Identification of the Right Ventricular Pacing Site for Cardiac Resynchronization Therapy (CRT) Guided by Electroanatomical Mapping (CARTO)

Multimodality Imaging for Selecting Candidates for CRT: Do We Have a Single Alley to Increase Responders?

Cardiac resynchronization therapy has evolved in recent years to provide a reduction of morbidity and mortality for many patients with heart failure. Its application and optimization is an evolving field and its use requires a multidisciplinary approach for patient and device selection, technical preprocedural planning, and optimization. While echocardiography has always been considered the first line for the evaluation of patients, additional imaging techniques have gained increasing evidence in recent years. Today different details about heart anatomy, function, dissynchrony can be investigated by magnetic resonance, cardiac computed tomography, nuclear imaging, and more, with the aim of obtaining clues to reach a maximal response from the electrical therapy. The purpose of this review is to provide a practical analysis of the single and combined use of different imaging techniques in the preoperative and perioperative phases of cardiac resynchronization therapy, underlining their main advantages, limitations, and information provided.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy

Cardiac resynchronization therapy (CRT) is an established therapy for heart failure patients who remain symptomatic despite optimal medical therapy, have reduced left ventricular ejection fraction (<35%) and wide QRS duration (>120 ms), preferably with left bundle branch block morphology. The response to CRT depends on the cardiac substrate: presence of correctable left ventricular mechanical dyssynchrony, presence of myocardial fibrosis (scar) and position of the left ventricular pacing lead. Patients with non-ischemic cardiomyopathy have shown higher response rates to CRT compared with patients with ischemic cardiomyopathy. Differences in myocardial substrate may partly explain this disparity. Multimodality imaging plays an important role to assess the cardiac substrate and the pathophysiological determinants of response to CRT.

Survival analysis in patients with preserved left ventricular function and standard indications for permanent cardiac pacing randomized to right ventricular apical or septal outflow tract pacing

BACKGROUND

Optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. A prospective randomized trial was done to compare long-term effect of permanent RV apex (RVA) vs RV outflow tract (RVOT) pacing on the all-cause and cardiovascular mortality.

METHODS AND RESULTS

A total of 122 consecutive patients (70 men, 69 +/-11 years), with standard pacing indications were randomized to RVA (66 patients) or RVOT (56 patients) ventricular lead placement. After the 10-year follow-up period the mortality data were summarized on the basis of an intention-to-treat analysis. During the long-term follow-up, 31 patients from the RVA group died vs 24 patients in the RVOT group (hazard ratio (HR), 0.96; 95% confidence interval (CI), 0.57-1.65; P=0.89). There were 10 cardiovascular deaths in the RVA and 12 in the RVOT group (HR, 1.04; 95%CI, 0.45-2.41; P=0.93). There were no differences in the all-cause or cardiovascular mortality between the pacing sites after adjustment for age, gender, arterial hypertension, atrial fibrillation, New York Heart Association class and left ventricular end-diastolic diameter.

CONCLUSIONS

The RVOT provides no additional benefit in terms of long-term survival over RVA pacing.

Relationship of maximum rate of pressure rise between aorta and left ventricle in pediatric patients. Implication for ventricular-vascular interaction with the potential for noninvasive determination of left ventricular contractility

BACKGROUND

The maximum rate of the ventricular pressure rise (dp/dt(max)) provides a reliable measure of ventricular contractility. However, its estimation requires invasive measurement of left ventricular (LV) pressure, limiting its bedside clinical applicability. In the present study, 2 hypotheses were tested: (1)that the ratio of dp/dt(max) between the aorta (Ao) and LV is consistent among patients despite marked differences in underlying cardiac disease, contractile state and heart rate when vascular mechanical and loading properties are taken into account, and (2)that using such a relationship, LV dp/dt(max) can be estimated from Ao dp/dt(max), potentially providing a method of noninvasive determination of LV contractility.

METHODS AND RESULTS

Data from 30 control children and 45 pediatric patients with various cardiovascular diseases revealed that the characteristic impedance (Zc) and mean arterial pressure were significant determinants of the Ao-LV dp/dt(max) relationship in both control and disease groups. LV dp/dt(max) estimated using the regression obtained in the control children (Ao dp/dt(max/)LV dp/dt(max) = 0.64+1.45*10(-4)*Zc-3.73*10(-3)*MAP, r=0.87) correlated well with the measured LV dp/dt(max) in the disease group, including measurements taken after dobutamine and atrial pacing (r=0.89).

CONCLUSIONS

Ao dp/dt(max) and LV dp/dt(max) are closely correlated through the vascular loading properties and LV dp/dt(max) can be derived from Ao dp/dt(max), which has potential as a noninvasive method of determining LV contractility.

The work-up and management of patients with apparent or subclinical cardiac sarcoidosis: with emphasis on the associated heart rhythm abnormalities

In patients with newly diagnosed AV block and/or ventricular tachycardia, cardiac sarcoidosis should always be considered in the differential diagnosis. In addition to the pacemaker implant, cardiac resynchronization therapy (CRT) should be selected for severe heart failure patients who have class III or IV heart failure, LVEF <or=35%, and a complete LBBB pattern. If the disease activity is high, corticosteroid therapy is recommended. Patients with extracardiac sarcoidosis need to be closely followed for potential cardiac involvement, as the mortality in sarcoidosis depends on cardiac involvement. Early diagnosis and treatment of cardiac sarcoidosis is essential. Positron emission tomography (PET) and cardiac magnetic resonance imaging (MRI) are considered to have high sensitivity for cardiac involvement, and are the preferred imaging modalities. However, even in the era of new technology, such as PET and cardiac MRI, early diagnosis of cardiac sarcoidosis is still difficult.