Ventricular pacing redundancy to prevent loss of capture: a fail-safe for pacemaker-dependent patients.

BACKGROUND: Patients who are entirely dependent on ventricular pacing are typically at the mercy of a single ventricular lead and pacemaker output in order to provide physiologic support. This study presents a number of high-risk cases (two of which previously exhibited failure with standard pacing) in which ventricular pacing redundancy (VPR) was utilized in order to provide additional backup. VPR was achieved using a variety of configurations, all of which employed a second ventricular lead and the potential for additional ventricular pacing. Seven cases are presented in which some form of VPR was successfully implemented in order to prevent device failure and resultant hemodynamic collapse.

Usefulness of live/real time three-dimensional transthoracic echocardiography in evaluation of prosthetic valve function.

We studied 31 patients with prosthetic valves (PVs) using two-dimensional and three-dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides an incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE both leaflets of the St. Jude mechanical PV can be visualized simultaneously, thereby increasing the diagnostic confidence in excluding valvular abnormalities and overcoming the well-known limitations of 2DTTE in the examination of PVs, which heavily relies on Doppler. Three-dimensional transthorathic echocardiography provides a more comprehensive evaluation of PV regurgitation than 2DTTE with its ability to more precisely quantify PV regurgitation, in determining the mechanism causing regurgitation, and in localizing the regurgitant defect. Furthermore, 3DTTE is superior in identifying, quantifying, and localizing PV thrombi and vegetations, in addition to the unique feature of providing a look inside mass lesions by serial sectioning. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of PVs and that it provides incremental knowledge to the echocardiographer.

Comparative assessment of left atrial appendage by transesophageal and combined two- and three-dimensional transthoracic echocardiography.

OBJECTIVE: Our objective was to compare the utility of combined two-dimensional (2D) transthoracic echocardiography (TTE) and three-dimensional (3D) TTE versus 2D transesophageal echocardiography (TEE) in evaluation of the left atrium (LA) and LA appendage (LAA) for clot. BACKGROUND: 2DTEE, usually performed to visualize the LAA, is semi-invasive and not without risks. With improved technology the LAA has been increasingly visualized by 2DTTE and 3DTTE in many patients. METHODS: We compared combined 2DTTE and 3DTTE with 2DTEE in evaluating the LA/LAA for a thrombus. Ninety-two patients underwent 2DTTE, 3DTTE, and 2DTEE. An additional 20 patients, in whom TEE could not be performed, underwent 2DTTE and 3DTTE. RESULTS: LA and LAA could be visualized in all patients. Of 92 patients studied, 74 had no thrombus and 7 had thrombus in the LAA by all modalities. Eleven patients, 9 with atrial fibrillation (AF), had a suspected thrombus by 2DTEE, but 3DTTE cropping clearly showed these to be prominent pectinate muscles which were seen in short axis on 2DTEE as rounded echo dense masses and therefore mimicked thrombi. These 9 patients with AF underwent successful cardioversion without any complications. Of the 20 patients in whom TEE could not be performed, 19 had no thrombus in the LA/LAA and 1 had a clot in the LAA. These 19 patients underwent successful cardioversion without complications. CONCLUSIONS: Our preliminary study suggests that combined 2DTTE and 3DTTE has comparable accuracy to TEE in evaluating the LA and LAA for thrombus. In some patients TEE, but not 3DTTE, may misdiagnose pectinate musculature as thrombus.

Two- and three-dimensional transthoracic echocardiographic assessment of hiatal hernia.

Using two- (2DTTE) and three-dimensional transthoracic echocardiography (3DTTE) and an oral contrast agent (a carbonated beverage), a mass-like lesion behind the left ventricular posterior wall in an elderly female was definitively diagnosed as a hiatal hernia. A 3DTTE provided a more comprehensive evaluation of the hiatal hernia as compared to the 2DTTE in terms of its size and extent and thickness of the wall. The size of the hernia was underestimated by 2DTTE (3.3 x 3.2 cm) as compared to 3DTTE (at least 7 x 4.8 cm). The maximum thickness of the gastric wall was also found to be larger by 3DTTE (11 mm) as compared to 2DTTE (5 mm). Both the size of the hernia and thickness of the wall have important clinical implications. The size has been reported to be the strongest predictor of severity of esophagitis and gastric wall thickness of 10 mm or more has been associated with malignant or potentially malignant gastric lesions.

Amorphous calcific tumor of the mitral annulus echocardiographically mimicking a vegetation.

We describe echocardiographic findings in an elderly patient with histologically proven amorphous tumor involving the posterior mitral annulus, mimicking a vegetation.

Initial experience with live/real time three-dimensional transesophageal echocardiography.

A new tool has been recently introduced to the echocardiography armamentarium, live/real time three-dimensional (3D) transesophageal echocardiography (TEE). In these cases, we describe our initial experience in 13 patients studied intraoperatively and in the echocardiography suite. This important technology promises improved anatomic definition, diagnostic confidence, and novel views of the complicated cardiovascular pathology encountered in common clinical practice.

The utility of implantable loop recorders for diagnosing unexplained syncope in 100 consecutive patients: five-year, single-center experience.

INTRODUCTION: The purpose of this study was to retrospectively review the 5-year experience of a university hospital with implantable loop recorders (ILR) for the diagnosis of recurrent, unexplained syncope or presyncope. METHODS: One hundred patients with syncope or presyncope of unknown etiology (negative tilt-table test, electrophysiology study and neurologic workup) underwent prolonged monitoring with an ILR from March 2000 to December 2004. All implants were performed using a first-generation (manual activation) or second-generation (manual plus automatic activation) ILR. RESULTS: One hundred patients (70 women, 30 men) with a mean age of 68 +/- 18 years received the ILR. Twenty-three patients had coronary artery disease; 2 patients had dilated cardiomyopathy. Ten patients received a first-generation ILR, and 90 patients received a second-generation ILR. After 9 +/- 8 months' follow up, ILR interrogation identified an arrhythmogenic etiology to the syncope/presyncope in 45 patients with 55 events. Eight patients had a diagnosis by ILR less than 2 months from the date of implantation. Twenty-six patients had documented symptomatic bradycardia (asystole, sinus pauses, atrial fibrillation with long pauses); 11 patients had episodes of sinus tachycardia with heart rates of 130 to 140 beats/minute; 2 patients had atrial tachycardia; 5 patients had multiple episodes of nonsustained ventricular tachycardia (NSVT); 1 patient had sustained ventricular tachycardia, and 4 patients had paroxysmal supraventricular tachycardia. All arrhythmias were treated successfully by pacemaker/ICD implantation, radiofrequency catheter ablation and/or medications. One patient had seizure activity, which was detected by ILR as high-frequency noise. Two patients failed to activate their device, as it was a first-generation device. CONCLUSION: Five-year experience with the ILR in 100 consecutive patients confirms the utility of this device in the diagnosis of recurrent, infrequent, unexplained syncope or presyncope. It helped diagnose 45% of patients with unexplained syncope with negative electrophysiologic and neurologic workup. Most of these patients had an arrhythmogenic etiology to their syncope. Medical therapy, device therapy, and/or catheter ablation helped successfully treat all patients with an arrhythmogenic etiology detected by ILR.