Clinical observations and outcome of ventricular tachycardia ablation in patients with left ventricular assist devices.

BACKGROUND: Ablation of ventricular tachycardia (VT) in patients with left ventricular assist devices (LVAD) is challenging and not well documented. This report describes our experience with endocardial VT ablation in six patients with an LVAD. METHODS: We retrospectively reviewed the clinical records of LVAD patients who underwent an ablation procedure for refractory VT. RESULTS: A total of eight ablation procedures were performed in six patients who, during the last 2 weeks before the ablation procedure, received a total of 101 appropriate shocks for VT. A closed aortic valve (n = 2) or aortic atheroma (n = 1) required a transseptal catheterization in three of six patients. The apical LVAD cannula served as a VT substrate in two of six patients. VT was eliminated in four patients and markedly reduced in two others. The latter two patients experienced a total of only four implantable cardioverter defibrillator (ICD) shocks during a follow-up of 130 and 493 days. Intravenous antiarrhythmic medications used in five of six patients before ablation were discontinued in all. The ablation procedures permitted hospital discharge in four of six patients. Five patients died during follow-up (228 ± 207 days after the procedure). The cause of death was unrelated to cardiac arrhythmias. One patient is still alive 1,205 days after the procedure. CONCLUSION: Ablation of VT in LVAD patients is feasible and can result in a markedly decreased VT burden with a reduction of ICD shocks. The subsequent discontinuation of intravenous antiarrhythmic medications may facilitate hospital discharge.

Site-specific differences in latency intervals during biventricular pacing: impact on paced QRS morphology and echo-optimized V-V interval.

OBJECTIVE: To investigate differences in latency intervals during right ventricular (RV) pacing and left ventricular (LV) pacing from the (postero-)lateral cardiac vein in cardiac resynchronization therapy (CRT) patients and their relationship to echo-optimized interventricular (V-V) intervals and paced QRS morphology. METHODS: We recorded digital 12-lead electrocardiograms in 40 CRT patients during RV, LV, and biventricular pacing at three output settings. Stimulus-to-earliest QRS deflection (latency) intervals were measured in all leads. Echocardiographic atrioventricular (AV) and V-V optimization was performed using aortic velocity time integrals. RESULTS: Latency intervals were longer during LV (34 ± 17, 29 ± 15, 28 ± 15 ms) versus RV apical pacing (17 ± 8, 15 ± 8, 13 ± 7 ms) for threshold, threshold ×3, and maximal output, respectively (P < 0.001), and shortened with increased stimulus strength (P < 0.05). The echo-optimized V-V interval was 58 ± 31 ms in five of 40 (12%) patients with LV latency ≥ 40 ms compared to 29 ± 20 ms in 35 patients with LV latency < 40 ms (P < 0.01). During simultaneous biventricular pacing, four of five (80%) patients with LV latency ≥ 40 ms exhibited a left bundle branch block (LBBB) pattern in lead V(1) compared to three of 35 (9%) patients with LV latency < 40 ms (P < 0.01). After optimization, all five patients with LV latency ≥ 40 ms registered a dominant R wave in lead V(1) . CONCLUSIONS: LV pacing from the lateral cardiac vein is associated with longer latency intervals than endocardial RV pacing. LV latency causes delayed LV activation and requires V-V interval adjustment to improve hemodynamic response to CRT. Patients with LV latency ≥ 40 ms most often display an LBBB pattern in lead V(1) during simultaneous biventricular pacing, but a right bundle branch block after V-V interval optimization.

Ablation of left ventricular tachycardia via transeptal approach and crossing of a mechanical mitral valve prosthesis.

This report describes the clinical course of a patient with left ventricular assist device (LVAD) and refractory ventricular tachycardia (VT) who underwent successful left ventricular (LV) mapping and ablation complicated by the presence of a bioprosthetic aortic and a mechanical mitral valve. LV catheterization was achieved by crossing the mechanical valve. The patient remained hemodynamically stable during the procedure most likely as a result of LVAD support. There were no complications. A recurrence of monomorphic VT 2 months later required a second VT ablation procedure using the same transseptal-transmitral approach. The patient has since been free of implantable cardioverter defibrillator shocks for 2 months since the second procedure.

Esophageal contour changes during cryoablation of atrial fibrillation.

BACKGROUND: We have observed contour changes of the barium-filled esophagus during atrial fibrillation (AF) ablation with cryo-energy delivered in direct proximity to the esophagus. OBJECTIVE: To evaluate the frequency, location, and severity of esophageal contour changes during cryo-energy application close to the esophagus. METHODS: We retrospectively analyzed cine-fluoroscopic images acquired during hybrid cryo-radiofrequency AF ablation in 100 consecutive patients with cryo-energy delivered only in direct proximity to the esophagus. RESULTS: Esophageal contour changes were observed in 28 (32%) of 89 patients (and 74 [6.2%] of 1,191 of all cryo applications). They were more frequent in the left common pulmonary vein (PV) (50%) and less so in the right common PV and the upper PVs (4-5%). The distance of the ablation catheter from the endoesophageal contour prior to cryo-energy applications associated with contour changes was 1.8 +/- 1.5 mm, which increased to 4.1 +/- 1.6 mm at the time of peak contour change (P < 0.001). The esophageal contour deformation was 2.3 +/- 0.9 mm. There were no apparent complications related to cryo-energy application for 3-4 minutes, even if associated with contour changes. CONCLUSION: Esophageal contour changes were observed in >6% of cryo applications in direct proximity to the esophagus (32% of patients) and were most frequent in the posterior aspect of the left common and right lower PV ostium when cryo-energy was delivered at a distance of

Echocardiographic optimization of the atrioventricular and interventricular intervals during cardiac resynchronization.

An optimized atrioventricular (AV) interval can maximize the benefits of cardiac resynchronization therapy (CRT). If programmed poorly, it may curtail beneficial effects of CRT. AV optimization will not convert non-responder to responder, but may convert under-responder to improved status. There are many echocardiographic techniques for AV optimization but there is no universally accepted gold standard. The optimal AV delay varies with time, necessitating periodic re-evaluation. As the optimal AV delay may lengthen on exercise, a rate-adaptive AV delay should not be routinely programmed. Intra- and interatrial conduction delays may require AV junctional ablation when AV optimization is impossible in patients with a poor clinical response. Fusion with the spontaneous QRS complex may be acceptable on a trial basis to seek a better clinical response or with a short PR interval. Routine VV optimization is presently controversial but programming may prove beneficial in some patients with a suboptimal CRT response where no cause is found. It may partially compensate for less than optimal left ventricular (LV) lead position and may correct for heterogeneous ventricular activation including a prolonged LV latency interval and slow conduction (scarring) near the LV pacing site. VV timing is generally programmed using the aortic velocity-time integral, and long-term variations of the optimal value necessitate periodic re-evaluation.

AV junctional ablation allowing more effective delivery of cardiac resynchronization therapy in patients with intra- and interatrial conduction delay.

We report two patients with cardiac resynchronization therapy (CRT) devices and evidence of refractory heart failure in whom impaired intraatrial conduction in one patient, and interatrial conduction in the other, prohibited optimization of the atrioventricular (AV) timing sequence. The patient with intraatrial conduction delay exhibited late right atrial sensing and latency during right atrial pacing that required programming of a short-sensed AV delay and long-paced AV delay (wide differential AV delay). In both patients AV junctional ablation and echocardiography-guided device optimization significantly improved heart failure.

Cardiac resynchronization therapy in patients with end-stage inotrope-dependent class IV heart failure.

Although cardiac resynchronization therapy (CRT) is beneficial in patients with drug-refractory New York Heart Association (NYHA) class III/IV heart failure (HF) and left ventricular (LV) dyssynchrony, CRT efficacy is not well established in patients with more advanced HF on inotropic support. Ten patients (age 55 +/- 13 years) with inotrope-dependent class IV HF (nonischemic [n = 6] and ischemic [n = 4]) received a CRT implantable cardioverter-defibrillator device. QRS duration was 153 +/- 25 ms (left branch bundle block [n = 7], intraventricular conduction delay [n = 2], and QRS <120 ms [n = 1]). The indication for CRT was based on either electrocardiographic criteria (n = 9) or echocardiographic evidence of LV dyssynchrony (n = 1). Intravenous inotropic therapy consisted of dobutamine (n = 6; 4.3 +/- 1.9 microg/kg/min) or milrinone (n = 4; 0.54 +/- 0.19 microg/kg/min) as inpatient (n = 3) or outpatient (n = 7) therapy for 146 +/- 258 days before CRT. One patient required ventilatory support before and during device implantation. All patients were alive at follow-up 1,088 +/- 284 days after CRT. Three patients underwent successful orthotopic cardiac transplantation after 56, 257, and 910 days of CRT. HF improved in 9 patients to NYHA classes II (n = 5) and III (n = 4). Intravenous inotropic therapy was discontinued in 9 of 10 patients after 15 +/- 14 days of CRT. LV volumes decreased (end-diastolic from 226 +/- 78 to 212 +/- 83 ml; p = 0.08; end-systolic from 174 +/- 65 to 150 +/- 78 ml; p <0.01). LV ejection fraction increased (23.5 +/- 4.3% to 32.0 +/- 9.1%; p <0.05). No implantable cardioverter-defibrillator shocks were recorded, and antitachycardia therapy for ventricular tachyarrhythmias was delivered in 1 patient. In conclusion, patients with end-stage inotrope-dependent NYHA class IV HF and LV dyssynchrony may respond favorably to CRT with long-term clinical benefit and improved LV function.

Mechanical esophageal deflection during ablation of atrial fibrillation.

To prevent esophageal damage during ablation of atrial fibrillation, we developed a technique to move the esophagus away from a desired ablation site too close to the esophagus. Under fluoroscopy, a transesophageal echocardiography probe was used to deflect the barium-opacified esophagus from the ablation site. This technique was successfully employed in three patients where critical sites of the posterior left atrial wall were very close to the esophagus.

Latency during left ventricular pacing from the lateral cardiac veins: a cause of ineffectual biventricular pacing.

We report three patients with cardiomyopathy and pronounced stimulus to QRS latency during left ventricular (LV) pacing from an epicardial cardiac vein. Delayed LV activation during simultaneous biventricular pacing produced an electrocardiographic pattern dominated by right ventricular stimulation. Hemodynamic parameters improved immediately after advancing LV stimulation (in one patient) or pacing the LV only (in two patients) coupled with dramatic improvement of heart failure symptoms.

First-degree atrioventricular block. Clinical manifestations, indications for pacing, pacemaker management & consequences during cardiac resynchronization.

Marked first-degree AV block (PR> or =0.30 s) can produce a clinical condition similar to that of the pacemaker syndrome. Clinical evaluation often requires a treadmill stress test because patients are more likely to become symptomatic with mild or moderate exercise when the PR interval cannot adapt appropriately. Uncontrolled studies have shown that many such symptomatic patients with normal left ventricular (LV) function improve with conventional dual chamber pacing (Class IIa indication). In contrast, marked first-degree AV block with LV systolic dysfunction and heart failure is still a Class IIb indication, a recommendation that is now questionable because a conventional DDD(R) pacemaker would be committed to right ventricular pacing (and its attendant risks) virtually 100% of the time. It would seem prudent at this juncture to consider a biventricular DDD device in this situation. Patients with suboptimally programmed pacemakers may develop functional atrial undersensing because the P wave tends to migrate easily into the postventricular atrial refractory period (PVARP). Retrograde vetriculoatrial conduction block is uncommon in marked first-degree AV block so a relatively short PVARP can often be used at rest with little risk of endless loop tachycardia. The usefulness of a short PVARP may be negated by special PVARP functions in some pulse generators designed to time out a long PVARP at rest and a gradually shorter one with activity. First-degree AV block during cardiac resynchronization therapy (CRT) predisposes to loss of ventricular resynchronization during biventricular pacing because it favors the initiation of electrical "desynchronization" especially in association with a relatively fast atrial rate and a relatively slow programmed upper rate. Patients with first-degree AV block have a poorer outcome with CRT than patients with a normal PR interval, a response that may involve several mechanisms. (1) The long PR interval may be a marker of more advanced heart disease. (2) Patients with first-degree AV block may experience more episodes of undetected "electrical desynchronization". (3) "Concealed resynchronization" whereupon ventricular activation in patients with a normal PR interval may result from fusion of electrical wavefronts coming from the right bundle branch and the impulse from the LV electrode. The resultant hemodynamic response may be superior because the detrimental effects of right ventricular stimulation (required in the setting of a longer PR interval) are avoided.

Treatment of sustained left atrial tachycardia by ostial pulmonary vein isolation.

This report describes two patients with sustained regular left atrial tachycardias originating from multiple pulmonary veins in the absence of clinical evidence of atrial fibrillation. The tachycardias were eliminated by activation map-guided pulmonary vein isolation. Stable sustained regular pulmonary vein tachycardias unassociated with atrial fibrillation are uncommon, and they belong to the spectrum of pulmonary vein arrhythmias that include the more common paroxysmal and unstable tachycardias engendering atrial fibrillation.

Functional anatomy of the normal mitral apparatus: a transthoracic, two-dimensional echocardiographic study.

BACKGROUND AND AIM OF THE STUDY: Normal mitral valve function relies on integrity of the leaflets, annulus, subvalvular apparatus, and the left ventricle. Echocardiography has contributed significantly to the understanding of normal and abnormal mitral valve function. Thus, plausible pathophysiologic mechanisms have been proposed for various etiologies of mitral regurgitation, based on echocardiographic measurement of a limited number of parameters. This study provides quantitative echocardiographic assessment of various components of the mitral valve-left ventricular (LV) complex. METHODS: Mitral annulus, leaflets, papillary muscles and basal LV posterior wall length were measured at end-systole and end-diastole in 10 adults (7 females, 3 males; mean age 61 +/- 15 years) with structurally and functionally normal hearts. In addition, LV size and function and left atrial and aortic root sizes were measured. RESULTS: Mitral valve competence in these normal hearts was achieved by systolic reduction in LV volume, diameter and length of 66%, 31% and 18%, respectively. The LV posterior wall (from mitral annulus to origin of the posteromedial papillary muscle) was shortened by 32%. The mitral annulus likewise showed a reduction in diameter of 6% in anteroposterior and 13% in mediolateral planes. Anterior mitral valve leaflet apposed with posterior leaflet by 23% in length in systole, whereas the papillary muscle shortened by 34%. The interpapillary muscle distance decreased by 51% in systole. CONCLUSION: These data provide echocardiographic reference values for various components of the mitral valve-LV complex in normal adults. Further studies are needed to identify the relative significance of each of these components in the pathogenesis of mitral regurgitation of various etiologies.

Cardiovascular imaging in clinical and experimental acute infectious myocarditis.

Acute myocarditis can be caused by a variety of organisms. Congestive heart failure and death may occur as a consequence of these infections. In recent years cardiac imaging, by echocardiography and magnetic resonance and nuclear imaging has become a useful adjunct in the diagnosis and management of infectious myocarditis. Specific examples of their usefulness will be given in the discussions of chagasic myocarditis, bacterial myocarditis, acquired immunodeficiency syndrome and peripartum cardiomyopathy. Finally, we explore the exciting area of cardiac imaging of small animals, such as mice infected with Trypanosoma cruzi.

Cross-sectional multiplane transesophageal echocardiographic measurements: comparison with standard transthoracic values obtained in the same setting.

BACKGROUND: Several algorithms developed for cost-effective use of transesophageal echocardiography (TEE) propose elimination of "screening" transthoracic echocardiographic (TTE) studies. Cross-sectional measurements obtained by TTE (left atrial diameter [LAD], left ventricular internal dimensions in diastole and systole [LVIDd, LVIDs], septal and posterior wall thickness in diastole [VSTd, PWTd], LV end-diastolic and end-systolic volumes [LVEDV and LVESV], and LV ejection fraction [LVEF]) have not been standardized for TEE. METHODS: Forty-six patients (age 27 to 85 years, 60 +/- 13 years, 25 [54%] women) underwent TEE and TTE studies. TTE was performed while the TEE probe was in place and the patient was still sedated. Standard TTE measurements were compared with corresponding TEE values obtained from mid-esophageal and transgastric views. RESULTS: Standard TTE measurements compared favorably with those obtained by TEE at the mid-esophageal three-chamber view for LAD (3.9 +/- 0.6 cm vs 4.0 +/- 0.7 cm, P = NS) and at the transgastric long-axis view for LVIDd (4.6 +/- 0.8 cm vs 4.7 +/- 0.8 cm, P = NS), LVIDs (3.1 +/- 0.9 cm vs 3.1 +/- 0.9 cm, P = NS), and VSTd (0.95 +/- 0.18 cm vs 0.98 +/- 0.19 cm, P = NS). Biplane TTE and TEE measurements of LVEDV (106 +/- 35 ml vs 112 +/- 38 ml, P = NS), LVESV (37 +/- 23 ml vs 37 +/- 25 ml, P = NS), and LVEF (67 +/- 14% vs 69 +/- 14%, P = NS) also correlated closely. The negative predictive values of TEE measurements for excluding abnormal LAD, LVIDd, VSTd, PWTd, and LVEF as defined by TTE were 83%, 94%, 95%, 97%, and 97%, respectively. CONCLUSION: Cross-sectional TEE measurements as obtained in this study are equivalent to standard TTE dimensions and provide reliable information that may facilitate interpretation of TEE studies in the absence of TTE information.

Associations of insulin levels with left ventricular structure and function in American Indians: the strong heart study.

We evaluated the association of insulin and echocardiographic left ventricular (LV) measurements in 1,388 (45% men) nondiabetic American Indian participants in the Strong Heart Study (SHS). Significant (all P < 0.05) relations were found in men and women between log(10) fasting insulin and LV mass (r = 0.24 and 0.26), left atrial diameter (r = 0.25 and 0.28), posterior wall thickness (r = 0.20 and 0.26), septal thickness (r = 0.19 and 0.24), LV diameter (r = 0.17 and 0.16), and cardiac output (r = 0.20 and 0.24) and in women relative wall thickness (r = 0.11) and peripheral resistance (r = -0.17). In regression analyses, adjusting for BMI, age, height, and systolic pressure, fasting insulin was independently correlated with cardiac output in men and relative wall thickness and septal thickness in women (all P < 0.05). The 97th percentiles of fasting insulin (25 microU/ml for men, and 23 microU/ml for women) in 163 apparently normal (BMI <26; blood pressure <140/90; and absence of diabetes, valvular disease, LV wall motion abnormality, or antihypertensive treatment) SHS participants were used to separate normal from elevated fasting insulin levels. Adjusting for age, BMI, and height, men with elevated insulin levels had larger LV diameters (5.41 vs. 5.16 cm; P = 0.05), higher cardiac output (5.5 vs. 4.9 l/min; P < 0.001), and lower peripheral resistance (1,487 vs. 1,666; P = 0.01), paralleling results of regression analyses. Positive relations between insulin and heart size in nondiabetic adults are largely due to associations with body size; after adjustments for covariates, fasting insulin levels are related to greater LV size and cardiac output in men and more concentric LV geometry in women.