Successful percutaneous cardiac resynchronization despite an occlusive Thebesian valve.

We report the case of a patient with symptomatic heart failure referred after an unsuccessful attempt at cardiac resynchronization therapy. An occlusive Thebesian valve prevented entry into the coronary sinus ostium. Careful analysis of the patient's cardiovascular physiology and anatomy revealed the "fortuitous" presence of a persistent left superior vena cava. Cannulation of this vessel permitted percutaneous retrograde placement of a left ventricular lead into a posterolateral cardiac venous branch resulting in successful cardiac resynchronization. This unique case provides strong evidence that thorough knowledge of cardiac embryology, anatomy, and physiology plays a pivotal role in percutaneous electromechanical intervention for drug-refractory heart failure.

Magnesium sensitive, adenosine resistant, repetitive monomorphic ventricular tachycardia.

Repetitive monomorphic ventricular tachycardia (RMVT) is characterized by episodes of ventricular ectopy and nonsustained VT exacerbated by catecholamines. Because this arrhythmia is frequently adenosine sensitive, its mechanism is believed to be cyclic adenosine monophosphate-mediated triggered activity due to delayed afterdepolarizations. We present a case of RMVT associated with significant hypomagnesemia (serum level = 1.1 mg/dL), which did not respond to intravenous (IV) adenosine and terminated repeatedly after IV magnesium. Electrophysiologic study demonstrated an origin from the left sinus of Valsalva, which was successfully ablated. The combination of adenosine resistance and magnesium sensitivity may be consistent with an atypical RMVT mechanism related to inhibition of sodium-potassium adenosine triphosphatase (Na(+)-K(+) ATPase).

Isthmus dependent atrial flutter cycle length correlates with right atrial cross-sectional area.

BACKGROUND: Right atrial flutter cycle length can prolong in the presence of antiarrhythmic drug therapy. We hypothesized that the cycle length of right atrial isthmus dependent flutter would correlate with right atrial cross-sectional area measurements. METHODS: 60 patients who underwent ablation for electrophysiologically proven isthmus dependent right atrial flutter, who were not on Class I or Class III antiarrhythmic drugs and had recent 2-dimensional echocardiographic data comprised the study group. Right atrial length and width were measured in the apical four chamber view. Cross-sectional area was estimated by multiplying the length and width. 35 patients had an atrial flutter rate >/= 250 bpm (Normal Flutter Group) and 25 patients had an atrial flutter rate < 250 bpm (Slow Flutter Group). RESULTS: Mean atrial flutter rate was 283 bpm in the normal flutter group and 227 bpm in the slow flutter group. Mean atrial flutter cycle length was 213 ms in the Normal Flutter Group and 265 ms in the Slow Flutter Group (p< 0.0001). Mean right atrial cross sectional area was 1845 mm(2) in the Normal Flutter group and 2378 mm(2) in the Slow Flutter Group, (p< 0.0001). Using linear regression, CSA was a significant predictor of cycle length (beta =0.014 p = 0.0045). For every 1 mm(2) increase in cross-sectional area, cycle length is 0.014 ms longer. CONCLUSIONS: In the absence of antiarrhythmic medications, right atrial cross sectional area enlargement correlates with atrial flutter cycle length. These findings provide further evidence that historical rate-related definitions of typical isthmus dependent right atrial are not mechanistically valid.

Rescue permanent iliac vein pacing after epicardial lead failure: an unusual reversal of pacing fortune.

Surgical lead placement is generally considered as a last resort for patients who require permanent pacing and who are unable to accommodate transvenous leads. The technique is limited by the need for direct epicardial access and reduced reliability of epicardial leads (compared with modern transvenous leads) [Belott and Reynolds. Permanent pacemaker and implantable cardioverter defibrillator implantation. In Ellenbogen KA, Kay GN, Lau CP, Wilkoff BL (eds). Clinical Cardiac Pacing, Defibrillation, and Resynchronization Therapy. Philadelphia: Saunders Elsevier, 2007; pp. 561-651]. We report a patient with limited venous access and a poorly functioning epicardial ventricular lead, who was successfully upgraded to a dual-chamber endocardial pacing system via the iliac vein. Pacemaker lead implantation from the iliac vein is an often overlooked option for patients with limited central venous access. In our patient, a pacing upgrade was achieved after the presumptive final option had been exhausted.