Optimal programming of the atrioventricular delay using the phonocardiogram.

PURPOSE: To predict the optimal atrioventricular (AV) delay using the phonocardiogram (PCG). METHODS: We studied 12 recipients of cardiac resynchronization therapy (CRT) system and eight recipients of dual-chamber pacemakers implanted for AV block with normal left ventricular (LV) function. The amplitude of the first heart sound (S1) was recorded by PCG and the LV outflow tract (OT) time-velocity integral (TVI) was measured by pulsed Doppler echocardiography. The AV delay was prolonged in 20-ms increments, from 60 ms to 240 ms. Ishikawa's method was used for the echocardiographic optimization of the AV delay. The relation between S1 amplitude and the AV delay was analyzed. RESULTS: The correlation between the amplitude of S1 and the length of AV delay showed an S-shaped curve. The AV delay at the inflection point of each patient's S-shaped curve (161.2 +/- 19.5 ms) was positively correlated with the optimal AV delay determined by echocardiography (148.3 +/- 16.9 ms, r = 0.83, P < 0.001). In addition, there was a positive correlation between the AV delay at the maximal TVI of LVOT (150.8 +/- 22.7 ms) and the AV delay at the inflection point of the S-shaped curve (159.5 +/- 24.9 ms, r = 0.87, P < 0.001). In two CRT system recipients, an optimal AV delay could not be found by echocardiography; however, an optimal AV delay could be determined by PCG. CONCLUSIONS: A high correlation was observed between the optimal AV delay determined by phonocardiography versus echocardiography.

Novel method of predicting the optimal atrioventricular delay in patients with complete AV block, normal left ventricular function and an implanted DDD pacemaker.

BACKGROUND: The optimal atrioventricular (AV) delay setting is important for achieving optimal AV synchrony in patients with an implanted DDD pacemaker. Using pulsed Doppler echocardiography is the most common method of predicting the optimal AV delay, but it is a complicated and time-consuming method. Therefore, an automatic optimizing function of the AV delay at different atrial rates is desirable for achieving a favorable hemodynamic state. This study aimed to predict the optimal AV delay using phonocardiography. METHODS AND RESULTS: The amplitude of the first heart sound (S1) recorded on the phonocardiogram was measured with different AV delays in 6 patents with complete AV block, normal left ventricular function and an implanted DDD pacemaker. The correlation between the amplitude of S1 and the length of the AV delay was a cubic curve (y=974.15x(3)-23.084x(2)-8.0074x+0.7495, R2=0.9511). The length of the AV delay at the inflection point of the curve showed a significant positive correlation with the optimal AV delay determined by pulsed Doppler echocardiography (R=0.9254, P<0.01). CONCLUSIONS: This study demonstrated a novel simple method of predicting the optimal AV delay using phono-cardiography.

Efficacy of consistent atrial pacing algorithm for suppression of atrial arrhythmias in patients with sick sinus syndrome and atrial fibrillation.

Atrial overdrive provides the best opportunity to suppress atrial arrhythmias. Atrial preference pacing (APP) algorithm has been designed to achieve a high percentage of atrial pacing. The aim of this study was to assess the efficacy of APP algorithm in patients with implanted pacemakers and tachycardia-bradycardia syndrome. The subjects were 17 patients (mean age, 71.7+/-9.0 years old, 4 males) implanted with a DDDR pacemaker Thera DR (Medtronic, Minneapolis, MN, USA). All patients had sick sinus syndrome and paroxysmal atrial fibrillation before pacemaker implantation. Informed consent was obtained from each participant before enrollment. DDDR and mode switch or APP were randomly programmed. After two weeks, the pacing mode was switched to another mode. The percentage of atrial pacing was significantly higher in APP than in DDDR (97.7+/-1.4 versus 52.3+/-30.8, P<0.0001). Atrial premature beat counts were significantly greater in DDDR than in APP (30689+/-42534 versus 7717+/-10700, P<0.005). There was no significant difference in mode switch episode counts between DDIR and APP (2.6+/-5.5 versus 8.4+/-19.2, NS). Although there was no significant difference in mode switch episode counts between DDDR and APP, APP algorithm can successfully prevent atrial premature beats in patients with tachycardia-bradycardia syndrome.

Diagnostic use of T2-weighted inversion-recovery magnetic resonance imaging in acute coronary syndromes compared with 99mTc-Pyrophosphate, 123I-BMIPP and 201TlCl single photon emission computed tomography.

BACKGROUND: The incidence of missed diagnoses of acute cardiac ischemia in the emergency department could be reduced by a new imaging modality. In the present study, the clinical significance of (99m)Tc-pyrophosphate (PYP), (123)I-beta-methyl-p-iodephenyl-pentadecanoic acid (BMIPP), (201)TlCl scintigraphy (imaging) and T2-weighted inversion-recovery magnetic resonance imaging (MRI) for the detection of culprit lesion in patients with acute coronary syndromes (ACS) was compared. METHODS AND RESULTS: The study group comprised 18 patients with ACS: 12 patients with acute myocardial infarction (AMI) (11 males; mean age, 63+/-11 years) and 6 patients with unstable angina (UA) (3 males, mean age, 67+/-5 years). Of the 12 patients with AMI, 10 underwent (201)TlCl and PYP single photon emission computed tomography (SPECT) studies as a dual-energy acquisition ((201)TlCl/PYP) and 8 underwent (201)TlCl SPECT within 1 week of the BMIPP study. All 18 patients underwent BMIPP SPECT and MRI. The MRI pulse sequence was black blood turbo short-inversion-time inversion recovery (STIR) (breath-hold T2-weighted studies). The T2-weighted inversion-recovery MRI showed higher sensitivity and negative predictive value than PYP and (201)TlCl, and higher specificity and positive predictive value than BMIPP and (201)TlCl. The area under the receiver-operating characteristic curve for PYP, BMIPP, (201)TlCl and MRI was 0.787, 0.725, 0.731 and 0.878, respectively. The difference between the areas of MRI and BMIPP was significant (p<0.05). CONCLUSION: Accurate detection of culprit lesion is improved by using MRI rather than BMIPP, particularly for patients with ACS.

Double-counting of intracardiac electrogram during biatrial pacing.

BACKGROUND: Biatrial pacing has a significant problem with memory function that misinterprets normal sinus rhythm as atrial tachyarrhythmias and in addition estimation of the atrial pacing thresholds (biatrial and uniatrial pacing thresholds) is sometimes difficult because of small P waves. METHODS AND RESULTS: The intracardiac electrograms recorded by a pacemaker in 10 patients (age, 66.7+/-10.7 (SD) years) with implanted biatrial pacemakers were analyzed. Atrial sensing within the atrial refractory period after atrial pacing was counted in 6 of the 10 patients (timing of the double counting was 143+/-64 ms) when pacing failed in the left or right atrium. Atrial sensing within the atrial refractory period after atrial pacing disappeared when biatrial pacing was successfully performed. Atrial double-counts depend on interatrial conduction delay. The memory function of implanted pacemaker devices misinterpreted normal sinus rhythm as atrial tachyarrhythmias because of atrial double-counts. On the other hand, the biatrial pacing threshold was easily recognized using this phenomenon. CONCLUSIONS: The memory function of pacemaker devices is unreliable because of atrial double-counting during sinus rhythm in patients with biatrial pacing. However, the biatrial pacing threshold is easily checked using this phenomenon.

Effect of biventricular pacing on myocardial glucose metabolism in patients with heart failure using fluoro-18-deoxyglucose positron emission tomography.

Biventricular pacing has recently been found beneficial in the treatment of congestive heart failure (CHF). Meanwhile, positron emission tomography (PET) has emerged as a new method to analyze glucose metabolism in the heart. Five patients (mean age 68.8 +/- 8.1 years, 4 men) who received biventricular pacing therapy for 5.8 +/- 6.6 weeks for CHF were studied. Myocardial glucose metabolism was evaluated by PET with fluoro-18-deoxyglucose (18F-FDG), and percent uptake (%uptake) of 18F-FDG was calculated during biventricular pacing and compared with that during 1 hour of conventional RV pacing. Biventricular pacing was associated with a significant decrease in NYHA functional Class from 3.67 +/- 0.52 to 2.50 +/- 0.55. After 18F-FDG PET, three of five patients remained clinically stable, and two died during follow-up. Mean 18F-FDG %uptake during biventricular pacing was not different than during short-term RV pacing (62.1 +/- 18.4 vs. 63.6 +/- 17.0%). However, patients who remained clinically stable had a lower value of 18F-FDG %uptake in the septal region than patients who died (46.9 +/- 5.6 vs 80.3 +/- 1.3%, P < 0.01). One patient whose cardiac function improved significantly also had a small septal region of decreased 18F-FDG uptake during RV pacing. In conclusion, biventricular pacing therapy was effective in this small group of patients with severe, drug-resistant CHF. An evaluation of the effects of biventricular pacing on glucose metabolism in the subacute phase may help identify patients with a favorable long-term response to this therapy.

[Biventricular pacing using two pacemakers and triggered VVT mode in patients with atrial fibrillation and congestive heart failure: a case report].

A 76-year-old female had undergone implantation of a single chamber pacemaker for sick sinus syndrome 20 years previously. She developed chronic atrial fibrillation and required repeated admission due to congestive heart failure. She had significant mitral and tricuspid regurgitation. Paradoxical movement of the intraventricular septum was severe. Due to right ventricular apical pacing, significant interventricular conduction delay was present with a paced QRS duration of 189 msec. The left ventricular pacing lead was positioned via the coronary sinus. The mode of the previously implanted pacemaker was set at VVT. Biventricular pacing could be achieved even in intrinsic beats by VVT mode. The battery life time was improved. This method is useful in patients with conventional pacemakers.

[Efficacy of biventricular pacing on myocardial glucose metabolism in a patient with heart failure using 2-deoxy-2[18F]fluoro-d-glucose positron emission tomography: a case report].

A 61-year-old-male with dilated cardiomyopathy and congestive heart failure was treated by implantation of a biventricular pacemaker. Myocardial glucose metabolism was evaluated by positron emission tomography with 2-deoxy-2[18F]fluoro-d-glucose (FDG) during atrial-right ventricular pacing or atrial-biventricular pacing. Percentage uptake of FDG decreased in the lower septal area of the left ventricle during right ventricular pacing, but the decrease was improved during biventricular pacing (74.7% vs 91.6%). Biventricular pacing may improve myocardial glucose metabolism in patients with congestive heart failure.

Anti-tachycardia therapy can improve altered cardiac adrenergic function in tachycardia-induced cardiomyopathy.

We investigated whether anti-tachycardia therapy might improve the altered cardiac adrenergic and systolic function in tachycardia-induced cardiomyopathy (TC) in contrast to dilated cardiomyopathy (DCM). The subjects were 23 patients with heart failure, consisting of 8 patients with TC (43.6 +/- 10.0 yrs) and 15 with DCM (45.3 +/- 8.2 yrs). TC was determined as impairment of left ventricular function secondary to chronic or very frequent arrhythmia during more than 10% of the day. All patients were receiving anti-tachycardia treatment. Cardiac 123I-MIBG uptake was assessed as the heart/mediastinum activity ratio (H/M) before and after treatment. LVEF was also assessed. In the baseline study, H/M and LVEF showed no difference between TC and DCM (2.21 +/- 0.44 vs. 2.10 +/- 0.42, 35.3 +/- 13.1 vs. 36.0 +/- 10.9%, respectively). After treatment, the degree of change in H/M and LVEF differed significantly (0.41 +/- 0.34 vs. 0.08 +/- 0.20, 20.5 +/- 14.4 vs. -2.1 +/- 9.6%, p < 0.01). In TC, heart failure improved after a shorter duration of treatment (p < 0.05). In conclusion, anti-tachycardia therapy can improve altered cardiac adrenergic function and systolic function in patients with TC over a shorter period than in those with DCM.