Kuan-Hung Yeh

Effects of altered volume loading on left ventricular hemodynamics and diastolic filling during hemodialysis.

Background. Changes in the circulating volume associated with hemodialysis (HD) resulted in alternations of left ventricular (LV) filling. However, previous studies offered conflicting findings. This study thus evaluated the impact of HD on LV diastolic filling indices and hemodynamics. Materials and Methods. Forty patients with end‐stage renal disease were studied by Doppler echocardiography immediately before and after HD. The cardiac size, volume and mass were determined by M‐mode and two‐dimensional echocardiography. LV diastolic filling parameters and hemodynamics were assessed from mitral inflow using Doppler echocardiography. Results. Left atrial and LV dimension, LV volume, and LV mass decreased significantly after HD (p < 0.001). Cardiac output declined from 5.74 ± 1.37 to 4.98 ± 1.27 L/min (p < 0.001), whereas, the ejection fraction remained unchanged. HD elicited marked changes in the early diastolic E (95.1 ± 20.5 to 70.3 ± 18.2 cm/s, p < 0.001) and late atrial filling A velocities (104.3 ± 20.9 to 88.9 ± 16.9 cm/s, p < 0.001). In addition, correction of the deceleration time of E and isovolumic relaxation time prolonged significantly (p = 0.011 and p < 0.001, respectively). Conclusions. Findings in this study indicate that HD altering the loading condition significantly influenced the LV diastolic function and hemodynamics. Moreover, Doppler echocardiography provides an effective means of assessing the effects on LV diastolic filling and hemodynamics during HD.

Successful lysis of right and left heart thrombus by tissue plasminogen activator.

Tissue plasminogen activator (t‐PA) was administered to three patients with newly developed intracardiac thrombi. Cases 1 and 2 developed right heart thrombi after radiofrequency ablation for atrioventricular nodal reentrant tachycardia and case 3 had tachycardia‐related cardiomyopathy and a left ventricular thrombus. In all three patients, the intracardiac thrombi were successfully eliminated following t‐PA therapy without major bleeding complications. These observations suggest that t‐PA is effective in lysing new thrombus complicating radiofrequency ablation or heart failure and may be the therapy of choice in these conditions. Cathet. Cardiovasc. Intervent. 49:91–96, 2000.

Radiofrequency catheter ablation therapy of swallowing-induced atrioventricular nodal reentrant tachycardia: report of two cases.

We describe two patients who presented with a history of recurrent palpitations on swallowing of solid food. The event‐recorder and Holter monitoring documented episodic supraventricular tachycardia (SVT) initiated by atrial premature contractions (APCs). During electrophysiological study (EPS), swallowing of solid food consistently induced APCs and their activation sequence, morphology of P wave were suggestive of their right atrial origin in them. Drug challenge did not affect the APC onset during the swallowing. During EPS, slow‐fast variety of atrioventricular nodal reentrant tachycardia (AVNRT) was induced and successful radiofrequency (RF) catheter ablation of slow pathway resulted in total relief of their symptoms.

Long‐Term Performance of Transvenous, Steroid‐Eluting, High Impedance, Passive‐Fixation Ventricular Pacing Leads

The long‐term performance of two high impedance, steroid‐eluting, passive‐fixation ventricular leads, porous platinum iridium electrode CPI Selute Picotip 4035 (131 patients), and platinized platinum electrode Medtronic Capsure Z 5034 (57 patients), was compared with one conventional 8.0‐mm2 porous platinum iridium electrode CPI Selute 4285 (38 patients). The mean follow‐up period was 28 ± 14 months. Capture threshold, R wave amplitude, and pacing impedance were measured at the time of implantation, immediately after implantation, 1 week, 1, 3, and 6 months after implantation and then every 6 months thereafter. The two high impedance leads revealed a higher sensing slew rate than the conventional lead, the R wave amplitude was similar among the three groups, but the voltage threshold at 0.5‐ms pulse width was significantly higher in porous platinum iridium groups at the time of implantation. During follow‐up, the conventional lead revealed a significantly higher R wave amplitude within the first 3 months, however, this pattern disappeared after 3 months. Pacing impedance was significantly higher in the high impedance porous platinum iridium electrode groups. Voltage threshold at 0.5‐ms pulse width was similar among the three groups in the first 3 months, however, it increased gradually and was significantly higher in porous platinum iridium electrode groups subsequently. The energy threshold at 0.5 ms was significantly lower in the two high impedance groups than the conventional group, but no difference was found in the two high impedance groups. Lead related complications were similar among the three groups. In conclusion, high impendence electrodes with different design and materials had different properties; platinized platinum electrode showed a lower pacing impedance but had a more stable long‐term capture threshold as compared to the porous platinum iridium electrode. Further studies are mandatory for the development of an ideal pacing lead.