Three-lead System Research Articles

The emerging role of cardiac contractility modulation in heart failure treatment.

Heart failure often progresses despite optimal medical and device therapies, and advanced mechanical circulatory support has limited availability and substantial associated morbidity. Cardiac contractility modulation (CCM) provides nonexcitatory stimulation to ventricular myocardium which increases cardiac contractility without increasing oxygen demand. This review describes the emerging role of CCM in heart failure treatment. The FIX-HF-5C2 study demonstrated similar safety and efficacy profile of the two-lead Optimizer device in comparison with the prior three-lead system, thereby decreasing procedural complexity and minimizing endocardial hardware. The FIX-HF-5C trial underscored the benefit of CCM in patients with mild-moderate left ventricular dysfunction (ejection fraction, 25-45%) with New York Heart Association (NYHA) Class III symptoms. The summarized randomized trial data show consistent improvements in peak VO2, 6-min walk distance, and NYHA functional class with CCM. Future trials are planned to determine the role of CCM in heart failure patients with preserved ejection fraction, obligate ventricular pacing, and atrial arrhythmias. Nonexcitatory extracellular electric potentials can facilitate inotropic improvements in the failing heart. The mechanism of CCM does not increase myocardial oxygen consumption and has been shown to mitigate heart failure symptoms, decrease hospitalizations, and work in synergy with guideline-directed therapy for heart failure.

Rates and Risk-Factors of Post Implantation Infection in Cardiac Implantable Electronic Devices

Background/Hypothesis: 
 Cardiac implantable electronic devices (CIED) include permanent pacemakers (PPM), implantable cardioverter defibrillators (ICD), and cardiac resynchronization therapy (CRT). Both ICDs and dual chamber PPMs are two-lead systems; whereas, CRT is a three-lead system. Indications for CIEDs include arrythmia, risk of sudden cardiac death and AV block. From 1993 to 2003, over 4 million CIEDs were implanted. With the upward trend in the rate of CIED implantations, the post-operative infection burden has increased concurrently. Device related infections are a serious complication of CIED implants. They are associated with a significant increase in the rate of mortality as well as a significant increase in financial burden. We hypothesize two-lead systems will have significantly lower rate of infection than three-lead devices 
 Methods: 
 This study will be a retrospective review of patient charts who are hospitalized in the Parkview Health medical system in Fort Wayne, Indiana over a three-year period. All patients who have received a CIED during that time frame will be included in the study. Patients will be categorized by specific implant type and recorded as developing post-operation infection or not. Demographic and health status data will also be collected and analyzed for correlation with the development of device related infection. 
 Results: 
 Our results will compare the device related infection rate for two-lead versus three lead systems, as well as the infection rate for each type of CIED. We also expect to find results which support a correlation between specific patient demographics and patient health factors. 
 
 Conclusion and Impact: 
 The results of this study will serve as a guide for identifying high risk procedures and patients. The objective is to provide providers with guidelines for the use of post-operative prophylaxis in order to reduce the incidence of CIED-related infection.

Myocardial Ischemia Diagnosis Using a Reduced Lead System.

This research presents a novel statistical model for diagnosing acute myocardial infarction (AMI). The model is based on features extracted from a reduced lead system consisting of a subset of three leads from the standard 12-lead ECG. We selected a set of relevant parameters commonly used in the clinical practice for ECG-based AMI diagnosis, namely ST elevation and T-wave maximum. We also selectedfeatures, not used in clinical practice, that were derived from vectorcardiography and computed on the reduced three-lead system (pseudo-VCG parameters). To validate the model, we used 104 patients coming from the Physionet STAFF III database which contains 12-lead ECG recordings at baseline and in coronary artery occlusion condition during angioplasty (PTCA). Results show that pseudo-VCG features are able to diagnose AMI slightly better than ST elevation and T-wave maximum features together (area under the ROC curve (AUC) 0.87 vs AUC 0.85). When combining pseudo-VCG features together with ST elevation, and T-wave maximum, the performance improved significantly (AUC 0.95, sensitivity 89.6% and specificity 82.7%). Results indicate a potential for diagnosing AMI using the proposed reduced lead system and the selected set of features. We suggest its possible use for diagnosing AMI in long-term, ambulatory and home monitoring situations, allowing an earlier and faster diagnosis.

EARLY CHANGES IN ELECTRICAL PROPERTIES OF ISCHEMIC HEART WITH AND WITHOUT ECE INHIBITION: THREE-DIMENSIONAL ELECTROCARDIOGRAPHY STUDY: PP.13.488

Little is known about the significance of ECE inhibition for modulation of electrical heart activity. The study aim was to assess three-dimensional electrocardiogram (ECG) changes during development of acute heart ischemia (AHI) due to global coronary arteries microembolization using 15 um microsphere with and without ECE inhibition. ECE inhibitor PP36 was used in current study. Two days before coronary embolization, male Wistar rats were randomized for treatment with PP36 (3.5 × 10–5 M/kg, AHI + PP36 group, n = 29) or with a vehicle (AHI group, n = 31 and sham control group, n = 15). Application of PP36 continued for two days post-embolization in AHI + PP36 group. Under anesthesia (sodium pentobarbital, 40 mg/kg), ECG were recorded with an orthogonal three-lead system before and after coronary vessels microembolization, and two days after global AHI induction. Data were analyzed with dedicated computer software. Invasively measured maximal left ventricular systolic pressure (LVSP) developed in response to aorta occlusion was similar between PP36 treated (261 + 5 mmHg) and untreated (261 + 4 mmHg) rats. Measured before induction of global heart ischemia magnitude of Q-wave and area under STT segment of controls and PP36 treated for two days rats were similar. ECG parameters of controls did not significantly change over time. However PP36 significantly reduced QRS-T angle after two days application. Immediately after induction of heart ischemia, LVSP was decreased by 26–27% and STT area was increased three-fold in AHI and AHI + PP36 groups. Differences between AHI and AHI + PP36 groups were reflected by depolarization changes in QRS-vector magnitude and repolarization changes in QRS- and T-axis orientation. In conclusion, three-dimensional ECG analysis appears to be very sensitive to early changes in ECE activity modulation. Induction of AHI with PP36 application is characterized by early ECG changes preceding left ventricular contractility changes compared to AHI group.

Epidural anaesthesia for caesarian section in a parturient with a single ventricle

Epidural anaesthesia for caesarian section in a parturient with a single ventricle

Early changes in rat hearts with developing pulmonary arterial hypertension can be detected with three-dimensional electrocardiography

The study aim was to assess three-dimensional electrocardiogram (ECG) changes during development of pulmonary arterial hypertension (PAH). PAH was induced in male Wistar rats (n = 23) using monocrotaline (MCT; 40 mg/kg sc). Untreated healthy rats served as controls (n = 5). ECGs were recorded with an orthogonal three-lead system on days 0, 14, and 25 and analyzed with dedicated computer software. In addition, left ventricular (LV)-to-right ventricular (RV) fractional shortening ratio was determined using echocardiography. Invasively measured RV systolic pressure was 49 (SD 10) mmHg on day 14 and 64 (SD 10) mmHg on day 25 vs. 25 (SD 2) mmHg in controls (both P < 0.001). Baseline ECGs of controls and MCT rats were similar, and ECGs of controls did not change over time. In MCT rats, ECG changes were already present on day 14 but more explicit on day 25: increased RV electromotive forces decreased mean QRS-vector magnitude and changed QRS-axis orientation. Important changes in action potential duration distribution and repolarization sequence were reflected by a decreased spatial ventricular gradient magnitude and increased QRS-T spatial angle. On day 25, LV-to-RV fractional shortening ratio was increased, and RV hypertrophy was found, but not on day 14. In conclusion, developing PAH is characterized by early ECG changes preceding RV hypertrophy, whereas severe PAH is marked by profound ECG changes associated with anatomical and functional changes in the RV. Three-dimensional ECG analysis appears to be very sensitive to early changes in RV afterload.

The pacer-cardioverter-defibrillator: function and clinical experience.

Pacer-Cardioverter-Defibrillator. This article reviews the function of the pacer-cardioverter-defibrillator (PCD). Detection of ventricular arrhythmias occurs in two programmable zones, with onset and stability modifiers available to diminish overdetection of sinus tachycardia and atrial fibrillation, respectively. The sensing circuitry utilizes an auto-adjusting sensitivity with exponential decay to allow detection of low-amplitude ventricular fibrillation electrograms without T wave oversensing. Treatment can be accomplished by tiered therapy with two types of antitachycardia pacing, cardioversion and defibrillation. Cardioversion and defibrillation shocks are programmable between single pathway when two leads are used and simultaneous or sequential shock delivery when a three-lead system is used. A telemetered marker channel and electrogram aid in assessing device function during implantation and follow-up. Previously published literature is cited to expand on various aspects of PCD function and programming.

Decision rules in electrocardiography and vectorcardiography.

The diagnostic classification of the ECG waveform can be performed either by visual inspection of the electrocardiogram or by a set of mathematical-statistical decision rules programmed into a computer. It can be demonstrated that if the visual inspection technique is used, the 12-lead ECG will be superior to three scalar orthogonal vectorcardiographic leads. Plane projection vector loops lack accurate data display. If computer techniques are used, suitable decision regions of the instantaneous heart vector will provide accurate decision rules on a three-lead system. Neither the 12-lead system nor the three-orthogonal lead system makes use of all the information available on the body surface. A detailed electrical torso mapping would be required if this information proves to be of diagnostic significance. Misclassification in electrocardiographic diagnosis may be due to (1) failure of electrical events to reflect hemodynamic, anatomic, or biochemical changes; (2) loss of information between the cardiac generator and the body surface; (3) inadequate data display; (4) inadequate mathematical-statistical decision regions; and (5) insufficient number of teaching samples or inadequate independent evidence.