diastolic dysfunction who has been shown to benefit from atrial synchrony with dual chamber (DDD,R/VDD), over single chamber rate response (VVI,R) ventricular pacing. The goal of this study was to noninvasively assess cardiac function in a group of young, RV-paced patients before and after establishment of atrial synchrony. Echocardiographic data were retrospectively analyzed from 10 patients with congenital or acquired complete AV block, who were VVI,R paced for 10.2 +/- 2 years (mean age at study 19.2 +/- 8.9 years), and were subsequently converted to DDD,R/VDD pacing (mean age at study 20.7 +/- 9.5 years). Paired t-test analysis of left ventricular (LV) systolic and diastolic function during VVI,R versus DDD,R/VDD pacing did not result in any short-term difference in LV short axis fractional area of change or FAC (53% +/- 7.5% vs 56.8% +/- 8.7%) or mitral maximal velocity (E) normalized to mitral flow velocity time integral (VTI) (5.2/s +/- 1.5 vs 4.4/s +/- 1.5). A decrease in mitral flow E/A ratio was observed after short-term DDD,R/VDD pacing (2.2 +/- 0.5 vs 1.9 +/- 0.3). Atrial synchronous dual chamber pacing in young patients with complete AV block does not lead to any appreciable early change in global LV function over single-site RV pacing. Therefore, early establishment of atrial synchrony in the young asymptomatic VVI,R-paced patient with normal intrinsic ventricular function may not be warranted.     

Helical distribution of hypertrophy in patients with hypertrophic cardiomyopathy: prevalence and clinical implications

Recently a novel pattern of helical distribution of hypertrophy has been described in patients with hypertrophic cardiomyopathy (HCM). Our aim was to determine its prevalence and potential implications in an unselected cohort. One-hundred- and eight consecutive patients diagnosed with HCM by cardiac magnetic resonance (CMR) were included (median clinical follow up of 1718 days). All clinical and complementary test information was prospectively collected. The presence of a helical pattern was assessed by a simple measurement of the maximal left ventricle (LV) wall thickness (LVWT) for each of the 17 classical LV segments and it was classified in one of three types according to its extension. A helical distribution was detected in 58% of patients, and was associated to a higher incidence of left ventricular outflow tract obstruction (LVOT; 35% vs. 10%; p?=?0.005) and systolic anterior motion of the mitral valve (SAM; 30% vs. 13%, p = 0.053). No significant difference in the maximal LVWT was observed. However, the presence of a helical pattern showed a significant association with non sustained ventricular tachycardia (NSVT; 22% vs. 7%; p?=?0.029) and was associated to a higher risk of sudden cardiac death (SCD) calculated with the European society of cardiology (ESC) calculator (p = 0.006). Notably, patients with a more extense spiral had a higher incidence of heart failure (75% vs. 34%, p = 0.012) and all-cause death (21 vs. 3%, p?=?0.049). A helical pattern is frequent in HCM and can be readily assessed on CMR standard cine sequences. In conclusion, a helical pattern carries negative clinical implications and is associated to a higher estimated risk of SCD.     

Dyssynchronization reduces dynamic obstruction without affecting systolic function in patients with hypertrophic obstructive cardiomyopathy: a pilot study

Dyssynchrony from biventricular pacing (BiV) can reduce dynamic obstruction in hypertrophic obstructive cardiomyopathy (HOCM), but its consequences on the left ventricular (LV) systolic function are unknown. We evaluate changes in LV systolic function and assess the effectiveness of BiV in HOCM. Thirteen patients with HOCM (55 [33/75] years, five males) received a BiV device and underwent 2D transthoracic echocardiography before the implantation and at 12 months follow-up. Global longitudinal and radial strain, and the timing of segmental displacement curves were measured by commercial speckle-tracking software to assess LV systolic function and dyssynchrony. Peak gradient in the LV outflow tract (LVOT) significantly decreased from 80 [51/100] to 30 [5/66] mmHg (p?=?0.005). LV global strain was preserved from baseline to follow-up: 35.1 [20.2/43.8]?% vs. 32.6 [27.1/44.1]?%, p?=?NS (radial), and ?16.6 [?19.1/?14.4]?% vs. ?15.7 [?17.0/?14.2]?%, p?=?NS (longitudinal). Dyssynchrony analysis using displacement curves showed inversion of wall motion timing with earlier displacement of the lateral wall at follow-up only in patients with reduction in LVOT gradient. BiV reduces LVOT obstruction in patients with HOCM when dyssynchronization of LV motion and inversion of the timing of LV wall activation are reached. Notably, this does not lead to further deterioration of LV systolic function at mid-term follow-up.     

4D flow MRI left atrial kinetic energy in hypertrophic cardiomyopathy is associated with mitral regurgitation and left ventricular outflow tract obstruction

To noninvasively assess left atrial (LA) kinetic energy (KE) in hypertrophic cardiomyopathy (HCM) patients using 4D flow MRI and evaluate coupling associations with mitral regurgitation (MR) and left ventricular outflow tract (LVOT) obstruction. Twenty-nine retrospectively identified patients with HCM underwent 4D flow MRI. MRI-estimated peak LVOT pressure gradient (?P_MRI) was used to classify patients into non-obstructive and obstructive HCM. Time-resolved volumetric LA kinetic energy (KE_LA) was computed throughout systole. Average systolic (KE_LA-avg) and peak systolic (KE_LA-peak) KE_LA were compared between non-obstructive and obstructive HCM groups, and associations to MR severity and LVOT ?P_MRI were tested.The study included 15 patients with non-obstructive HCM (58.6 [45.9, 65.2] years, 7 females) and 14 patients with obstructive HCM (51.9 [47.6, 62.6] years, 6 females). Obstructive HCM patients demonstrated significantly elevated instantaneous KE_LA over all systolic time-points compared to non-obstructive HCM (P?<?0.05). Obstructive HCM patients also demonstrated higher KE_LA-avg (14.8 [10.6, 20.4] J/m³ vs. 33.4 [23.9, 61.3] J/m³, P?<?0.001) and KE_LA-peak (22.1 [15.9, 28.7] J/m³ vs. 57.2 [44.5, 121.4] J/m³, P?<?0.001) than non-obstructive HCM. MR severity was significantly correlated with KE_LA-avg (rho?=?0.81, P?<?0.001) and KE_LA-peak (rho?=?0.79, P?<?0.001). LVOT ?P_MRI was strongly correlated with KE_LA metrics in obstructive HCM (KE_LA-avg: rho?=?0.86, P?<?0.001; KE_LA-peak: rho?=?0.85, P?<?0.001).In HCM patients, left atrial kinetic energy, by 4D flow MRI, is associated with MR severity and the degree of LVOT obstruction.

     

Hypertrophic Cardiomyopathy: valuation and Treatment of Patients at High Risk for Sudden Death

Hypertrophic cardiomyopathy (HCM) is a heritable disease characterized by LV hypertrophy with markedly variable clinical, morphological, and genetic manifestations. It is the most common cause of sudden death in otherwise healthy young individuals. HCM patients often have disabling symptoms and are prone to arrhythmias. Frequently, there is associated LV systolic and diastolic dysfunction, LV outflow obstruction, and myocardial ischemia. Over the past decade, progress has been made in identifying patients who are at high risk for sudden death, in elucidating potential mechanisms of sudden death, and in defining therapeutic algorithms that may improve prognosis. It has also been possible to determine the genetic defect in some of the patients and to correlate clinical findings with the molecular defects. An exciting development has been the use of the dual chamber pacemaker as an alternative to cardiac surgery to improve symptoms and relieve LV outflow obstruction.     

Isoproterenol induced cardiovascular hypersensitiviy in nonpheochromocytoma patients with paroxysmal hyperadrenergic symptoms

The objective of this study was to determine whether graded isoproterenol infusion test identifies a specific hypersensitivity response of the LV diastolic relaxation properties in nonpheochromocytoma patients with paroxysmal symptoms of hyperadrenergic surges. We hypothesized that patients with hyperadrenergic surges, not due to pheochromocytoma, have hypersensitivity of cardiac beta-adrenergic receptor responses to exogenous catecholamines, resulting in enhancement of LV relaxation. We assessed the physiological beta 1 and beta 2 receptor responsiveness to graded isoproterenol infusion (0.01, 0.02, 0.03 and 0.04 microgram/kg per min) in 32 patients presented with hyperadrenergic surges not due to pheochromocytoma. Two major observations were made. First, systemic hemodynamic evaluation using 99m Technetium first pass method revealed hyperkinetic state only in 21 patients (20 females and 1 male; aged 31 +/- 9 years); the other 11 patients were without hyperkinetic circulatory state (10 females and 1 male; aged 41 +/- 9 years). At baseline, plasma catecholamines were not significantly different between the two groups. The baseline corrected LV peak filling and ejection rates (cPFR and cPER) were significantly higher in hyperkinetic group (cPFR: 10 +/- 2 vs 8 +/- 2 x 10(-2) Hz/ms, P = 0.03; cPER: 11 +/- 2 vs 8 +/- 1 x 10(-2) Hz/ms, P = 0.002) and their baseline HR was faster (85 +/- 16 vs 70 +/- 9 beats/min, P = 0.006). Second, the cardiac and vascular responses to isoproterenol infusion were compared between these two groups. During the graded isoproterenol infusion, the response of HR, systolic, and diastolic BP were not significantly different between the two groups at all doses of isoproterenol, but cPFR and cPER had a more marked response to the lowest dose of 0.01 mg/kg per min in the hyperkinetic group. Thus, the graded isoproterenol infusion test can differentiate between two groups of nonpheochromocytoma patients presenting with paroxysmal symptoms of hyperadrenergic surges. Only patients with baseline hyperkinetic hemodynamic profile had accentuated cardiac hyperresponsiveness to a low dose of isoproterenol. We concluded that cPFR and cPER is a more sensitive index to assess the response to isoproterenol, because of metabolic determinants affecting the rate of change in LV volume.     

Effect of cardiac resynchronization on gradient reduction in patients with obstructive hypertrophic cardiomyopathy: preliminary study

Background: The purpose of this study was to assess the effectiveness of cardiac resynchronization therapy (CRT) in terms of outflow tract gradient reduction and functional improvement in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM) requiring implantable cardioverter‐defibrillator (ICD) implantation. Methods: Eleven consecutive symptomatic HOCM patients with a significant (≥40 mmHg) gradient and indications for ICD, but without indications for resynchronization, underwent CRT‐D implantation. Nine of them (four female, median age of 50 years) in whom the procedure succeeded were screened for New York Heart Association (NYHA) class, outflow gradient, mechanical dyssynchrony, QRS‐width change, and 6‐minute walking distance (6MWD) and peak oxygen consumption (VO₂peak) improvement after 6 months and remotely. Results: After 6 months of pacing, NYHA class decreased (median 1 vs 2, respectively); peak (33 vs 84 mmHg) and mean (13 vs 38 mmHg) outflow tract gradients were reduced; and QRS width (143 vs 105 ms), intraventricular dyssynchrony (35 vs 55 ms), and VO₂peak (19.5 vs 14.2 mL/kg/min) increased significantly (all P < 0.05) compared to baseline. In six of nine patients (67%), the peak gradient was reduced >50% and reached <40 mmHg. After a median of 36 months, the outflow gradient decreased even more (8 mmHg) and was significantly (P < 0.05) lower than after 6 months of CRT. Conclusions: These preliminary data suggest that CRT seems to be an effective method of reducing the outflow tract gradient and improving the functional status of symptomatic HOCM patients requiring ICD implantation. Our findings need to be confirmed by more extensive studies. (PACE 2011; 34:1544–1552)     

Treatment of post resuscitation myocardial dysfunction: aortic counterpulsation versus dobutamine

BACKGROUND: Post resuscitation myocardial stunning is well described and recognized as a significant contributor to poor long-term outcome following cardiac arrest. Optimal strategies for treatment have not been determined. METHODS: Ten domestic swine (49+/-3 kg) underwent 15 min of untreated ventricular fibrillation before being successfully resuscitated. Left ventricular systolic and diastolic function was measured at pre-arrest baseline, at 30 min and at 6 h post resuscitation. Five animals were treated immediately after resuscitation with intra-aortic balloon counterpulsation (IABP) and five were given dobutamine (5 mcg/kg per min). RESULTS: No baseline differences were found. At 30 min post resuscitation pulmonary capillary wedge pressure and LVEDP were significantly higher (16+/-3 vs. 7+/-1 and 20+/-2 vs. 11+/-1 mmHg) while LV isovolumic relaxation ('Tau') was significantly longer (34+/-2 vs. 20+/-2 ms) in the IABP treated versus the dobutamine treated animals. Likewise, at 6 h post resuscitation LV ejection fraction was significantly less (21+/-6 vs. 39+/-4%), and LVEDP significantly higher (18 vs. 10 mmHg) in the IABP group. Heart rate was not different between the groups at any time post resuscitation. CONCLUSION: Dobutamine was superior to IABP for treatment of post resuscitation left ventricular systolic and diastolic dysfunction. The hypothesized advantage of IABP for treatment of post resuscitation myocardial stunning without excessively raising the heart rate like dobutamine was not realized.     

Left ventricular cavity obliteration during dobutamine stress echocardiography in diabetic patients

Prevalence of dynamic left ventricular outflow tract obstruction (DLVO) during dobutamine stress-echo (DSE) seems disproportionally high among diabetic patients. We retrospectively identified 212 diabetic (D+) and 212 non diabetic (D-) subjects, who underwent DSE for suspected coronary artery disease (CAD); we evaluated DSE-induced DLVO prevalence and correlates. During DSE, 105 patients in D+ (50%) and 83 in D- group (39%, P = 0.032) developed a DLVO, with similar maximum gradient (94 ± 49 mmHg in D+ vs. 86 ± 49 mmHg in D-, P = NS). D+ and D- patients with DLVO showed reduced LV end-diastolic and end-systolic dimension. Compared with diabetic subjects without DLVO, diabetic patients with DLVO had higher left ventricular (LV) ejection fraction (EF), lower LV mass index; diastolic function was normal in a higher proportion of cases. Non diabetic patients with moderate or severe DLVO had higher LV EF compared with patients without DLVO. At multivariate analysis, in D+ patients, the only independent predictor was a smaller LV end-diastolic diameter (HR 0.779, CI 0.655-0.926, P = 0.005); in D- patients lower age (HR 0.878, CI 0.806-0.957, P = 0.003), higher LV EF (HR 1.087, CI 1.003-1.177, P = 0.042) and lower peak WMSI (HR 0.017, CI 0.001-0.325, P = 0.007) were associated to presence of DLVO. In D+ patients, during a median follow-up of 924 ± 134 days, we observed 11 new cardiac events, only 1 in patients with DLVO (P = 0.0041). DSE-provoked DLVO had a very high prevalence in patients evaluated for suspected CAD, especially among diabetic patients; echocardiographic predictors were a reduced LV dimension in D+ and a preserved systolic function, both at rest and at peak stress, in D- patients.     

速度向量成像技术评价肥厚型心肌病心脏扭转运动

目的 应用超声心动图速度向量成像(VVI)技术对肥厚型心肌病(HCM)患者心脏扭转运动(cardiac twist)进行初步分析,探讨HCM患者在左室射血分数(LVEF)正常时心脏局部和整体扭转功能是否已有改变.方法 对30例HCM患者(其中左室流出道梗阻13例)和33例正常人(对照组)行常规超声心动图检查,测量LVEF、左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)、每搏量(SV)等.采用VVI技术测量左室基底部腱索水平、乳头肌水平和心尖水平收缩期心内膜下心肌和心外膜下心肌的最大旋转角度、峰值旋转速率、圆周应变(circumferential strain,CS)、圆周应变率(circumferential strain rate,CSR)、径向应变(radial strain,RS)、径向应变率(radial strain rate,RSR);测定舒张期峰值解旋转速率和解扭转率,以分析两组的心脏旋转和扭转运动.结果 HCM组与正常组相比,LVEF差异无统计学意义,LVEDV、LVESV、SV明显减低,心内膜下心肌的左室扭转角度、CS较正常人明显增高,心外膜下心肌的旋转速率、解旋转速率、CS、CSR均明显减低(P＜0.05),HCM组左室三个短轴水平的RS、RSR均明显低于对照组(P＜0.01);舒张期解扭转率低于对照组.HCM组分组资料显示:左室流出道梗阻组患者心外膜下心肌的旋转速率、解旋转速率、CS、CSR进一步减低.结论 HCM患者心脏整体扭转角度较正常人增大,局部心肌圆周方向变形能力下降,左室流出道梗阻加剧局部心功能的损伤.     

Degree and distribution of left ventricular hypertrophy as a determining factor for elevated natriuretic peptide levels in patients with hypertrophic cardiomyopathy: insights from cardiac magnetic resonance imaging

Whether the left ventricular (LV) mass index (LVMI) and LV volumetric parameters are associated independently with natriuretic peptide levels is unclear in hypertrophic cardiomyopathy (HCM). Therefore, we investigated which parameters have an independent relationship with N-terminal pro-B type natriuretic peptide (NT-proBNP) levels in HCM patients using echocardiography and cardiac magnetic resonance imaging (CMR). A total of 103 patients with HCM (82 men, age 53 ± 12 years) were evaluated. Echocardiographic evaluations included left atrial volume index (LAVI) and early diastolic mitral inflow E velocity to early annular Ea velocity ratio (E/Ea). LVMI, maximal wall thickness and LV volumetric parameters were measured using CMR. The median value of NT-proBNP level was 387.0 pg/ml. The mean NT-proBNP level in patients with non-apical HCM (n = 69; 36 patients with asymmetric septal hypertrophy, 11 with diffuse, and 22 with mixed type) was significantly higher than in those with apical HCM (n = 34, P < 0.001). NT-proBNP level was negatively correlated with LV end-diastolic volume (LVEDV) (r = -0.263, P = 0.007) and positively with LVMI (r = 0.225, P = 0.022) and maximal wall thickness (r = 0.495, P < 0.001). Among the echocardiographic variables, LAVI (r = 0.492, P < 0.001) and E/Ea (r = 0.432, P < 0.001) were correlated with NT-proBNP. On multivariable analysis, non-apical HCM, increased maximal wall thickness and LAVI were independently related with NT-proBNP. Severity of LV hypertrophy and diastolic parameters might be important in the elevation of NT-proBNP level in HCM. Therefore, further evaluation of these parameters in HCM might be warranted.     

The role of imaging in the diagnosis and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, affecting approximately 1:500 people. As the yield of genetic testing is only about 35–60%, the diagnosis of HCM is still clinical and based on the demonstration of unexplained and usually asymmetric left ventricular (LV) hypertrophy by imaging modalities. In the past, echocardiography was the sole imaging modality used for the diagnosis and management of HCM. However, in recent years other imaging modalities such as cardiac magnetic resonance have played a major role in the diagnosis, management and risk stratification of HCM, particularly when the location of left ventricular hypertrophy is atypical (apex, lateral wall) and when the echocardiographic imaging is sub-optimal. However, the most unique contribution of cardiac magnetic resonance is the quantification of myocardial fibrosis. Exercise stress echocardiography is the preferred provocative test for the assessment of LV outflow tract obstruction, which is detected only on provocation in one-third of the patients.     

Severe aortic valve stenosis with preserved and reduced systolic left ventricular function: diagnostic usefulness of the Tei index.

BACKGROUND: In patients with severe aortic valve stenosis (AS), the onset of heart failure is associated with increased mortality and higher operative risk. Heart failure may result from either systolic, diastolic, or "overall" left ventricular dysfunction. The index "isovolumic contraction time and isovolumic relaxation time divided by ejection time" was shown to be a sensitive indicator of "overall" cardiac dysfunction in patients with dilated cardiomyopathy and cardiac amyloidosis. We sought to define the role of the Tei index in patients with severe AS and to validate this index against conventional measures of systolic and diastolic LV function. PATIENTS AND METHODS: Fifty-three participants underwent left heart catheterization for invasive measurement of LV end-diastolic pressure as a marker of diastolic function: 10 AS patients (valve orifice 0.6 +/- 0.2 qcm) with depressed systolic LV function (defined by LV ejection fraction < or = 45% [mean 32% +/- 8%], 7 male/3 female, 72 +/- 10 years old, DAS group), 22 AS patients (valve orifice 0.7 +/- 0.2 qcm) with preserved systolic LV function (ejection fraction > 45% [mean 55% +/- 6%], 13 male/9 female, 71 +/- 11 years old, PAS group) and 21 asymptomatic control participants (ejection fraction > 45% [mean 62% +/- 8%], 14 male/7 female, 66 +/- 8 years old, CON group). Within 24 hours from catheterization, conventional 2-dimensional and Doppler echocardiographic examination including measurement of the Tei index was performed. RESULTS: LV end-diastolic pressure was elevated in the DAS and in the PAS group in comparison with control participants (32 +/- 6 mm Hg and 22 +/- 7 mm Hg vs 11 +/- 4 mm Hg, respectively, P <.01 for both comparisons). DAS patients were in a higher New York Heart Association functional class than PAS patients (3.2 +/- 0.4 vs 2.2 +/- 0.4, P <.001) The Tei index was easily and reproducibly obtained in all study participants. In the DAS group, isovolumic contraction time was prolonged and ejection time was shortened in comparison with the CON group (102 +/- 20 ms vs 52 +/- 15 ms, P <.01; and 235 +/- 44 ms vs 316 +/- 45 ms, P <.01), resulting in a significantly increased Tei index (0.78 +/- 0.28 vs 0.40 +/- 0.11, P <.01). In the PAS group, isovolumic relaxation time was shortened (62 +/- 18 ms vs 81 +/- 26 ms for the CON group, P <.01) and ejection time was prolonged (335 +/- 34 ms vs 316 +/- 45 ms for the CON group, P <.05), resulting in a decreased Tei index (0.29 +/- 0.12 vs 0.40 +/- 0.11, P <.05). Receiver operating characteristic curve analysis for the Tei index yielded an area under the curve of 0.98 +/- 0.03 for separating DAS and PAS patients. Using a Tei index greater than 0.42 as a cutoff, DAS patients were identified with a sensitivity of 100% and a specificity of 91%. CONCLUSION: The Tei index is significantly increased in patients with severe AS and depressed overall cardiac LV function. In AS patients with predominant diastolic dysfunction, in whom systolic function is preserved, the index is decreased in comparison with control patients. The index differentiates between symptomatic AS patients with depressed and less symptomatic AS patients with preserved systolic LV function, and may thus provide relevant information in the work-up and care of such patients.     

Relief of Left Ventricular Outflow Tract Obstruction Following Inadvertent Left Ventricular Apical Pacing in a Patient with Hypertrophic Cardiomyopathy

Dual chamber (DDD) pacing improves symptoms and relieves left ventricular (LV) outflow obstruction in hypertrophic Cardiomyopathy. The ventricular lead is usually positioned at the right ventricular apex (RVA). We report a patient in whom the ventricular lead had inadvertently penetrated the septum, resulting in DDD pacing from the LV apex. However, after 3 months, obstruction was reduced and symptoms were improved. Pacing from LV apex and RVA resulted in comparable hemodynamic improvement. This case suggests that the asynchronous wave of septal contraction, originating from the apex, irrespective of ventricular site, accounts for the reduction in LV outflow obstruction.