Optimization of ultrasound parameters of myocardial cavitation microlesions for therapeutic application

Intermittent high intensity ultrasound scanning with contrast microbubbles can induce scattered cavitation microlesions in the myocardium, which may be of value for tissue reduction therapy. Anesthetized rats were treated in a heated water bath with 1.5 MHz focused ultrasound pulses, guided by an 8 MHz imaging transducer. The relative efficacy with 2 or 4 MPa pulses, 1:4 or 1:8 trigger intervals and 5 or 10 cycle pulses was explored in six groups. Electrocardiogram premature complexes (PCs) induced by the triggered pulse bursts were counted, and Evans blue stained cardiomyocyte scores (SCSs) were obtained. The increase from 2 to 4 MPa produced significant increases in PCs and SCSs and eliminated an anticipated decline in the rate of PC induction with time, which might hinder therapeutic efficacy. Increased intervals and pulse durations did not yield significant increases in the effects. The results suggest that cavitation microlesion production can be refined and potentially lead to a clinically robust therapeutic method.

Effect of premature activation in analyzing QT dynamics instability using QT-RR model for ventricular fibrillation and healthy subjects

Perturbations in the normal heart rate are generally represented by the presence of premature activation (PA) beats in the surface electrocardiogram (ECG). The presence of PA is one of the main reasons of instability in QT dynamics which could initiate arrhythmia. Analyzing Boundary-Input Boundary-Output (BIBO) stability of the short term linear autoregressive QT-RR model is a way of detecting instability in QT dynamics from the ECG. The aim of this paper is to investigate if PA is the only reason for instability in the ventricular repolarisation process, which is denoted by QT interval of surface ECG. Ten healthy subjects with normal sinus rhythm and seven patients with sustained ventricular tachycardia (VT) were analyzed in this study. 10 min long ECG data were collected from each subject of the healthy group and 10 min ECG before the start of VT were taken for each subject of the VT group. Autoregressive QT-RR model was derived for each non-overlapping 1 min long ECG segment of the 10 min long ECG data. Instability in QT dynamics was quantified by measuring the numbers of unstable segments in ECG data for each subject ( ). Results of this study revealed that like the VT group subjects, QT instability detected by QT-RR model is also found in healthy subjects whose ECG segments are mostly free from PA beats. This finding indicates that BIBO unstable QT characteristics might arise from other inherent factors of cardiovascular system in addition to PA.

[Comparison of the probability of meeting up with premature contraction during scanning in 320-area detector computed tomography with that in 64-multidetector CT coronary angiography]

BACKGROUND

Because coronary computed tomography angiography (CCTA) by 320-area detector CT (320-ADCT) can be obtained in a short time, the probability of meeting up with premature contraction (PC) during scanning may be lower in 320-ADCT compared to 64-MDCT. The purpose is to compare the probability of meeting up with PC, scanning time, and image quality in patients with PC between the 2 groups (320-ADCT vs 64-MDCT).

METHODS

We have never rejected any CCTA examination due to arrhythmias. The 320-ADCT was performed in 2424 consecutive patients to include 70 atrial fibrillations (Afibs) and 64-MDCT in 1905 consecutive patients to include 51 Afibs. After exclusion of the patients with Afibs, we studied the probability of meeting up with PC during scanning and we compared the scanning time, image quality, and reconstruction phase for patients with PC between the 2 groups.

RESULTS

The probability of meeting up with PC during scanning in 320-ADCT (2.0%) is significantly lower (P<0.0001) than 64-MDCT (5.6%). For patients with PC, scanning time in 320-ADCT (2.9±0.6 s) was significantly shorter (P<0.0001) than 64-MDCT (9.5±1.9 s) and image quality in 320-ADCT (2.9±0.3 points) was significantly higher (P<0.0001) than 64-MDCT (2.2±0.8 points). CCTA was reconstructed in mid-diastolic phase in 93% of patients with PC using the 320-ADCT with arrhythmia rejection system.

CONCLUSION

The scanning time of 320-ADCT was 1/3 in comparison with that of 64-MDCT, and the probability of meeting up with PC during scanning in 320-ADCT was 1/3 in comparison with that in 64-MDCT.

Evaluation of fetal arrhythmias from simultaneous pulsed wave Doppler in pulmonary artery and vein

OBJECTIVE

To evaluate the clinical application of simultaneous recordings of pulsed wave Doppler (PWD) signals in pulmonary artery and vein as alternative sampling site for assessment of arrhythmias in the fetus.

DESIGN

Prospective, cross-sectional study.

SETTING

Tertiary referral centre for fetal cardiology.

PATIENTS AND METHODS

From July 1999 to July 2005 PWD was used in pulmonary vessels to assess fetal arrhythmias at 15-40 weeks' gestation. Sample volume placement in the peripheral lung vessels was guided by colour flow mapping on a four-chamber section of the fetal heart. Atrial and ventricular systoles were identified from the pulmonary venous and arterial signals respectively. M-mode recordings were used for comparison.

OUTCOME MEASURES

Diagnosis of fetal arrhythmias.

RESULTS

Of 129 cases, 15 had supraventricular tachycardia, 12 with 1:1 atrioventricular conduction and 3 with atrial flutter and 2:1 block. There were 96 cases of atrial and 7 of ventricular premature beats, 2 of sinus bradycardia, 8 of variable degree heart block and 1 of ventricular tachycardia. PWD was diagnostic in 119 cases. PWD was better than M mode for diagnosis of premature beats and added information about mechanisms of tachycardia. Both methods facilitated interpretation of all arrhythmia patterns, although PWD was of less practical value in cases of complete heart block.

CONCLUSION

Simultaneous PWD recording of pulmonary vessels in the fetus allows accurate diagnosis of arrhythmias. It is easily obtained with standard ultrasound equipment and adds to the armamentarium of diagnostic techniques for assessment of rhythm abnormalities prenatally.

Improving Diagnostic Accuracy of MDCT Coronary Angiography in Patients with Mild Heart Rhythm Irregularities Using ECG Editing

OBJECTIVE

The objective of our study was to compare diagnostic accuracy of MDCT coronary angiography in a population of patients with mild heart rhythm irregularities before and after editing the ECG.

SUBJECTS AND METHODS

Thirty-eight patients who underwent MDCT coronary angiography and conventional coronary angiography were enrolled in the study. The inclusion criterion was the presence of mild heart rhythm irregularities (i.e., premature beats; atrial fibrillation; mistriggering; or low heart rate, defined as 40 beats per minute or less) during the scan. All patients underwent MDCT with the following parameters: 16 detectors; collimation, 0.75 mm; gantry rotation time, 375 msec; 120 kV; and effective milliampere-second setting, 500-600. Images were reconstructed in two settings: before ECG editing and after ECG editing (i.e., arbitrary modification of temporal windows within the cardiac cycle at the site of mild heart rhythm irregularities). Data sets were scored for the presence of significant stenoses (> or = 50% lumen reduction) in coronary segments > or = 2 mm diameter. The results of the two groups were compared with a McNemar test, and a p value of less than 0.05 was considered significant.

RESULTS

The sensitivity, specificity, and negative and positive predictive values of MDCT coronary angiography for the detection of significant stenoses before and after ECG editing were 63% (41/65) and 92% (78/85); 97% (251/260) and 96% (305/317); 87% (62/71) and 87% (81/93); 91% (251/275) and 97% (305/313), respectively (p < 0.05). The proportion of nonassessable segments was reduced from 17% (70/416) before ECG editing to 2% (10/416) after.

CONCLUSION

ECG editing significantly improves diagnostic accuracy in a selected population of patients with mild heart rate irregularities.

[Analysis of cases with fetal extrasystole coexisting with cardiac and extracardiac pathology]

OBJECTIVE

The paper presents a review of cases with fetal extrasystole coexisting with different cardiac and extracardiac pathology.

DESIGN

The aim of the study is to analyse the results of echocardiographic examinations of fetuses with premature atrial contractions (PAC) quantitatively significant (bigeminy, trigeminy) or coexisting with other abnormal findings in fetal heart or other extracardiac pathologies.

MATERIAL AND METHOD

Selected group of 33 (24%) fetuses from 135 with fetal extrasystole was analyzed. The mean gestational time of diagnosis was 29.2 + 4.1 weeks.

RESULTS

Quantitatively significant arrhythmia (bigeminy, trigeminy) was diagnosed in 14 fetuses. Blocked PAC (2:1) occurred in two cases causing fetal bradycardia. Premature atrial extrasystole coexisting with different type of arrhythmias were diagnosed in 10 cases (4 x with SVT, 4 x with sinus bradycardia, 2 x with ventricular extrasystole). Heart defects in the analyzed group with PAC were recognized in two fetuses (1 x d-TGA, 1 x heterotaxy syndrome--common a-v canal). Myocarditis was diagnosed in 3 (9%) cases. From the group of 33 fetuses 6 newborns died (1 x d-TGA, 1 x T18, 1 x myocarditis, 1 x circulatory centralization). Mortality in the analyzed group was 18.2%.

CONCLUSION

In cases of fetal arrhythmias echocardiography should be widely applied in order to evaluate the kind of arrhythmia, sufficiency of circulation and coexistence of heart defects, extracardiac malformations or functional abnormalities with arrhythmia in fetal circulation.

Clinical implications of fetal magnetocardiography

OBJECTIVES

To test the usefulness and reliability of fetal magnetocardiography as a diagnostic or screening tool, both for fetuses with arrhythmias as well as for fetuses with a congenital heart defect.

METHODS

We describe 21 women with either a fetal arrhythmia or a congenital heart defect discovered during prenatal evaluation by sonography. Four fetuses showed a complete atrioventricular block, two an atrial flutter, nine ventricular extrasystole, and one a complete irregular heart rate. Five fetuses were suspected to have a congenital heart defect. In all cases magnetocardiograms were recorded.

RESULTS

Nine fetuses with extrasystole showed a range of premature atrial contractions, premature junctional beats or premature ventricular contractions. Two fetuses with atrial flutter showed typical flutter waves and four fetuses with complete atrioventricular block showed an uncoupling of P-wave and QRS complex. One fetus showed a pattern suggestive of a bundle branch block. In three of four fetuses with confirmed congenital heart defects the magnetocardiogram showed abnormalities.

CONCLUSION

Fetal magnetocardiography allows an insight into the electrophysiological aspects of the fetal heart, is accurate in the classification of fetal arrhythmias, and shows potential as a tool in defining a population at risk for congenital heart defects.

Fetal and neonatal arrhythmia in one of the twins--a case history

There are a lot of publications about fetal arrhythmia in singletons, but up to now there are no published data about fetal arrhythmia in multiple pregnancies. In the present study a case history of fetal and neonatal arrhythmia in one of twins from two mothers treated with betamimetic agents due to imminent preterm labor is reported and discussed. A first case with fetal bradycardia due to complete A-V block had congenital cordis abnormalities (VSD and PFO). The second case with prenatal detected extrasystoles had normal heart anatomy. Digoxin was administered to the mother, in the aim to treat fetal arrhythmia without success, because the baby had postnatal bradycardia. After hospitalisation in Cardiology Department the described cases were successfully treated. In both cases the second twins were without neonatal arrhythmia and with no structural heart abnormalities. We summarise that in situation of detection fetal arrhythmia the complexity of the problems experienced may warrant early referral to a tertiary centre where the overall management of the mother, fetus and neonate, may be undertaken.

Premature depolarization concealed in two pulmonary veins

A case is presented in which a premature depolarization emanated from a partially activated left inferior pulmonary vein, activated the entire left superior pulmonary vein, but did not activate the atria ("concealed"). The site of conduction block between each vein and the left atrium was the anatomic atriovenous junction. At times, the same depolarization would activate the atria and initiate atrial fibrillation. The shortest depolarization coupling interval that activated the atria was significantly longer than the atrial fibrillation cycle length recorded in either vein. Observations in this case support two concepts: (1) the existence of myocardial "tracts," extending into and between pulmonary veins; and (2) a "mismatch" between pulmonary vein activation ingress and egress.

Increased left ventricular dimensions in patients with frequent nonsustained ventricular arrhythmia and no evidence of underlying heart disease

INTRODUCTION

To test the hypothesis that frequent nonsustained ventricular premature beats (VPBs) in patients without underlying heart disease are the first marker of mild systolic dysfunction of the left ventricle, we evaluated whether a subclinical abnormality of left ventricular function and/or an intraventricular conduction defect was present at the first clinical documentation of the arrhythmia.

METHODS AND RESULTS

We compared 57 patients (mean age 46 +/- 14 years) with > 30 VPBs/hour and no heart disease (A) to 32 healthy volunteers (mean age 42 +/- 12 years) without arrhythmia (B). Left ventricular echocardiographic parameters and signal-averaged ECG were evaluated. Filtered QRS duration (98 +/- 10 msec in A vs 98 +/- 7 msec in B) was similar in the two groups. End-diastolic left ventricular diameter (EDLVD) was 50 +/- 6 mm in A versus 47 +/- 3 mm in B (P < 0.005); 15 patients (26%) and none of the controls had EDLVD > or = 55 mm (P < 0.005). Filtered QRS interval was longer in the subgroup of patients (n = 15) with increased EDLVD (> or = 55 mm) compared with the subgroup (n = 42) with EDLVD < 55 mm (106 +/- 9 msec vs 95 +/- 9 msec; P < 0.001) and was related to greater left ventricular mass.

CONCLUSION

We documented a subclinical but significant increase of left ventricular dimensions that suggests that frequent VPBs may be an initial marker of mild systolic dysfunction of the left ventricle. However, an effect of VPBs per se in modifying left ventricular dimensions cannot be excluded.

Diagnostic and perinatal management of fetal extrasystole

Fifty fetuses referred to the Polish Mother's Memorial Hospital for fetal echocardiography between January 1, 1991 and June 1, 1995 were evaluated. The mean fetal gestational age at the time of diagnosis of arrhythmia was 34.1 weeks, and the mean gestational age at the time of delivery was 38.7 weeks. Checkup echocardiographic examinations were performed every 10-14 days, for a mean 2.4 studies per fetus. In most cases (48/50, 96%), premature atrial contractions were present during the first echocardiography examination. The fetal heart study was normal in 30 cases; in 7 (14%) there was tricuspid valve regurgitation, in 7 (14%) an atrial septal aneurysm, in 4 congenital heart defects, in 1 myocardial hypertrophy, and in 1 disproportion in the four-chamber view. Of the 50 fetuses, 43 underwent regular echocardiographic monitoring alone; in 7 cases, based on the presence of additional echocardiographic findings, pharmacotherapy was applied (digoxin, verapamil, or both). Three neonates died after delivery owing to malformations in two cases (one critical aortic stenosis, one spina bifida plus hygroma colli) and due to myocarditis in one case. In six of seven newborns treated in utero, myocarditis was diagnosed after birth (including the one with neonatal demise). Most of the newborns were in good condition after birth, their mean Apgar score being 8.6 and the mean birth weight 3259 g. We concluded that most extrasystoles represent an isolated anomaly, not affecting the fetal condition. Their presence should not influence the obstetric care and may require only echocardiographic monitoring. In most of our cases the premature contractions subsided after birth, although sometimes they preceded fetal supraventricular tachycardia or appeared after congenital myocarditis.

Postextrasystolic potentiation and dobutamine echocardiography in predicting recovery of myocardial function after coronary bypass revascularization

BACKGROUND

Identification of viable but hibernating myocardium remains a relevant issue in the current era of myocardial revascularization. Echocardiography can be helpful in detecting reversible contractile dysfunction and optimizing the selection of patients for coronary bypass surgery.

METHODS AND RESULTS

Eighty-four consecutive candidates for bypass surgery with chronic multivessel coronary artery disease were screened, and 60 were included in this prospective study. Preoperative evaluation of a reversible contractile dysfunction in asynergic myocardial regions was performed by dobutamine infusion at 5 (low dose) and 10 (intermediate dose) microg x kg(-1) x min(-1) with each stage lasting at least 5 minutes; postextrasystolic potentiation (PESP), with a coupling interval ranging from 500 to 300 ms with a progressive 10-ms decrease; or a combination of both dobutamine infusion and PESP. Sensitivity (92% versus 86%) and predictive accuracy (89% versus 84%) were higher with PESP than dobutamine (P=.009 and P=.001, respectively), but the combination did not improve sensitivity or accuracy. Dobutamine induced ischemic dysfunction in 15% of patients at the intermediate dose; however, the low dose resulted in loss of sensitivity.

CONCLUSIONS

PESP echocardiography is a useful and cost-effective method to identify viable myocardium in patients with multivessel coronary disease undergoing revascularization and is more sensitive and accurate than dobutamine infusion.

Thresholds for premature contractions in murine hearts exposed to pulsed ultrasound

A single pulse of high intensity ultrasound can produce either a premature ventricular contraction or a reduction in the aortic pressure in frog hearts. The objective of this study was to determine whether similar ultrasound exposures can produce premature contractions in the mammalian heart. The cardiac activity of murine hearts in vivo was monitored noninvasively using electrocardiography and plethysmography. Each ultrasound exposure was a single pulse of ultrasound, several milliseconds in duration, delivered to the murine heart during diastole. The thresholds for producing a premature contraction with a 5-ms ultrasound pulse at 1.2 MHz was approximately 2 MPa peak positive pressure. The occurrence of premature contractions decreased as the duration of the ultrasound pulse decreased. These results found with the mammalian heart are similar to those reported earlier for the frog heart. No damage to cardiac tissue was observed grossly, although significant hemorrhage occurred to adjacent lung tissue.

Comparison of catheterization and Doppler-derived pressure gradients in a canine model of subaortic stenosis

The relationship between Doppler-estimated and catheterization-measured pressure gradients was examined by repeated-measures linear regression analysis and difference plots in 15 dogs with naturally occurring subvalvular aortic stenosis. Thirty left ventricular outflow tract gradients were compared during sinus rhythm and 142 gradients during premature or postextrasystolic beats for the following pairs of data: (1) mean catheterization gradient versus mean Doppler gradient, (2) maximal instantaneous catheterization gradient versus maximal Doppler gradient, and (3) peak-to-peak catheterization gradient versus maximal Doppler gradient. The correlation between Doppler-derived and catheterization-derived pressure gradients was excellent (r = 0.99; p < 0.001) for the maximal instantaneous (sinus rhythm: standard error of the estimate [SEE] = 5.7 mm Hg; premature and postextrasystolic beats: SEE = 6.7 mm Hg) and mean gradients (sinus rhythm: SEE = 3.6 mm Hg; premature and postextrasystolic beats: SEE = 4.5 mm Hg). There was also a strong correlation between the peak-to-peak catheterization gradient and the maximal Doppler gradient (sinus rhythm: r = 0.99, p < 0.001, SEE = 5.3 mm Hg; premature and postextrasystolic beats: r = 0.97, p < 0.001, SEE = 7.2 mm Hg). Agreement between the two techniques was best for mean gradients and most disparate for the comparisons of maximal Doppler gradients and peak-to-peak catheterization gradients.

[Fetal supraventricular extrasystole: indication for fetal echocardiography?]

The purpose of this study was to assess the incidence of congenital heart disease (CHD) in fetuses with premature atrial contractions (PAC) and to check whether these fetuses should be referred for a special fetal echocardiogram. Out of 120 fetuses with PACs and 75 fetuses with CHD both conditions were present in only 9 fetuses (= 7.5%). Two pregnancies were terminated because of associated severe fetal anomalies. After birth PACs disappeared in all other cases spontaneously. Despite higher numbers, the incidence of fetal CHD was not statistically significant higher in fetuses with PACs. Thus, recognition of fetal PACs should lead to a referral for a special fetal echocardiographic examination.

[The spectral characters of pulsed Doppler in fetal arrhythmia]

Blood flow spectra of left ventricular inflow and outflow of the fetus were measured by pulsed Doppler echocardiography in 82 cases who were diagnosed as fetal arrhythmia clinically. By analysing the order of atrio- ventricular excitation, the spectral characters and the relationship of time- phase, the classification of fetal arrhythmia was confirmed. Among the 82 cases, there were 17 cases of sinus bradycardia, 16 cases of sinus tachycardia, 28 cases of atrial premature beats, 16 cases of ventricular premature beats, 3 cases of II degrees atrioventricular conduction block, 2 cases of atrial fibrillation. These common spectral characters of fetal arrhythmia were confirmed by the examination of neonatal Doppler echocardiography and ECG. This study indicated that this method could be used as one of the diagnostic methods for fetal arrhythmia.

Effects of diltiazem, metoprolol, enalapril and hydrochlorothiazide on frequency of ventricular premature complexes

Ventricular arrhythmias occur frequently in patients with hypertensive left ventricular (LV) hypertrophy and have been associated with increased incidence of sudden death. In this study, the effect of various antihypertensive medications on ventricular arrhythmias was evaluated in 31 hypertensive patients with moderate to severe LV hypertrophy. Patients were assessed at baseline (after 3 weeks of placebo treatment) and after treatment with each of 4 monotherapies: diltiazem 120 or 240 mg/day, metoprolol 100 or 200 mg/day, enalapril 10 or 20 mg/day and hydrochlorothiazide 50 or 100 mg/day. Each drug therapy was administered for 4 weeks. The sequence of each treatment was determined at random. Echocardiographic measurements and electrocardiograms were obtained only at baseline. Biochemical measurements and 48-hour Holter monitoring were obtained at baseline and at the end of each treatment. All treatments resulted in a significant but similar decrease in blood pressure. In the group as a whole diltiazem decreased ventricular premature complexes (VPCs) by 65% (p < 0.05) and metoprolol by 52% (p = 0.07). Enalapril and hydrochlorothiazide had no effect. In 12 patients with > or = 5 VPCs/hour at baseline, diltiazem and metoprolol decreased VPCs by 66% (p < 0.05). It is concluded that in hypertensive patients with moderate to severe LV hypertrophy, both diltiazem and metoprolol significantly reduce VPCs.

Influence of left ventricular filling profile during preceding control beats on the occurrence of pulse deficit caused by ventricular premature contractions

This study was designed to investigate whether the left ventricular filling profile during preceding control beats significantly affects the pulse deficit caused by ventricular premature contractions (VPCs). The study group consisted of 18 patients (10 men, eight women, 15-85 years old) who underwent electrophysiological catheterization because of sinus bradycardia. Using a temporary pacing lead inserted in the right ventricular apex, isolated VPCs with various coupling intervals were produced by electrical stimulation of the right ventricle. During the production of the VPCs, the mitral filling flow velocity using pulsed wave Doppler echocardiography, the femoral arterial pressure curve and the electrocardiogram were simultaneously recorded. The right ventricle was stimulated 800, 750, 700, 650, 600, 550, 500, 450 and 400 ms after the triggered control beat QRS complex. Pulse pressures during VPCs gradually decreased in relation to the shortening of the extrasystolic beat coupling interval. The longest coupling interval for each subject, which caused complete abolition of the pressure pulse during the VPC, was defined as the pulse deficit coupling interval. The early to late diastolic velocity-time integral ratio (Ei/Ai ratio) of the mitral filling flow velocity during the control beats which precede the VPC was obtained as an index expressing the left ventricular filling profile. The Ei/Ai ratio of the mitral filling flow velocity ranged from 0.7 to 4.5 (1.8 +/- 1.0). The pulse deficit coupling interval ranged from 440 to 640 ms (510 +/- 60 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of R wave changes in exercise-induced supraventricular extrasystoles. Angiographic correlates

To evaluate the clinical significance of observed R wave amplitude changes in exercise-induced supraventricular extrasystoles in comparison to the preceding sinus beat, 94 patients catheterized for possible coronary artery disease (CAD) were studied. Significant CAD was documented in 63 patients--34 with myocardial infarction (group A1) and 29 without (group A2)--whereas 31 patients had normal coronary arteries or coronary lesions less than 30% (group B). All patients underwent treadmill stress testing using the Bruce protocol within a month after cardiac catheterization. R wave amplitude increased or remain unchanged in extrasystole (R(x-s) > or = 0) in patients with CAD, while it decreased (negative R(x-s) in patients without significant CAD (P < .0001). In patients with CAD R(x-s) values were positively related to the number of obstructed coronary arteries (P < .01), while no significant difference was found between groups A1 and A2. The correlations of R wave amplitude changes in extrasystoles were significant with coronary obstruction score values (r = .82 and .85 in groups A1 and A2, respectively) and with left ventricular ejection fraction values (r = -.88, -.86 and -.90 in groups A1, A2, and B, respectively). R(x-s) > or = 0 value had a sensitivity of 79% and a specificity of 90% for CAD detection, while sensitivity was higher (89%) and specificity was lower (57%) for the prediction of left ventricular dysfunction. It is concluded that R(x-s) > or = 0 value is indicative of CAD, multivessel disease, and poor left ventricular performance, while its negative value is combined with minimal or no CAD and normal ejection fraction values.

Evaluation of fetal cardiac arrhythmias. Ultrasound findings and neonatal outcome

During a four-year period, 3,882 fetal diagnostic ultrasounds were performed and 162 patients (4% of all patients scanned) were referred to our perinatal center for evaluation of fetal cardiac arrhythmia. Fetal echocardiography subsequently revealed an arrhythmia in 80 (49%) of these patients. The rhythm disturbances noted were premature atrial or ventricular contractions (n = 65, 81%), tachyarrhythmia (n = 8, 10%), and bradyarrhythmia (n = 7, 9%). Three of the bradycardic fetuses evaluated had complete heart block associated with anatomic abnormalities. In seven tachycardic fetuses, the finding of fetal compromise was followed by intervention. The majority of fetuses with cardiac rhythm disturbance will have premature atrial or ventricular contractions and will have normal echocardiographic evaluation and neonatal outcome. Sustained tachyarrhythmias and bradyarrhythmias are more likely to be associated with fetal morbidity. Based upon the findings of this study and others, we propose a scheme for follow-up of the fetus referred with an irregular cardiac rhythm.

[Anomalous origin of the left coronary artery from the pulmonary artery (Bland-White-Garland syndrome) in a 29-year-old male with absolute tachyarrhythmia]

We report on a man without any symptoms until the age of 29 years when a ventricular tachyarrhythmia occurred for the first time. There were electrocardiographic signs of a previous myocardial infarction of the anterior wall, but there had not even been any episode of angina pectoris. The cause was the anomalous origin of the left coronary artery from the pulmonary trunk (Bland-White-Garland syndrome). Therapy consisted of ligation of the left coronary artery and the implantation of an aortocoronary vein graft to the left coronary artery in order to reinstall a two-coronary system. Diagnosis is easily made by coronary angiography. At a 3-year follow-up there was an increase of the ejection fraction/cardiac output, a stable sinus rhythm, and an improved physical endurance.

[Localization of premature and ectopic ventricular depolarization using a new nuclear medicine tomographic technique]

In planar radionuclide ventriculography (RNV) identification of the site of initial contraction is possibly by the Fourier phase. First clinical experiences will be presented with a new integrated tomographic technique--ISPECT--in noninvasively assessing the site of ectopic or premature ventricular depolarization. In six patients Fourier phases of RNV and ISPECT were performed and compared in five with results from the corresponding electrophysiologic study. It was possible to exactly localize the beginning of mechanical contraction in the two orthogonal planes: during pacemaker stimulation at the apex of the right ventricle, at the lateral border of a large aneurysm during ventricular tachycardia, and at the site of three of five WPW bundles. In the other two bundles the site of first contraction was near the area found during invasive mapping procedure. Thus, this new ISPECT approach together with planar radionuclide imaging may help in noninvasively localizing the site of ectopic and premature depolarization in addition to surface ECG.

Premature ventricular complex morphology. A marker for left ventricular structure and function

The shape of a premature ventricular complex (PVC) might reflect the presence or absence of myocardial disease. To test this, 100 patients with a PVC on a 12-lead electrocardiogram at cardiac catheterization or nuclear angiography were classified according to PVC morphology. Group 1 (n = 50) had PVC QRS complexes with either smooth and uninterrupted contour or with narrow (less than 40 msec) notching. Group 2 (n = 50) demonstrated PVC with broad (greater than or equal to 40 msec) notching or shelves. Clinical, electrocardiographic and angiographic variables were assessed to define group differences. All patients had one or more etiological forms of heart disease none of which distinguished either group. Groups 1 and 2 differed with respect to a history of congestive heart failure (12% vs. 66%, p = 0.0004), dilated cardiomyopathy (2% vs. 38%, p = 0.0005), and the presence of mitral regurgitation (13% vs. 58%, p = 0.001), respectively. In group 1, 45 of 50 (90%) patients with a PVC had no notching. Patients in group 2 had greater PVC QRS duration as compared with patients in group 1 (181 +/- 6 vs. 134 +/- 3 msec, p = 0.0001). End-diastolic volume index (EDVI) (78 +/- 3 vs. 139 +/- 11 ml/m2, p = 0.0000) and ejection fraction (EF) (0.59 +/- 0.02 vs. 0.34 +/- 0.03, p = 0.0000) significantly discriminated between group 1 and 2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of postextrasystolic potentiation in the right ventricle

The mechanism of postextrasystolic potentiation (PESP) has been studied in the left ventricle in humans; however, this phenomenon has not been evaluated in the right ventricle. Accordingly, 18 sinus beats were compared to postextrasystolic beats during the same cineventriculogram using simultaneous high-fidelity right ventricular (RV) and pulmonary artery pressures and cast-validated biplane cineventriculographic volumes in normal patients. The increase in cycle length was 22 +/- 12% (standard deviation) in the postextrasystolic beats. Right ventricular ejection fraction increased from 61 +/- 10 to 68 +/- 4% (p less than 0.001) and RV stroke volume increased from 99 +/- 18 to 128 +/- 20 ml (p less than 0.001) due to an increase in RV end-diastolic volume (165 +/- 34 to 189 +/- 30 ml, p less than 0.001) as RV end-systolic volume (65 +/- 24 to 61 +/- 17 ml, difference not significant) and RV end-systolic pressure (16 +/- 7 to 17 +/- 6 mm Hg, difference not significant) remained unchanged. Despite an increase in RV systolic pressure from 29 +/- 7 to 31 +/- 7 mm Hg (p less than 0.01) and an increase in RV end-diastolic pressure from 8 +/- 4 to 10 +/- 5 mm Hg (p less than 0.001), RV +dP/dtmax did not change (318 +/- 102 to 294 +/- 82 mm Hg/s, difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular ectopy in totally symptom-free subjects with defined coronary artery anatomy

Ambulatory ECG recordings were obtained from 313 consecutive, totally symptom-free male subjects on whom cardiac catheterization was subsequently performed for occupational reasons. These recordings were examined for ventricular ectopy and the results were studied in relation to the findings on selective coronary angiography. Ventricular ectopy was a common finding, with 58% of those subjects with normal coronary artery anatomy having at least one ventricular premature beat during the period of monitoring (mean 16 1/2 hours), 22% having greater than one such complex per hour, and 10% having greater than 10 per hour. Complex ventricular ectopy was present in 21% of the normal subjects. No association between the extent or complexity of ventricular ectopy and the presence or grade of anatomic coronary artery disease was demonstrated, nor was ventricular ectopy overrepresented in those with both significant coronary artery disease on angiography and evidence of ischemia on provocative testing.

Biventricular function during postextrasystolic potentiation in man. A study using list-mode radionuclide ventriculography

The effects of postextrasystolic potentiation during spontaneous ventricular ectopy on both left and right ventricular function were studied in 12 patients with the aid of list-mode radionuclide ventriculography. The left ventricular ejection fraction showed a significant increase (+ 11.0 +/- 5.0%; p less than .001) with associated mild increases in end-diastolic volumes (+ 4.9 +/- 4.6; p less than .01) and significant decreases in end-systolic volumes (-13.4% +/- 7.3%; p less than .001). A more heterogeneous response was seen for the right ventricle. Right ventricular ejection increased significantly in 8/12 patients (+ 3.3 +/- 3.0%; p less than .02). Despite a large increase in end-diastolic volumes (+ 10 +/- 7.9%; p less than .001), there were only mild changes in end-systolic volumes (+ 2.2 +/- 9.0; p = NS). It is concluded that, for spontaneous ventricular ectopy in man, the increase in right ventricular ejection fraction reflects improved ventricular filling whereas the increase in left ventricular ejection fraction is linked to improved emptying.

Characterization of right or left ventricular contraction heterogeneity using Fourier phase analysis. Application to a group of patients with severe ventricular arrhythmias

The standard deviation of the first harmonic Fourier phase histogram is an indicator of the contraction heterogeneity of the heart ventricles. This approach has been applied to analyse tomographic blood pool (99mTc) examinations in a group of 32 patients with angiographically verified mainly right (RV) but also left (LV) kinetic disorders in relation to severe ventricular arrhythmias and suspicion of arrhythmogenic right ventricular dysplasia (ARVD). The reference group consisted of ten patients with low probability of cardiac kinetic abnormalities. Thick tomographic slices including both ventricles have been reconstructed in the horizontal long axis orientation from a series of 32 gated projections recorded over a 360 degrees rotation. Separately for each ventricle the Fourier phase histograms have been computed and characterized by their standard deviations (PSD). Normal values (mean +/- standard deviation, LV = 11 degrees +/- 5 degrees, RV = 12 degrees +/- 5 degrees) were significantly lower (P less than 0.01 and P less than 0.001) than those measured in abnormal cases (LV = 19 degrees +/- 10 degrees and RV = 31 degrees +/- 17 degrees). Detailed analysis of the data supports the hypothesis of a primary RV disease in ARVD, with secondary LV extension. PSD seems to be a good predictor of an organic cardiac disease underlying ventricular arrhythmias and may be used for screening the patients.

The noninvasive localization of ventricular pacing sites by radionuclide phase imaging

This study was designed to investigate the potential role of radionuclide angiographic phase imaging in defining ventricular pacing sites. Twenty patients were paced from multiple right ventricular and left ventricular sites. Ten patients had both normal wall motion and normal electrocardiograms (ECGs), while 10 patients had segmental wall motion abnormalities and/or bundle branch block. Both continuous pacing and premature ventricular stimuli were performed. Multiple (two to three) views of each pacing site were obtained by radionuclide angiography and the ventricular site was determined by subsequent phase imaging. Simultaneous 12-lead ECGs were also obtained. The phase-imaging technique accurately localized all 35 right ventricular and 21 of 25 (84%) left ventricular sites to a specific segment. Statistically, this localization ability was independent of baseline wall motion or conduction system disease. In addition, sites as close as 1.5 cm were identified. The 12-lead ECG distinguished left ventricular from right ventricular pacing sites in all patients. Segmental localization by ECG in the right ventricle was accurate in 24 of 35 (69%) and in the left ventricle in 17 of 25 (68%). Thus, radionuclide angiographic phase imaging provides excellent descriptive information regarding the focus of ventricular pacing ectopy and can define both sites of continuous pacing and intermittent premature ventricular stimulation. These findings provide a basis for further assessment of the role of phase imaging in the evaluation of patients with spontaneous ventricular ectopy.

Postextrasystolic potentiation during spontaneous ventricular ectopy in man. Associated left ventricular volume changes determined by list mode radionuclide ventriculography

Five patients with spontaneously arising frequent ventricular ectopia were studied by list mode radionuclide ventriculography. Changes in left ventricular volumes reflected the increased inotropy of the postextrasystolic sinus beats: stroke volume increased by +36.0 +/- 32.8% (P less than 0.05) and end-systolic volumes decreasing by 13.6 +/- 7.3% (P less than 0.02) leading to an increased ejection fraction (+31.1 +/- 23.8%; P less than 0.05). There were no significant increases in end-diastolic volumes (+2.2 +/- 5.4%; P:NS). The reproducibility of the left ventricular volume estimates was confirmed by comparing the control sinus beats with the interrupted sinus beats. There were no significant changes in end-diastolic (+1.8 +/- 5.5%), end-systolic (+1.8 +/- 3.7%) and stroke volumes (+5.4 +/- 14.6%). List mode radionuclide ventriculography can be used to accurately monitor left ventricular volume changes associated with spontaneously arising ventricular ectopia. In these patients, the contribution of Frank-Starling mechanism to postextrasystolic potentiation was minimal.

Ventricular postextrasystolic potentiation in the dog. A study using list mode radionuclide ventriculography

The first and second postextrasystolic sinus beats (PESB) were isolated and analyzed in five open-chested dogs with the aid of list mode radionuclide ventriculography. Ventricular stimulation was delivered using a coupling interval of 150 msec from electrodes positioned at two (in two animals) or five (in three animals) different ventricular sites. There were marked increases in both left ventricular ejection fraction (41.5 +/- 4% vs. 56.8 +/- 3.9%; control vs. PESB, p less than 0.001) and stroke volume (+ 51.6 +/- 16.8%; PESB vs. control, p less than 0.001) in all first postextrasystolic sinus beats. Concomitant decreases in end-systolic volumes (-16.2 +/- 5.2%; PESB vs. control beat, p less than 0.001) confirmed the increased inotropy seen during these beats. During the second postextrasystolic sinus beats a mild but statistically significant increase in ejection fraction (+ 1.6 +/- 1.6%; PESB vs., control, p less than 0.01) was also seen despite a small decrease in end-diastolic volume (-2.8 +/- 2.5%; PESB vs control, p less than 0.01). In the dog postextrasystolic potentiation affects mostly the first PESB and causes only a mild increase in inotropy during the subsequent sinus beat. List mode radionuclide ventriculography is a useful and reproducible method for assessing changes in ventricular function following ventricular ectopics that have a fixed coupling interval to the preceding QRS complex.

Evaluation of cardiac function in the presence of frequent ventricular premature beats

Frequent ventricular ectopia in an otherwise healthy person is often benign. Nevertheless, for optimal patient management, serious underlying heart disease should be excluded. The authors illustrate the use of list-mode equilibrium blood-pool ventriculography for defining left ventricular function.

Cardiac function, fiber shortening, and dynamic geometry

Many models for the study of the pump function of the heart emphasize the importance of cardiac geometry and detailed dimensional data. Because of the lack of accurate measuring techniques, approximate geometries such as shells of revolution have been applied. In this study, methods are presented that measure the dynamic geometry of the working, isolated canine heart by means of ultrasound-velocity tomography techniques. In addition, cardiac dimensions, intramural deformations, and fiber shortening have been measured dynamically in the in situ canine heart throughout the cardiac cycle with implanted radiopaque markers and biplane roentgen techniques. Results of regional contraction and relaxation patterns are presented. Epicardial fiber shortening between apex and base were computed and found to be dependent on the duration of the preceding RR interval.

[Ventricular extrasystoles in the convalescence phase of myocardial infarction. Relation to angiographic data]

A series of 80 patients hospitalised for recent myocardial infarction underwent: --three continuous ambulatory 24 hour recordings (Holter method) on the 15th, 22nd days, and 6 months after infarction; --selective coronary angiography with left ventriculography, with a study of left ventricular performance and analysis of segmental contractility (Leighton's method). Five patients died over a mean follow-up period of 16 months. At the third week when physical activities were reintroduced 72,3 p. 100 of patients had frequent ventricular extrasystoles (Lown's Class II) or repeated ventricular extrasystoles (Classes III, IV, V). Holter monitoring gave reproducible results with a tendency to aggravation between the Ist and the 6th month (repetitive ventricular activity increasing from 35 to 45 p. 100). 55 p. 100 of posterior infarcts had few extrasystoles whilst 47 p. 100 of anterior infarcts had severe arrhythmias (Classes III, IV and V). There was a significant correlation between the presence of multivessel disease and severe ventricular extrasystoles 60 p. 100 of patients with multiple vessel lesions had repetitive ventricular activity (p less than 0,02). Positive correlations were established between: severe ventricular arrhythmias and a reduction in ventricular ejection fraction (p less than 0,01), dyskinesia in the infarcted zone (p less than 0,01) and reduction in wall motion of the non infarcted zones. The presence of incomplete occlusion of early revascularisation by collateral circulation in the infarcted zone seemed to favour severe ventricular arrhythmias. Five patients died (arrhythmias or cardiac failure): the association of severe hypokinesia and reduced left ventricular performance with repetitive ventricular activity was demonstrated. It is concluded from the correlations obtained between ventriculography and continuous electrocardiographic monitoring that repetitive ventricular activity is associated with severe reduction in left ventricular performance. The immediate gravity and poor prognosis of the ventricular arrhythmias are the result of the extent of the myocardial damage.

The similarity of changes in segmental contraction patterns induced by postextrasystolic potentiation and nitroglycerin

Despite a fundamental difference in their underlying mechanisms, both postextrasystolic potentiation (PESP) and administration of nitroglycerin (TNG) have been utilized to predict reversibility of abnormal segmental wall motion in patients with ischemic heart disease. To determine whether these interventions induce the same changes in segmental contraction pattern, we analyzed biplane ventriculograms of 14 patients who had an adequately visualized PESP beat on a basal ventriculogram as well as a post-TNG ventriculogram. Four segments in each plane were defined and the area ejection fraction of each segment was calculated for a basal sinus, PESP, and post-TNG beat. To correct for global differences in the response to PESP and TNG, we normalized each segmental ejection fraction (NSEF) by the ventricular ejection fraction for that beat and then compared the differences in NSEF from the basal value after PESP and TNG. Eleven patients demonstrated similar responses to both interventions. The three patients whose responses were discordant had elevated or unchanged left ventricular systolic or end-diastolic pressures at the time of the TNG ventriculogram. Our data suggest that, provided these pressures are lower than basal values at the time of the TNG ventriculogram, PESP and TNG will induce similar changes in segmental contraction patterns. Seven patients with similar responses had a PESP beat on their post-TNG ventriculogram. Changes in NSEF after PESP+TNG were identical to those after either intervention. This implies that the combination of interventions does not induce further changes in segmental contraction pattern beyond that produced by either intervention alone.