In vivo assessment of coronary artery angioplasty and stent deployment from balloon pressure-volume data.

This study assessed the clinical and practical value of angioplasty balloon pressure-volume data, obtained by a computer-controlled balloon inflation device, during standard percutaneous coronary intervention (PCI) procedures. Stent deployment was studied for 57 lesions in 34 patients. Angiographic predilation data were available in 9 patients. Vessel lumen improvement with pre-dilation was determined using the area difference under the pressure-volume curves of two consecutive inflations and compared to the angiographically determined lumen improvement. Stent opening pressure, the inflation volume needed to unfold the stent and the shape of the pressure-volume curve were assessed for differences between stent sizes (diameter, length) and manufacturer types. A Pearson correlation of 0.8 between the pressure-volume area difference and the angiographic lumen improvement was significant (p = 0.01), confirming that pressure-volume curves are useful in assessing lumen improvement after pre-dilation. There was a significant difference in stent opening pressure between stent types but not between different stent sizes (length, diameter). The inflation volume measured during the unfolding process of the stent correlated with the calculated stent lumen when deployed (Pearson correlation: 0.65, p = 0.001). The shape of the pressure-volume curve during stent deployment illustrated differences between different stent sizes (length, diameter) during inflation. Pressure-volume curves obtained from an automatic balloon inflation device have shown their usefulness in providing additional feedback about lumen improvement and the mechanical characteristics and quality of stent deployment.

Surgery for postinfarction ventricular tachycardia in the pre-implantable cardioverter defibrillator era: early and long term outcomes in 100 consecutive patients.

OBJECTIVE: To report outcome following surgery for postinfarction ventricular tachycardia undertaken in patients before the use of implantable defibrillators. DESIGN: A retrospective review, with uniform patient selection criteria and surgical and mapping strategy throughout. Complete follow up. Long term death notification by OPCS (Office of Population Censuses and Statistics) registration. SETTING: Tertiary referral centre for arrhythmia management. PATIENTS: 100 consecutive postinfarction patients who underwent map guided endocardial resection at this hospital in the period 1981-91 for drug refractory ventricular tachyarrhythmias. RESULTS: Emergency surgery was required for intractable arrhythmias in 28 patients, and 32 had surgery within eight weeks of infarction ("early"). Surgery comprised endocardial resections in all, aneurysmectomy in 57, cryoablations in 26, and antiarrhythmic ventriculotomies in 11. Twenty five patients died < 30 days after surgery, 21 of cardiac failure. This high mortality reflects the type of patients included in the series. Only 12 received antiarrhythmic drugs after surgery. Perioperative mortality was related to preoperative left ventricular function and the context of surgery. Mortality rates for elective surgery more than eight weeks after infarction, early surgery, emergency surgery, and early emergency surgery were 18%, 31%, 46%, and 50%, respectively. Actuarial survival rates at one, three, five, and 10 years after surgery were 66%, 62%, 57%, and 35%. CONCLUSIONS: Surgery offers arrhythmia abolition at a risk proportional to the patient's preoperative risk of death from ventricular arrhythmias. The long term follow up results suggest a continuing role for surgery in selected patients even in the era of catheter ablation and implantable defibrillators.

Characteristics of local electrograms with diastolic potentials: identification of different components of return pathways in ventricular tachycardia.

BACKGROUND: Diastolic potentials are often sought as a possible site for catheter ablation in post-infarct ventricular tachycardia. However, delivery of energy at such sites is often unsuccessful. The purpose of this study was to determine the characteristics of local electrograms with diastolic potentials and to identify activation pattern which might indicate the critical portion of the return path of the ventricular tachycardia reentry circuit. METHODS: In 17 patients with post-myocardial infarction ventricular tachycardia, 30 ventricular tachycardias were mapped with an 112 bipolar endocardial balloon at the time of surgery. Diastolic mapping of the return tract in ventricular tachycardia was performed. Four activation patterns were observed (15 figure 8 patterns, 2 circular patterns, 2 biregional patterns and 11 monoregional patterns). Of 3,360 local electrograms, 207 (6.2%) demonstrated a diastolic potential in ventricular tachycardia. They were classified into following four categories, based on the appearance and timing of the systolic component. Type A-1 electrogram: systolic activation was of low amplitude (< 2 mV) and was prolonged (> or = 100 msec), but preceded the onset of the surface QRS in ventricular tachycardia. Type A-2 electrogram: systolic activation was of low amplitude, was prolonged, but followed the onset of the surface QRS. Type B electrogram: systolic electrogram was fractionated, but relatively normal amplitude (2.0-3.6 mV). Type C electrogram: systolic electrogram was almost normal. RESULTS: Of all electrograms with diastolic potentials, three type A-1 electrograms (1.4%) were located at the exit of the return pathway, 11 type A-1 electrograms (5.3%) were located at the pre-exit site. No type A-1 was found at an entrance/bystander area. 21 type A-2 electrograms (10.1%) were at the pre-exit and 83 type A-2 electrograms (40.2%) were located at the entrance/bystander area, but such electrograms were never found at the exit site. 71 type B electrograms (34.3%) and 18 type C electrograms (8.7%) were located at the entrance/bystander area. To distinguish the type A-2 electrograms at the pre-exit site from those at the entrance/bystander area, the diastolic potential to QRS interval was measured. This interval at the pre-exit was significantly shorter than that at the entrance/bystander area (-47.2 +/- 10.7 vs -96.3 +/- 31.3 msec, p = 0.0001). CONCLUSION: Type A-1 electrograms indicated the exit or pre-exit site of return pathway. Type A-2 electrograms with diastolic potential to QRS interval < -50 msec indicated the pre-exit site. However, the other types of local electrograms with diastolic potential did not indicate the critical portion of the ventricular tachycardia circuit. These observations may be helpful during catheter mapping and ablation of patients with post-infarct ventricular tachycardia. CONDENSED ABSTRACT: Diastolic potentials are often sought to direct catheter ablation in post-infarct ventricular tachycardia. We investigated the characteristics of local electrograms showing diastolic activity in an attempt to determine whether critical portions of the ventricular tachycardia circuit could be identified by a typical "signature." In 17 patients with a remote myocardial infarction, 30 ventricular tachycardias were mapped with 112 bipolar endocardial balloon at the time of surgery. Diastolic potentials in association with low amplitude (< 2 mV) and prolonged (> or = 100 msec) systolic electrograms preceding the onset of QRS were found at the exit site and pre-exit site of return pathway. A similar systolic electrogram occurring after QRS onset with a diastolic potential to QRS interval of < -50 msec was found at the pre-exit site. However, other local electrograms with diastolic activity were at sites remote from the exit or pre-exit of the return pathway. These observations may be helpful during catheter mapping and ablation in patients with ventricular tachycardia.

Drug-induced cardiac arrhythmias: incidence, prevention and management.

Drugs can cause cardiac arrhythmias in a number of clinical situations, and many of the implicated agents are used to treat non-cardiac conditions. These adverse effects are frequently idiosyncratic, but are often mediated via triggered activity causing torsade de pointes. Drugs being used for treatment of cardiac conditions may promote arrhythmias by re-entrant mechanisms or via triggered activity. Many drugs may cause cardiac arrhythmic complications when taken in excessive amounts. Keys to reducing the incidence of drug-induced cardiac arrhythmias include increased awareness among the medical, pharmaceutical and nursing professions of the potential problems in using certain agents, especially in specific situations. Appropriate monitoring when such treatment is essential and, after diagnosis, prompt withdrawal of the offending agent and treatment for the arrhythmia should be initiated.

Right ventricular disarticulation procedures: the role of late potentials in the genesis of postoperative ventricular arrhythmias.

Arrhythmogenic right ventricular disease may be associated with life-threatening and drug refractory ventricular arrhythmias. Right ventricular disarticulation procedures are effective antiarrhythmic surgical approaches in selected patients. This study examined the role of late potentials in the postoperative development of new ventricular arrhythmias, and showed that right ventricular isolation is effective, probably because it destroys the tissue giving rise to late potentials. Total disarticulation is associated with fewer postoperative arrhythmias than partial isolation procedures. Total disarticulation may be the surgical approach of choice in such patients.

Electrocardiographic features of septal location of right ventricular outflow tract tachycardia.

A consistent 12-lead electrocardiogram (ECG) morphology and characteristic frontal plane axis shift from sinus rhythm to ventricular tachycardia (VT) was demonstrated in 10 consecutive patients with idiopathic right ventricular outflow tract (RVOT) VT. All arrhythmias were successfully ablated on the septal side of the RVOT.

Coronary sinus morphology in patients with atrioventricular junctional reentry tachycardia and other supraventricular tachyarrhythmias.

BACKGROUND: Coronary sinus access by electrode catheters is easier in patients with atrioventricular junctional reentry tachycardia (AVJRT) than in patients with other supraventricular tachyarrhythmias. The reason for this has not been addressed. METHODS AND RESULTS: The size and shape of the proximal coronary sinus were measured in 15 patients with AVJRT and 14 control subjects after angiographic visualization. Coronary sinus dimensions, morphology, and angle of origin from the right atrium were measured. The proximal coronary sinus in patients with AVJRT was larger than in the control population. The mean ostium diameter was 12.2 +/- 2 mm compared with control dimensions of 8.5 +/- 1.5 mm, P = .00001. At a distance of 5 mm from the ostium, the coronary sinus measured 10.2 +/- 1.8 mm compared with 8.1 +/- 1.9 mm, P = .007. The dilatation persisted 10 mm into the coronary sinus, with a measurement of 9 +/- 1.4 mm compared with 7.6 +/- 2 mm, P = .04. In 73% of AVJRT patients, the proximal coronary sinus had the appearance of a wind sock. This morphology was seen only in 7% of control patients, in whom the coronary sinus was tubular (in 93%). There was considerable interindividual variability in the angle of origin. CONCLUSIONS: The proximal coronary sinus in patients with AVJRT was significantly different from a control population. The ostium was 44% larger and remained more dilated to at least 10 mm from the ostium. The appearance was like a wind sock in AVJRT patients and tubular in the control patients. These findings may have important implications for arrhythmia pathogenesis in such patients.

Ventricular tachycardia in ischaemic heart disease: insights into the mechanisms from cardiac mapping and implications for patient management.

Ventricular tachycardia following myocardial infarction in man is thought to be due to a reentrant mechanism, with a zone of slow conduction forming the critical element of the return pathway. Cardiac mapping has helped characterize the anatomical and functional nature of reentrant pathways, and is used to direct antiarrhythmic surgery and catheter ablation. This review will explore how cardiac mapping has contributed to our understanding of reentrant ventricular tachycardia. The role of diastolic mapping will be emphasised, and the implications for future management of ventricular tachycardia discussed.

Endocardial mapping of ventricular tachycardia in the intact human ventricle. III. Evidence of multiuse reentry with spontaneous and induced block in portions of reentrant path complex.

OBJECTIVES: This study was conducted to characterize the functional nature of the reentrant tract responsible for ventricular tachycardia due to ischemic heart disease. BACKGROUND: A zone of slow conduction forming the return path is though to form a critical component of the reentrant mechanism in ventricular tachycardia. Despite its importance, detailed knowledge of the return path is rare in clinical studies. METHODS: Multielectrode arrays were used intraoperatively to obtain unipolar and high gain bipolar recordings of left ventricular endocardium in patients undergoing map-directed surgical ablation of ventricular tachycardia. A total of 224 local electrograms were analyzed for each tachycardia. RESULTS: Of 10 consecutive patients undergoing intraoperative cardiac mapping, detailed recording of the return tracts of eight ventricular tachycardias were obtained in three patients. The recordings demonstrated that return tracts can be complex and extensive, with multiple paths of entry and exit. Potential and actual alternate paths were observed. Spontaneous and induced block occurred within portions of the complex. Intermittent block in one of two paths of entry resulted in intermittent cycle length changes of the tachycardia without a change in configuration. Block in one exit path resulted in a shift to alternative exit paths, with dramatic changes in ventricular activation and tachycardia configuration. Termination of the tachycardia could result from block close to the entrant or exit portion of the return tract. Different tachycardias were seen to share common portions of a return tract. CONCLUSIONS: These observations enlarge and extend our knowledge of the functional repertoire of complex reentrant tracts that occur in infarct-related ventricular tachycardia. The use of common portions of a reentrant tract by several tachycardias is confirmed. Utilization of alternate pathways can account for changes in configuration and cycle length. Spontaneous and induced block can occur at points of entry and exit in a reentrant tract and may identify optimal targets for ablation attempts. Further advances will require greater emphasis on diastolic activation mapping.

Errors in manual measurement of QT intervals.

OBJECTIVE: To quantify the errors associated with manual measurement of QT intervals and to determine the source of the errors. DESIGN: A randomised study of QT measurement by four cardiologists of electrocardiograms plotted on paper in presentations with different noise levels, paper speeds, amplifier gains, and with and without a second QRST complex to indicate the RR interval. SUBJECTS: Four electrocardiograph leads (I, aVR, V1, V5) recorded in eight healthy people relaxing in a semirecumbent position. MAIN OUTCOME MEASURES: Manual measurement of QT interval in 512 electrocardiograms (eight subjects x four leads x eight presentations x two repeats) by each of four cardiologists. RESULTS: QT intervals measured were significantly longer with greater amplifier gain: by 8 ms for a doubling of gain (p < 0.005), equivalent to a doubling of T wave height. QT intervals measured were significantly longer at slower paper speeds: by 11 ms when paper speed was reduced from 100 to 50 mm/s (p < 0.001) and by 16 ms when speed was further reduced from 50 to 25 mm/s (p < 0.001). Neither the presence of noise nor the presence of a second QRST complex altered the mean QT measurements. There were consistent differences in the measurements between cardiologists, amounting to a maximum mean difference of 20 ms. CONCLUSIONS: Manual measurement of QT interval is significantly affected by the paper speed used to plot the electrocardiogram and by electrocardiogram gain, and hence also T wave amplitude. Manual QT measurement also differed consistently with different cardiologists.

Intercostal neuralgia associated with internal mammary artery grafting.

Two patients who underwent coronary artery bypass grafting in which the internal mammary arteries were used, developed chronic, atypical chest pain. After further investigation a diagnosis of intercostal neuralgia was made. It is thought that this condition is due to damage to the intercostal nerves when the internal mammary arteries are dissected. Intercostal neuralgia should be included in the differential diagnosis of chest pain after coronary artery surgery, as its recognition may save the patient unnecessary investigation and suffering.

Transthoracic and transoesophageal echocardiography in the diagnosis and management of a biatrial myxoma.

A 40-year-old female presented with a year's history of atrial fibrillation. Transthoracic echocardiography identified the presence of a biatrial mass and transoesophageal echocardiography delineated its extent. At surgery, a huge myxoma originating from the fossa ovalis and straddling the inter-atrial septum was removed and the atrial septum repaired. This report highlights the role of transthoracic and transoesophageal echocardiography in the diagnosis and management of this extremely rare cardiac tumour.

Pericardial effusion--an uncommon complication of Salmonella enteritis.

A 62-year-old lady who was receiving corticosteroids for rheumatoid arthritis was admitted suffering from dehydration due to salmonella enteritis. Despite rehydration and appropriate chemotherapy she remained unwell and developed hypotension and elevation of her jugular venous pressure. Echocardiography and subsequent aspiration demonstrated a purulent pericardial effusion from which S typhimurium was cultured. Following aspiration and a change of antibiotic therapy, her condition improved dramatically.

Post-infarction communication between a left ventricular aneurysm and the right atrium.

A 70-year-old patient presented with ventricular tachycardia and left ventricular failure. He was found to have a communication between a posterior left ventricular aneurysm and the right atrium. The causal myocardial infarction had been silent. This defect was satisfactorily closed at operation from which he made an uneventful recovery. This is the first report of a left ventricular-right atrial communication developing in association with ischaemic heart disease and highlights the role of transoesophageal echocardiography in the diagnosis and surgical management of such a condition.

Incessant atrial tachycardia accelerated by pregnancy.

A 24 year old patient presented with incessant atrial tachycardia during the course of a twin pregnancy. Medical treatment slowed the ventricular response without restoring sinus rhythm. During labour the tachycardia spontaneously reverted to sinus rhythm. Subsequently the same arrhythmia was documented with a slower ventricular response than during pregnancy.

Effect of single lung transplantation on pulmonary hypertension in patients with end stage fibrosing lung disease.

OBJECTIVE: To investigate the effect of successful single lung transplantation on pulmonary haemodynamic variables and right ventricular function. DESIGN: Pulmonary haemodynamic variables and right ventricular function were measured at right heart catheterisation after single lung transplantation. The results were compared with the preoperative pulmonary haemodynamic variables measured at the time of assessment for transplantation. SETTING: A tertiary referral centre. PATIENTS: Five survivors of single lung transplantation performed for end stage lung disease. INTERVENTIONS: Cardiac catheterisation in all five patients at a mean of 18 months postoperatively. Preoperative catheter data were available for comparison in four. Right heart pressures and cardiac output were measured and right ventricular angiography was performed. Perfusion scans performed for clinical reasons were used to assess the percentage of cardiac output passing through each lung. MAIN OUTCOME MEASURES: Right heart pressures, cardiac output, right ventricular function, percentage perfusion to lungs. RESULTS: After operation mean peak right ventricular pressure fell from 53 mm Hg to 33 mm Hg, mean pulmonary artery pressure from 33 mm Hg to 18 mm Hg, total pulmonary resistance from 11.2 U x m2 to 5.8 U x m2, and pulmonary arteriolar resistance from 8.9 U x m2 to 3.6 U x m2. Pulmonary artery wedge pressure and cardiac index were unchanged. Right ventricular function improved in all patients. The transplanted lung received most of the cardiac output. CONCLUSION: In patients with moderate pulmonary hypertension and right ventricular dysfunction secondary to end stage fibrosing lung disease single lung transplantation was followed by an improvement in pulmonary haemodynamic variables and right ventricular function.

Acute and chronic hemodynamic impact of total right ventricular disarticulation.

Right ventricular disarticulation is a radical operation to control ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia. This report describes the acute and chronic hemodynamic impact of the procedure based on our experience of five patients with life-threatening arrhythmias unresponsive to medical therapy who have undergone total disarticulation of the right ventricle. Although all patients suffered acute postoperative hemodynamic problems, all survived and returned to an excellent functional class. Right ventricular disarticulation should be considered in patients with drug refractory ventricular tachycardias due to arrhythmogenic right ventricular dysplasia when the arrhythmia either poses a life threat or results in chronic morbidity.

Salmonella: a rare cause of subacute effusive-constrictive pericarditis.

A 36 year old woman had emergency pericardectomy because of subacute effusive-constrictive pericarditis. The pericardial fluid and tissue culture showed that this was caused by infection with Salmonella enteritidis. Cardiac involvement with salmonella does not usually present in such an aggressive manner and it has not previously been reported to cause this rare type of cardiac constriction.

The misuse of intravenous cannulae.

The use of indwelling venous cannulae is commonplace and of undoubted value. However, they are associated with complications, notably thrombophlebitis and infection. This study seeks to show that they may now have become overused and abused, especially in general wards. It is recommended that the indications for them be more critically examined, that they must be routinely heparinised and regularly inspected, and be removed without unnecessary delay.