右室梗死临床诊疗新进展

右室梗死过去只能在尸检时确诊。20世纪70年代以来,随着医师诊断水平和检测设备的不断进步,临床上已能在患者生病确诊右室梗死[1],现对国内有关资料综述如下,仅供同道参考。1右心室栓塞发病及研究进展右心室心肌梗死是指累及右心室壁的心肌梗死。临床上相对少见。尸检病例中,单独右心室梗死不到3%,左心室心肌梗死同时延伸至右心室者占43%[1]。按其梗死发生部位分为:右心室游离下壁;右心室游离前壁;右心室游离下壁、前壁及右心室乳头肌。受累部位取决于受损血管的来源,右心室前壁和前乳头肌由左前支和圆锥支供血,前者分支较多,一般不会全部阻…     

Left ventricular growth in a patient with critical coarctation of the aorta and hypoplastic left ventricle

An infant is presented who at birth met criteria consistent with hypoplastic left heart syndrome. He was followed clinically and by 11 weeks of age demonstrated substantial growth of the left ventricle. He underwent successful repair of coarctation of the aorta and continues to do well with moderate aortic stenosis. The difficulties of predicting left ventricular growth and function are discussed, and management options are reviewed.     

Effect of atrial pacing therapy with selective pacing algorithms on paroxysmal atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia among the elderly. Its incidence increases dramatically with increasing age and decreasing left ventrieular function, peaking in subjects with overt congestive heart failure, Because of the unsatisfactory efficacy and possible serious side effects of clinically available anti-AF drugs for AF patients with sick sinus syndrome, pacing techniques have recently been applied in the treatment of AF. The cardiac pacemaker Vitatron     

The vanishing vast ventricular thrombus.

A 54-year old man presented with multiple pulmonary emboli and an incidental finding of a huge left ventricular thrombus. Transthoracic echo images demonstrated a globally dilated heart with very poor left ventricular function. It was elected to manage the patient medically, and he was commenced on warfarin therapy, resulting in completed resolution of the thrombus over 10 weeks. No underlying cause was found and he did not experience any further embolic events. This illustrates a rare case of a large ventricular thrombus in a patient with no underlying risk factors.     

Ventricular rate smoothing for atrial fibrillation: a quantitative comparison study.

AIMS: To quantitatively compare the ventricular rate-smoothing (VRS) effects of different ventricular pacing (VP) protocols for atrial fibrillation (AF). METHODS AND RESULTS: Using a recently developed open-source model that can simulate the ventricular response in AF and VP, the performance of fixed-rate pacing and four previously published VRS algorithms were assessed by the mean RR (mRR), the root mean square of successive RR differences (RMSSD), the percentage of ventricular senses (VS%), and the percentage of short RR intervals (sRR%). All pacing protocols cause rate-dependent reduction of RMSSD, VS%, and sRR% with or without shortening of mRR compared to spontaneous AF. Fixed-rate pacing was more sensitive to the intrinsic rate than the VRS algorithms. The performance was generally comparable between different VRS algorithms, although higher mRR and VS% can be achieved at the expense of larger RMSSD and sRR%. CONCLUSION: The effect of VP on ventricular rhythm in AF depends on both intrinsic rate and the aggressiveness of the pacing protocol. Adequate rate control is necessary for effective operation of the VRS algorithm. Choosing VRS algorithm should balance between the beneficial effects of rate regularization and the negative effects of increasing heart rate and percentage of VP.     

Management of Patients After Catheter Ablation of Ventricular Tachycardia

The management of patients after catheter ablation of ventricular tachycardia is not well defined. In this article we summarize recently published results and report our own experience. Factors influencing the clinical outcome of these patients and methods to identify patients with an increased risk of recurrence of ventricular tachycardia are discussed. Furthermore, a review is given on current concomitant therapeutic tools including antiarrhythmic drugs and the implantation of an automatic cardioverter defibrillator.     

On the mechanism of increased potassium conductance by the potassium channel opener BRL 34915 in Isolated ventricular myocytes

The potassium conductance increased by BRL 34915 (BRL, cromakalim) was studied in single guinea pig ventricular myocytes by using a whole cell voltage-clamp technique. In control voltage-clamp recordings, the late current-voltage relation showed a distinct inward rectification. BRL (1–100 μM) shortened the action potential and diminished or abolished inward rectification but had no effect on the slope conductance and currents flowing during hyperpolarizing clamp steps. BRL did not decrease the slow inward current but accelerated the time constant of activation and amplitude of the outward current. Cd markedly decreased (0.2 mM) or abolished (0.4–0.6 mM) the slow inward current and BRL induced a faster outward shift of late current to a greater value. Glybenclamide (10 μM), a blocker of ATP-sensitive K⁺ channels, had little effect of its own on action potential, membrane currents, and I-V relation. However, in the presence of BRL, glybenclamide abolished BRL effects on action potential and currents and restored inward rectification. It is concluded that the mechanism by which BRL shortens the action potential is a faster growth of an outward current due to the reduction or abolition of the inward rectification of an ATP-dependent potassium channel. The reduction in force in non-isolated tissues appears to be an indirect result of the action potential shortening and not of a decreased slow inward current.     

Impact of photon energy recovery on the assessment of left ventricular volume using myocardial perfusion SPECT

BACKGROUND: Photon energy recovery (PER) is a spectral deconvolution technique validated for scatter removal in patients and phantom studies. The purpose of this study was to examine the impact of PER on left ventricular volume measurement based on myocardial perfusion single photon emission computed tomography (SPECT). METHODS AND RESULTS: SPECT acquisitions were performed by use of a static cardiac phantom and in 25 patients after a rest injection of technetium 99m sestamibi by use of multiple energy windows (126-136, 137-144, and 145-154 keV). Data were successively reconstructed with and without PER, by use of iterative reconstruction and post-processing filtering (Butterworth filter; order, 5; cutoff, 0.30 cycles/pixel). Image contrast was evaluated in reconstructed data, and volumes were calculated by use of QGS. PER increased reconstructed image contrast from 62% +/- 2.7% to 84.3% +/- 5.7% in the phantom studies (P <.0001) and from 49% +/- 2% to 73% +/- 2% in patients (P <.0001). Although it remained underestimated (P <.0001), phantom volume was higher after PER correction compared with uncorrected data (50.9 +/- 0.8 mL vs 44.6 +/- 1 mL, P <.0001). The error in volume measurement was decreased by PER correction (16.6% +/- 1.3% vs 27% +/- 1.7% [uncorrected data], P <.0001). In patients, left ventricular volume increased from 83 +/- 10 mL to 91 +/- 10 mL (P <.0001), and the PER-induced volume increase was correlated with the image contrast increase (r = 0.61, P =.001). Finally, the percentage of volume increase was higher in patients with small left ventricular volumes. CONCLUSIONS: PER has a significant impact on image contrast and left ventricular volume measurement by use of perfusion SPECT. PER improves the accuracy of phantom volume assessment. In patients, volume increase is correlated to image contrast increase and is higher in those with small ventricles.     

EFFECT OF CIGARETTE SMOKING ON THE FREQUENCY OF VENTRICULAR PREMATURE COMPLEXES IN NORMAL SUBJECTS

1. Ambulatory ECG monitoring was undertaken in healthy cigarette smokers (33) and non-smokers (20) of similar age (21-66 years). 2. The frequency of ventricular premature complexes (VPC) was less in habitual smokers (P less than 0.05; Mann-Whitney rank test) and an average of more than 1 VPC per hour occurred in a higher proportion of non-smokers than smokers: eight of 20 (40%) vs two of 33 (6%) (P less than 0.01; Chi-square test).     

Effects of Right Ventricular Failure on Renal Function During Pneumatic Left Ventricular Assist

Abstract: In an experimental dog model of acute biventricular failure, the effects of left ventricular (LV) assist on renal hemodynamics and function were evaluated. After the induction of severe cardiac failure by multiple ligation of the coronary arteries, LV assist with a 40 ml pneumatic pulsatile pump was initiated, and the aortic flow was maintained at control values. The right atrial pressure (RAP) rose to 21.3 mm Hg with the appearance of profound right ventricular (RV) failure. Renal arterial blood flow (RAF) decreased to about 60% of the control value after 2 h of LV assist. The urine volume decreased and renal function deteriorated progressively. RV assist decreased the RAP to 4.8 mm Hg, and the reduced RAF recovered. After 3 h of RV assist, the RAF returned to initial values and the urine volume increased, but renal function did not recover. Advanced biventricular failure with elevated RAP during LV assist reduced renal perfusion and impaired renal function and may be an indication for early RV assist