Intractable Ventricular Tachycardia Research Articles

Abstract 646: Epicardial Ablation Of Ventricular Tachycardia - A Single Centre Experience

Background: Radiofrequency current ablation (RFA) of ventricular tachycardia (VT) focuses on endocardial (endo) substrates. However, if endo RFA fails, an epi approach is a potential treatment option. We report a single centre experience of epi VT ablation. Patients and Methods: Between 06/2005 and 02/2008 42 pts (14 female, mean age 49 ± 18 years) underwent electroanatomical endo and epi mapping and ablation for intractable VT, syncope or VT storm with multiple ICD discharges. Pts with normal heart (n=7), ischemic cardiomyopathy (ICM; n=8), NICM (n=11), ARVD (n=8), LV-aneurysm (n=7) or sarcoidosis (n=1) were studied. Mean LV ejection fraction was 45±12%. 20/42 had had at least 1 previous ablation attempt for VT (range 1– 4 ablations). Acute success was defined as non-inducibility of the previously inducible VT. Chronic success was defined as recurrence of any VT. Results: Acute procedural success rate was 79% (30/38). In 4 pts VTs were not inducible during EPS. In 28/42 pts endo mapping revealed no pathologic potentials. In 23/38 pts and 7/38 the succesful RFC ablation site was epi and endo, respectively. In 9/38 pts endo ablation failed and VT could only be ablated from epi. Further 7/38 pts needed both endo and epi ablation. In In 4/8 failed ablations epi RFC ablation was impossible due to failed access to target site (adhesions; n=2), close vicinity of a coronary artery (n=1) or the phrenic nerve (n=1). Procedure duration was 263±97 min. Unfortunately, 1 pt died due to perforation of RV and 1 pt had severe hepatic bleeding after epi puncture. One pt died in cardiogenic shock 1 d after the procedure. In 2 pts a sterile pericarditis occurred which resolved without any further intervention. After a median follow-up of 293 days (1–929 days) 53% of pts were alive and free from any VT. Conclusion: In pts with failed endo RFC ablation for VT due to different etiologies epi RFC ablation was acutely successful in 61% of pts with a moderate chronic success rate. However, major complications occured in approximately 5% of pts. Epi mapping should be considered if endo pathologic potentials are absent or if endo ablation failed.

Successful Radiofrequency Ablation Therapy for Intractable Ventricular Tachycardia With a Ventricular Assist Device

Refractory ventricular tachycardia (VT) can be a potentially life-threatening rhythm in the presence of non-ischemic dilated cardiomyopathy, particularly when it results in hemodynamic compromise. A 65-year-old man with non-ischemic cardiomyopathy was referred for multiple episodes of VT. A HeartMate left ventricular assist device (LVAD) was implanted to stabilize and control the VT. However, he had multiple episodes of VT and the frequency of ventricular arrhythmias did not improve after LVAD implantation. He required electrical cardioversion to treat each episode. On Day 41 post-operatively, radiofrequency ablation was performed. Two significant areas of scarring were identified and were successfully ablated. After ablation, he did not have significant sustained VT episodes and was discharged.

Regional myocardial function in an arrhythmogenic milieu: tissue velocity and strain rate imaging in a patient who had hypertrophic cardiomyopathy with recurrent ventricular tachycardia

We report the use of tissue velocity and strain rate imaging for detecting marked segmental variations and asynchrony in left ventricular systolic and diastolic functions of a 40-year-old patient with hypertrophic obstructive cardiomyopathy who died of an intractable ventricular tachycardia. These newer techniques have advantages for identifying heterogeneity in regional myocardial function in hypertrophic cardiomyopathy.

Intractable ventricular tachycardia and bridging to heart transplantation with a non-pulsatile flow assist device in a patient with isolated left-ventricular non-compaction

Intractable ventricular tachycardia was investigated in a 51-year-old man with isolated left ventricular non-compaction during implantation of an automated internal cardioverter-defibrillator. Favorable bridging to cardiac transplantation was achieved with the DeBakey left ventricular assist device (LVAD).

Does magnesium have a role in the treatment of patients with coronary artery disease?

Hypomagnesemia is common in hospitalized patients, especially in elderly patients with coronary artery disease (CAD) and/or those with chronic heart failure. Hypomagnesemia is associated with increased all cause mortality and mortality from CAD. Magnesium supplementation improves myocardial metabolism, inhibits calcium accumulation and myocardial cell death; it improves vascular tone, peripheral vascular resistance, afterload and cardiac output, reduces cardiac arrhythmias and improves lipid metabolism. Magnesium also reduces vulnerability to oxygen-derived free radicals, improves endothelial function and inhibits platelet function, including platelet aggregation and adhesion, which potentially confers upon magnesium physiologic and natural effects similar to adenosine-diphosphate inhibitors such as clopidogrel. However, data regarding the use of magnesium in patients with acute myocardial infarction (AMI) are conflicting. Although some previous relatively small randomized clinical trials demonstrated a remarkable reduction in mortality when intravenous magnesium was administered to relatively high risk AMI patients, two recently published large-scale randomized clinical trials (the Fourth International Study of Infarct Survival [ISIS 4] and Magnesium in Coronaries [MAGIC]) were unable to demonstrate any advantage of intravenous magnesium over placebo. Nevertheless, the theoretical benefits of magnesium supplementation as a cardio-protective agent in CAD patients, promising results from animal and human studies, its relatively low-cost and ease of handling requiring no special expertise, together with its excellent tolerability, gives magnesium a place in treating CAD patients, especially in those at high risk, such as CAD patients with heart failure, the elderly and hospitalized patients with hypomagnesemia. Furthermore, magnesium therapy is indicated in life-threatening ventricular arrhythmias such as torsades de pointes and intractable ventricular tachycardia.

An effective case of nifekalant hydrochloride for intractable ventricular tachycardia in coronary artery bypass graft

An effective case of nifekalant hydrochloride for intractable ventricular tachycardia in coronary artery bypass graft

Bridge to recovery with the abiomed BVS-5000 device in a patient with intractable ventricular tachycardia

J Thorac Cardiovasc Surg 1999;117:831-2

Fatal Hepatotoxicity Following Oral Administration of Amiodarone

To report a case of fatal hepatotoxicity associated with the chronic use of oral amiodarone. Long-term administration of amiodarone for the control of intractable ventricular tachycardia was associated with fatal hepatotoxicity in a patient receiving amiodarone for 14 months. Although most hepatic adverse effects associated with amiodarone are transient and reversible with time, deaths resulting from amiodarone-induced hepatotoxicity have been reported. The relation of hepatotoxicity to cumulative dose and duration of therapy is debated. The histopathologic features of amiodarone-induced hepatotoxicity include Mallory bodies, steatosis, intralobular inflammatory infiltrates, fibrosis, and phospholipidosis. Evidence pertaining to both mild and severe amiodarone toxicity indicates that cumulative dose may correlate with overall toxicity and, therefore, maintenance doses should be kept as low as possible. Patients should be followed with monitoring of liver function test results every 3-6 months.

Reply

We appreciate Dr. Kouchoukos pointing out to us his use of 32° to 35° C hypothermia. Considering the fact that surgical techniques were in the process of evolving at the time of these publications, the outcome of patients subjected to mild hypothermia was quite good, and we are surprised that this technique was not adapted as routine. However, neither of these groups used atriofemoral bypass or aortofemoral bypass and controlled body temperature at 30° C during the period of spinal cord visceral and renal ischemia. We have now performed 40 operations under controlled bypass and have encountered a single instance of intractable ventricular tachycardia. This patients was relatively healthy and only 56 years old and had development of ventricular tachycardia without any preceding signs when his temperature was 30.4° C. Cardioversion was unsuccessful, and full bypass was induced, passing a biomedicus venous cannula for venous return and using a femorofemoral circuit. Left ventricular distension was relieved by use of the rapid infuser backwards. After a total inefficient near arrest time of 35 minutes, normal sinus rhythm was established simultaneously when body temperature reached 36° C. Transesophageal echocardiography was carried out disclosing good equal LV contraction, enabling us to proceed with the correction of a thoracoabdominal aneurysm, going back to aortofemoral bypass, and 34° C hypothermia. The patient had an uneventful recovery. However, this frightening experience has tempered our enthusiasm for routine application of 30° C hypothermia, and we now target 32° C and have a low prime femorofemoral bypass circuit in the immediate vicinity should defibrillation occur. With regard to Dr. Kouchoukos' second question of intercostal implantation, we have continued to study every patient undergoing elective repair to determine the site of origin of the artery of Adamkeiwicz. We have now studied more than 60 patients without significant neurologic morbidity, but with two instances of atheroembolism, neither of which resulted in limb loss or organ failure. The artery of Adamkeiwicz varies not only with regard to location (T-8 to L-2), but in regard to size and importance. On three instances, very large contributions were visualized that perfused the anterior spinal artery in a cephalad, as well as a caudad fashion. In all other cases, perfusion has been caudad. When the artery of Adamkeiwicz has been identified, we always implant the appropriate intercostal artery and no other pairs. When we cannot identify the artery of Adamkeiwicz, which occurs in about 40% of the cases, the largest pair of intercostal arteries has always been implanted. With the techniques of sequential repair, renal perfusion is sustained by the pump during the period of intercostal attachment. Thus we believe there is everything to gain and virtually nothing to lose by attaching a specific one whenever possible and taking the best guess when this is not known. We agree with Dr. Kouchoukos that paraplegia is multifactorial in these patients. That being the case, we believe that all modalities designed to prevent or limit spinal cord ischemia should be harnessed. In our extended series, consisting of 29 patients with Crawford group II or DeBakey IIIB aneurysms, two have had development of late onset paraparesis. In each case, spinal fluid drainage, although attempted before the induction of general anesthesia, was unsuccessful. Both patients have had a good recovery and are walking. In essence, our own experience suggests that all adjunctive methods are helpful in the treatment of patients with extensive thoracoabdominal aneurysms.

Pathological Study of an Explanted Heart Due to Intractable Ventricular Fibrillation

Pathology of the Explanted Heart. A 35-year-old male had multiple admissions for polymorphic sustained ventricular tachycardia (VT) associated with cardiac arrest, uncontrolled by beta blockers and antiarrhythmic drugs including amiodarone. Electro-physiologic testing was negative and there was no evidence for conduction system abnormalities. Retrograde atrioventricular (AV) conduction was present. The left ventricular ejection fraction was 68% with normal left ventricular size. Multiple myocardial biopsies were reported normal except for one suggesting myocarditis. Atrial pacing (rates > 90) and high-dose isoproterenol (> 300 grams/min) helped suppress VT. A DDD pacer was implanted but VT still recurred. An internal cardioverter defibrillator was implanted with attempted selective ventricular sympathetic denervation. Six months later, he had a recurrent cardiac arrest that did not respond to internal defibrillator shocks. Multiple external shocks returned him to sinus rhythm. He underwent heart transplantation despite normal left ventricular function and no heart failure. Pathology of the explanted heart without the atria revealed a weight of 442 grams. Both* ventricles were hypertrophied and enlarged. Serial section examination of the conduction system revealed chronic myocarditis of the approaches to the AV node, the AV node, and beginning of the right bundle branch. The AV node was in part within the central fibrous body, and the AV bundle showed fibro-fatty change and was left sided. There was marked fibrosis of the left bundle branch, chronic epicarditis, arteriolosclerosis of the summit of the ventricular septum, and fibrosis on both sides of the heart. Conclusions: (1) The above findings suggest that myocarditis of a smoldering type and/or fibrosis of the ventricular septum probably caused the intractable VT and fibrillation; and (2) A new indication for cardiac transplantation may include intractable VT associated with cardiac arrest. (J Cardiovasc Electrophysiol. Vol. 3, pp. 437–441, October 1992)

Signal‐averaged electrocardiography: History, techniques, and clinical applications

Signal averaging principles have been utilized since around 1875. Their application in medicine to enhance biologic signals was first made in 1947 for improved detection of electroencephalographic signals. The year 1963 marked the first application of this technique to cardiac signals. The more prevalent use in adult cardiology is in the detection of ventricular late potentials (VLPs) which correspond to areas of delayed ventricular activation as slowed conduction velocity. These VLPs have value in predicting the likelihood of malignant ventricular arrhythmias after myocardial infarction (MI). Negative predictive values on the order of 96-99% are convincing as to their ability to predict no arrhythmic event post-MI. Positive predictive values, on the other hand, are poor (10-29%) but improve (35-62%) in combination with other parameters such as depressed left ventricular function and frequent ventricular ectopy. Additional accepted uses for the signal-averaged electrocardiogram (SAECG) include prediction of successful ablative surgery for intractable ventricular tachycardia and facilitating evaluation of patients presenting with syncope of an unclear etiology. Potential future applications of the SAECG are (1) in following patients for rejection after cardiac transplant, (2) as a screening tool for the need for electrophysiologic study, (3) as a predictor of vessel patency after thrombolysis or percutaneous transluminal coronary angiography, and (4) as a tool to assess proarrhythmia. As the technique of signal averaging continues to evolve, its applications may become more diverse and its clinical effectiveness may improve.

Clinical experience in patients with implantable cardioverter defibrillators.

Forty patients (36 men and 4 women) with life-threatening arrhythmia received an implantable cardioverter defibrillator (ICD). Mean age was 63 years (range, 46 to 80 years). All patients had structural heart disease, with coronary artery disease in 32 patients, idiopathic cardiomyopathy in 7 patients, and hypertensive heart disease in 1 patient. Mean left ventricular ejection fraction was 29 +/- 13%. The clinical arrhythmia was out-of-hospital cardiac arrest in 14 patients (35%), symptomatic sustained ventricular tachycardia in 21 patients (53%), and episodes of syncope without documented spontaneous ventricular arrhythmia but ventricular tachycardia that was easily provoked at the time of electrophysiologic testing in 5 patients (13%). Sustained ventricular tachycardia was induced in 37 patients (93%) at basic electrophysiologic testing. The average number of drug failures was 2.9 +/- 1.4 per patient. One patient (2.5%) died perioperatively because of intractable ventricular tachycardia and ventricular fibrillation. During a median follow-up period of 5.5 months (range 2-21 months) 2 sudden deaths occurred. No patient had a serious complication during the follow-up period. Ten patients (25%) received antiarrhythmic drugs to suppress spontaneous ventricular tachycardia. Appropriate shock treatment was received by 18 patients (45%), and inappropriate shock treatment was received by 2 patients (5%). Several issues regarding use of the ICD must be considered, but the device seems to be useful, and it is associated with an acceptable rate of complications and good long-term success at the present time.

Termination of Ventricular Tachycardia by an Implantable Atrial Pacemaker and External Pacemaker Activator

An atrial pacemaker was implanted in a patient who had dilated cardiomyopathy, sinus node dysfunction, and drug-resistant ventricular tachycardia (VT). VT episodes were terminated by atrial overdrive pacing using an implanted pacemaker and a newly developed hand-held external programmer/transmitter. Although successful cases of termination of intractable VT by ventricular pacing have recently been reported, the ventricular method might increase the risk of accelerating VT. Atrial overdrive pacing is a safer method since it minimizes the possibility of tachycardia acceleration and, combined with antiarrhythmic drugs, it appeared to be a unique and useful approach for the treatment of drug-resistant VT.

Endocardial mapping by simultaneous recording of endocardial electrograms during cardiac surgery for ventricular aneurysm

A technique was developed for the simultaneous recording of 30 endocardial electrograms during cardiac surgery in patients undergoing aneurysmectomy or endocardial resection, or both, for medically intractable ventricular tachycardia. An inflatable balloon covered with 30 terminals at distances of 1.5 to 2 cm was used to record from the entire endocardial surface; a smaller silicone rubber sheet with 30 terminals at distances of 0.7 cm was used to obtain a better spatial resolution. The multielectrodes were inserted into the left ventricular cavity by way of an incision in the aneurysm. A transportable minicomputer was used for the acquisition and analysis of the signals. After initiation of ventricular tachycardia by programmed stimulation, signals of a 1.5 second period were stored and analyzed. The earliest activated terminal could be determined within 2 to 5 minutes. The technique was applied in 32 patients and proved especially useful in those patients in whom sustained tachycardia could not be evoked and in whom conventional mapping with a roving electrode would have been impossible or very time consuming. In all patients, the isochronic maps showed that the ectopic impulses originated from a rather localized area and no evidence was found for large endocardial circus movements, thereby excluding these as a mechanism underlying the tachycardia. Isochronic maps, depicting activation sequences during consecutive ectopic beats with the same QRS morphologic features, showed the same site of origin in all but six patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between late potentials on the body surface and directly recorded fragmented electrograms in patients with ventricular tachycardia

The relation between low-amplitude, late potentials on the body surface and directly recorded electrograms in 8 patients with and 11 patients without ventricular tachycardia (VT) was studied. Bipolar X,Y,Z leads were signal-averaged and filtered with a digital technique. All patients had catheter endocardial left ventricular maps. The VT group had medically intractable VT and an endocardial excision was performed for control of VT. Before bypass, epicardial maps were obtained in the operating room. All studies were performed during normal sinus rhythm. Four patients without VT, each with a previous myocardial infarction, had fragmented endocardial electrograms recorded at 2.0 +/- 1.2 sites. The latest electrogram for each patient ended 87 +/- 8 ms after QRS onset, within the high-amplitude portion of the filtered QRS complex. All patients with VT had fragmented electrograms recorded at 6.1 +/- 3.1 sites/patient. Eighty-eight percent of the fragmented electrograms were endocardial. The latest fragmented electrogram for each patient ended 161 +/- 43 ms after QRS onset, significantly later than the fragmented electrograms from the patients without VT (p = 0.002). Six VT patients had low-amplitude, late potentials at the end of the filtered QRS complex. In these patients, the last 40 ms of the filtered QRS complex contained a higher proportion of fragmented electrograms compared with earlier segments of the QRS complex (68% versus 27%, p less than 0.001). Two patients with VT did not have late potentials. One patient with left bundle branch block had delayed left ventricular epicardial activation which masked the fragmented electrograms. The other had fragmented electrograms of brief duration which ended 80 +/- 12 ms after QRS onset, during the time of normal ventricular activation. It is concluded that the late potential corresponds to delayed, fragmented electrographic activity. Failure to record a late potential may arise from delayed ventricular activation at other sites from bundle branch block or fragmented electrograms of a brief duration.

Amiodarone therapy in symptomatic, sustained refractory atrial and ventricular tachyarrhythmias

Amiodarone was utilized in 70 patients with symptomatic, sustained refractory tachyarrhythmias. Of these, 29 had atrial arrhythmia (20 recurrent atrial fibrillation and nine sustained supraventricular tachycardia). Control was achieved in eight with supraventricular tachycardia and in 16 with atrial fibrillation. Recurrence has been prevented in these 24 patients (83%) during an average follow-up of 13.4 months. An additional 41 patients had recurrent ventricular tachycardia. In 19 with symptoms consisting of dizziness or lightheadedness without syncope or clinically apparent hemodynamic compromise, treatment was limited to amiodarone. Of these, 14 responded (74%) and have been free of arrhythmia during an average follow-up of 13 months. In 22 who experienced either syncope or life-threatening hemodynamic impairment, amiodarone was added to those agents which had only partially suppressed advanced grades of ventricular premature beats. Fourteen of these patients (64%) have remained free of recurrent ventricular arrhythmia during an average follow-up of 12 months. After drug loading, maintenance therapy consisted of a daily dose ranging from 200 to 600 mg. Only mild side effects have been encountered in the 17 patients (23%) with any untoward responses. This experience confirms that oral amiodarone is an effective and safely applied agent against recurrent refractory atrial tachyarrhythmia and sustained intractable ventricular tachycardia with moderate symptoms. While also efficacious in refractory sustained life-threatening ventricular tachyarrhythmia, usage of the agent is often difficult in this condition owing in part to insufficient information concerning amiodarone pharmacokinetics.

Resection of ventricular aneurysm modified by electrophysiologic assessment in patients with intractable ventricular tachycardia and left ventricular aneurysm

Resection of ventricular aneurysm modified by electrophysiologic assessment in patients with intractable ventricular tachycardia and left ventricular aneurysm

Surgical Treatment of Ventricular Arrhythmias Using Epicardial, Transmural, and Endocardial Mapping

In 3 patients with ischemic coronary disease or primary myocardiopathy who were unresponsive to conventional and experimental antiarrhythmia therapy, surgical treatment of intractable ventricular tachycardia was performed using epicardial, transmural, and endocardial mapping techniques. An experimental canine model of acute and chronic myocardial ischemia with recurrent ventricular tachycardia was developed to refine the mapping technique for clinical use. In patients and animals alike, atrial overdrive pause pacing, premature ventricular pacing, or both were used to bring out a repeatable pattern of tachycardia. Mapping techniques distinguished the irritable focus so that surgical excision of the site of earliest activation could be performed. In addition, the mapping techniques were used in the validation following excision. The limitations of epicardial mapping alone in locating all areas of premature focus are discussed, and the need for mapping in ventricular aneurysm is demonstrated.

Late development of intractable ventricular tachycardia after acute myocardial infarction

Four cases are reported in which medically refractory and ultimately fatal ventricular tachycardia developed relatively late during hospital convalescence from acute myocardial infarction. All 4 had tachycardia refractory to combinations of antiarrhythmic agents, and they required almost continuous ventricular defibrillation. Mechanical circulatory assistance (Avco intra-aortic balloon pumping) proved ineffective in controlling the recurrent arrhythmias. Emergency cardiac catheterization performed in 3 patients and postmortem examination in the fourth patient demonstrated the following: (1) complete occlusion of the left anterior descending coronary artery near its origin and diffuse circumflex obstruction; (2) extensive myocardial infarction involving two thirds of the anterior wall; and (3) ventricular ejection fractions of less than 25 per cent. Emergency surgery also proved ineffective in 2 patients. These findings suggest that recurrent ventricular tachycardia developing late in the course of recovery from an acute myocardial infarction is an ominous prognostic sign in patients such as these. Mechanical circulatory assistance in combination with various antiarrhythmic agents appears to be of little benefit in controlling this type of ventricular arrhythmia.

Surgery for ventricular tachycardia unresponsive to medical treatment.

Surgery is indicated in patients with ventricular tachycardia refractory to medical management, provided, a correctable cardiac lesion is present Published data, as well as our own experience, would indicate that surgery in myocardial disease associated with tachyarrhythmia may terminate the disturbances of rhythm with no further need for medication. Direct myocardial revascularization with preinfarction angina, or revascularization early in the course of myocardial infarction, or resection of an older lesion may be the procedure of choice for secondary ventricular tachycardia unresponsive to conservative measures. The operative findings and procedures, and the immediate and late postoperative results in 11 patients operated on for intractable ventricular tachycardia are given. Surgery was performed with the hope that improved cardiac function would terminate dysrhythmia and improve the function of the myocardium.