超声心动图四维自动左心室容积测定技术在左心室室壁瘤成形术中的应用价值

目的 探讨四维自动左心室容积测定（4D auto LVQ）在室壁瘤左心室成形术中的应用价值。方法 采用4D auto LVQ技术评价7例广泛前壁心肌梗死合并心尖部室壁瘤患者左心室容积和功能,并与心脏MR测量心室容积及室壁瘤成形术后左心室收缩功能比较。结果 5例术前行心脏MR检查,5例行室壁瘤成形术。与二维超声心动图相比,4D auto LVQ测量室壁瘤患者左心室容积与心脏MR检查结果更接近。采用4D auto LVQ技术术前预测左心室收缩功能与术后实际左心室收缩功能接近。结论 4D auto LVQ技术可更精准、快捷地评价左心室容积和收缩功能,为制定室壁瘤成形手术方案提供客观资料。     

Left ventricular hypertrophy, compliance and ventricular filling.

A total of 20 untreated hypertensive patients were divided into two equal groups matched for sex, age and blood pressure but with [mean diastolic wall thickness (MDWT) greater than 1.2 cm] or without (MDWT greater than 1.2 cm) left ventricular hypertrophy (LVH). All patients underwent pulsed doppler echocardiography and 99Tc radionuclide ventriculography at rest to assess diastolic and systolic abnormalities. In hypertensives with LVH the interventricular wall thickness, posterior wall thickness and relative diastolic wall thickness were significantly (P less than 0.01) higher and peak filling rate was significantly (P less than 0.01) lower than in hypertensives without LVH. The indices of systolic function, however, were not significantly different in the two patient groups. In hypertensives without LVH peak filling rate directly correlated with heart rate, whereas in those with LVH peak filling rate directly correlated with heart rate and the ratio of peak velocity of early left ventricular filling : peak velocity of late left ventricular filling due to atrial contraction. It is concluded that diastolic parameters may be useful tools for assessing myocardial compliance and may be effective markers of diastolic dysfunction.     

New strategies for ventricular tachycardia and ventricular fibrillation ablation

Patients with ventricular tachycardia (VT) and ventricular fibrillation (VF) and no reversible cause are difficult to treat. While implantable defibrillators prolong survival, many patients remain symptomatic due to device shocks and syncope. To address this, there have been recent advances in the catheter ablation of VT and VF. For example, non-invasive imaging has improved arrhythmia substrate characterisation, 3D catheter navigation tools have facilitated mapping of arrhythmia and substrate and ablation catheters have advanced in their ability to deliver effective lesions. However, the long-term success rates of ablation for VT and VF remain modest, with nearly half of treated patients developing recurrence within 2–3 years, and this drives the ongoing innovation in the field. This review focuses on the challenges particular to ablation of life-threatening ventricular arrhythmia, and the strategies that have been recently developed to improve procedural efficacy. Patient sub-groups that illustrate the use of new strategies are described.     

Effect of pacing-induced ventricular dyssynchrony on right ventricular function

Background: Asynchronous electrical activation induced by right ventricular (RV) pacing can cause several abnormalities in left ventricular (LV) function. However, the effect of ventricular pacing on RV function has not been well established. We evaluated RV function in patients undergoing long‐term RV pacing. Methods: Eighty‐five patients and 24 healthy controls were included. After pacemaker implantation, conventional echocardiography and strain imaging were used to analyze RV function. Strain imaging measurements included peak systolic strain and strain rate. LV function and ventricular dyssynchrony by tissue Doppler imaging (TDI) were assessed. Intra‐ and interobserver variabilities of TDI parameters were tested on 15 randomly selected cases. Results: All patients were in New York Heart Association functional class I or II and percentage of ventricular pacing was 96 ± 4%. RV apical induced interventricular dyssynchrony in 49 patients (60%). LV dyssynchrony was found in 51 patients (60%), when the parameter examined was the standard deviation of the time to peak myocardial systolic velocity of all 12 segments greater than 34 ms. Likewise, septal‐to‐lateral delay ≥65 ms was found in 31 patients (36%). All echocardiographic indexes of RV function were similar between patients and controls (strain: ?22.8 ± 5.8% vs ?22.1 ± 5.6%, P = 0.630; strain rate: ?1.47 ± 0.91 s^?1 vs ?1.42 ± 0.39 s^?1, P = 0.702). Intra‐ and interobserver variability for RV strain was 3.1% and 5.3%, and strain rate was 1.3% and 2.1%, respectively. Conclusions: In patients with standard pacing indications, RV apical pacing did not seem to affect RV systolic function, despite induction of electromechanical dyssynchrony. (PACE 2011; 34:155–162)     

室性早搏对左心室功能的影响

室性早搏是临床上最常见的心律失常,本文综述了室性早搏的形态、起源、负荷等特点对左心室功能的影响。室性早搏负荷大于20%,QRS时限>150 ms以及右心室起源的室性早搏更容易伴随或导致左心室功能下降。临床上对于频发室性早搏的及时治疗,能够起到改善心功能或预防心功能恶化的目的。导管射频消融治疗已成为特发性室性心律失常的最有效的治疗方法。     

室性心动过速和心室颤动治疗进展

室性心动过速（室速）和心室颤动（室颤）是心源性猝死最常见的原因。本文就器质性、特发性和离子通道病性室速/室颤的药物、器械、导管消融术及其他治疗等的最新进展进行了总结,以期能够达到规范临床诊疗的作用。     

Right ventricular enlargement

Right ventricular enlargement (RVE) encompasses dilatation and hypertrophy of the right ventricular chamber. Severe RVE produces characteristic ECG changes including right axis deviation and large S waves in the left precordial leads. Treatment is directed at the underlying cause.     

Surgical ventricular restoration

Surgical left ventricular restoration has been introduced to reshape the dilated cardiac chamber and improve cardiac function for patients with severe congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy. The operations for ischemic cardiomyopathy (Dor, SAVER, etc) provide significant improvements of cardiac function and good short- and long-term survival. Ongoing prospective study (STICH trial) may make those more standard procedures. On the contrary, the operation for idiopathic dilated cardiomyopathy (Batista procedure) carries high risks of operative mortality and recurrence of congestive heart failure. Modifications of operative indications and surgical techniques are under investigation.     

Left ventricular function

The Doppler indexes of tricuspid porcine bioprosthetic valves were evaluated in twelve patients without clinical and two-dimensional echocardiographic evidence of valve dysfunction. Peak and mean pressure gradients across the prostheses were measured using the simplified Bernoulli equation. All the Doppler measurements were compared during inspiration and expiration. During inspiration peak velocity, peak gradient and mean gradient (1.52 ± 0.28 m/s; 9.7 ± 3.05 mmHg; 4.07 ± 1.16 mmHg) were significantly higher than during expiration (1.28 ± 0.8 m/s; 6.58 ± 2.7 mmHg; 2.98 ± 1.13 mmHg; p < 0.01) but pressure half time was not significantly different (122 ± 62 ms versus 134 ± 75 ms; p > 0.05). Inspiratory range of peak velocities, peak gradients, mean gradients and pressure half times were respectively 0.8–2.04 m/s; 4.9–16.6 mmHg; 1.2–7.2 mmHg; 42–340 ms while expiratory range of values was 0.8–1.93 m/s; 2.6–15 mmHg; 1.1–5.7 mmHg; 46–345 ms. These data suggest that even very long pressure half times do not indicate valve dysfunction. This study demonstrates that large variation of Doppler parameters are present during respiration and could produce inaccuracy in the assessment of bioprostheses in tricuspid position if they are not taken in consideration.     

Right ventricular infarction

Right ventricular infarction is present in up to 80% of autopsy specimens following fatal myocardial infarction. The clinical features suggestive of right ventricular infarction such as raised systemic venous pressure, clear lung fields, hypotension and atrio-ventricular nodal disturbances usually occur in association with inferior myocardial infarction, with an incidence of 30–50%. Kussmaul‘s sign of a paradoxical rise in the jugular venous pressure wave on inspiration is both sensitive and specific for right ventricular infarction. A 1mm rise in the V4R ST segment on ECG has a positive predictive value for right ventricular infarction of over 70%, increasing to 90% with the addition of ST elevation in leads VSR and V6R. ECG changes are often transient. Acute management of right ventricular infarction includes fluid loading and inotropic support with dobutamine as necessary, with avoidance of vasodilators and diuretics. Mortality from acute myocardial infarchon is increased by right ventricular infarction, but may be lessened by thrombolytic therapy in eligible patients.     

Sonographic measurement of lateral ventricular width in early ventricular dilation

Cerebral real-time ultrasound examinations from 35 high-risk premature newborn infants and 25 normal-term infants were reviewed for early signs of ventricular dilation. Measurements of the midbody lateral wall of the lateral ventricle to falx distance and ratio of this distance to the hemispheric width were obtained. Midbody lateral ventricular widths were also measured. Results indicate that displacement of the medial wall of the body of the lateral ventricle toward the midline is an earlier sign of ventricular dilation than is displacement of the lateral wall away from the midline.     

Asynchronous ventricular pacing: a rare cause of ventricular tachycardia

Asynchronous cardiac pacing may induce ventricuiar tachycardia and fibrillation, particularly in patients with ischemic heart disease and possibly other types of myocardial abnormalities. All patients with implanted asynchronous pacemakers, and those whose demand pacemakers operate in asynchronous mode for any reason, are to he considered at risk from this complication. In patients with serious myocardial abnormalities consistent demand pacing should be assured, even if it requires early pacemaker replacement. Anti-arrhythmic agents may prove useful for temporary suppression of pacemaker-induced arrhythmias. (PACE, Vol. 5, July-August, 1982)     

Positional ventricular tachycardia

A 60-year-old man showed nonsustained repetitive monomorphic VT in the left lateral position, but this was terminated by deep inspiration. Echocardiography and MRI demonstrated a false tendon extending from the apex to the basal septum where the VT could have originated. Spontaneous remission occurred during the 16-year follow-up.