Optimizing the hemodynamic performance of the DDD pacemaker: impact of the atrioventricular delay on the pulmonary venous flow pattern

Spectral Doppler of the Hepatic Veins in Rate, Rhythm, and Conduction Disorders

Doppler interrogation of blood flow in the hepatic veins (HVs) provides valuable information regarding a wide spectrum of pathological processes that affect the right heart. Systematic analysis of the direction, velocity, and phasicity of the HV waveforms allows one to distinguish normal from abnormal patterns and provides important diagnostic information. Abnormalities in heart rate, rhythm, and intracardiac conduction are commonly encountered during echocardiographic studies. Sinus bradycardia and tachycardia, bradyarrhythmias and tachyarrhythmias as well as atrioventricular conduction disturbances influence the flow pattern in the HVs and may pose a challenge to the correct interpretation of the HV Doppler. Alterations in HV flow that are induced by the electrical abnormalities may mimic right heart pathology. Awareness of these alterations allows one to avoid misinterpretation of the HV signal, helps diagnose the underlying rhythm or conduction abnormality, and permits assessment of the impact on right heart hemodynamics.

Atrioventricular block and problems with atrioventricular conduction

This chapter has summarized briefly the current state of our knowledge on the incidence, etiology, presentation, investigation, and management of patients with AV block. The scope of the material covered has been widened intentionally to include a plethora of AV-conduction abnormalities because of the increases in the understanding of their clinical importance and contribution to left ventricular dysfunction. Under this heading, the critical importance of heart rate, maintenance of AV synchrony, and the sequence of ventricular activation and relaxation have been introduced and summarized briefly. The authors make a strong plea that, in the future, the reader consider AV-conduction abnormalities to be the parent topic, with the more-traditional, narrower subject of AV block forming a subunit thereof.